Effects Of Sewage Pollution

6 Pages 1405 Words

Issue

What are the negative influences of Sewage Pollution on Marine Life?

Introduction

By far the greatest volume of waste discharged to the marine environment is sewage. Without treatment, crude sewage flows into natural waters and causes pollution. Sewage effluent contains industrial waste, rainwater and water from domestic baths and washing machines, fats, faecal matter and anything washed down drains or flushed down the toilet. Untreated sewage contains bathroom waste such as condoms, cotton bud sticks and sanitary products. Within the report Beachwatch 2003 - the MCS national beach litter survey – “sewage related debris constituted 7.8% of the total litter collected”. (Beachwatch 2003)

Faecal material in low concentrations has little effect on the marine environment and may actually benefit the ecosystem through the input of particulates and nutrients. Sewage pollution is caused when high concentrations of untreated industrial and domestic waste enter the marine environment. This degrading pollution is not only a concern because it is a risk to human health, but in particular it causes algae blooms and weed growth, which kills corals and other environmental areas.

Biological Significance

Sewage is mainly organic in nature and therefore produces bacterial decay consequently the oxygen concentration in the water is reduced, which greatly affects the marine life. Sewage is said to have a high Biological Oxygen Demand, which means it uses up lots of dissolved oxygen. This can starve aquatic life of the oxygen they need, and also causes the breakdown of proteins, anaerobic bacteria and other nitrogenous compounds, releasing hydrogen sulphide and ammonia, which are potentially toxic to marine organisms in small concentrations. Solids suspended in sewage may also blanket river and seabed’s preventing respiration of the benthic flora and fauna.

This decaying matter also boosts plant growth. Exces...