Levels and distribution of organophosphorus flame retardants and plasticizers in fishes from Manila Bay, the Philippines.

Organophosphorus compounds (OPCs) and stable isotope ratios (δ(13)C and δ(15)N) were determined in 58 fishes belonging to 20 species collected from Manila Bay, the Philippines. OPCs were detected in most of the samples and found up to µg/g lw (lipid weight) level, suggesting their ubiquitous presence in the coastal marine environment of the Philippines. Higher levels (>1000 ng/g lw) of total OPCs were determined in yellowstriped goatfish, silver sillago, tripletail wrasse and bumpnose trevally indicates either their active uptake from ambient water or lower metabolic capacity of these species. Levels of triphenyl phosphate (TPhP) in demersal species showed a positive correlation with δ(15)N, indicating that TPhP was adsorbed onto the particle, settled down to the bottom sediment and accumulated through the benthic food web rather than the pelagic. Estimated dietary intake of OPCs in Manila Bay fishes were four to five orders of magnitude lower than the proposed reference dose (RfD).

Contamination and bioaccumulation of benzotriazole ultraviolet stabilizers in fish from Manila Bay, the Philippines using an ultra-fast liquid chromatography-tandem mass spectrometry.

Benzotriazole ultraviolet stabilizers (BUVSs) used in plastic products, building materials and personal hygiene products were analyzed in fishes collected from Manila Bay, the Philippines. BUVSs were detected at ng g⁻¹ level in all the fish samples, indicating their ubiquitous contamination in coastal waters. Among the targeted eight BUVSs, UV-328 was predominantly found with a mean concentration of 34.2 ng g⁻¹ lipid weight, implying large scale production and use of this compound in the Philippines. High concentrations of ∑BUVSs were found in bumpnose trevally (Carangoides hedlandensis), bluetail mullet (adult) (Valamugil buchanani), common ponyfish (Leiognathus equulus) and coral grouper (adult) (Epinephelus corallicola) indicating their active uptake and/or lower metabolic capacity to eliminate BUVSs. Among BUVSs, UV-P showed significant positive relationship (p<0.05) between concentration and fish length (r=0.29) and fish weight (r=0.31). Levels of UV-P in demersal species had positive correlation with δ¹5N, indicating that possibile sink of UV-P is bottom sediment in the bay, and ultimately accumulate through benthic food web rather than pelagic food web. To our knowledge, this is the first study on BUVSs distribution in fish from developing countries.

Determination of preservative and antimicrobial compounds in fish from Manila Bay, Philippines using ultra high performance liquid chromatography tandem mass spectrometry, and assessment of human dietary exposure.

Ultra high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of four paraben preservatives (methyl, ethyl, propyl and butyl) and two antimicrobial agents (triclosan and triclocarban) belonging to personal care products (PCPs) in 20 species of fish from Manila Bay (Philippines) was performed. Detection of PCPs with greater frequency indicates the ubiquitous contamination of Manila Bay. Concentrations of total paraben were one order of magnitude higher than the antimicrobials in almost all fish, except in Stolephorus indicus and Leiognathus equulus. A positive correlation was observed between parabens concentration and fish length (r = 0.31-0.49; p<0.05 to <0.001) and fish weight (r = 0.28-0.49; p<0.05 to <0.001), but not for the antimicrobials. The estimated dietary exposure values of the four parabens in the Philippines through fish is four orders of magnitude lower than the acceptable daily intake (ADI) of 10mg/kg/day, but the values of antimicrobials are just half of the ADI of TCS. To our knowledge, this is the first report of PCPs contamination in fish from Philippines.

Hypoxia in Manila Bay, Philippines during the northeast monsoon.

Herein we present results from one of the first extensive bay-wide oceanographic surveys of Manila Bay, wherein 31 stations were sampled during the northeast monsoon (cold and dry season). A band of hypoxic bottom water (dissolved oxygen<2.8 mg/L) spanned the midsection of the bay from east to west. Bottom nitrate concentrations (5.7-16.8 µM; avg. 11.1 µM) and total organic carbon values in sediments (1.7-3.1%; avg. 2.4%) were high in the midsection, which coincided with the band of hypoxic bottom water. Physical processes and site-specific accumulation of organic material likely lead to hypoxic conditions in Manila Bay, even during the northeast monsoon period when the water column is relatively well mixed. The results of this study complement the previously reported widespread hypoxia that occurs during the rainy season. Thus, hypoxia may be pervasive in the bay throughout the year, although it varies in intensity and spatial extent.

Spatial distribution and corresponding determining factors of metal concentrations in surface sediments of Beppu Bay, southwest Japan.

This study determined the factors contributing to the spatial distribution of 14 metal concentrations in the surface sediments of Beppu Bay on the basis of comparisons of the organic geochemical properties and environmental parameters through principal component analysis (PCA) and redundancy analysis (RDA). The results of PCA and RDA showed that the concentrations of V, Cr, Co, and As were closely related to the distances between the sampling sites and the Oita River. This indicated that these metals originated from the river's drainage area. The Mn, Cu, Mo, and Cd concentrations were related to the water depth. These results indicated that the Mo, Cd, and Cu deposition processes were controlled by oxygen depletion, and that these elements accumulated in the deeper parts of the bay under anoxic conditions.

Effects of environmental regulations on heavy metal pollution decline in core sediments from Manila Bay.

We investigated the high-resolution heavy metal pollution history of Manila Bay using heavy metal concentrations and Pb isotope ratios together with (210)Pb dating to find out the effects of environmental regulations after the 1990 s. Our results suggested that the rate of decline in heavy metal pollution increased dramatically from the end of the 1990 s due to stricter environmental regulations, Administrative Order No. 42, being enforced by the Philippines government. The presented data and methodology should form the basis for future monitoring, leading to pollution control, and to the generation of preventive measures at the pollution source for the maintenance of environmental quality in the coastal metropolitan city of Manila. Although this is the first report of a reduction in pollution in Asian developing country, our results suggest that we can expect to find similar signs of pollution decline in other parts of the world as well.

Reconstruction of pollution history of organic contaminants in the upper Gulf of Thailand by using sediment cores: first report from Tropical Asia Core (TACO) project.

This paper reports the first reconstruction of a pollution history in tropical Asia from sediment cores. Four sediment core samples were collected from an offshore transect in the upper Gulf of Thailand and were analyzed for organic micropollutants. The cores were dated by measurement of (137)Cs and geochronometric molecular markers (linear alkylbenzenes, LABs; and tetrapropylene-type alkylbenzenes, TABs). Polychlorinated biphenyl (PCB) concentrations showed a subsurface maximum in layers corresponding to the 1970s, indicating the effectiveness of regulation of PCBs in Thailand. LAB concentrations increased over time, indicating the increase in input of sewage into the Gulf during the last 30 years. Hopanes, biomarkers of petroleum pollution, also increased over time, indicating that the inputs of automobile-derived hydrocarbons to the coastal zone has been increasing owing to the increased number of cars in Thailand since the 1950s. Polycyclic aromatic hydrocarbons (PAHs) increased in the layers corresponding to the 1950s and 1960s, probably because of the increased inputs of automobile-derived PAHs. PAH concentrations in the upper layers corresponding to the 1970s and later remained constant or increased. The absence of a subsurface maximum of PAHs contrasts with results observed in industrialized countries. This can be explained by the facts that the Thai economy did not depend on coal as an energy source in the 1960s and that economic growth has continued since the 1970s to the present. The deposition flux of PAHs and hopanes showed a dramatic offshore decrease, whereas that of LABs was uniform.

Optimal aerobic cultivation method for 1,4-dihydroxy-2-naphthoic acid production by Propionibacterium freudenreichii ET-3.

To investigate the effects of oxygen supply on Propionibacterium freudenreichii ET-3 metabolism and 1,4-dihydroxy-2-naphthoic acid (DHNA) production in detail, the strain was cultured by switching from anaerobic condition to aerobic condition at 72 h (termed anaerobic-aerobic switching culture hereafter) employing different oxygen transfer rates (OTRs) in the range of 0.08-0.90 mg/(l.h). It was found that a 0.08 mg/(l.h) OTR could not change the metabolism or improve the DHNA production of P. freudenreichii ET-3. When the OTR was in the range of 0.23-0.66 mg/(l.h), propionate, which inhibits DHNA production significantly, was consumed during the aerobic phase. Final DHNA concentration increased to 0.22 mM, irrespective of OTR. When the OTR was 0.90 mg/(l.h), a sudden increase in dissolved oxygen (DO) concentration during the aerobic phase resulted in a sudden decrease in DHNA concentration. To attenuate the stresses caused by propionate and oxygen exposure, we designed an optimal cultivation in which the anaerobic and aerobic phases were repeated three times alternately. As a result, propionate concentration was maintained below the level that inhibits DHNA production, and no DO concentration was detected throughout the culture. The final DHNA concentration in this culture was 0.33 mM, which is 2.7-fold that in the anaerobic culture and 1.5-fold that in the anaerobic-aerobic switching culture.