The location where a particular plant or animal lives and its surroundings, both living and non-living. Includes the presence of a group of particular environmental conditions surrounding an organism including air, water, soil, mineral elements, moisture, temperature, and topography.

Hadal zone
The part of the ocean that lies in very deep trenches below the general level of the deep-ocean floor (the abyssal zone). Deep ocean trenches over 6km deep. (See also bathyal zone, abyssal zone).

These man-made substances are similar to chlorofluorocarbons but contain bromine. They also destroy the ozone layer.

Hazardous waste
A hazardous waste is a solid waste which because of its quantity, concentration, or characteristics may cause an increase in mortality or serious irreversible illness or pose a substantial hazard to human health or the environment when improperly treated, stored, transported, disposed of, or otherwise managed. Hazardous wastes are identified and managed as a result of their being specifically placed on lists, or because they exhibit at least one of four particular characteristics (ignitability, corrosively, reactivity, or toxicity). Defined, in fact, by the Environmental Protection (Special Waste) Regulations 1996 (as amended) and is broadly any waste on the European Hazardous Waste List that has one or more of fourteen hazardous properties.

The energy of a material due to the random motion of its particles. The word “heat” is used when energy is transferred from one substance to another.

Heavy metals
Metallic elements with high atomic weights, e.g., mercury, chromium, cadmium, arsenic, and lead; can damage living things at low concentrations and tend to accumulate in the food chain.

An organism which feeds chiefly on plants.

Refers to organisms, such as animals, that depend on preformed organic molecules from the environment (or another organism) as a source of nutrients/energy.

Winter dormancy in animals characterized by a great decrease in metabolism.

Historical resource
A building, structure, site, district or object belonging to a landscape which has significant historical and artistic value.

Horizontal drilling
The technique for cutting a hole in geological strata in a horizontal, rather than the normal vertical. The angle of deviation of the wellbore reaches at least 80 degrees from the vertical, maximizing the length of wellbore exposed to the formation.

Horizontal well
A class of nonvertical wells where the wellbore axis is near horizontal (within approximately ten degrees of the horizontal), or undulating (fluctuating above and below 90 degrees deviation).

1 Chemical products of ductless glands that are carried by the circulatory system and that influence various physiological processes in the body. ..2 An organic molecule synthesized by a plant that exerts, even in low concentrations, profound regulation of growth and/or development.

Horse power
A British unit of the measure for the rate at which energy is produced or used. 1 Hp = 746 watts.

The main structural body or shell of the boat, not including the deck, keel, mast, or cabin.

Human ecosystem
Environment surrounding and envolving human life and activity.

Humic compounds
Humic substances- Series of relatively high-molecular-weight, brown-to-black substances formed by secondary synthesis reactions. The term is generic in a sense that it describes the colored material or its fractions obtained on the basis of solubility characteristics, such as humic acid or fulvic acid.

Complex material resulting from partial decomposition of plant or animal matter and forming the organic portion of soil.

Hydraulic conductivity
Refers to the capability of subsurface materials (sand, rock etc.) to allow a fluid (usually water) to flow through it.

Hydro power
Power obtained from the natural movement of masses of water. Man has always tried to develop technology that converts energy from a natural resource into an energy he can harness to perform daily tasks. Remarking the continuous flow of water in streams, rivers, and tides, he has uncovered the potential of the renewable source. The waterwheel was the first development, using water flow to produce mechanical energy. In the last century, the creation of hydroelectric power has dramatically expanded the use of hydropower from mechanical energy to electrical energy. Being a renewable resource, water flow has an advantage over the consumption of fossil fuels. Because of its ability to produce large amounts of power, hydropower remains a major method of converting energy.

Hydrocarbon indicator
A type of seismic amplitude anomaly, seismic event, or characteristic of seismic data that can occur in a hydrocarbon-bearing reservoir. Although “bright spots,” as hydrocarbon indicators are loosely called, can originate in numerous ways, they are not all indicative of the presence of hydrocarbons. Criteria to distinguish true hydrocarbon indicators (sometimes called HCIs) from other types of amplitude anomalies include: -amplitude variation with offset -bright or dim spot(s) in amplitude as a result of variations in lithology and pore fluids, sometimes occurring in groups of stacked reservoirs -change or reversal in polarity because of velocity changes, also called phasing -diffractions that emanate from fluid contacts -shadow zones below the accumulation.

Hydrocarbonclastic bacteria
Bacteria and fungi able to feed on Hydrocarbonic molecules found in crude oil.

Organic chemical compounds of hydrogen and carbon atoms forming the basis of all petroleum products. They may exist as gases, liquids, or solids. An example of each is methane, hexane, and asphalt.

Hydrocyanic acid
Also known as Prussic Acid, which is Hydrogen Cyanide. These terms refer to the extremely poisonous derivative of certain plants.

Science concerned with mutual relations between living organisms and their water environment.

A refining process which improves some of the qualitative characteristics of refined distillates. Is the case of petroleum, when is treated with hydrogen in the presence of a catalyst under relatively mild conditions of temperature and pressure. Some hydrocracking may occur under more severe conditions.

The simpliest and lightest of the elements, that is normally a colorles, ordorless, highly flammable diatomic gas, that occurs in the free state only sparely on the earth and in its atmosphere though abundantly in the sun.

Hydrogen sulphide
Gas emitted during organic decomposition. Also a by-product of oil refining and combustion. Smells like rotten eggs and, in heavy concentration, can kill or cause illness.

The science that deals with subsurface waters and geologic aspects of surface waters.

The science that deals with global water (both liquid and solid), its properties, circulation, and distribution, on and under the Earth’s surface and in the atmosphere, from the moment of its precipitation until it is returned to the atmosphere through evapotranspiration or is discharged into the ocean. In recent years the scope of hydrology has been expanded to include environmental and economic aspects.

A device designed for use in detecting seismic energy in the form of pressure changes under water during marine seismic acquisition. Hydrophones are combined to form streamers that are towed by seismic vessels or deployed in a borehole. Geophones (see), unlike hydrophones, detect motion rather than pressure.

Hydroskimming refinery
A refinery with a configuration which only includes distillation (see), reforming (see), some hydrotreating (see), and occasionally sulphur recovery processes.

The aqueous envelope of the Earth, including the oceans, freshwater lakes, rivers, saline lakes and inland seas, soil moisture and vadose water, groundwater, and atmospheric vapor.

Usually refers to the hydrodesulphurisation process, but may also be applied to other treating processes using hydrogen.

A chemical compound containing the hydroxyl group (see).

Hydroxyl group
The hydroxide (OH) attached to a compound as a functional group. The functional group of an alcohol.




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