Risk Assessment of Heavy Metals, Nitrogen, and Phosphorus in Seawater of Taizhou Bay, China

Heavy metals, nitrogen, and phosphorus play a significant role in the marine ecosystem and human health. In this work, the concentrations of heavy metals, inorganic nitrogen, and phosphorus were determined to assess the distribution characteristics, risk levels, and possible sources in seawater from Taizhou Bay. The concentration ranges of Cu, Pb, Zn, Cd, Hg, As, ammonia, nitrate, nitrite, and phosphate were 1.87-3.65 μg/L, 0.10-0.95 μg/L, 2.98-16.80 μg/L, 0.07-0.38 μg/L, 0.011-0.043 μg/L, 0.93-2.06 μg/L, 0.011-0.608 mg-N/L, 0.012-0.722 mg-N/L, 0.001-0.022 mg-N/L, and 0.004-0.044 mg-P/L, respectively. The ecological risks were evaluated by the single factor index, Nemerow pollution index, and risk quotient. The results indicated that Taizhou Bay is not currently facing ecological risk related to heavy metals, nitrogen, and phosphorus, but the RQ values emphasized the urgency of strengthening continuous monitoring of As, Cu, and Zn. The results of Pearson's correlation indicated that salinity and chemical oxygen demand had a significant impact on nitrogen and phosphorus but little impact on heavy metals. Principal component analysis was then applied to analyze the probable origins of heavy metals and inorganic pollutants, suggesting that these pollutants were mainly derived from human activities along the bay.