Screening and analysis of 940 organic micro-pollutants in river sediments in Vietnam using an automated identification and quantification database system for GC-MS.

In order to obtain a detailed picture of pollution by organic micro-pollutants in Vietnamese rivers, 940 semi-volatile organic compounds in river sediments collected from four major cities were examined by a comprehensive gas chromatography-mass spectrometry-database. The number of detected chemicals at each site ranged from 49 to 158 (median 96 out of 940) with 185 analytes detected at least once in the survey. The substances detected with high frequency (over 80%) and high concentrations were n-alkanes, phthalates, sterols and PAHs. For most substances, sediments from metropolitan areas (Hanoi and Ho Chi Minh City) were more heavily contaminated than those in rural and suburban areas. Sterols were observed in nearly 100% of sediments at extremely high concentrations, suggesting that the studied rivers were contaminated by sewage. Pyrethroids (permethrin-1 and -2) were the most dominant insecticides found in inner canals of Hanoi and Ho Chi Minh City. Deltamethrin was only detected at a site in Hanoi at an elevated concentration. This reflects that pyrethroids are used for the protection of private and public health rather than for agriculture. p,p'-DDE and p,p'-DDD were the dominant members of the DDT family of chemicals detected, indicating no recent inputs of DDTs in the study areas. PCBs residues were lower than those in other Asian countries, which suggest historically much lower use of PCBs in Vietnam. PAHs pollution in urban areas is caused by the runoff of petroleum products and vehicle exhaust gases, whereas in rural and suburban areas, the combustion of fossil fuels and biomass is major sources of PAHs. Overall, the study confirmed that rivers in Vietnam were heavily polluted mainly by domestic wastewater.

Target and screening analysis of 940 micro-pollutants in sediments in Tokyo Bay, Japan.

Urban societies are using an increasingly diverse array of chemicals, many of which ultimately end up accumulating in urban harbors, where they can act as contaminants alone or as part of a mixture. In attempt to grasp a more complete picture of anthropogenic chemicals in an urban harbor, we analyzed 940 organic chemicals in sediments in Tokyo Bay, one of the most densely populated and modernized areas in the world. For the chemical analysis, we used targeted analytical methods using a GC-MS-MS and a GC-MS-SIM, and a screening analysis using an automated identification and quantification system with a GC-MS database. We detected 195 organic chemicals in the sediments; the sum of concentrations of compounds detected varied from 6095 to 39140µgkg(-1)dry wt. Since their concentrations increased with proximity to the innermost part of the bay, their sources seem to be mainly sewage treatment plants (STPs) and rivers flowing to this area. Additional confirmation comes from the nature of the identified pollutants, which are characteristic of chemicals used in households as well as fecal matter, business activities and urban run-off. From these results, it was confirmed that sediments in Tokyo Bay are still polluted with a wide range of chemicals, particularly domestic chemicals, despite nearly 100% of wastewater from household and business activities being treated by STPs.

Screening analysis of hundreds of sediment pollutants and evaluation of their effects on benthic organisms in Dokai Bay, Japan.

Dokai Bay in Kitakyushu, Japan, is polluted with complex mixtures of micro-pollutants originating from the extensive industry and urbanization. In order to evaluate effects of these micro-pollutants on benthic organisms in this almost completely enclosed bay, we screened for the occurrence of approximately 900 organic chemicals and heavy metals, and in addition quantified the density and biomass of benthic animals. For the chemical analysis, we used a newly developed comprehensive analytical method using an automated identification and quantification system with a GC-MS database. We detected 184 organic chemicals in the sediments. Since their concentrations, as well as those of metals, increased with proximity to the innermost part of the bay, their source seem to be factories and a sewage treatment plant located in this area. Confirming this, the identified pollutants in this area are characteristic of industrial chemicals and residues, as well as household chemicals, fecal matter and sewage effluent. Several polycyclic aromatic hydrocarbons (PAHs) and metals had concentrations higher than the effects range-median of the sediment quality guidelines of National Oceanic and Atmospheric Administration. The species richness and abundance of benthic animals were lowest in areas where concentrations of metals, PAHs and other organic pollutants were high, suggesting that these contaminants are having an adverse effect on benthic animals in the bay.

Development of a comprehensive analytical method for semi-volatile organic compounds in sediments by using an automated identification and quantification system with a GC-MS database.

A comprehensive analytical method for nearly 1000 semi-volatile organic compounds (SVOC) in sediments has been developed using an automated identification and quantification system with a GC-MS database. The results of recovery tests using model compounds, which comprise of 119 non-polar to polar compounds, showed that the method can quantitatively analyze most SVOC, except for very polar substances. Analytical results of a standard reference material were close to certified concentrations. The detection limits of the method were 4 µg/kg when measuring by TIM and 0.4 µg/kg by SIM. The method was applied to actual sediments in rivers in Ho Chi Minh City, Vietnam. A large number of substances, including persistent organic pollutants, which seem to be discharged from domestic sources, were found at relatively high concentrations. From these results, it is confirmed that the developed method is a useful way to obtain a holistic picture of pollution by SVOC, and is a good tool for rapid screening of chemical pollution in sediments.