Environment terminology · MLC-0121

Environment terms: H (1,010)

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High Test HypochloriteCalcium hypochlorite or Ca(OCl)2
High Throughput ApproachMethod involving the rapid processing of large amounts of data.
High Throughput ToxicologyResearch area focused on addressing the limitations of current chemical testing methods and fulfilling EPA’s...
High Throughput Transfer Rack1. Transfer racks that transfer greater than or equal to a total of 11.8 million liters per year (3.12...
High Tide Line1. Line of intersection of the land with the water's surface at the maximum height reached by a rising tide...
High Traffic RoadMay include highways, local roads experiencing heavy congestion, local roads with significant stop and go...
High traffic roadsMay include highways, local roads experiencing heavy congestion, local roads with significant stop and go...
High Velocity Air FilterAir pollution control filtration device for the removal of sticky, oily, or liquid aerosol particulate matter...
High Viscosity Poly(ethylene Terephthalate)Poly(ethylene terephthalate) that has an intrinsic viscosity of 0.9 or higher and is used in such...
High Volume Low Concentration Collection SystemGas collection and transport system used to convey gases from the HVLC system to a control device.
High Volume Low Pressure Spray Equipment1. Spray equipment that is used to apply coating by means of a spray gun that operates at 10.0 psig of...
High Volume Sampling TechnologyAn example of a high volume water sampling technology is the Infiltrex 300 high volume sampler which has been...
high water markA demarcation between the publicly owned land along the water and privately owned land which has legal...
High Wind Dust EventEvent that includes the high-speed wind and the dust that the wind entrains and transports to a monitoring...
High-Air PhaseStage of the batch operating cycle when the primary chamber reaches and maintains maximum operating...
High-Bleed Pneumatic DeviceAutomated, continuous bleed flow control devices powered by pressurized natural gas and used for maintaining...
High-Build Specialty CoatingCoating that contains 960 grams per liter (8 pounds per gallon) or more elemental zinc incorporated into an...
High-Carbon FerrochromeAlloy as defined by ASTM Designation A101-73 or 93 (incorporated by reference - see § 60.17) grades HC1...
High-Concentration Polychlorinated BiphenylsPCBs that contain 500 ppm or greater PCBs, or those materials which EPA requires to be assumed to contain 500...
High-Contact Industrial SurfaceSurface in an industrial setting which is repeatedly touched, often for relatively long periods of time...
High-Cost Warranted PartComponent covered by the emission-related warranty with a replacement cost (at the time of certification)...
High-end exposureAn estimate of individual exposure or dose for those persons at the upper end of an exposure or dose...
high-end exposure estimateA plausible estimate of individual exposure or dose for those persons at the upper end of an exposure or dose...
High-End RiskA risk descriptor representing the high-end, or upper tail of the risk distribution, usually considered to be...
High-end Risk DescriptorA plausible estimate of the individual risk for those persons at the upper end of the risk distribution...
Higher EducationHigher Education refers to education beyond the secondary level; specifically, education provided by a...
Higher heating valueQuantity of heat liberated by the complete combustion of a unit volume or weight of a fuel assuming that the...
Higher Volume Port AreaInclude(1) Boston, MA;(2) New York, NY;(3) Delaware Bay and River to Philadelphia, PA;(4) St. Croix, VI;(5)...
Highest Attainable UseModified aquatic life, wildlife, or recreation use that is both closest to the uses specified in section...
Highest Dose TestedThe highest dose of a chemical or substance tested in a study.
Highest-Hazardous Air Pollutant Product Recipe1. Recipe of the product with the highest total mass of HAP charged to the reactor during the production of a...
Highest-Level Parent Company1. Highest-level company of the site's ownership hierarchy as of the start of the submission period during...
High-Frequency Electromagnetic SoundingHigh-frequency EM sounding, the technology used for nonintrusive geophysical exploration, projects...
High-Gloss Specialty CoatingAny coating that achieves at least 85 percent reflectance on a 60 degree meter when tested by ASTM D523-89...
High-Grade1. Generally refers to white or cream-colored paper recovered from offices, homes, schools, and other...
High-Grade PaperGenerally refers to white or cream-colored paper recovered from offices, homes, schools, and other sources...
High-Idle SpeedEngine speed at which an engine governor function controls engine speed with operator demand at maximum and...
High-Level Nuclear Waste FacilityPlant designed to handle disposal of used nuclear fuel, high-level radioactive waste, and plutonium waste.
High-Level Radioactive Waste1. Waste generated in core fuel of a nuclear reactor, found at nuclear reactors or by nuclear fuel...
High-Level WasteThe highly radioactive waste material that results from the reprocessing of spent nuclear fuel, including...
High-Level WindThe horizontal motion of the air past a given point at a high-altitude. Winds begin with differences in air...
High-Line JumpersPipes or hoses connected to fire hydrants and laid on top of the ground to provide emergency water service...
High-Load EngineEngine for which the engine manufacturer can provide clear evidence that operation below 75 percent of...
Highly Erodible LandLand that is very susceptible to erosion, including fields that have at least 1/3 or 50 acres of soils with a...
highly erodible landsLand that is very susceptible to erosion, including fields that have at least 1/3 or 50 acres of soils with a...
High-Permeability MaterialAny nonmetal material that does not qualify as low-permeability material.
High-Pressure Appliance1. An appliance that uses a refrigerant with a liquid phase saturation pressure between 170 psia and 355 psia...
High-Pressure MixheadMixhead where mixing is achieved by impingement of the high pressure streams within the mixhead.
High-Priority SubstanceChemical substance that EPA determines, without consideration of costs or other non-risk factors, may present...
High-Processing PackinghousePackinghouse which processes both animals slaughtered at the site and additional carcasses from outside...
High-Risk GroupA a group of persons whose risk for a particular disease, injury, or other health condition is greater than...
High-Risk PollutantHazardous air pollutant listed in Table 1 of §63.74
High-Speed GovernorAny device, system, or element of design that modulates the engine output torque for the purpose of limiting...
High-Strength SteelSteel with tensile strength at or above 350 MPa.
High-Sulfur Diesel Fuel1. For in-use fuels, high-sulfur diesel fuel means a diesel fuel with a maximum sulfur concentration greater...
High-Temperature Specialty CoatingAny coating that during normal use must withstand a temperature of at least 426 °C (800 °F).
High-Throughput, Cell/Pathway/Protein-Based ApproachHigh throughput approach applied to drug development in which particular cells, pathways, or proteins within...
High-Throughput ScreeningAny method of initial testing which allows rapid processing of many (tens of thousands) samples in a short...
High-Throughput Sequencing1. A fast method of determining the order of bases in DNA.
High-Throughput SystemsIn vitro biochemical or cellular assays that can be run efficiently on a large number of compounds to...
High-Throughput ToolMeans for processing large amounts of data quickly and inexpensively; often used in gene sequencing.
High-to-Low-Dose Extrapolation1. The process of prediction of low exposure risks to rodents from the measured high exposure-high risk data.
High-Volatility Organic CompoundAny organic compound that exerts a vapor pressure greater than 80 millimeters of mercury when measured at 20...
High-Volume Low-Pressure spray gunsA spray gun that uses columns of low pressure air to cause turbulence within the paint as the first stage of...
Highway1. The term highway includes roads, streets, and parkways and all their appurtenances (23 U.S.C. 101).
Highway Fuel Economy1. Estimated miles-per-gallon on the highway. Highway fuel economy represents a mixture of rural and...
Highway Fuel Economy TestTest procedure described in § 600.111(b).
Highway Fuel Economy Test ProcedureDynamometer driving schedule, dynamometer procedure, and sampling and analytical procedures described in...
Highway Project1. Highway project or transit project.
hi-input turfTurf that requires irrigation, frequent mowing, fertilization and/or pesticide treatment.
HikingWalking in a natural setting, such as a park or mountain range, for fun and leisure.
Hill Equation1. A dose-response curve, frequently used for enzyme kinetics, that monotonically approaches an asymptote...
Hillslope1. The part of the landscape included between the crest of hills and their drainage lines or channel networks.
Hillslope TargetsQuantitative measure that links the upslope sources of sediment and instream impacts of sediment discharge.
HindgutShort posterior section of the digestive tract between midgut and anus
HindmilkMilk produced at the end of the breastfeeding.
HipThe lateral prominence of the pelvis from the waist to the thigh.
Hispanic Individual1. For 2010 Census: People who identify with the terms “Hispanic,” “Latino,” or “Spanish” are those who...
Hispanic or Latino IndividualFor 2010 Census: People who identify with the terms “Hispanic,” “Latino,” or “Spanish” are those who classify...
HistamineAn amine derived by enzymatic decarboxylation of histidine. It is a powerful stimulant of gastric secretion...
Histamine DegradationHistamine Degradation consists of conjugation, transport, oxidation, or enzymatic breakdown of a...
Histamine ProductionHistamine Production consists of synthesis of a decarboxylation product of histidine (histamine), found...
Histamine Receptor BindingA process that involves the non-covalent binding of histamine to one of four known histamine receptor...
HistidineA semi-essential amino acid (children should obtain it from food) needed in humans for growth and tissue...
histogram1. A graphic representation of the frequency distribution of a continuous variable. Rectangles are drawn in...
Histologic ProgressionThe evolution of a low-grade neoplastic pathologic process to a high grade malignancy.
HistologyThe study of the structure of cells and tissues; usually involves microscopic examination of tissue slices.
Histone AcetylationHistone Acetylation involves covalent linkage of acetyl groups to highly basic histone proteins associated...
Histone DeacetylationHistone Deacetylation is the covalent post-translational enzymatic addition of an acetyl group(s) to a...
Histones1. Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the...
Histopathological TestTest that examines the structure of cells and tissues to determine if any damage has been caused by exposure...
Histoplasma capsulatumHistoplasma fungus grows as a mold in the soil. You can get sick when you breathe in spores produced by the...
HistoplasmosisA lung disease caused by the fungus Histoplasma capsulatum.
Historic Designed LandscapeA landscape that was consciously designed or laid out by a landscape architect, master gardener, architect...
Historic PreservationA process that organizes preservation activities include, identification, evaluation, registration and...
Historic PropertyAny prehistoric or historic district, site, building, structure, or object included in, or eligible for...
Historic Vernacular LandscapeA landscape that evolved through use by the people whose activities or occupancy shaped it. Through social or...
Historical AreaU.S. Forest Service usage. Sites and areas which have been designated by the Forest Service as containing...
Historical conditionWater quality conditions observed prior to significant anthropogenic impacts that provide a basis for...
Historical DataData sets from previous studies, which can range from handwritten field notes to published journal articles.
Historical Estimated DataData estimated from known recorded data and known historical trends by a specialist using inferential...
Historical FloodFlood events documented by human observation but recorded prior to the development of systematic streamflow...
Historical Water Quality ConditionsWater quality conditions observed prior to significant anthropogenic impacts that provide a basis for...
History EffectThis threat to internal validity refers to specific events, other than the program, which may have taken...
HISTORY FILESElectronic files copied from inactive master files for long-term or permanent retention.
HistosolWet organic soils, such as peats and mucks.
Histosols1. The central concept of Histosols is that of soils forming in organic soil materials. The general rule is...
Hobby CoatingCoating which is designed and labeled exclusively for hobby applications and is sold in aerosol containers of...
Hobby EngineEngines used in reduced-scale models of vehicles that are not capable of transporting a person (for example...
Hoboken ConverterBatch copper converter in which copper matte is oxidized to form blister copper by a process that is...
Hodgkin's LymphomaA cancer of the lymphatic system that is characterized by enlargement of lymph nodes, the spleen, or other...
HogGeneric term, usually applied to growing swine.
Hog CholeraA typically acute, highly contagious disease of pigs, caused by the Classical swine fever virus. It has a...
Hog Fuel Dryer1. Equipment that combusts fine particles of wood waste (hog fuel) in a fluidized bed and directs the heated...
Hold AllowanceAllowances recorded by the Administrator, or submitted to the Administrator for recordation in accordance...
HOLDING AREAAgency space assigned for the temporary storage of records after their cutoff and removal from office space...
Holding Mode1. Operating mode for a batch copper converter during which the molten bath is maintained in the vessel but...
Holding PenAn area in which cows congregate prior to entering a milking parlor to be milked.
Holding PondA pond or reservoir, usually made of earth, built to store polluted runoff.
Holding Time1. The period of time a sample may be stored before analysis. While exceeding the holding time does not...
Holding Times1. The maximum times that samples may be held, after the sample is taken, prior to analysis and still be...
HoleA generally more steep- sided indentation or depression that is lower than the surrounding surface formed...
Hole/PitA generally more steep- sided indentation or depression that is lower than the surrounding surface formed...
hollow stem auger drilling1. A conventional drilling method that uses rotating augers to penetrate the soil. As the augers are rotated...
Home Air CleanerTechnologies which reduce or remove the sources of pollutants and ventilate with clean outdoor air. [MK[]
Home and Garden User SectorInvolves pesticides applied by homeowners to homes and gardens, including lawns; single and multiple unit...
Home Area NetworkA communication network within the home of a residential electricity customer that allows transfer of...
Home Energy Rating1. Home Energy Rating is an analysis of a home's construction plans and onsite inspections. Based on the...
Home Energy Rating System indexA nationally recognized energy rating system that gives homeowners, sellers, buyers, builders, mortgage...
Home Insect ControlProcedure to eliminate insect pests, via natural or chemical means, within the household environment.
Home Page1. A home page is the entry point to a Web site. Although the term "home page" is commonly used as a synonym...
Home Range1. The area to which an animal confines its activities. (PERTAINING TO ECOLOGICAL ASSESSMENTS)
Home Satellite DishHome receiver that permits the consumer to receive existing satellite transmissions.
Home Scrap MetalScrap metal as generated by steel mills, foundries, and refineries such as turnings, cuttings, punchings, and...
Homeland SecurityHomeland Security involves protecting the nation against terrorist attacks. This includes analyzing threats...
Homeland Security EmergenicesBombings, hijackings, cyber attacks and other acts of terrorism made against the United States including the...
Homeless PersonPersons who have no permanent residence. The concept excludes nomadic peoples.
Homeostatic Process1. The body's maintenance of a consistent internal environment within a narrow range of variation. It is...
Homeotherm‘Warm-blooded’ animals that regulate their body temperature, keeping it constant and not reliant on the...
Homeowner Water SystemAny water system which supplies piped water to a single residence.
Home-produced foodsFruits and vegetables produced by home gardeners, meat and dairy products derived from consumer-raised...
HomoaggregationConglomeration of like substances
HomobrassinolideCAS No.: 74174-44-0; chemical formula: C29H50O6
HomodimerizationHomodimerization involves a biophysical interaction between two identical biological molecules or subunits...
homogeneityCharacteristic of a medium in which material properties are identical throughout. Although heterogeneity, or...
homogeneousUniform in structure or composition at all locations in space.
Homogeneous Area1. In accordance with Asbestos Hazard and Emergency Response Act (AHERA) definitions, an area of surfacing...
Homogeneous MixtureMixture which has the same composition or characteristic in every part of it.
Homogeneous NucleationFormation of a particle from the vapor phase involving only one compound.
Homolog1. Group of isomers that have the same degree of halogenation. For example, the homologous class of...
Homologous RecombinationThe process of exchange of genetic material between autonomous replicons, which depends on regions of...
Homology MappingHomology mapping is an analytic technique in which similarities in the geographical, land-use, and...
HomopolymersPolymers that incorporate a single monomer.
Homothallic FungusA fungus which can produce sexual spores without a second individual
HomozygoteWith respect to a particular trait or condition, an individual who has inherited identical alleles at a...
HoodAny device used to capture fugitive volatile organic compounds.
Hood Capture EfficiencyRatio of the emissions captured by a hood and directed into a control or disposal device, expressed as a...
Hookworm InfectionInfection of humans or animals with hookworms other than those caused by the genus Ancylostoma or Necator.
Hoop StructureA low cost, uninsulated and naturally ventilated building used for older swine. The floor is mostly earthen...
Hoop Type BarnA barn with a hooped roof. The sidewalls consist of wood and wood structures, but the roof is made of steel...
HopperDevice for temporarily storing dust collected by an air pollution control device. Hoppers funnel solids into...
horizontal directional drillingA technology that uses a specialized drill rig and drillhead locating equipment to create a curved borehole...
Horizontal drillingDrilling a portion of a well horizontally to expose more of the formation surface area to the wellbore.
Horizontal Gene TransferTransfer of a gene from one species to another.
horizontal remediation well1. An environmental remediation well installed using horizontal directional drilling equipment.
Horizontal Stud Soderberg ProcessMethod of primary aluminum reduction using the Soderberg process in which the electrical current is...
Horizontal WellWell bore that has a planned deviation from primarily vertical to a primarily horizontal inclination or...
Horizontal-Axis Wind TurbineWind turbine which has a horizontal rotor axis.
Hormone MetabolismThe chemical reactions and pathways involving any hormone, naturally occurring substances secreted by...
Hormone SynthesisAnabolic formation of hormones in organisms or living cells.
Hormones1. A chemical produced in one part of the body and passed through the blood to another part of the body to...
Horse DiseasesDiseases of domestic and wild horses of the species Equus caballus.
Horseback RidingRecreational activity of riding horses for sport or pleasure.
Horticultural CroplandA subcategory of Cropland used for growing fruit, nut, berry, vineyard, and other bush fruit and similar...
Horticultural SocietyA society which is based on cultivating plants, both fruits and vegetables. These societies differ from...
hose barbA twist-type connector used for connecting a small diameter hose to a valve or faucet
Hose Bib1. Faucet. A location in a water line where a hose is connected.
Hosiery Product FinishingInternal subdivision of the knit fabric finishing subcategory for facilities that are engaged primarily in...
Hospital1. A facility that provides medical care and treatment for patients who are acutely ill or chronically ill on...
Hospital Central Services StaffHealthcare professional, including manager and technician, who is either directly involved in or responsible...
Hospital WasteDiscards generated at a hospital, except unused items returned to the manufacturer. The definition of...
HospitalizationAdmission for treatment to a hospital, clinic or other health care facility. Treatment as an out-patient is...
Hospitalized PatientIndividual admitted to a hospital generally for medical treatment.
Hospital/Medical/Infectious Waste Incinerator1. Any device that combusts any amount of hospital waste and/or medical/infectious waste.
Hospital/Medical/Infectious Waste Incinerator Operator1. Any person who operates, controls or supervises the day-to-day operation of an HMIWI.
Hospital/Medical/Infectious Waste Incinerator Shutdown1. Period of time after all waste has been combusted in the primary chamber. For continuous HMIWI, shutdown...
Hospital/Medical/Infectious Waste Incinerator UnitDevice that combusts any amount of hospital waste and/or medical/infectious waste.
Hospitals1. Point locations for buildings where the sick or injured may receive medical or surgical attention (e.g...
Host1. In genetics, the organism, typically a bacterium, into which a gene from another organism is transplanted.
host characterizationEvaluation of the characteristics of a potentially exposed human population that may influence susceptibility...
Host DefenseHost defenses against pathology include physical barriers to pathogens, immediate nonspecific and...
Host FactorIntrinsic factor (age, race, sex, behaviors, etc.) which influences an individual’s exposure, susceptibility...
host pathogen profileA qualitative and/or quantitative evaluation of the nature and potential magnitude of human health effects...
Host PlantLiving plant attacked by (or harboring) a living parasite and from which the invader is obtaining part or all...
Host SeekingThe behavior of insects trying to find a host animal on which to feed
Host Specific AssayAssay technique making use of, e.g., genes which are specific to a particular host species.
HostlerEmployee who drives a tractor for the purpose of moving cargo within a container yard.
Hostler (or hustler)An employee who drives a tractor for the purpose of moving cargo within a container yard.
Host-Parasite RelationshipThe interactions between two organisms, one of which lives at the expense of the other. (NCI)
Host-Tumor InteractionThe efforts by the host to reject a tumor, and the mechanisms by a tumor to evade recognition by the immune...
Hot Dip Coating1. Using various processes to coat an iron or steel surface with zinc. In hot dipping, a base metal is coated...
Hot FormingSteel operations in which solidified, heated steel is shaped by rolls.
Hot Metal Transfer StationFacility where molten iron is emptied from the railroad torpedo car or hot metal car to the shop ladle. This...
Hot Mix AsphaltHot mixture of asphalt binder and size-graded aggregate, which can be compacted into a uniform dense mass...
Hot Mix Asphalt FacilityAny facility, as described in § 60.90, used to manufacture hot mix asphalt by heating and drying aggregate...
Hot PressingForming a powder metallurgy compact at a temperature high enough to effect concurrent sintering.
Hot QuarterA quarter of the udder that is infected and may actually feel hard or hot to the touch due to elevated...
Hot Soak EmissionsEvaporative emissions after termination of engine operation.
Hot SpotAn area of concentrated heat in the mantle that produces magma that rises to the Earth's surface to form...
Hot StandbyPeriods when the catalytic cracking unit is not receiving fresh or recycled feed oil but the catalytic...
Hot Strip and Sheet MillSteel hot forming operations that produce flat hot-rolled products other than plates.
Hot TubWater-filled wood, plastic, or ceramic container in which up to 12 people can lounge. Normally equipped with...
Hot WasteRefers to materials in the overburden, mining refuse, mine tailings or mining spoils piles that are highly...
Hot Water Heater1. An automatically controlled, thermally insulated vessel designed for heating water and storing heated...
Hot Water SealHeated water bath (heated to approximately 180 °F) used to seal the surface coating on formed aluminum which...
Hot WorkWork involving electric or gas welding, cutting, brazing, or similar flame or spark-producing operations.
Hotel PowerPower provided by an engine on a locomotive to operate equipment on passenger cars of a train; e.g., heating...
Hot-Mix Asphalt OperationOperations involved in mixing asphalt cement and aggregates to produce materials for paving roadways and...
Hot-Soak Loss1. Hot soak emissions.
HotspotA geographic area with a high level of pollution/contamination within a larger geographic area of low or...
Hot-Spot AnalysisEstimation of likely future localized CO, PM10, and/or PM2.5 pollutant concentrations and a comparison of...
Hourly Average1. Arithmetic average of at least four CMS data values representing the four 15-minute periods in an hour, or...
Hourly capacity factorThe fraction of an EGU’s total available capacity that is utilized in an hour.
Household1. A household includes all the people who occupy a housing unit as their usual place of residence.
Household AdhesiveAny household product that is used to bond one surface to another by attachment. “Household adhesive” does...
Household Appliance1. Any device which contains and uses a fluorinated greenhouse gas refrigerant and which is used for...
Household, Commercial/Retail, and Institutional WasteIncludes Yard waste; Refuse-derived fuel; and Motor vehicle maintenance materials limited to vehicle...
Household Do-It-Yourselfer Used OilOil that is derived from households, such as used oil generated by individuals who generate used oil through...
Household Do-It-Yourselfer Used Oil GeneratorIndividual who generates household “do-it-yourselfer” used oil.
Household DryerHome appliance that is extensively employed for drying clean clothes.
Household Hazardous Waste1. Refers to hazardous products that are used and disposed of by residential-rather than...
Household Hazardous WastesHazardous products used and disposed of by residential as opposed to industrial consumers. Includes paints...
Household Landscape DeviceDevice or equipment meant for use to manage and care for a lawn or garden area, such as a garden hose or lawn...
Household Member(Member of a household which includes) all the people who occupy a housing unit as their usual place of...
household or domestic wasteSolid waste, composed of garbage and rubbish, which normally originates from residential, private households...
Household ProductAny consumer product that is primarily designed to be used inside or outside of living quarters or...
Household production functionsA representation of the various processes through which members of a household produce goods and services for...
Household UseUse of a product in a home or its immediate environment.
Household Waste1. Solid waste, composed of garbage and rubbish, which normally originates from residential, private...
HouseholderThe person, or one of the people, in whose name the home is owned, being bought, or rented. If there is no...
HousingResidential housing, can also include consideration of emergency housing such as sheltering and refugee...
Housing BurdenThis dataset contains census tract level percentiles for housing cost, which is the share of households that...
Housing Rehabilitation CodeTake into account that renovation of existing (particularly historic) buildings requires more flexibility in...
Housing Rehabilitation CodesTake into account that renovation of existing (particularly historic) buildings requires more flexibility in...
Housing Unit1. A house, an apartment, a mobile home or trailer, a group of rooms, or a single room occupied as separate...
HR StrategyHR Strategy develops effective human capital management strategies to ensure federal organizations are able...
HSWA ClusterThere are two multi-year clusters that cover most of the HSWA regulations: Cluster I covers regulations...
HSWA Statutory ChecklistThe HSWA Statutory Checklist was initially developed as part of the state's application for authorization for...
HubPart of the turbine to which the blades are attached.
HUC Region1. A hierarchical, numeric code that uniquely identifies hydrologic units. The first two digits identify the...
Hull Coating LeachateAntifouling agents that leach into surrounding waters from hull coatings designed to prevent corrosion and to...
Human Activity ModelModeling which simulates the human activities and behaviors that result in pollutants.
Human AdaptationAdjustment in human systems in response to current natural hazards and actual or expected climate change...
Human BehaviorAn action or process carried out by humans.
human capital approachA method for estimating the impact of an individual’s illness or premature death on society by measuring the...
Human CharacteristicFeatures which characterize an individual, i.e., smoker, sex, developmental stages such as child or adult.
Human Community1. An interacting population of various types of individuals (in this case, people) in a common location.
Human Disease Carrier1. An individual who does not display the symptoms of a disease, but harbors the pathogen which causes it, or...
Human Disease ModelRepresentation of processes that are involved in human disease
Human Dominated EcosystemEcosystems dominated by agriculture or the built environment.
Human EnvironmentComprehensively the natural and physical environment and the relationship of present and future generations...
Human Equivalent Concentration1. The human concentration (for inhalation exposure) or dose (for other routes of exposure) of an agent that...
Human Equivalent Concentration or DoseThe human concentration (for inhalation exposure) or dose (for other routes of exposure) of an agent that is...
Human Equivalent Dose1. A dose which, when administered to humans, produces an effect equal to that produced by a dose in animals.
Human Exposure1. What does the Site-Wide Human Exposure EI measure? - The Site-Wide Human Exposure (HE) environmental...
Human Exposure Control StatusSee definitions for Current human exposure is under control, Current human exposures is not under control...
Human Exposure Evaluation1. A component of risk assessment that involves describing the nature and size of the population exposed to a...
Human Exposure ModelA computer model used primarily for conducting inhalation risk assessments for sources emitting air toxics to...
Human Exposure Under Control1. A "yes" indicates that there are no unacceptable human exposures to contamination that can reasonably be...
Human GroupA number of persons, normally individuals, considered as a collective unit. For example, families...
Human Group BehaviorAn action performed or behavior exhibited by a number of persons as a collective unit. (Social Behavior - A...
Human Group CharacteristicFeatures which characterize a number of persons as a collective unit.
Human Health Effects ModelProvides a statistical relationship between a dose of a chemical and an adverse human health effect. Health...
Human Health Indicator ModelRepresentation of processes that indicate human health
Human Health Inhalation AssessmentA process that evaluates the likelihood of an adverse impact of a chemical or group of chemicals on human...
Human Health Multi-pathway AssessmentA process that evaluates the likelihood of an adverse impact of a chemical or group of chemicals on human...
Human Health ResearchActivities to develop original scientific information on human health issues related to environmental...
Human Health Risk1. The likelihood that a given exposure or series of exposures may have damaged or will damage the health of...
Human Immunodeficiency Virus1. The virus isolated and recognized as the etiologic agent of AIDS. HIV-1 is classified as a lentivirus, a...
Human Injury1. Any effect on a human that results either from direct exposure to toxic concentrations; radiant heat; or...
Human Intentional Exposure ResearchStudy of a substance in which the exposure to the substance experienced by a human subject participating in...
Human International MigrationMovement of people across international borders.
Human IntrusionBreaching of any portion of the Yucca Mountain disposal system, within the repository footprint, by any human...
Human Life Stage1. Temporal stages of life that have distinct anatomical, physiological, and behavioral or functional...
Human Mortality ModelRepresentation of processes that indicate human mortality rates
Human Pathogenic BacteriaBacteria that have harmful effects on people such as causing a disease
Human Pathogenic FungusFungi that cause disease in humans, such as aspergillis and cryptococcus, among others.
Human Pathogenic MicroorganismAny microorganism which has harmful effects on people
Human Research EthicsEthics in research using or studying human subjects
Human Resource ManagementHuman Resource Management involves all activities associated with the recruitment and management of personnel.
Human Subject1. Living individual about whom an investigator (whether professional or student) conducting research obtains...
Human Subjects Intentional Exposure ResearchStudy of a substance in which the exposure to the substance experienced by a human subject participating in...
Human Subjects ResearchResearch involving the collection of data through interaction with a living individual or collection of...
Human Subjects TestingUse of human individuals to test the efficacy of drugs, the toxicity of chemical substances, etc.
Human Time ScaleThat portion of the pedogenic time scale that covers periods of centuries, decades, or less.
Human Waste DischargeDischarge into the environment of human body wastes and the waste from toilets and other receptacles intended...
Human Water ConsumptionDrinking, bathing, showering, hand washing, teeth brushing, food preparation, dishwashing, and maintaining...
human well-being1. Broadly, the condition of humans and society, defined in terms of the basic material needs for a good...
Human/Animal SystemA group of body organs or structures and the life-supporting processes that they perform.
Human-dominatedEcosystems dominated by agriculture or the built environment [Original source: Biomes of Earth' (Woodward...
HumectantMoistening or diluent substance
HumerusBone in humans and primates extending from the shoulder joint to the elbow joint.
Humidifier FeverA respiratory illness caused by exposure to toxins from microorganisms found in wet or moist areas in...
HumidityThe measure of moisture in the atmosphere.
HummockA low, rounded, natural hill of unspecified origin, which is generally less than 3 meters high and composed...
Humoral ImmunityAntibody-mediated immune response. Humoral immunity is brought about by antibody formation, resulting from...
Humulus japonicusJapanese hop, or hops, is an herbaceous, usually annual vine that lacks tendrils and climbs by twining. It is...
HumusOrganic portion of the soil remaining after prolonged microbial decomposition.
Hurricane1. A giant swirling storm characterized by a low pressure center and numerous thunderstorms that produce...
Hurricane KatrinaOn August 29, 2005, Hurricane Katrina made landfall on the Mississippi coast. Katrina devastated the Gulf...
Hurricane PreparednessUnderstanding the risk from hurricanes, making sure multiple ways of receiving forecasts and alerts are...
HutchAn individual housing unit for young calves. Often made of white fiberglass or polyvinyl.
HyalinizationA process of tissue replacement where the tissue is being replaced by hyaline or the tissue has degenerated...
Hyaluronic Acid BindingHyaluronic Acid Binding involves a biophysical interaction between a biological molecule, such as a protein...
HybridThe offspring of any cross between two organisms of different genotypes.
Hybrid ApproachMethod that the initial recipient [as defined in paragraph (b) of this section] may elect to use for...
Hybrid CloudThe cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community...
Hybrid Electric Vehicle1. Hybrid electric vehicles combine features of internal combustion engines and electric motors. Unlike 100%...
Hybrid Engine1. Engine or powertrain that includes energy storage features other than a conventional battery system or...
Hybrid Generation FacilityPlant that generates electrical energy derived from a combination of qualified renewable energy (wind, solar...
Hybrid ModelFor continuous data establishes abnormal values based on the extremes in controls (unexposed individuals or...
Hybrid Powertrain1. Engine or powertrain that includes energy storage features other than a conventional battery system or...
Hybrid Suspension Grate BoilerBoiler designed with air distributors to spread the fuel material over the entire width and depth of the...
Hybrid SystemThese systems combine the features of both the closed-cycle and open-cycle systems. In a hybrid system, warm...
Hybrid Vehicle1. Vehicle that includes energy storage features (other than a conventional battery system or conventional...
Hybrid VehiclesHybrid electric vehicles combine features of internal combustion engines and electric motors. Unlike 100%...
Hybridization ArrayA molecular biology device that utilizes a set of defined oligonucleotide probes, recombinant clones, or...
HybridizeTo crossbreed a plant or animal.
HydranencephalyA rare congenital brain disorder in which the cerebral hemispheres are absent and replaced by sacs that...
Hydrated LimeLimestone that has been burned and treated with water under controlled conditions until the calcium oxide...
Hydraulic BarkingWood processing operation that removes bark from wood by the use of water under a pressure of 6.8 atm (100...
hydraulic conductivity1. A coefficient of proportionality describing the rate at which water can move through a permeable medium...
hydraulic connectivityThe ability of the soil to transmit water. Also commonly known as the permeability. Darcy found that to...
Hydraulic FluidPetroleum-based hydraulic fluids.
Hydraulic fracturing1. The creation of fractures within a reservoir that contains oil or natural gas to increase flow and...
Hydraulic Fracturing SubstanceSubstances used in hydraulic fracturing which is the creation of fractures within a reservoir that contains...
Hydraulic Fracturing WaterThe lifecycle of water in the hydraulic fracturing process, encompassing the acquisition of water, chemical...
Hydraulic Grade LineThe surface or profile of water flowing of hydraulic gradient. The slope of the hydraulic grade line is under...
hydraulic gradient1. The change in total potentiometric (or piezometric) head between two points divided by the horizontal...
hydraulic headHeight above a datum plane (such as mean sea level) of the column of water that can be supported by the...
Hydraulic Lift TankTank holding hydraulic fluid for a closed-loop mechanical system that uses compressed air or hydraulic fluid...
Hydraulic LoadingThe flowrate per unit plan or surface area in sedimentation facilities or cross-sectional area in screening...
Hydraulic MulchMulch that is a cellulose-based (paper or wood) protective covering that is mixed with water and applied...
Hydraulic RefracturingConducting a subsequent hydraulic fracturing operation at a well that has previously undergone a hydraulic...
hydraulic residence timeThe average time an element spends in a given environment between the time it arrived and the time it is...
hydraulic resistanceIn hydraulics, resistance is the condition engendered by an obstruction or restriction in the flow path...
Hydraulic Retention TimeThe average length of time any particle of manure remains in a manure treatment or storage structure. The HRT...
Hydraulic SystemSystem where pressurized fluid acts upon a section of a containing vessel and creates force or power that can...
Hydraulic Zone of InfluenceThat portion of the source waterbody hydraulically affected by the cooling water intake structure withdrawal...
Hydric soil1. Soil that is saturated or flooded with water for long enough during the growing season that its upper...
Hydro (Small-scale)In addition to very large hydroelectric plants in the West, the United States also has many smaller...
HydrobromofluorocarbonAn ozone-depleting substance consisting of hydrogen, bromine, fluorine, and carbon.
Hydrobromofluorocarbons1. An ozone-depleting substance consisting of hydrogen, bromine, fluorine, and carbon.
Hydrocarbon1. A hydrocarbon is an organic compound containing only hydrogen and carbon, often occurring in petroleum...
Hydrocarbon Condensate1. Hydrocarbon liquid separated from natural gas which condenses due to changes in the temperature and/or...
Hydrocarbon Fuel-Based Combustion Emission Control SystemHydrocarbon fuel-based combustion device or equipment that is designed to destroy or remove gas emissions in...
Hydrocarbon Gas LiquidA group of hydrocarbons including ethane, propane, normal butane, isobutane, and natural gasoline, and their...
Hydrocarbon LiquidAny naturally occurring, unrefined petroleum liquid. [40 CFR 63.761 (CFR 2013)]
Hydrocarbon StandardEmission standard for total hydrocarbons, nonmethane hydrocarbons, or total hydrocarbon equivalent; or a...
Hydrocarbons1. Chemical compounds that consist entirely of carbon and hydrogen.
Hydrocarbons (Chemicals)1. Chemical compounds that consist entirely of carbon and hydrogen.
Hydrochloric Acid PicklingOperations in which steel products are immersed in hydrochloric acid solutions to chemically remove oxides...
Hydrochloric Acid Regeneration PlantHydrochloric acid regeneration plant means the collection of equipment and processes configured to...
Hydrochloric Acid Regeneration Plant Production ModeOperation under conditions that result in production of usable regenerated acid or iron oxide.
Hydrochloric Acid Storage VesselStationary vessel used for the bulk containment of virgin or regenerated hydrochloric acid.
Hydrochlorination(Hi-poe-KLOR-uh-NAY-shun) The application of hypochlorite compounds to water for the purpose of disinfection.
Hydrochlorinators(Hi-poe-KLOR-uh-NAY-tors) Chlorine pumps, chemical feed pumps or devices used to dispense chlorine solutions...
HydrochlorofluorocarbonA compound consisting of hydrogen, chlorine, fluorine, and carbon. Hydrochlorofluorocarbons (HCFCs) are one...
Hydrochlorofluorocarbons1. Compounds containing hydrogen, fluorine, chlorine, and carbon atoms. Although ozone depleting substances...
HydrochlorothiazideA thiazide diuretic often considered the prototypical member of this class. It reduces the reabsorption of...
HydrocodoneNarcotic analgesic related to codeine, but more potent and more addicting by weight. It is used also as cough...
Hydrocyanic AcidHydrogen cyanide (HCN); A toxic liquid or colorless gas. It is found in the smoke of various tobacco products...
HydrodehalogenationDehalogenation is a chemical detoxification process that removes and/or substitutes halogen atoms from an...
hydrodynamic climateThe characteristics of nearshore or continental shelf currents in an area that typically result from waves...
Hydrodynamic ModelMathematical formulation used in describing fluid flow circulation, transport, and deposition processes in...
hydrodynamic simulationsComputer simulations of the motion or movement of water in a stream, lake or estuary.
HydrodynamicsThe branch of science that deals with the dynamics of fluids, especially incompressible fluids, in motion.
Hydroelectric damA power plant that uses the energy from moving water to produce electricity. Moving water spins a turbine...
Hydroelectric Power (Large)The process of generating electricity by harnessing the power of moving water is called hydroelectricity...
Hydroelectric power plantStructure in which the energy of fading or flowing water spins a turbine generator to produce electricity.
Hydroelectric Power Water UseThe use of water in the generation of electricity at plants where the turbine generators are driven by...
HydrofluorocarbonA compound consisting of hydrogen, fluorine, and carbon. Hydrofluorocarbons (HFCs) are a class of...
Hydrofluorocarbons1. Man-made compounds containing hydrogen, fluorine, and carbon, many of which have been developed as...
HydrofluoroethersNon-ozone depleting organic solvents and cleaning agents with the general ether structure R-O-R with a...
HydrofluoroolefinA compound consisting of hydrogen, fluorine, and carbon. Hydrofluoroolefins (HFOs) are alternatives to...
Hydrofluoroolefins1. A compound consisting of hydrogen, fluorine, and carbon. Hydrofluoroolefins (HFOs) are alternatives to...
Hydroform ClassMajor group of oceanic and coastal water column forms.
HydroformingCatalytic reforming of naphtha at elevated temperatures and moderate pressures in the presence of hydrogen to...
Hydrofrac FluidSpecially engineered fluids containing chemical additives and proppant that are pumped under high pressure...
HydrogelsWater swollen, rigid, 3-dimensional network of cross-linked, hydrophilic macromolecules, 20-95% water. They...
HydrogenThe first chemical element in the periodic table. It has the atomic symbol H, atomic number 1, and atomic...
Hydrogen BondingThe physical association between an electronegative atom and a hydrogen atom that is directly bound to a...
Hydrogen Chloride1. Emissions of hydrogen chloride that serve as a surrogate measure of the total emissions of the HAPs...
Hydrogen Fuel TankStores hydrogen gas onboard the vehicle until it's needed by the fuel cell.
Hydrogen Gas StreamHydrogen stream formed in the chlor-alkali cell denuder.
Hydrogen Halides and Halogen Hazardous Air PollutantHydrogen chloride, hydrogen fluoride, and chlorine.
Hydrogen Halides and HalogensHydrogen chloride (HCl), chlorine (Cl2), and hydrogen fluoride (HF).
Hydrogen Peroxide1. Hydrogen peroxide is a colorless liquid at room temperature with a bitter taste. Small amounts of gaseous...
Hydrogen SulfideGas emitted during organic decomposition. Also a by-product of oil refining and burning. Smells like rotten...
Hydrogen Sulfide MonitorAir monitor that analyzes, measures and evaluates hydrogen sulfide in and around animal feeding operations.
HydrogenerationThe chemical addition of hydrogen to a material in the presence of a catalyst.
Hydrogeologic ConditionsConditions stemming from the interaction of ground water and the surrounding soil and rock.
Hydrogeologic CycleThe natural process recycling water from the atmosphere down to (and through) the earth and back to the...
Hydrogeological CycleThe natural process recycling water from the atmosphere down to (and through) the earth and back to the...
Hydrogeologist(HI-dro-gee-ALL-uh-gist) A person who studies and works with groundwater.
Hydrogeology1. Hydrogeology is the study of ground water, including its origin, occurrence, movement, and quality.
HydrogeomorphicClassification: A wetland classification system based on the position of a wetland in the landscape...
Hydrogeomorphic approachA functional assessment method which compares a wetland's condition to similar wetland types (as defined by...
Hydrograph1. A graphical plot of streamflow data over time.
Hydrokinetic EnergyEnergy generated by the movement of a body of water. The earth's tides, waves, ocean currents and...
Hydrokinetic Power System ImpactCareful site selection is critical to minimizing the environmental impacts of hydrokinetic power systems...
Hydrolases1. Any member of the class of enzymes that catalyze the cleavage of the substrate and the addition of water...
Hydrologic Cycle1. The circuit of water movement from the atmosphere to the earth and its return to the atmosphere through...
hydrologic extremesHydrologic events that change stream flow conditions, such as droughts and floods, of significant magnitude...
Hydrologic FunctionThe capacity of the site to capture, store, and safely release water from rainfall, run-on, and snowmelt...
Hydrologic RegimeThe system that describes the occurrence, distribution, and circulation of water on the earth and between the...
Hydrologic Unit Code1. The code used to identify the hydrologic unit of the station based on FIPS. The entire reference table can...
Hydrologic Unit Code 121. Subdivisions within a watershed. Subwatersheds are the sixth level (12-digit) of the hydrologic unit...
Hydrologic Unit Code-12 CodeCode assigned by the US Geological Survey used to classify watersheds in the United States and the Caribbean...
Hydrologic Unit RegionThe first two digits in the Hydrologic Unit Code that divides the country into twenty-one regions. Visit the...
hydrological cycleThe movement of water form that atmosphere to the surface of the land, soil, and plants and back again to the...
Hydrological DroughtHydrological drought usually occurs following periods of extended precipitation shortfalls that impact water...
Hydrological ModelModel designed to predict flows in water bodies and runoff from precipitation, both of which govern the...
hydrological powerEnergy that is generated by dams, which use water to turn turbines and generate electricity.
Hydrological/Geological SupportProvides for hydrological and/or geological support in response to a component of the Superfund program.
Hydrology1. Hydrology is the science that deals with the properties, movement, and effects of water found on the...
Hydrolysis1. A chemical reaction that occurs between a substance and water resulting in the cleaving of a molecular...
Hydrolysis, Alkaline or AcidAddition of an acid or base (e.g., sodium or potassium hydroxide) to enhance biodegradability of organic...
Hydrolyzable LipidsType of lipids, including fatty acids, waxes, triacylglycerols and phospholipids, that may be broken into...
HydromodificationAlteration of the hydrologic characteristics of landscapes, drainage ways and waters of the United States...
HydronicA ventilation system using heated or cooled water pumped through a building.
Hydronic Heating SystemA type of heating system where water is heated in a boiler and either moves by natural convection or is...
Hydrophilic1. Having an affinity for water ("water-loving"), or capable of dissolving in water; soluble or miscible in...
Hydrophilic HormonesLipophobic hormones, such as insulin and epinephrine, that cannot cross the cell membrane and therefore bind...
Hydrophobic1. Tending not to combine with water, or incapable of dissolving in water; insoluble or immiscible in water...
Hydrophobic DyeHydrophobic dye is added to liquids to assist in the observation of the presence of items that are colorless.
Hydrophyte1. A plant that grows only in or on water or very moist soil.
HydrophytesA plant that grows only in water or very moist soils.
Hydrophytic VegetationVegetation that only grows in water or substrate that is at least periodically deficient in oxygen during a...
Hydropneumatic1. (Hi-dro-new-MAT-ick) A water system, usually small, in which a water pump is automatically controlled...
Hydropower1. Electrical energy produced by falling or flowing water.
Hydropower InfrastructureThose physical structures that are unique to electricity generation by the movement of water.
HydroseedingProcess of spraying seeds mixed with water through a mechanical sprayer (hydroseeder). Hydraulic mulch...
Hydrosphere1. The component of the climate system comprising liquid surface and subterranean water, such as: oceans...
Hydrostatic Pressure1. (Hi-dro-STAT-ick) The pressure at a specific elevation exerted by a body of water at rest.
Hydrostatic TestingChecking a gas pressure vessel for leaks or flaws. The vessel is filled with a nearly incompressible liquid -...
HydrotestingTesting of piping or tubing by filling with water and pressurizing to test for integrity.
Hydrothermal ActivityOccurs when the heat from the center of the earth emerges at the earth's surface in the form of heated water...
Hydrothermal PlumeA discharge of hot fluids from sea-bottom vents associated with volcanic or tectonic activity. The fluids are...
Hydrothermal VentStructures on the seafloor through which materials related to volcanic activity are extruded. These often...
Hydrotreated Light Petroleum DistillateLow odor paraffinic solvent
HydrovacingAlternative method to digging up a lead service line to identify it using high-pressure water and a vacuum...
Hydroxyl RadicalAn extremely reactive moiety. The hydroxyl radical is formed by the photolysis of ozone by sunlight and the...
HydroxylationPlacing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed)
HydroxyprolineA nonessential amino acid derivative formed during post-translational protein modification through...
Hyetograph1. A graphical plot of precipitation data over time.
HygroscopicReadily taking up and retaining moisture
HygroscopicityThe quality of absorbing or attracting moisture from the air.
Hymenachne amplexicaulisWest Indian marsh grass (Hymenachne amplexicaulis), also known as trompetilla, is a perennial grass adapted...
Hyoid BoneA mobile U-shaped bone that lies in the anterior part of the neck at the level of the third cervical...
HypalonChlorosulfonated polyethylene that is a synthetic rubber produced for uses such as wire and cable insulation...
Hyperactivity1. Abnormally increased activity
HyperalimentationIngestion or administration of a greater than optimal amount of nutrients
HyperbilirubinemiaAn excess of bilirubin in the blood
HypercalcemiaExcess of calcium in the blood
Hypercoagulability SyndromeAbnormally increased tendency of the blood to form clots. Set of symptoms or conditions that occur together...
Hyperendemic DiseaseDisease that is constantly present at a high incidence and/or prevalence rate.
hypergeometric distribution1. An important distribution used to model discrete events, especially the count of defectives when sampling...
HyperhydricityA physiological disorder occurring in plant tissue cultures characterized by high water retention capacity...
Hypericum perforatumCrowds out native species; toxic to livestock.
HypermethylationHypermethylation appears to be a controlled, epigenetic, heritable, and aberrant DNA methylation reaction on...
HyperparathyroidismAbnormally increased activity of the parathyroid glands which affects and is affected by serum calcium levels
HyperpyrexiaA highly elevated body temperature
HyperreflexiaExaggeration of reflexes
HypersalivationExcessive secretion of saliva
Hypersensitivity1. Great or excessive sensitivity.
Hypersensitivity Diseases1. Diseases characterized by allergic responses to pollutants; diseases most clearly associated with indoor...
Hypersensitivity Measurement(Measurement of) an exaggerated response by the immune system to a drug or other substance.
Hypersensitivity PneumonitisA group of respiratory diseases that cause inflammation of the lung (specifically granulomatous cells). Most...
Hypertension1. Persistently high arterial blood pressure
Hyper-Text Mark-Up LanguageHyper-Text Mark-up Language is the programming language used to design and present computer sites on the...
HyperText Markup Language1. HyperText Markup Language (HTML) is a simple markup system used to create Web pages and is the backbone of...
Hyper-Text Transport ProtocolThe method for moving "hypertext" files across the Internet. Requires an HTTP pro-gram at one end and a...
HyphaeLong chains of cells formed by fungi usually occurring between aggregates rather than within micropores.
Hyphae Apical GrowthFungal hyphae extending continuously at their extreme tips to penetrate cell walls of other organisms, and...
Hyphae Branching GrowthWhen each hypha of a fungi branches out, extending away from other hypha in search of new sources of...
HypobilirubinemiaAbnormally low levels of bilirubin in the blood
HypocalcemiaAbnormal reduction of blood calcium levels
Hypocenter1. The hypocenter is the point within the earth where an earthquake rupture starts. The epicenter is the...
Hypochlorite(Hi-poe-KLOR-ite) Chemical compounds containing available chlorine; used for disinfection. They are available...
HypochloritesSodium hypochlorite is generally used dissolved in water at various concentrations. Although available, solid...
HypocotylThe region of the stem beneath the stalks of the seed leaves (cotyledons) and directly above the young root...
Hypoglycemic AgentSubstances which lower blood glucose levels.
Hypolimnetic anoxiaDeep-water depletion of dissolved oxygen.
Hypolimnetic Oxygen Depletion RateThe hypolimnetic oxygen depletion rate describes changing dissolved oxygen concentrations in the hypolimnion...
Hypolimnion1. (Hi-poe-LIM-knee-on) The lowest layer in a thermally stratified lake or reservoir. This layer consists of...
Hypopharynx1. The lower part of the pharynx that connects to the esophagus.
HypospadiasA birth defect found in boys in which the urinary tract opening is not located properly at the tip of the...
Hypothalamo-Hypophyseal SystemA collection of neurons, tracts of nerve fibers, endocrine tissue, and blood vessels in the hypothalamus and...
HypothermiaA medical condition in which a person's body temperature becomes abnormally low, usually because of exposure...

1,010 of 30,736 terms in Environment terminology (MLC-0121). Request the full dataset.