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Arsenic (As) is a naturally occuring element in soils. It is a non essential trace metal that can have toxic effects in both plants and animal at relatively low concentrations. Anthropogenic sources of As have included its use in insecticides, herbicides and defoliants in the past while today its commonly used in agricultural production include mining and smelting of non-ferrous metals from runoff or mine tailing waste or smelter emissions.  It is widely used as a feed additive for poultry and swine, and the resulting manures can contain elevated As concentrations. Minor sources of As are also derived from phosphate fertilisers, and fossil fuel combustion. This study was completed to investigate the potential sources of the seasonal elevated concentrations of As in Christchurch municipal compost and to investigate potential issues arising from the application of the compost product to agricultural soils in terms of trace metal accumulation. Results indicated a significant trend in As where concentrations were at a minimum during winter while also having significant positive correlations with both chromium (Cr) and copper (Cu). Additionally, As had a significant negative correlation with average Christchurch temperatures, which all suggested CCA treated timber could be a possible source of the variation due to the burning of the treated timber and subsequent addition of the ashes to the green waste bins. An accumulation model was also formulated to attempt to quantify the accumulation of As, Cu, and lead (Pb) within agricultural soil.

To determine the impact that chromated copper arsenate (CCA)-contaminated mulch imposes on the environment and human health, forty commercially purchased mulch samples from Cincinnati Metropolitan area were studied. This study was conducted in three phases; (1) quantified TCLP metal concentrations leached from each mulch, (2) conducted bioavailability studies to determine potential threats to human health from mulch, and (3) analyzed rhizosphere microbial communities before and after mulch application through plate counts. It was found that the mulches leached chromium, copper, and arsenic. In the bioavailability and microbial studies, there were no significant differences observed between the composite mulch and negative control mulch treatments. In all cases, metals accumulated in the edible plant portions were at concentrations below the recommended daily doses. These results provide an indication of the potential threat to human health from CCA-contaminated mulch, and calls for public awareness / educational programs about mulch uses.