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The impact of fecal contamination from human and agricultural animal waste on water quality is a major public health concern. Identification of the dominant source(s) of fecal pollution in a watershed is necessary for assessing the safety of recreational water and protecting water resources. A field study was conducted using quantitative PCR (qPCR) for the 16S rRNA gene of Brevibacterium sp. LA35 to track feces-contaminated poultry litter in environmental samples. Based on sensitivity and specificity characteristics of the qPCR method, the Bayesian conditional probability that detection of the LA35 marker gene in a water sample represented a true-positive result was 93%. The marker's covariance with fecal indicator bacteria (FIB) and metals associated with poultry litter was also assessed in litter, runoff, surface water, and groundwater samples. LA35 was detected in water and soil samples collected throughout the watershed, and its concentration covaried with concentrations of Escherichia coli, enterococci, As, Cu, P, and Zn. Significantly greater concentrations of FIB, As, Cu, P, and Zn were observed in edge-of-field runoff samples in which LA35 was detected, compared to samples in which it was not detected. Furthermore, As, Cu, P, and Zn concentrations covaried in environmental samples in which LA35 was detected and typically did not in samples in which the marker gene was not detected. The covariance of the poultry-specific LA35 marker gene with these known contaminants from poultry feces provides further evidence that it is a useful tool for assessing the impact of poultry-derived fecal pollution in environmental waters.

From a human health perspective, knowledge of Cr speciation in soils is important in assessing risk related to ingestion of Cr‐contaminated soils, and in selecting appropriate remedial alternatives that are protective of ground‐water quality. In this study, good agreement was found between Cr (VI) soil concentrations and the mass of Cr (VI) leached from columns over a range of Cr (III):Cr (VI) soil ratios (0.2‐28) and ΣCr concentrations (27–290 mg/kg). In batch tests, adsorption of Cr(VI) to sandy soils was rapid and linear, with a KdCr(VI) of 0.2 liters/kg, suggesting Cr(Vl)‐contaminated vadose‐ and saturated‐zone materials may be remediated by soil flushing or pump‐and‐treat methods. In column tests, soil flushing removed 85% of the soil‐Cr(VI), while pump‐and‐treat leached only 17% of Cr attributable to aquifer contamination. Use of oxidizing agents increased Cr released from Cr(III)‐contaminated soils, but only from 1.3% to 2.3% of ΣCr mass. Based on Cr speciation in soils, Cr(VI) was mobile, while Cr(III)was retained in the soil column, indicating that reduction of Cr(VI) to Cr(III), and the proportion of Cr(III) in the soil, will constrain remedial efficiency. Reduction of Cr(VI) to Cr(III), and subsequent precipitation of CrxFe1−x (OH)3, occurred in a Cr(VI)‐contaminated soil augmented with Fe+2, resulting in < 0.01 mg/1 Cr in the supernatant, suggesting that in situ Cr fixation may mitigate Cr‐contaminated ground water.

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Water quality degradation in the Illinois River Watershed (IRW) has been linked to excess nutrients, primarily phosphorus (P). A mass balance study was performed on the IRW in Oklahoma and Arkansas to quantify the magnitude of P entering the watershed between the closure of Lake Tenkiller’s dam in 1954 to 2006. Results showed that a substantial mass of P was, and is, being imported into the watershed relative to the mass of P leaving the watershed. The study demonstrated that poultry production has been the major contributor of P imported to the watershed since 1964, and is currently responsible for more than 76% of the net annual P additions to the IRW. Between 1949 and 2002, more than 200,000 tonnes of P was added to the IRW. A P delivery ratio for the IRW was computed from the mass balance results and observed loads indicating that 4% of annual P applied to the IRW landscape reached Lake Tenkiller between 1999 and 2006. Allocation of P loads from 1949 to 2002 to Lake Tenkiller computed with the delivery ratio showed that wastewater treatment plant (WWTP) discharges were responsible for more than 50% of P reaching Lake Tenkiller in 1949, followed by dairy cattle (32% of loads). Poultry contribution to P reaching Lake Tenkiller was 5% in 1949 but increased rapidly to become the largest source in 1969 at approximately 49%, and in 2002 at 54%. Both dairy and WWTP portions of the loads declined from 1949 levels with less than 4% attributable to dairy and less than 34% assigned to WWTP in 2002.

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