Use of Chemical Monitors or Accumulator Species in Biomonitoring

Many organisms accumulate large quantities of specific pollutants in their bodies. Metals or persistent pesticides present in undetectable quantities in the soil or water may occur in plants and animals in concentrations many times higher than the soil or the surrounding medium in which they grow.

Chemical analyses of these organisms enable us to detect very small amounts of persistent pollutants which are very difficult otherwise even with the help of very sophisticated physico- chemical and spectrophotometric or nuclear methods of analyses available to us.

Higher concentrations of persistent pollutants are built up and maintained by accumulator organisms during the period of their active vegetative growth till an optimum level of pollutant is reached within their systems after which the absorption tapers off and may stop altogether. If these organisms are collected, analysed after a period of active vegetative growth the results may provide reliable estimate of the concentration of the pollutant concerned in the medium. Plants are particularly useful in this respect.

Many members of family Brassicaceae can absorb enormous amounts of heavy metals and clean up the soil Alyssium lebiacum extracts and accumulates Nickel from the soil. Thlaspicoerulescens is an efficient accumulator of Cadmium. Selenium is accumulated by Brassica napus. Festuca sp. accumulates lead. Plants of Agrostic sp. efficiently accumulate copper from the soil.

The use of chemical monitors or accumulator species not only enables us to detect very low levels of toxicants in the environment but also gives us an idea of long term concentration and accumulation trends. Chemical analysis usually provides us information about the concentration of pollutant at a specific time and place only.

By examining the toxicant’s concentration in the organicms in different age groups, we can have an idea of past absorption trends and by extending these studies to different trophic levels we can get an idea of the movement of toxicant through different components of the food chain.