Water Quality

Water is a primary component of the biosphere.

Adequate supplies of clean water are vital for agriculture, domestic use, recreation, wildlife, and thousands of manufacturing and mining process.

Environmental quality play a major role in development of designs and managament strategies.

Intensive Livestock production in some areas of the United State.

Many common used herbicides have been found in water supplies.

Many municipal waste treatment plants land-apply waste water and sludge that contains trace amounts of heavy metals.

Examples that can be found throughout the world where production oriented practices have resulted in environmental threats

Parameters where quality of aquatic habitat involve

Temperature Channel characteristics Turbidity Dissolved oxygen

Water Quality Issues

pH Alkalinity Temperature Dissolved oxygen Turbidity Sediments macronutrients Other inorganic

species

Hardness Organic matter Salinity Pesticides Nonaqueous-phase

liquids solvent

Factors may be involved in any water quality situation

Oligotrophic –clear water with little organic matter or sediment and minimum biological activity.

Mesotropic –water with more nutrients, and therefore, more biological productivity.

Eutropic –water extremely rich in nutrients, with high biological productivity. Some species may be choked

out.

Trophic States

Hypereutropic –Murky, highly productive water, closest to the wetland

status. Many clear water species cannot survive.

Dystropic –low in nutrients, highly colored with dissolved humic organic material.

The quality of natural water as habitat for aquatic species is strongly related to the amount of oxygen available in water.

The amount of dissolved oxygen (DO) naturally varies with depth in water column.

Dissolved Oxygen

Contaminants are naturally occurring, but their release may be influenced by human activity.

Contaminants sources that are particularly important in rural areas include fertilizer, pesticides, septic tank effluent, animal wastes, and agricultural and municipal sludges.

Contaminant Sources

Protozoan cysts range from 2 to 15 microns. The most common include Giardia lamblia, Entamoeba histolytica, and Cryptosporidium.

Schitosomiasis is found in streambanks in the tropic and is a major cause of disease in those regions.

Protozoa

Bacteria range in size from 0.2 to 0.6 microns.

It can cause cholera (Vibrio cholerae), typhoid fever (Salmonella serogroup Typhi) and epidemic dysentery.

Bacteria

Viruses are the smallest microorganisms, ranging from 0.01 to 0.03 microns.

Enteric viruses infect the gastrointestinal tract of mammals and are excreted in feces.

Water-borne viruses of particular concern include hepatitis A, most of which infect the intestine and/or the upper respiratory tract.

Viruses

Concentration Units◦ Molal concentration (molality)◦ Molar concentration (molarity)◦ Normal concentration (normnality)◦ Mass concentration◦ Equivalent per liter◦ Parts per million (ppm)

Chemical Contaminants

Macronutrients- Nitrogen and Phosphorus

◦ Nitrogen(N) and phosphorus (P) are the primary macronutrients of concern with water quality.

◦ In fresh water systems, cyanobacteria (blue-green algae) are able to fix nitrogen from the atmosphere, so P is usually the limiting nutrient.

◦ Nitrogen accounts for about 78% of the atmosphere, but the dominant gaseous form(N2) cannot be used directly by most plants.

Inorganic Chemicals A few of the most common that are subject

to federal regulation include arsenic, barium, selenium, beryllium, cadmium, chromium, copper, cyanide, fluoride, lead, mercury, selenium, and thallium.

Heavy metals typically adsorb to soil minerals or organic matters, or form complexes or chelates.

Water hardness is defined as the total concentration of the metallic cations.

Organic Chemicals◦ It includes thousands of compounds, both

synthetic and natural. Those of greatest concern for water quality include pesticides, and industrial chemicals.

◦ Organic materials can be quantified with collective parameters such as : Chemical Oxygen Demand (COD) Biological Oxygen Demand (BOD) Dissolved Organic Carbon (DOC) Total Organic Carbon (TOC)

Sediments◦ The most common contaminant and far the

largest (by mass).ExamplesSoil particles that have become suspended either

through erosion from upland areasStreambank erosionDetachment of streambed particles

Physical Contaminant

Carbonate and silica biocrystals are a minor source of sediment.

Biocrystals are formed by organisms such as mollusk, foraminifers, sponges, and diatoms.

Maximum Contaminant Level (MCL) Maximum Contaminant Level Goal (MCLG) Maximum Residual Disinfectant Level

(MRDL) Maximum Residual Disinfectant Level Goal

(MRDL) Treatment Techniques (TT)

Selected drinking water standards

The term turbidity refers to the murkiness of the water. It is quantified by measuring the degree to which light is scattered by suspended particulates( sediment and organic matter) in the water.

Turbidity

Clarification Filtration Ion Exchange Disinfection Reverse Osmosis Distillation

Water Treatment