<Tr> <Td> </Td> <Td> Clam * </Td> <Td> 0.009 </Td> <Td> 0.011 </Td> <Td> 0.002 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> Salmon * </Td> <Td> 0.008 </Td> <Td> 0.017 </Td> <Td> n / d </Td> <Td> Canned </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> Scallop </Td> <Td> 0.003 </Td> <Td> 0.007 </Td> <Td> n / d </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> Shrimp * </Td> <Td> 0.001 </Td> <Td> 0.013 </Td> <Td> 0.009 </Td> <Td> </Td> <Td> </Td> <Td> 6.5 </Td> </Tr>

Where does mercury in the water come from