lti_ecn_abs.html

Two sites are being monitored on Loch Lomond in considerable detail for a wide range of chemical and biological parameters as part of a long-term UK programme to monitor environmental changes in rivers and lakes.

Water, sediment and biota samples will be collected at the frequency shown and for the following determinands, as required by the UK programme, or included in addition to the required list because of environmental interest:

Environmental Change Network (Water Chemistry) - Pesticide Survey

The results that have been obtained to date from surveys of rivers and discharges for the presence of a range of pesticidal substances (see Red List/Annex 1A survey) have shown that the great majority are at undetectable levels. This is because many of the pesticidal substances in the Red List of substances have been phase out of use, some many years ago.

However, pesticides are used in agriculture to eliminate problems of insects, weeds fungus and by local authorities and Railtrack to keep roads, paths and railway lines free of weeds. Pesticides are also used in forestry operations to protect trees from insect damage and to clear undergrowths of competing weeds.

For weedkilling, the preferred substances were the triazine compounds, particularly simazine and atrazine. However, these pesticides have been withdrawn for most uses because of problems with their persistence in drainage water and receiving streams, and new compounds have been introduced as replacements.

Details of the replacement substances were sought from the District and Regional Councils and from Railtrack. They responded that the triazines have been replaced by glyphosate and/or diuron. Both of these substances are readily biodegradable, with diuron having a greater toxicity to freshwater fish than glyphosate.

Although the concentration of the triazine herbicides in urban rivers has declined markedly in the last three years, monitoring of rivers for their presence, and for diuron will continue over the weedkilling season (April- September).

For the agricultural pesticides, information has been obtained from the Scottish Agricultural Science Agency about the most commonly used pesticidal materials used on farms in the former CRBs area. From the data supplied, the relative toxicity to freshwater fish of the main substances used has been assessed.

Further information: Environmental Change Network - Sampling Determinands Abstract:

Further information: Environmental Change Network - Sampling Determinands
Abstract: