Bioavailability evaluation of naphthalene in soil using persulfate oxidation and ultrasonic extraction method

Bioavailability is defined as the fraction of a soil contaminant readily available for microbial degradation and for naphthalene it could be estimated by conventional exhaustive extraction methods. In this study, a novel method that employed persulfate oxidation in combination with ultrasonic extraction (POUSE) was developed. Three parameters, temperature, duration of persulfate oxidation, and the ratio of persulfate to soil organic matter (2S,082 /SOM; g g-1), were investigated to obtain an optimum operating conditions. Under the condition, naphthalene bioavailability estimated by the POUSE method was verified and compared with other three exhaustive methods i.e. sonicator, supercritical fluid extraction (SFE), and soxhlet extraction (SE). When the S2,O(8)2-/SOM ratio was controlled at 11.6 g g-1, the optimum operating conditions of the POUSE method were 70 degreesC and 3 hr, for the temperature and duration. Under these conditions, the residual naphthalene concentrations were correlated well with the residual naphthalene concentrations for both the cases of freshly spiked and aged soils. By contrast, the sonicator, SFE, and the SE overestimated the naphthalene bioavailability since these three methods extracted naphthalene much more than that of biodegradation test. These results demonstrated that the POUSE could estimate more precisely the naphthalene bioavailability.     

Lead contamination in surface soil on roads from used lead–acid battery recycling in Dong Mai,Northern Vietnam

Used lead–acid battery (ULAB) recycling has caused numerous health and environmental issues in developing countries. Surface soil pollution from ULAB recycling activities has been linked with elevated levels of lead in human blood. We measured surface soil lead in and surrounding the ULAB recycling village of Hung Yen in northern Vietnam in 2011, 2013, and 2014. The data were analyzed statistically and discussed with respect to distance from the contamination source, year of measurement, contamination pathway, and countermeasures against the contamination. Transportation routes from the smelter or collection site displayed the greatest concentration of surface soil lead (median 6400–10,000 mg/kg). Surface soil lead decreased significantly with distance along the road from the ULAB recycling site, although such a decrease was not observed for rice fields, agricultural roads, or garden soil. Re-suspension and adherence by traffic were identified as key pollution pathways. Distance from the source, covering of the surface of roads, construction of walls, and position relative to the source were shown to be the most effective factors in the reduction of surface soil lead pollution. Application of a combination of these measures should result in improvement in the health of residents.     

Plastic waste as a valuable resource: strategy to remove heavy metals from wastewater in bench scale application

Environmental Science and Pollution Research - Single-use plastic waste is gradually considered a potential material for circular economy. Ion exchange resin obtained from polystyrene waste by...     

Assessment of some water quality parameters in the Red River downstream,Vietnam by combining field monitoring and remote sensing method

Environmental Science and Pollution Research - The Red River is the largest river in northern Vietnam, and it serves as the main water source for production and human activities in the Red River...     

Primary biosorption mechanism of lead (II) and cadmium (II) cations from aqueous solution by pomelo (Citrus maxima) fruit peels

Environmental Science and Pollution Research - The present work investigates the primary adsorption mechanisms of lead (II) and cadmium (II) cations onto pomelo fruit peel (PFP) from aqueous...     

皇天畈试验场地下水的砷、铁污染及自净作用

研究了中国水稻研究所皇天畈试验场被砷、铁污染的地下深井水的自净作用。结果表明,其自净机制是地下深井水抽出地面后,由于体系的氧化还原势瞬时提高,Fe~(2+)氧化成Fe~(3+),As~(3+)氧化成As~(5+)。Fe~(3+)水解后,形成Fe(OH)_3,并聚合,水中的As~(5+)被氢氧化铁吸附后,形成共沉淀,沉降在底部。实验证明,若提高深井水的氧化势,则能加速自净的进程。     

船舶溢油卫星监测与信息高速公路

溢油污染严重威胁海洋环境,建立常规化的卫星遥感监测系统并纳入信息高速公路计划是非常必要的。本文在考察了其它船舶溢油监测方法的基础上,提出了利用卫星遥感监测溢油的可能性及在我国目前国力条件下利用卫星遥感方法实现常规监测的可行性,并探讨了在３Ｓ技术支持下建立常规化的船舶溢油卫星遥感监测系统的基本问题。     

Seasonal variations of organic-carbon and nutrient transport through a tropical estuary (Tsengwen) in southwestern Taiwan

This paper reports the fluvial fluxes and estuarine transport of organic carbon and nutrients from a tropical river (Tsengwen River), southwestern Taiwan. Riverine fluxes of organic carbon and nutrients were highly variable temporally, due primarily to temporal variations in river discharge and suspended load. The sediment yield of the drainage basin during the study period (1995–1996, 616 tonne km^–2 year^–1) was ca. 15 times lower than that of the long-term (1960–1998) average (9379 tonne km² year^–1), resulting mainly from the damming effect and historically low record of river water discharge (5.02 m³ s^–1) in 1995. The flushing time of river water in the estuary varied from 5 months in the dry season to >4.5 days in the wet season and about 1 day in the flood period. Consequently, distributions of nutrients, dissolved organic carbon (DOC) and particulate organic carbon (POC) were of highly seasonal variability in the estuary. Nutrients and POC behaved nonconservatively but DOC behaved conservatively in the estuary. DOC fluxes were generally greater than POC fluxes with the exception that POC fluxes considerably exceeded DOC fluxes during the flood period. Degradation of DOC and POC within the span of flushing time was insignificant and may contribute little amount of CO₂ to the estuary during the wet season and flood period. Net estuarine fluxes of nutrients were determined by riverine fluxes and estuarine removals (or additions) of nutrients. The magnitude of estuarine removal or addition for a nutrient was also seasonally variable, and these processes must be considered for net flux estimates from the river to the sea. As a result, nonconservative fluxes of dissolved inorganic phosphorus (DIP) from the estuary are –0.002, –0.09 and –0.59 mmol m^–2 day^–1, respectively, for dry season, wet season and flood period, indicating internal sinks of DIP during all seasons. Due to high turbidity and short flushing time of estuarine water, DIP in the flood period may be derived largely from geochemical processes rather than biological removal, and this DIP should not be included in an annual estimate of carbon budget. The internal sink of phosphorus corresponds to a net organic carbon production (photosynthesis–respiration, p–r) during dry (0.21 mmol m^–2 day^–1) and wet (9.5 mmol m^–2 day^–1) seasons. The magnitude of net production (p–r) is 1.5 mol m^–2 year^–1, indicating that the estuary is autotrophic in 1995. However, there is a net nitrogen loss (nitrogen fixation–denitrification < 0) in 1995, but the magnitude is small (–0.17 mol m^–2 year^–1).     

A preliminary risk assessment of trace elements accumulated in fish to the Indo-Pacific Humpback dolphin (Sousa chinensis) in the northwestern waters of Hong Kong

In order to assess the potential risks associated with consumption of contaminated prey items to the Indo-Pacific Humpback dolphin (Sousa chinensis), fish species (Collichthys lucida, Pseudosciaena crocea, Johnius sp., Thryssa sp., Mugil sp. and Trichiurus sp.) representing the main food items of the dolphin were collected from the northwestern waters of Hong Kong, including the Sha Chau and Lung Kwu Chau Marine Park, which form the main habitat of the dolphin in Hong Kong. Within these waters, there are several potential sources of pollution including significant inputs from the Pearl River catchment, several major sewage outfalls and a series of mud pits that receive contaminated dredged sediments. Concentrations of thirteen trace elements (Ag, As, Cd, Co, Cr, Cs, Cu, Hg, Mn, Ni, Se, V, and Zn) in the fish tissue were analyzed by inductively coupled plasma mass spectrometer (ICP-MS). An assessment of the risks of adverse effects on the dolphin due to consumption of tainted fish was undertaken using two toxic reference benchmarks, namely the reference dose (RfD) and toxicity reference value (TRV). The risk quotient (RQ) calculated for each element showed that the risks from consumption of fish were generally low and within safe limits. The risks associated with arsenic, cadmium and mercury were, however, elevated. The highest calculated RQ was associated with total arsenic; however, the majority of arsenic in marine organisms tends to be in the non-toxic organic form, and the actual risk to the dolphin due to this metalloid is likely to be lower.     

Relationship between copper speciation in sediments and bioaccumulation by marine bivalves of Taiwan

This paper evaluates the relationships between copper species in sediments and accumulation by the purple clam (Hiatula diphos) and venus clam (Gomphina aeguilatera) collected from the field and culture (aquaculture) ponds in the polluted coastal area of Lukang, Taiwan. Sediment was sampled along with the molluscs, including oysters (Crassostrea gigas), purple clams (Hiatula diphos), rock-shells (Thais clavigera), venus clams (Gomphina aeguilatera), and hard clams (Meretrix lusoria), from two unique environments of Lukang during the period from August 1993 to July 1994. The data indicate that the total copper concentrations in sediments from culture ponds (185 microg g(-1)) was higher than those of the field (44.0 microg g(-1)). Copper species in sediments were analyzed by a sequential leaching technique. Results show that concentrations of various copper species in the sediments are in the range of 1.14 +/- 0.59 to 13.2 +/- 22.4 microg g(-1) and 0.36 +/- 0.24 to 133 +/- 36.7 microg g(-1) for the two environments, respectively. Also the exchangeable copper in sediment from culture ponds was 15 times higher than that from the field. In addition, the sum of exchangeable and copper carbonates had the highest percentages of copper in both the pond sediment (86.6 %) and the field sediment (50.7 %). Maximum copper concentrations (309 +/- 35.1 microg g(-1)) in oysters were much higher than those in the other benthic organisms by about 4-127 times. Similarly, the data also showed that copper concentrations in Thais clavigera were 12-32 times higher than those in other benthic organisms. Copper concentrations in various benthic organisms differed significantly (p < 0.05) from that in Thais clavigera. This capacity makes Thais clavigera a potential candidate for monitoring copper in marine sediments. In terms of copper species, the best correlation was generally obtained between copper carbonates in sediments and copper concentrations in Hiatula diphos (r = 0.886*). A strong multiple regression correlation (p < 0.05, r2 = 0.7894) also indicates that the copper carbonates may dominate as the available form of copper to Hiatula diphos from various environments in the Lukang coastal area under natural physicochemical conditions.