Spatiotemporal variations, sources, and atmospheric transformation potential of volatile organic compounds in an industrial zone based on high-resolution measurements in three plants.

Industrial emissions are significant sources of volatile organic compounds (VOCs). This study conducted a field campaign at high temporal and spatial resolution to monitor VOCs within three plants in an industrial park in southern China. VOC concentrations showed significant spatial variability in this industrial zone, with median concentrations of 75.22, 40.53, and 29.41 µg/m3 for the total VOCs in the three plants, respectively, with oxygenated VOCs (OVOCs) or aromatics being the major VOCs. Spatial variability within each plant was also significant but VOC-dependent. Seasonal variations in the VOC levels were governed by their industrial emissions, meteorological conditions, and photochemical losses, and they were different for the four groups of VOCs. The temporal and spatial variations in the VOC compositions suggest similar sources of each class of VOCs during different periods of the year in each plant. The diurnal patterns of VOCs (unimodal or bimodal) clearly differed from those at most industrial/urban locations previously, reflecting a dependence on industrial activities. The secondary transformation potential of VOCs also varied temporally and spatially, and aromatics generally made the predominant contributions in this industrial park. The loss rate of OH radicals and ozone formation potential were highly correlated, but the linear relationship substantially changed in summer and autumn due to the intensive emissions of an OVOC species. The lifetime cancer and non-cancer risks via occupational inhalation of the VOCs in the plants were acceptable but merit attention. Taking the secondary transformation potential and health risks into consideration, styrene, xylene, toluene, trichloroethylene, and benzene were proposed to be the priority VOCs regulated in the plants.

Disposable Plastic Waste and Associated Antioxidants and Plasticizers Generated by Online Food Delivery Services in China: National Mass Inventories and Environmental Release.

China's online food delivery (OFD) services consume enormous amounts of disposable plastics. Here, we investigated and modeled the national mass inventories and environmental release of plastics and chemical additives in the plastic. The extra-tree regression identified six key descriptors in determining OFD sales in Chinese cities. Approximately 847 kt of OFD plastic waste was generated in 2021 (per capita 1.10 kg/yr in the megacities and 0.39 kg/yr in other cities). Various additives were extensively detected, with geomean concentrations of 140.96, 4.76, and 0.25 µg/g for ∑8antioxidants, ∑21phthalates, and bisphenol A (BPA), respectively. The estimated mass inventory of these additives in the OFD plastics was 164.7 t, of which 51.1 t was released into the atmosphere via incineration plants and 51.0 t was landfilled. The incineration also released 8.07 t of polycyclic aromatic hydrocarbons and 39.1 kt of particulate matter into the atmosphere. Takeout food may increase the dietary intake of phthalates and BPA by 30% to 50% and raise concerns about considerable exposure to antioxidant transformation products. This study provides profound environmental implications for plastic waste in the Chinese OFD industry. We call for a sustainable circular economy action plan for waste disposal, but mitigating the hazardous substance content and their emissions is urgent.

[Cadmium and Arsenic Interactions During Co-adsorption onto Goethite].

Cadmium (Cd) and arsenic (As) are commonly co-adsorbed onto iron oxides in the soil environment, especially in south China. This study aimed to elucidate the regulatory mechanisms in determining the As(Ⅴ)-Cd(Ⅱ) interactions on a goethite interface after excluding pH interference. At pH 6.0, the results obtained illustrated that As(Ⅴ) and Cd(Ⅱ) adsorbed onto goethite obeyed the pseudo-second-order kinetic model, and the adsorption processes were mainly chemical adsorption. Furthermore, As(Ⅴ) adsorbed onto goethite were mainly inner ring adsorption and monolayer adsorption both in the single adsorption process and in co-adsorption processes with Cd(Ⅱ). For comparison, Cd(Ⅱ) adsorbed onto goethite also demonstrated inner ring adsorption and monolayer adsorption during single adsorption, and As(Ⅴ)-Cd(Ⅱ) co-adsorption were transformed to outer ring adsorption and multilayer adsorption processes. Through analysis by Zeta potential, X-ray diffraction, and X-ray photoelectron spectroscopy, electrostatic adsorption and formation of ternary complexes (Fe-As-Cd) were proven to be the critical mechanisms in determining the interactions between As(Ⅴ) and Cd(Ⅱ) during their co-adsorption processes. The results obtained in this study should help us to further understand the micro-chemical interaction processes of heavy metals on the soil environment.

Accumulation and translocation of traditional and novel organophosphate esters and phthalic acid esters in plants during the whole life cycle.

Organophosphate esters (OPEs) and phthalic acid esters (PAEs) are widespread contaminants in the environment. The variations of these chemicals in plants throughout their life cycle is little known. In this study, OPEs, OPE metabolites, and PAEs in peanut and corn grown under field conditions, soil, and air were measured to understand the uptake and translocation, distributions in the plant compartments, and metabolism in the plants. The soil concentrations showed an enrichment effect of OPEs onto the rhizosphere soil but a depletion effect of PAEs on rhizosphere soils. The PAE concentrations between peanut (with a mean of 1295 ng/g dw) and corn (3339 ng/g dw) were significantly different, but the OPE concentrations were not significantly different (with means of 15.6 and 19.2 ng/g dw, respectively). OPE metabolites were also detected in the plants, with lower concentrations and detection rates. Similarities and differences in the temporal variations of the concentrations of traditional OPEs, novel OPEs, and PAEs in plants during their growth were observed. The variations were dependent on both plant species and particular tissues. The leaf compartment is the most important reservoir of OPEs and PAEs (but not OPE metabolites) for both species, highlighting the importance of an aerial uptake pathway. The chemicals have a low potential to be translocated into peanut and corn kernels, reducing their risks via food consumption. Less hydrophobic compounds have higher root concentration factors in this study. These observations differ from those of previous hydroponic experiments.

Particle size-resolved emission characteristics of complex polycyclic aromatic hydrocarbon (PAH) mixtures from various combustion sources.

Combustion of domestic solid fuels is a significant source of polycyclic aromatic hydrocarbons (PAHs). Some oxygenated PAHs (o-PAHs) and PAHs with molecular weight of 302 (MW302 PAHs) are more toxic than the traditional 16 priority PAHs, whereas their emissions were much less elucidated. This study characterized the size-dependent emissions of parent PAHs (p-PAHs), o-PAHs, and MW302 PAHs from various combustion sources. The estimated emission factors (eEFs) from biomass burning sources were highest for most of the PAHs (391-8928 µg/kg), much higher than that of anthracite coal combustion (43.0-145 µg/kg), both which were operated in an indoor stove. Cigarette smoking had a high eEF of o-PAHs (240 ng/g). MW302 PAHs were not found in the emissions of smoking, cooking, and vehicular exhausts. Particle-size distributions of PAHs were compound- and source-dependent, and the tendency to associate with smaller particles was observed especially in biomass burning and cigarette smoking sources. Furthermore, the inter-source differences in PAH eEFs were associated with their dominance in fine particles. PAH composition profiles also varied with the particle size, showing increasing contributions of large-molecule PAHs with decreasing sizes in most cases. The size distributions of p-PAHs are much more significantly dependent on their n-octanol/air partition coefficients and vapor pressures than those of o-PAHs, suggesting differences in mechanisms governing their distributions. Several molecular diagnostic ratios (MDRs), including two based on MW302 PAHs, specific to these combustion scenarios were identified. However, the MDRs within some sources are also strongly size-dependent, providing a new explanation for the uncertainty in their application for source identification of PAHs. This work also highlights the necessity for understanding the size-resolved atmospheric behaviors and fate of PAHs after their emission.

Influence of biofilms on the adsorption behavior of nine organic emerging contaminants on microplastics in field-laboratory exposure experiments.

Microplastics (MPs) are ubiquitous in aquatic environments, which are important carriers of emerging contaminants (ECs). Biofilms can be attached to the surface of MPs in a natural aquatic environment, which may influence chemical adsorption; however, knowledge of its impact is still limited. This study investigated the effect of biofilms on MPs on the adsorption of ECs through field-laboratory exposure experiments. Three types of MPs were naturally colonized with biofilms in lake. Then, biofilm-absent/biofilm-attached MPs were exposed to nine EC solutions at a concentration of 8 µg/L of each compound in laboratory. Most compounds exhibited 3.8 times lower concentrations on biofilm-attached MPs than on biofilm-absent MPs; only a few compounds showed enhanced adsorption. Pseudo-equilibrium was achieved within 72 h based on adsorption kinetics, implying fast adsorption of ECs on biofilm-attached MPs. The partition coefficients (Kd) for biofilm-attached MPs were 0.14 (diclofenac) to 535 (miconazole) L/kg and were positively correlated with octanol/water partition coefficients (Kow). This indicated that chemical properties (such as Kow) of the compounds determined their final adsorption amounts on MPs, although these were influenced by the presence of the biofilm. Hence, multiple influencing factors should be considered when evaluating the carrier potential of MPs for ECs in aquatic environments.

PM2.5-bound phthalates and phthalate substitutes in a megacity of southern China: spatioseasonal variations, source apportionment, and risk assessment.

Plasticizers are ubiquitous pollutants in the environment, whereas few efforts have been made to elucidate their emission sources in the atmosphere. In this research, the spatioseasonal variations and sources of particle-bound (PM2.5) phthalates (PAEs) and their substitutes (APs) at residential sites in seven districts and at four potential point-source sites across a megacity in South China were revealed. The total concentrations of PAEs ranging from 10.7 to 528 ng/m3 were substantially higher than those of APs (1.45.58.5 ng/m3). Significant spatial variations in the concentrations of the pollutants were observed, which were generally higher at the sites with intensive industrial activities and the point-source sites. Most atmospheric plasticizer levels peaked in summer, probably due to the temperature-promoted volatilization. Seven sources of plasticizers were identified by the positive matrix factorization (PMF) model. The sources in less industrialized districts are mainly associated with domestic and commercial emissions and with industry in the industrialized districts. Specifically, plastics and personal care products together contributed 60% of the plasticizers in the atmosphere of this city, followed by solvents and polyester industry sources. The incremental lifetime cancer risk of inhalation exposure to bis(2-ethylhexyl) phthalate in the study city is below the acceptable level. Relatively higher risks were found for residents living around sites with intensive industrial activities and around wastewater treatment plant.

Uptake, elimination, and toxicokinetics of selected pharmaceuticals in multiple tissues of Nile tilapia (Oreochromis niloticus) exposed to environmentally relevant concentrations.

Pharmaceuticals in aquatic environment displayed adverse effects to fish. The effects are usually related to the internal levels of pharmaceuticals accumulated in specific fish tissues. In this study, we investigated the uptake, elimination, and toxicokinetics of six pharmaceuticals, e.g. naproxen (NAX), diclofenac (DCF), ibuprofen (IBU), carbamazepine (CBZ), fluoxetine (FLX), and sertraline (SER), in 11 fish tissues of Nile tilapia. The experiments were conducted in a flow-through system with an 8-day uptake/8-day elimination periods. The fish exposure groups involved the control, single FLX, and mixture of six pharmaceuticals at environmentally relevant concentration of 4 µg/L. FLX and SER showed the maximum concentrations of 145 and 201 ng/g wet weight, respectively, in fish spleen tissue, while NAX and IBU were not detected in any tissue. The mean concentrations for the pharmaceuticals in Nile tilapia tissues generally followed the order: bile> kidney, gut, stomach, liver> brain, gill, spleen> plasma, skin, muscle. The steady-state bioconcentration factors in various tissues generally range at 0.74-437.58 L/kg. The uptake and elimination toxicokinetics illustrated the rapid accumulation and depuration of pharmaceuticals in fish tissues. The results help to understand the internal bioconcentration, tissue distribution, and toxicokinetics of pharmaceuticals in multiple fish biological compartments.

Profile and removal of bisphenol analogues in hospital wastewater, landfill leachate, and municipal wastewater in South China.

The presence of bisphenol analogues (BPs) in wastewater can have adverse effects to organisms in the environment. However, knowledge of the wastewater sources, such as hospitals and landfills, as well as the removal of BPs are still limited. Fifteen BPs were investigated in hospital, landfills, and municipal wastewater treatment plants (WWTPs) in South China. Eleven BPs were detected in various source wastewaters, and bisphenol A (BPA) is generally the dominant pollutant. In 4 hospitals, the total concentrations of BPs (∑BPs) in hospital wastewater and treated wastewater ranged from 122 to 1040 ng/L. In the landfill, ∑BPs in leachate and treated leachates were 32,130 and 145 ng/L, respectively. In 5 municipal WWTPs, ∑BPs was up to 17,200 ng/L in influents, 502 ng/L in effluents, and 291 ng/g in sludges. The modified A2/O process exhibited best removal profile for BPs, while the UNITANK process had no advantages. The annual mass load estimates of hospital treated wastewater, landfill treated leachate, and WWTP effluents in Guangdong Province, South China, were 630, 9.46, and 4697 kg/y, respectively. The risk quotient values in source effluents revealed low to medium estrogenic risks to receiving rivers. Control measures should be applied to further remove BPs not only from WWTP effluents but also from other sources.

Traditional and novel organophosphate esters (OPEs) in PM2.5 of a megacity, southern China: Spatioseasonal variations, sources, and influencing factors.

Organophosphate esters (OPEs) are ubiquitous contaminants in the environment, whereas their atmospheric processes and fate are poorly understood. The present study revealed the spatial heterogeneity and seasonal variations of traditional and novel OPEs in PM2.5 (particulate matter with diameters < 2.5 µm) across a megacity (including residential areas and potential source sites) in South China. Potential influencing factors on the contamination levels of OPEs were addressed. The total concentrations of 11 traditional OPEs ranging from 262 to 42,194 pg/m3 (median = 1872 pg/m3) were substantially higher than those of 10 novel OPEs (33.5-3835 pg/m3, median = 318 pg/m3). Significant spatial and temporal variations in the concentrations of most OPEs were observed. The overall district-specific contamination levels in this city showed dependence on the secondary industry sector for non-predominant OPEs and on the tertiary industry for predominant OPEs. The seasonal variations of the OPE concentrations suggest difference in their sources or influence of meteorological conditions. The correlations between the individual OPEs in PM2.5 are determined largely by either their applications or physicochemical properties (in particular vapor pressure). The correlations between OPE concentrations and each meteorological factor (temperature, relative humidity, wind speed, and surface solar radiation) were inconsistent (positive and negative). Wind speed had the greatest effect on the OPE levels; While most OPEs bound to PM2.5 were not efficiently scavenged by below-cloud rainfall. The results suggest that atmospheric half-life and Henry's Law Constant of OPEs are also determining factors for the wind speed and rainfall influence, respectively. However, mechanisms underlying the influence of meteorological conditions on atmospheric OPEs still need further research.

Anthropogenic activities have contributed moderately to increased inputs of organic materials in marginal seas off China.

Sediment has been recognized as a gigantic sink of organic materials and therefore can record temporal input trends. To examine the impact of anthropogenic activities on the marginal seas off China, sediment cores were collected from the Yellow Sea, the inner shelf of the East China Sea (ECS), and the South China Sea (SCS) to investigate the sources and spatial and temporal variations of organic materials, i.e., total organic carbon (TOC) and aliphatic hydrocarbons. The concentration ranges of TOC were 0.5-1.29, 0.63-0.83, and 0.33-0.85%, while those of Σn-C14-35 (sum of n-alkanes with carbon numbers of 14-35) were 0.08-1.5, 0.13-1.97, and 0.35-0.96 µg/g dry weight in sediment cores from the Yellow Sea, ECS inner shelf, and the SCS, respectively. Terrestrial higher plants were an important source of aliphatic hydrocarbons in marine sediments off China. The spatial distribution of Σn-C14-35 concentrations and source diagnostic ratios suggested a greater load of terrestrial organic materials in the Yellow Sea than in the ECS and SCS. Temporally, TOC and Σn-C14-35 concentrations increased with time and peaked at either the surface or immediate subsurface layers. This increase was probably reflective of elevated inputs of organic materials to marginal seas off China in recent years, and attributed partly to the impacts of intensified anthropogenic activities in mainland China. Source diagnostics also suggested that aliphatic hydrocarbons were mainly derived from biogenic sources, with a minority in surface sediment layers from petroleum sources, consistent with the above-mentioned postulation.

Sedimentary record of polycyclic aromatic hydrocarbons in a sediment core from a maar lake, Northeast China: evidence in historical atmospheric deposition.

A maar lake is an excellent ecosystem to study the atmospheric deposition of pollutants, as its contaminants are primarily by atmospheric deposition. In this study, a sediment core from Sihailongwan Maar Lake, Northeast China, was collected and the historical atmospherically deposited polycyclic aromatic hydrocarbons (PAHs) were analyzed. The concentrations of TPAHs (the sum of the US EPA proposed 16 priority PAHs, excluding naphthalene and pyrene) ranged from 473.9 to 2289 ng g(-1) with a slow increasing stage in the deeper sediments and a sharp increasing stage in the upper sediments. The input rate of TPAHs, especially that of PAH(9) (the sum of fluoranthene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, dibenzo(ah)anthrathene, and benzo(ghi)perylene), correlated well to the Chinese historical socioeconomic data. This indicates that sediment PAHs were mainly derived from human activities and PAH(9) can be regarded as a better indicator of the local socioeconomic development. Source identification suggested that PAHs were originated primarily from mixed sources (e.g., coal and biomass burning and petroleum combustion), except for perylene which was mostly of diagenetic origin. In addition, the down-core PAHs profile clearly illustrated that PAHs sources in Northeast China experienced a transformation from low- and moderate temperature to high-temperature combustion processes, especially after the late 1980s. Additionally, an ecological risk assessment using two redefined biological thresholds (TEQ(ERL) and TEQ(ERM)) indicated that most of the PAHs measured in the present sediment core would not cause an immediate toxic effect; only FLU and PHEN are a potential source of concern for biological impairment.

Sediment records of polycyclic aromatic hydrocarbons (PAHs) in the continental shelf of China: implications for evolving anthropogenic impacts.

Sources, compositions, and historical records of polycyclic aromatic hydrocarbons (PAHs) in sediment cores collected from the Yellow Sea and the South China Sea were analyzed to investigate the influence of anthropogenic activities. The occurrence of PAHs was mainly derived from various combustion sources, especially the combustion of biomass and domestic coal. Uniform composition of sedimentary PAHs (52-62% of phenanthrene, benzo[b]fluoranthene, indeno[1,2,3-cd]pyrene, and benzo[g,h,i]perylene) suggested air-borne mixtures intractable to degradation. The concentrations of the sum of 15 PAHs (16 priority pollutants designed by the United States Environmental Protection Agency minus naphthalene; designed as Σ(15)PAH) in Yellow Sea sediment cores were generally higher than those in the South China Sea. The profiles of Σ(15)PAH concentrations recorded in the sediment cores closely followed historical socioeconomic development in China. In general, Σ(15)PAH concentrations started to increase from the background pollution level posed by agricultural economy at the turn of 20th century. In addition, a Σ(15)PAH concentration reduction was observed during the Chinese Civil War (1946-1949) and Great Cultural Revolution (1966-1976), suggesting them as setbacks for economic development in Chinese history. Increasing PAH emissions as a result of increasing coal combustion associated with the rapid urbanization and industrialization since the implementation of the Reform and Open Policy (since 1978) accounted for the fast growth of Σ(15)PAH concentrations in sediment cores. The decline of Σ(15)PAH concentrations from subsurface maximum until sampling time was inconsistent with current-day economic development in China, and may possibly suggest emission reductions due to decreasing proportional use of domestic coal and increasing consumption of cleaner energies (natural gas and liquefied petroleum gas).

Use of aliphatic hydrocarbons to infer terrestrial organic matter in coastal marine sediments off China.

Sediment samples from the marine systems along the coast of China, covering Yellow Sea, inner shelf of the East China Sea (ECS) and the South China Sea (SCS), were analyzed for n-alkanes and organic carbon. The concentrations of Σn-C(15-35) were 120-1680 ng g(-1) dry weight with an average of 560 ng g(-1). Short-chain n-alkanes (C(21)) were mainly derived from terrestrial higher plants. Organic carbon deposited into Yellow Sea and Southeast Hainan within the SCS was mainly of terrestrial (13-110%; mean: 58%) and marine (48-110%; mean: 86%) sources, respectively. On the other hand, organic carbon accumulated in the SCS adjacent to the Pearl River Estuary was derived from both terrestrial and marine sources.

Polycyclic aromatic hydrocarbons (PAHs) in continental shelf sediment of China: implications for anthropogenic influences on coastal marine environment.

Sediments collected from the continental shelf of China, embracing Yellow Sea, inner shelf of the East China Sea (ECS), and the South China Sea (SCS), were analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of anthropogenic PAHs (Σ(18)PAH) were 27-224 ng/g dry weight, with an average of 82 ng/g. Sedimentary PAHs in the continental shelf off China were mainly derived from mixed residues of biomass, coal, and petroleum combustion. Fluvial transport and atmospheric deposition mainly accounted for sediment PAHs in the ECS inner shelf and Yellow Sea (and the SCS), respectively. Furthermore, statistically higher levels of Σ(18)PAH (28-224 ng/g; mean 110 ng/g) in the Yellow Sea sediment than in the SCS sediment (28-109 ng/g; mean 58 ng/g) were probably resulted from higher PAH emissions from coke industry and domestic coal combustion in North China than in South China.

Polycyclic aromatic hydrocarbons in upstream riverine runoff of the Pearl River Delta, China: an assessment of regional input sources.

Water samples collected from upstream tributaries of the Pearl River Delta (PRD) and from locations within the PRD (South China) were analyzed for 27 polycyclic aromatic hydrocarbons (PAHs). Average concentrations (aqueous plus particulate) of total 27 PAHs (Σ(27)PAH), 16 priority PAHs designated by the United States Environmental Protection Agency (USEPA) except naphthalene (Σ(15)PAH), and the seven carcinogenic PAHs (Σ(7)PAH) classified by the USEPA were 260 ± 410, 130 ± 310, and 15 ± 12 ng/L, respectively. Riverine PAHs were predominantly generated from coal and vegetation combustion, coke production, vehicle exhausts, and petroleum residues, accounting for 28%, 25%, 22% and 21%, respectively, on average. Upstream riverine fluxes of Σ(27)PAH and Σ(15)PAH amounted to 38.9 and 12.9 tons/year, respectively. The net contributions of Σ(27)PAH and Σ(15)PAH from sources within the PRD were estimated at 21.4 and 21.0 tons/year, respectively.

Proteomic analysis identifies translationally controlled tumor protein as a mediator of phosphatase of regenerating liver-3-promoted proliferation, migration and invasion in human colon cancer cells.

BACKGROUND: Considerable evidence suggests that phosphatase of regenerating liver-3 (PRL-3) plays multiple roles in cancer metastasis; however, the molecular mechanisms remain largely unknown. The aim of this study was to identify proteins associated with PRL-3-promoted colon cancer metastasis, by comparative proteomic analysis. METHODS: Proteomes of human colon cancer LoVo cells transfected with PRL-3 gene (LoVo-PRL-3) or empty vector PAcGFP-C3 (LoVo-control) were compared using 2D gel electrophoresis. Proteins that varied significantly in concentration were selected and identified using mass spectrometry. Expression of translationally controlled tumor protein (TCTP) mRNA and protein in LoVo-PRL-3 and LoVo-control cells was detected by real-time PCR and Western blotting. Small interfering RNA (siRNA) targeting TCTP was used for silencing TCTP expression in LoVo-PRL-3 cells. Functional significance of TCTP in PRL-3-promoted colon cancer cell proliferation, migration and invasion was investigated by Cell Counting Kit-8 assay and transwell chamber. RESULTS: Seventeen proteins displaying significant and reproducible differences between LoVo-PRL-3 and LoVo-control cells were identified. Ten proteins were upregulated and seven were downregulated in LoVo-PRL-3 cells when compared with LoVo-control cells. Eight identified proteins are associated with distinct steps of tumor metastasis: ubiquitin-like protein ISG15, interleukin-18, TCTP, serpin B5, annexin A3, macrophage-capping protein, ATP-dependent RNA helicase DDX3X, and cathepsin D. Real-time PCR and Western blotting results showed that both TCTP mRNA and protein were significantly increased in LoVo-PRL-3 cells compared to LoVo-control cells. Transfection with TCTP siRNA significantly reduced the expression of both mRNA and protein levels of TCTP in LoVo-PRL-3 cells. Knockdown of TCTP by siRNA inhibited PRL-3-promoted proliferation, migration and invasion of LoVo-PRL-3 cells. CONCLUSION: Our results imply that TCTP might be a mediator of PRL-3-promoted proliferation, migration and invasion of human colon cancer cells.

Fecal steroids in riverine runoff of the Pearl River Delta, South China: levels, potential sources and inputs to the coastal ocean.

Domestic sewage is a potential source of contamination deteriorating water quality in rivers and coastal environments. The present study determined the concentrations of eight steroids in both filtrate and suspended particulate matter (SPM) samples collected monthly at the eight major riverine runoff outlets of the Pearl River Delta (PRD), South China, from March 2005 to February 2006. The concentration of the eight steroids (sum of which is defined as Sigma(8)steroid) in the filtrate and SPM samples ranged 16.7-1340 ng L(-1) and 0.44-240 microg g(-1), respectively. The filtrate samples contained the highest levels of cholesterol (CHOE) and stigmasterol (STIG) on average, whereas the SPM samples had the largest relative abundances of CHOE and coprostanol (COP). In general, larger proportions of the steroids were associated with SPM than with the filtrate phase. The combined (filtrate plus SPM) concentrations of COP in riverine runoff of the PRD were at the midpoint of the global range in surface water. The concentrations of Sigma(8)steroid and COP in SPM were not significantly correlated with particulate organic carbon (POC), riverine runoff, or SPM concentrations, which indicates the dominance of nonpoint input sources for the occurrence of steroids in the PRD. The annual riverine inputs of Sigma(8)steroid and COP were estimated at 360 and 31.6 tons yr(-1), respectively, and the monthly inputs of both Sigma(8)steroid and COP were positively correlated with monthly runoff discharge. Furthermore, the concentrations of Sigma(8)steroid, COP, and CHOE showed significant temporal and spatial variability. These results can be explained by a combination of climatic characteristics, socioeconomic conditions, and steroid sources. Analyses of the diagnostic indices of COP and background information suggested that riverine runoff from the PRD may have been affected by domestic wastewater, which appeared to be a major COP source to the Pearl River Estuary and South China Sea.

Occurrence, bioaccumulation and potential sources of polybrominated diphenyl ethers in typical freshwater cultured fish ponds of South China.

To determine the potential input sources of polybrominated diphenyl ethers (PBDEs) to fish farming environments in South China, samples of seven various environmental matrices were collected from October 2006-September 2007. Tri- to deca-BDEs were detected in all samples analyzed, with mean concentrations (+ or - standard deviations) at 5.7 + or - 3.6 ng/L in pond water, 15 + or - 11 ng/g dry wt. in pond sediment, 12 + or - 3.8 ng/g dry wt. in bank soil, 21 + or - 20 ng/g lipid wt. in fish, and 93 + or - 62 ng/g lipid wt. in fish feeds. In addition, BDE-209 was the major constituent in all samples except fish and BDE-47 was predominant in fish samples. Relatively high abundances of BDE-49 were detected in all the samples compared to those in the penta-BDE technical products. Several bioaccumulation factors were evaluated. Finally, statistical analyses suggested that fish feed, as well as pond water at a lesser degree, may have been the major source of PBDEs in freshwater farmed fish.

Occurrence of polybrominated diphenyl ethers in air and precipitation of the Pearl River Delta, South China: annual washout ratios and depositional rates.

On the basis of a one-year (from October 2006 to September 2007) sampling campaign, 34 air samples and 23 bulk precipitation samples were collected in the Pearl River Delta (PRD) in southern China and analyzed for polybrominated diphenyl ethers (PBDEs). Fifteen tri- to deca-BDE congeners (sum of which is defined as Sigma15PBDE) were detected in more than 70% of the samples. In three urban-rural regions, Sigma15PBDE concentrations ranged from 77 to 372 pg/m3 in air (particulate + vapor) and 1.98 to 15.5 ng/L in rain (particle+dissolved) from Dongguan, from 195 to 1450 pg/m3 in air and 4.71 to 17.2 ng/L in rain from Shunde, and from 23.7 to 148 ng/L in rain from Guangzhou. Among the BDE congeners, BDE-209 was the predominant component. Linear correlations between the gas-particle partition coefficients (Kp) and the subcooled vapor pressures (P(O/L)) of individual BDE congeners were observed for both the wet and dry seasons, but the slopes (-0.572 to -0.525) of the fitted equations all substantially deviated from equilibrium condition (slope = -1). The total washout ratio by bulk rainfalls was determined to be 2 x 103 for tri-BDEs and 6 x 104 for BDE-209. The estimated annual dry and wet depositional rates were 6720 and 2460 kg/yr, respectively, for BDE-209, and 7270 and 2940 kg/yr for Sigma15PBDE in the PRD, indicating a dominant pathway for PBDEs input into the PRD soil and aquatic environments.