Bohai Bay, Biomonitoring, Antioxidant enzyme, Mollusk, DNA Damage - drug effects, Water Pollutants, Chemical, Metallothionein - metabolism, Environmental Monitoring, Snails - genetics, Biomarkers - analysis, Snails - drug effects, Snails - metabolism, Snails - chemistry, Genetic Variation, Animals, China, Polycyclic Aromatic Hydrocarbons - analysis, Geologic...