Heavy metal contaminations and influence on the red-crowned crane (Grus japonensis) in Wuyur catchments, Northeastern China

Five heavy metal concentrations, copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), and cadmium (Cd), in the sediments and six typical aquatic animal taxa were analyzed to determine the contamination from heavy metals in the habitat of the red-crowned cranes in Northeastern China. The body burden of these metals in the cranes was analyzed to examine the impact of these hazards on the rare species. Results indicated that all detected concentrations of the five heavy metals in the sediments were higher than the natural background levels. Pb and Cd were the most abundant elements in the sediments, with concentrations ranging from 9.85 to 129.72 mg kg⁻¹ and from 1.23 to 10.63 mg kg⁻¹ (dry weight, dw), respectively. Their absolute fractions were relatively stable phases, i.e., bound to iron-manganese oxides fraction and bound to organic matter fraction at 16.28 and 23.23 mg kg⁻¹ for Pb and 0.33 mg kg⁻¹ and 3.15 mg kg⁻¹ (dw) for Cd. Six common water animal taxa were found to contain detectable heavy metal concentrations. The internal tissues of the red-crowned cranes contained significantly high metal concentrations compared with their external tissues (feather, feces and residual eggshell). Cd concentrations in the feather and liver of red-crowned cranes exceeded a level considered to be potentially toxic in birds, with levels ranging from 0.41 to 3.06 mg kg⁻¹ and 0.37 to 4.42 mg kg⁻¹ (dw), respectively. Similarly, we found increased levels of Pb in the both external and internal tissues, with levels ranging from 0.21 to 3.21 mg kg⁻¹ dw, which indicated likely contamination by the metal.