How do phosphate levels affect river water quality?

Answer 1

Phosphate will stimulate the growth of plankton and aquatic plants which provide food for larger organisms, including: zooplankton, fish, humans, and other mammals. this increased productivity will cause an increase in the fish population and overall biological diversity of the system. But as the phosphate loading continues and there is a buildup of phosphate in the lake or surface water ecosystem, the aging process of lake or surface water ecosystem will be accelerated. Eutrophication is enhanced production of primary producers resulting in reduced stability of the ecosystem. In situations where eutrophication occurs, the natural cycles become overwhelmed by an excess of one or more of the following: nutrients such as nitrate, phosphate, or organic waste. The system then reacts by producing more phytoplankton/vegetation than can be consumed by ecosystem. This overproduction can lead to a variety of problems ranging from anoxic waters (through decomposition) to toxic algal blooms and decrease in diversity, food supply and habitat destruction.

Answer 2

Phosphates, like organophosphates, are powerful pollutants in the correct form.

They are usually water-soluble with short life spans but accumulate quickly in organisms that are exposed to them, i.e. fish. Fish will accumulate the phosphates where an enzyme called acetylcholinesterase (AChE) is inhibited. This blocks receptor signals from crossing the synapses in our brains so that the signal can be processed.

There are many knock-on effects from this, such as physiological and behavioural degradation of the organisms exposed to the water, as well as effects seen in organisms that are higher up in the food chain that have been indirectly exposed.

In essence, higher phosphate levels decrease water quality.

Answer 3

Nitrates are primarily found in runoff from agricultural fertilizer usage. It is a major component of most fertilizers, both commercial and naturally produced. The purpose of nitrates in fertilizers is to promote green leaf growth. This promotes better photosynthesis in the plants, thus more lush growth. The concern in rivers and waterways is that water runoff from fertilized lands from rains and floods into the waterways, the nitrates promote algae growth, as well as some weed growth. These algae and weeds by growing disproportionately to other species have the undesirable result of chocking out more beneficial species of plants. Also the die out of these plants diminish food sources for aquatic animals, and in addition have another detrimental effect of removing oxygen from the water creating anaerobic "dead zones" in the rivers and waterways. A prime example of this is the growing dead zones at the outfall of the Mississippi River into the Gulf of Mexico where fish and natural salt marshes are being depleted in a large part as a result of run off containing nitrates.