Integrated Ecological Risk Assessment of the Agricultural Area under a High Anthropopressure Based on Chemical, Ecotoxicological and Ecological Indicators

Agricultural land is often located close to highly urbanised/industrialised areas and is subject to continuous anthropogenic pressure associated with the emission of many pollutants, ultimately deposited in the soil. Most studies on ecological risk assessment have only analysed the total contaminants' concentration, which does not reflect their bioavailability or toxicity and often leads to an overestimation of risk. Therefore, in our study, we used an interdisciplinary approach, whereby the final conclusions about the risk in a given area are based on the integration of detailed data from chemical, ecotoxicological and ecological analysis. The research was carried out on agricultural land exposed to high levels of anthropopression for more than 100 years. Chemical measurements comprised both the total and bioavailable PAH content. A battery of bio-assays describing effects on soil retention and habitat function was used for ecotoxicity testing, and ecological indicators included enzymatic activity, respiration, microbial biomass, carbon mineralisation and nitrification. The integrated IntRisk index ranged from 0.19 to 0.94, and this was mainly due to high values of the chemical risk index, while the ecotoxicological and ecological results indicated no or low risk. The majority of the area (almost 90%) had acceptable risk levels, no/low risk (IntRisk < 0.5) at 57% of the sites and medium risk at 28% of the area. Very high unacceptable risk (IntRisk 0.77-0.94) was only at three sampling sites. The integration of data from a set of 15 indicators allowed us to derive quantitative risk indexes and delineate the limited area which needs additional action.