Question

a) Give examples of 2 different biomonitoring approaches that could be used to assess the toxicity of a water source b) Define what WET tests are and how you wold apply them for the biomonitoring of a water body c) Discuss the difference between the olfactory and chemical analysis for the assessment of odorous emissions

Answer 1

1. Biological monitoring, or biomonitoring, is the use of biological responses to assess changes in the environment, generally changes due to anthropogenic causes. Biomonitoring programs may be qualitative, semi-quantitative, or quantitative. Biomonitoring is a valuable assessment tool that is receiving increased use in water quality monitoring programs of all types.

There are two types of biomonitoring. One type of biomonitoring is surveillance before and after a project is complete or before and after a toxic substance enters the water. The other type of biomonitoring is to ensure compliance with regulations or guidelines or to ensure water quality is maintained.

2. Whole Effluent Toxicity (WET) refers to the aggregate toxic effect to aquatic organisms from all pollutants contained in a facility's wastewater (effluent). It is of two type 1. Acute toxicity tests and 2. Chronic toxicity tests. The acute test involves 20 test organism and done within 24 to 96 hrs whereas Chronic is done within 8 to 9 days. The output gives Lethal combination i.e LC50 that kills 50% of the aquatic organism. and NOEL indicates no observed effect level.

3.

Olfactory	chemical analysis
The main instrument used here is human olfactory gland along with human brain make a perception of different odor which is based on the experience of thousands of years of evolution.	On the other hand, this method uses the application of Gas Chromatography along with mass spectroscopy to analyze the human perception of a complex chemical in compounds.
This method is accurate and tells the likes and dislikes of the emission quickly	This method is still in the development stage and yet not accurately define human acceptance with a complex chemical mixture available.