No abstract

In Brazil, there is a lack of combined soil-plant data attempting to explain the influence of specific climate, soil conditions, and crop management on heavy metal uptake and accumulation by plants. As a consequence, soil-plant relationships to be used in risk assessments or for derivation of soil screening values are not available. Our objective in this study was to develop empirical soil-plant models for Cd, Cu, Pb, Ni, and Zn, in order to derive appropriate soil screening values representative of humid tropical regions such as the state of São Paulo (SP), Brazil. Soil and plant samples from 25 vegetable species in the production areas of SP were collected. The concentrations of metals found in these soil samples were relatively low. Therefore, data from temperate regions were included in our study. The soil-plant relations derived had a good performance for SP conditions for 8 out of 10 combinations of metal and vegetable species. The bioconcentration factor (BCF) values for Cd, Cu, Ni, Pb, and Zn in lettuce and for Cd, Cu, Pb, and Zn in carrot were determined under three exposure scenarios at pH 5 and 6. The application of soil-plant models and the BCFs proposed in this study can be an important tool to derive national soil quality criteria. However, this methodological approach includes data assessed under different climatic conditions and soil types and need to be carefully considered.

There is a political demand on the efficiency of environmental policy. Cost-benefit analyses (CBAs) can play a role in answering that demand. This societal CBA for nationwide soil remediation operations in The Netherlands distinguishes 4 alternatives for future investments. In the zero alternative government funding will be terminated. Besides this, 3 policy alternatives are distinguished that are government financed. Soil remediation benefits human health, the drinking water supply, housing, perceptions, and the ecosystem. Soil remediation also answers the concerns of the Dutch population. The benefits to health (exposure to cadmium, lead, and carcinogens), drinking water supply, and housing are expressed in monetary terms. The extent that benefits equal the money spent depends partly on the value-loaded choice for the discount rate. Use of the current discount rate of 4% will mean a slightly negative balance whichever policy alternative is chosen. Focusing on nonmoneterized benefits, such as ecology, can cause the scales to tip in another direction. Using a lower discount rate will make future benefits, such as health and drinking water supply, more important. If the discount rate drops to 2% or less, all policy alternatives lead to a positive balance. Predominantly, the health benefits that are veiled in uncertainty can become a reason for applying a surcharge and, in turn, a higher discount rate. In that case, each of the alternatives will result in a net negative balance.