Persistent Organic Pollutants in Singapore's Coastal Marine Environment: Part II,Sediments

Polycyclic aromatic hydrocarbons (PAHs) can enter the marine environment from a variety of anthropogenic sources. As some PAHs are known or suspected carcinogens and mutagens, their potential hazard to human health and the natural environment warrants investigation. This is the first reported study on the prevalence and concentration of PAHs in marine sediments from Singapore's coastal environment, and accompanies the report by Basheer et al. (2003) on the measurement of persistent organic pollutants (POPs) in seawater. The concentration of 16 PAH, classified as USEPA priority pollutants were analysed in sediments from 22 sample stations located within the northeastern and southwestern regions of Singapore's marine waters. The total PAH concentration varied between 15.22 μg g^-1 and 82.41 μg g^-1 in the northeastern region and between 13.63 μg g^-1 and 84.92 μg g^-1in the southwestern region. The highest concentration of total PAH i.e. 84.92 μg g^-1 was recorded at a site adjacent to a petrochemical refinery. Among the sixteen individual PAHs, chrysene, indeno[1,2,3-cd]pyrene and benzo[a]anthracene were most prevalent in the sediments. The relatively low kinetic/thermodynamic isomer ratios for PAHs suggest that PAHs of pyrogenic origin are predominant in Singapore's coastal environment. The distribution of higher molecular weight i.e. (4–5 ring) individual PAHs corresponded to mixture profiles typical of those originating from high temperature combustion processes subjected to photolytic degradation during long-range atmospheric transportation. A comparison of total PAH concentration data for sediments collected from Singapore relative to those reported for other countries indicates a moderate level of PAH contamination in Singapore's coastal marine sediments.     

Persistent Organic Pollutants in Singapore's Coastal Marine Environment: Part I,Seawater

Persistent organic pollutants (POPs) continue to receive widespread attention as harmful contaminants in the global environment. Increasingly, there have been concerns regarding adverse effects on marine wildlife due to the potential of POPs to induce adverse health effects, including the disruption of endocrine systems. Marine water samples within one kilometer of the coastline of Singapore were analysed to determine prevalent concentrations of a range of persistent organic pollutants (POPs). Samples were collected from 0.5 m and mid-depth (approximately 14 m depth) at twenty-two locations. POPs analysed are classed as USEPA priority pollutants, and included: sixteen polycyclic aromatic hydrocarbons (PAHs); eight polychlorinated biphenyls (PCBs); and twelve organochlorine pesticides (OCPs). Total PAH concentrations varied from 88.44 to 1419.57 ng l^-1 at the surface, and 129.78 to 940.41 ng l^-1 at mid-depth. Total OCP concentrations varied between 4.90 ng l^-1 to 22.04 ng l^-1 at surface, and 4.09 to 18.05 ng l^-1 at mid-depth. Total PCB concentrations varied from 0.22 ng l^-1 to 20.41 ng l^-1 at surface and 0.4 to 10.79 ng l^-1 at mid-depth. In general, the distribution profile shows that the surface concentrations of POPs are higher than at mid depth. Concentrations of PAHs were considered higher than reported levels for several other countries, whereas levels of OCPs and PCBs are generally lower than reported levels for other Asian countries.