A healthy river or estuary is comprised of a number of different factors, including water flow, biodiversity, sedimentation, turbidity and water quality. When the system is in good condition, all of these factors are in balance and the rest of the catchment or marine environment are also in better condition. When any of these factors are thrown out of balance through inappropriate land use, the entire system is affected.

For many reasons, degradation is not easily seen but scientists recently measured its effect by accident as shown on the diagram. We have some 17 coastal marine reserves, and the Poor Knights Islands, located far out in sea on the edge of the continental shelf, is certainly our best, still with the cleanest water of all. Yet we observed a sharp decline in the quantity and quality of fish since the late 1980s, followed by mass mortalities in 1983, 1992 and 2001 (see degradation timeline). See similar questions...

There are a variety of factors that can impact the taste or smell of tap water but not change the quality of the water. In Charleston Water System's case, algae in our surface water, when put through the treatment process, can give off harmless compounds that may cause the water to taste earthy or musty. In most cases, taste and odor is a purely aesthetic concern, and is not a reliable indicator of water quality. See similar questions...

elephant has much more genetic information in its genes, which took many hundreds of millions of years to evolve by trial and error. Thus both the amount of evolutionary time and the amount of genetic information in a species are objective measures of quality. Bacteria just do not come near. Besides, it takes only a few days to generate a new bacterium species, and what's more, they can exchange genetic information readily by means of viruses. See similar questions...

Mud and diatom strings need calm water before they can settle out. Waves (and strong currents) prevent this. But even when sediment has accrued over a period of calm weather, successive large waves have a cleansing effect. Near the surface it is the sheer force of the water movement which cleanses the rock and organisms. But also in the deep large waves pick up the sand and cleanse the substrate and organisms by scouring them as in sand blasting. See similar questions...

Polymer degradation is the opposite of crosslinking. When the electron from an E-beam hits a molecule, it can break the molecular bonds. This is useful in a number of areas. Electron beam is used to treat Teflon (PTFE: Poly Tetra Fluoro Ethylene). Teflon is commonly used as a lubricant in inks; this requires the Teflon to be ground into a very fine powder. The E-beam is required to break the bonds within the long strings of the Teflon molecule in order to allow the grinding. See similar questions...

Water that is hard contains calcium and magnesium compounds. Rain water is naturally soft - it does not contain any minerals, but as it seeps through the ground it can pick up minerals, such as calcium and magnesium compounds, from the soil and rocks it passes through. If rain water passes through soft rocks like chalk or limestone, it picks up these minerals. If it passes through hard rocks, such as granite or through peaty soils, it does not pick up these minerals and so remains soft. See similar questions...

Iron and manganese, which occur naturally in well water, can cause a rusty color. It is not harmful. Water can also become discolored from a malfunctioning water softener. The hardness is 17 grains per gallon. After leaving the water treatment plant, the iron and manganese content are both less than 0.008 parts per million. See similar questions...

It is most likely sediment from your water heater - chemicals added to tap water tend to clump and fall to the bottom of a water heater when it is not being used. It may also be from the dip tube inside the heater. The best solution in this case is to replace your water heater and clean out your pipes. If you live in an area with hard water, it may be caused by calcium deposits as well. See similar questions...

There are many possible causes, but the most usual reason is the disturbance of any deposits present in the water mains. This can happen when there is a change in the direction or speed of flow of the water. See similar questions...

Dirt and oil from bathers is the largest cause. Regular brushing and using cleaners designed for pools is suggested for cleaning this from the surface. See similar questions...

Cy, JUDGE DREDD, Madtoscratch, Lianne, lutece, SueB, akesingland, riaY, bryndavell, Groovygirl, david_8, SJ, Terrimayormaynot, jjoblogs1, anglichanin, Tom_B, bubble, TrishR, squoink, GATTACA, willy, Roger, margurita_simpson, snowy, beacon, LyndsayA, stripe77, Snow Surfer, lighthearted The material has been extracted from Psoriasis at your fingertips by Dr Tim Mitchell & Rebecca Penzer (Class Publishing). See similar questions...

It has been misconceived that "degradation" means being unable to use because of total loss of oil properties. But nearly for all cases, it means that it is contaminated.. Removing contaminants, oil can be used for a long time. However, the additives, very important in oils, are consumed during service, and thus they have to be replenished by adding oils. Generally, by keeping oil always in normal conditions, one can reduce the additive consumption as well. See similar questions...

This stain comes from the chemical copper. Copper is present in your home plumbing and may be being dissolved into the drinking water. If you would like to have your water tested for Lead and Copper, please contact the Portland Water District. See similar questions...

Colored water results either from algae blooming or the oxidation of minerals in the water. Algae comes in a variety of colors and can be found on the surface of the water or the pool itself. The more likely reason occurs after shocking a freshly filled pool that is full of natural minerals like iron, copper or magnesium. The shock oxidizes the metals causing the discoloration of brown, green or red. See similar questions...