The discharge of nutrients, phytoplankton and pathogenic bacteria through ballast water may threaten the Cayo Arcas reef system. To assess this threat, the quality of ballast water and presence of coral reef pathogenic bacteria in 30 oil tankers loaded at

The spatial and vertical distribution of organochlorine pesticides (OCPs) has been investigated in Daya Bay, China. The concentration of total OCPs in surface sediment range from 16.66 to 44.04 ng/g dry weight with a mean concentration of 26.60 ng/g. DDTs and HCHs were the predominant species. The ratios of (DDD + DDE)/DDT reflected a cocktail input pattern of fresh and weathered DDTs. The predominant α-HCH and the α/β-HCH ratios indicated that the technical HCH contamination was mainly due to historical usage, although there was fresh input of lindane. The variation profiles of concentrations showed that OCPs were extensively applied between the late 1950s and early 1980s in China. A recent increasing trend in concentrations of DDTs and HCHs was found in both cores. The increasing ratios of (DDE + DDD)/DDT with corresponding decreases of DDE/DDT ratio implied that most of the DDTs deposited after their production ban were more likely “weathered” DDTs derived from soil residues.