Heavy metal contamination of pasture soils by irrigated municipal sewage

Effect of long-term irrigation with sewage effluent on the metal content of soils, Berlin, Germany

This study aimed to determine whether >110 years of sewage application has led to recognizable changes in the metal chemistry of soils from former sewage farms, Berlin, Germany. Background concentrations of soils and element enrichment factors were used for the evaluation of possible perturbations of natural element abundances in sewage farm soils. Calculations verify that precious metals (Ag, Au) as well as P, C(org), and heavy metals (Cd, Cu, Ni, Pb, Sn, and Zn) are invariably enriched in sewage farm topsoils (0-0.1 m depth) compared to local and regional background soils. Long-term irrigation of soils with municipal wastewater has caused significant heavy metal contamination as well as a pronounced enrichment in precious metals. Leaching of metals including Ag into underlying aquifers may impact on the quality of drinking water supplies.

Effects of sulfur dioxide pollution on the translocation and accumulation of heavy metals in soybean grain

BACKGROUND

Open-top chambers were used to study the impact of simultaneous exposure to atmospheric SO(2) pollution and heavy metal contamination in soils on the metal contents and productivity of soybean plant.

METHODS

Plants were exposed at ambient levels as control SO(2) (1.2 ppb), low SO(2) (97 ppb), and high SO(2) (490 ppb) over the whole growing season while simultaneously being exposed to either Cd (0.5 mg kg(-1)), Pb (250 mg kg(-1)), Cu (100 mg kg(-1)), or Zn (150 mg kg(-1)) in soil.

RESULTS

This experimental study covering the whole growth season has shown that SO(2) has a synergistic effect in enhancing the heavy metal contents in aboveground tissues of soybean plant, and the effects of high SO(2) treatment were found to be highly significant, showing increases of 42% and 29% for Cu and Cd content of grain, respectively.

CONCLUSION

The research findings are of practical significance in the environmental control for the combined pollution of air and soil to ensure the quality of agricultural products and therefore benefits for human health.

Quantifying effects of soil heterogeneity on groundwater pollution at four sites in USA

Four sites located in the north-eastern region of the United States of America have been chosen to investigate the impacts of soil heterogeneity in the transport of solutes (bromide and chloride) through the vadose zone (the zone in the soil that lies below the root zone and above the permanent saturated groundwater). A recently proposed mathematical model based on the cumulative beta distribution has been deployed to compare and contrast the regions' heterogeneity from multiple sample percolation experiments. Significant differences in patterns of solute leaching were observed even over a small spatial scale, indicating that traditional sampling methods for solute transport, for example the gravity pan or suction lysimeters, or more recent inventions such as the multiple sample percolation systems may not be effective in estimating solute fluxes in soils when a significant degree of soil heterogeneity is present. Consequently, ignoring soil heterogeneity in solute transport studies will likely result in under- or overprediction of leached fluxes and potentially lead to serious pollution of soils and/or groundwater. The cumulative beta distribution technique is found to be a versatile and simple technique of gaining valuable information regarding soil heterogeneity effects on solute transport. It is also an excellent tool for guiding future decisions of experimental designs particularly in regard to the number of samples within one site and the number of sampling locations between sites required to obtain a representative estimate of field solute or drainage flux.