Pesticides water quality indicator

In this section, we concentrate on indicators that are appropriate for evaluating the impact of different farming systems on water quality, such as nitrate leaching and pesticides. 

Using the thermodynamic distribution coefficient for the choice of the best LLE parameters for quantitative extraction of pesticides from water is usually not done. The time to determine the distribution coefficient of a pesticide under different water quality conditions and with different solvents has seemed to justify picking these parameters arbitrarily. Then the parameters chosen are tested by fortifying, usually in distilled water. As indicated above, the arbitrary approach does not work well. A systematic procedure based upon the distribution coefficient is strongly suggested to replace the arbitrary approach. In time a Standard Method for choosing the parameters of LLE for quantitative pesticide analysis may evolve from careful comparative study of parameters. 

Water quality is of paramount importance in the Nedierlands. This applies to both ground water and surface water. The OECD indicators emphasise nitrate and phosphoms. Nitrate load is sometimes lower and sometimes higher in organically managed soils. Phosphate pollution in, and eutrophication of surface water will occur less in organic production systems. Additionally, the pesticide load in ground and surface water evidently is lower in organic production systems than in conventional systems. 

In practice, the framework indicates that water quality, temperature, tank environment and feeding should be optimal, while invasive manipulation of the stock should be minimal. Therefore, for a broodstock or potential broodstock, the water quaUty should be the best available, oxygen levels, pH and contaminants (ammonia, nitrates and pollutants such as fertilisers, herbicides and pesticides) need to be in optimal ranges for the species. 

The principles of ecotoxicological quality classification based on the TU index are included in the 2002 recommendations of the Helsinki Commission (HELCOM). The classification applies to samples of treated effluents discharged to waters from industrial plants manufacturing chemicals,98 textiles,99 and pesticides.100 HELCOM recommends testing the acute toxicity of effluent samples using two of the four suggested indicator organisms (Table 9.6). 

---