ABSTRACT:
During the 2004 and 2005 breeding seasons, a total of 50 common tern (Sterna hirundo) eggs and 42 chicks were collected from three Maine offshore islands where chick developmental abnormalities had been previously reported, and from two nearby reference islands. Samples were analyzed individually for organochlorine compounds and trace elements. Three 3-egg composite samples from three islands (two target, one reference) were also analyzed for dioxin, furan, and polychlorinated biphenyl (PCBs) congeners. Dioxin toxic equivalents (TCDD-TEQ) in composite egg samples ranged from 17 to 65 pg/g. Congener PCB #77 was the dominant contributor to the TCDD-TEQ. Mean Total PCB concentrations in eggs and chicks were 0.36 ﾱ 0.19 ﾵg/g and 0.62 ﾱ 0.46 ﾵg/g, respectively. DDE, a metabolite of the pesticide DDT, was detected in all samples at concentrations less than 0.10 ﾵg/g. Other organochlorine compounds (e.g., chlordane compounds, cyclodiene pesticides, hexachlorcyclohexanes, etc.) were also detected in eggs and chicks at even lower concentrations (< 0.005 ﾵg/g). Mean mercury concentrations in eggs and chicks were 0.11 ﾱ 0.03 ﾵg/g and 0.16 ﾱ 0.07 ﾵg/g, respectively. Except for a few anomalous elevated detections, concentrations of 18 other trace elements were within previously reported ranges, low, sporadically detected, or below detection limits. Significant differences (p < 0.05) were found for various contaminants among islands and by sample type. However, organochlorine compound and trace element concentrations in eggs and chicks were below levels associated with embryotoxicity or developmental abnormalities.