Assessment of domestic landfill leachate toxicity to the Asian clam Corbicula fluminea via biomarkers.

In order to evaluate the effects of domestic landfill leachate to bivalves Corbicula fluminea, clams were exposed to different leachate concentrations (v/v): 2, 3, 6 and 10 percent, corresponding to dilutions observed along a stream that receives this effluent, or only to clean water for comparisons. After 5 and 15 days of exposure the activity of the biotransformation enzymes 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST), the multixenobiotic resistance mechanism (MXR) and lipid peroxidation (LPO) in gills and digestive gland and metallothionein (MT) content in gills were evaluated. Differences in biomarkers responses were observed between gills and digestive gland, except for MXR that decreased in both tissues of clams exposed to 6 percent for 5 days. EROD activity in gills was reduced in all leachate concentrations after 5 days and only in 2 percent after 15 days exposure, while an EROD increase was observed in digestive gland after 15 days exposure to 6 percent. GST activity increased only in the gills of clams exposed to 10 percent for 5 days. LPO varied between tissues and different conditions. A significant increase in LPO was observed in the gills, after 5 days exposure to 2 and 6 percent, and in digestive gland after 5 and 15 days exposure to 2 and 3 percent. MT content in the gills increased after 15 days exposure to 2 percent. In conclusion, different leachate concentrations tested here caused biochemical changes in C. fluminea, but due to the observed variability in biomarkers responses among leachate concentrations, it was difficult to determine patterns or thresholds concentrations.

Geophysical technique and groundwater monitoring to detect leachate contamination in the surrounding area of a landfill--Londrina (PR--Brazil).

The aim of the present study was to define leachate plume by using two techniques: geophysical and groundwater sampling in order to evaluate groundwater contamination. After performing a topographic survey and using geophysics, the leachate plume was identified. With this data, the wells for groundwater monitoring were located. Groundwater samples were analyzed for: COD, BOD, pH, alkalinity, conductivity, TKN and heavy metals. Through the electroresistivity method it was possible to define the shape of plume contamination. This method was important to locate the groundwater monitoring wells. The results of the physicochemical parameters showed the suitability of the geophysical study. The highest values of electric conductivity and alkalinity correspond to the wells located in the area interpreted as contaminated by leachate in the map of the resistivity. Even with seasonal variations, BOD values are low if compared to Brazilian environmental regulations, but COD values are higher up to 40 times the values of BOD. The concentrations of Ni, Zn, Cd and Cu in the groundwater are below the limits established by the potable water quality standards in Brazil, except for Pb whose concentration in groundwater were higher if compared to Brazilian legislation.