Arsenic (As) and chromium (Cr) are two contaminants that are detected in aquatic and terrestrial habitats. Using the spotted salamander, Ambystoma maculatum, to assess impacts from these contaminants may be advantageous as adults live and breed in such environments. Adult amphibians typically exhibit elevated tissue concentrations of contaminants present in their environment, while larval stages were found to exhibit increased sensitivity to pollutants. From January through March of 2015, during the spring breeding season, 5 adults and approximately 32 egg masses were collected from a local breeding site. Field levels of As and Cr ranged from 5.99 to 8.88 µg/L and 1.45 to 2 µg/L, respectively, while mean adult As tissue concentrations were 56.74 µg/g dry weight for heart, 0.92 µg/g for liver, and 1.21 µg/g for tail tissue. Mean tissue concentrations for Cr were 87.64 µg/g for heart, 1.47 µg/g for liver, and 6.92 µg/g for tail. Developing larvae that were collected from the field and exposed in a lab setting for 12 d to 0.2 or 20 mg/L of either As or Cr displayed little DNA damage attributed to As, but marked damage due to exposure to 20 mg/L Cr when assessed using the comet assay. Exposure to a mixture of either 0.25:0.1 or 25:10 mg/L As and Cr resulted in significant DNA damage at the lower concentration of 0.25:0.1 mg/L. As adult spotted salamanders were found to possess high concentrations of these contaminants in cardiac tissue, and larvae were shown to be susceptible to DNA damage from increased exposures, assessing impacts and potential declines of amphibian populations exposed to As and Cr is needed.

Using biosolids from the Hampton Roads Sanitation District (HRSD), laboratory studies were conducted to provide an insight into the behavior of this material when it is applied on land. The interaction and affinity of the biosolids for heavy metals was determined by packing reactor columns with known amounts of the biosolids and passing through the packed columns aliquots of several heavy metal solutions including, cobalt, copper, lead, iron, manganese, and zinc. The process was repeated until the retention capacity of the columns was reached. Solution parameters were varied to allow investigations of the influence of pH, ionic strength, and inter-elemental effects. The affinity of the biosolids for each metal was determined by calculating the mass of the metal that was adsorbed on the biosolids (removed from the solution) per gram of the biosolids. Using batch and reactor column procedures, samples of the biosolids were fractionated to determine water soluble, exchangeable, adsorbed, organically bound, carbonate, and sulfide fractions and to determine the lability, mobility, and availability of the heavy metal and other contaminants in those fractions. A fractional distribution extraction protocol was specifically conducted for the lead-biosolids complex to provide an insight into the lability and bioavailability of the biosolids-bound lead. The affinity of metal ions for the biosolids was found to increase in the order Pb>Fe>Cu>Zn>Ni>Mn>Co. Correspondingly, synergistic effects of the different metals led to characteristic decreases in the respective binding capacities. A decrease in system pH led to a decrease in the binding capacity, a trend that was also observed when the ionic strength increased. Using lead as a model, fractionation studies revealed that adsorption of lead by biosolids is mainly associated with the carbonate fraction.

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Anthropogenic activity has contributed to elevated environmental concentrations of arsenic (As) and chromium (Cr). The spotted salamander, Ambystoma maculatum, may be useful for identifying developmental effects produced by exposure to these contaminants as adults breed and larvae develop in water that may contain As or Cr. Three sample sets among 700 developing larvae were exposed to a range of As, Cr, or 2.5:1 mixture of As:Cr concentrations, respectively. From these 700 larvae, samples containing approximately 24 larvae showed different patterns of whole-body As and Cr from individual and mixture exposure. Whole-body As concentrations were 20.27 and 45.4 µg/g dry weight for larvae exposed to 20 mg/L As and 25:10 mg/L As:Cr, respectively, while whole-body Cr concentrations were 24.8 and 22 µg/g dry weight for larvae exposed to 20 mg/L Cr and 25:10 As:Cr, respectively. Observed malformations included edema, tail kinking, facial deformities, and abnormal bending. Twelve-day lethal concentrations for As and Cr in Ambystoma maculatum larvae were 261.17 mg/L and 71.93 mg/L, respectively, while 12-d effective concentrations to induce malformations were 158.82 and 26.05 mg/L, giving teratogenic indices of 1.64 and 2.76 for individual metal exposure. Exposure to a mixture of As and Cr resulted in a response addition and yielded lower lethal and effective concentration values with a teratogenic index of 2.78, indicating that these contaminants are developmentally toxic at lower concentrations when exposed as a mixture. Data demonstrate that As and Cr affect development of amphibian larvae, and that Ambystoma maculatum may be a useful indicator of environmental toxicity for these metals.