ABSTRACT
It is difficult to predict the effects of pollutants on organisms to an acceptable degree of accuracy by simply measuring concentrations of a chemical in the abiotic environment (figure 11.1). Factors which affect bioavailability of chemicals to organisms include temperature fluctuations, interactions with other pollutants, soil and sediment type, rainfall, pH and salinity. Even using biotic monitoring of chemical residue levels (see section 11.3), there are considerable difficulties in knowing the effects of this level of chemical on the organism. This process is made more difficult by the presence of mixtures (see Chapter 10) and the considerable interspecies differences in response. In situ biological monitoring attempts to get around these problems by analysing various parameters of natural populations which reflect the situation in the field rather than the standardized conditions of laboratory experiments.
