Impact of peri-urban landscape on the organic and mineral contamination of pond waters and related risk assessment.

Abstract

Ponds are important for their ecological value and for the ecosystem services they provide to human societies, but they are strongly affected by human activities. Peri-urban development, currently one of the most pervasive processes of land use change in Europe, exposes ponds to both urban and agricultural contaminants, causing a potential combination of adverse effects. This study, focused on 12 ponds located in a peri-urban area, has two main objectives: (1) to link the physico-chemical characteristics of the waters and the nature of their contaminants, either organic or mineral, with the human activities around ponds, and (2) to estimate the environmental risk caused by these contaminants. The ponds were sampled during two consecutive years in both spring and in autumn. Although the ponds were distributed over a limited geographical area, their contamination profiles were different and more correlated with the agricultural than the urban land use. In terms of aptitude for biology, half of the ponds were classified in degraded states due to their physico-chemical parameters, but without correlation with the endocrine disrupting activities and the levels of organic pollutants as indicators. The main quantified organic pollutants, however, were pesticides with sufficiently high levels in certain cases to induce an environmental risk exceeding the classical thresholds of risk quotient.