RESUMO
Estuaries serve as crucial filters for land-based pollutants to the open sea, but there is a lack of information on the migration and fate of organophosphate flame retardants (OPFRs) within estuaries. This study focused on the Pearl River Estuary (PRE) by examining the co-occurrence of OPFRs and their metabolites and quantifying their transport fluxes using a mass balance model. The seawater concentrations of OPFRs and their metabolites exhibited significant seasonal variations (p < 0.01), while the sediment concentrations of OPFRs reflected the long-term distributional equilibrium in the PRE. The concentration of Σ9OPFRs in seawater showed a relentless dilution from the entrance to the offshore region in the normal and wet seasons, which was significantly in accordance with the gradients of pH, dissolved oxygen (DO), and salinity (p < 0.05). Furthermore, horizontal migration dominated the transport of OPFRs, and the inventory assessment revealed that both the water column and sediment were important reservoirs in the PRE. According to the estimated fluxes from the mass balance model, riverine input emerged as the principal pathway for OPFR entry into the PRE (1.55 × 105, 6.28 × 104, and 9.00 × 104 kg/yr in the normal, dry and wet seasons, respectively), whereas outflow to the open sea predominantly determined the main fates of the OPFRs. The risk quotient (RQ) results showed that EHDPHP (0.835) in water posed medium ecological risk, while other OPFRs and metabolites presented relatively lower risk (RQ < 0.1). The risk control effects were evaluated through scenario simulations of mathematical fitting between controllable source factors and the RQ of risky OPFR. The risk of EHDPHP in the PRE could be effectively reduced by restricting its concentrations in entrance region (<9.31, 8.67, and 12.7 ng/L in the normal, dry and wet seasons, respectively) of the PRE. This research offers foundational insights into environmental management and pollution control strategies for emerging pollutants in estuaries.
Assuntos
Poluentes Ambientais , Retardadores de Chama , Poluentes Químicos da Água , Organofosfatos/análise , Estuários , Retardadores de Chama/análise , Rios , Poluentes Químicos da Água/análise , Água , ChinaRESUMO
Tetrabromobisphenol A (TBBPA) analogues have been investigated for their prevalent occurrence in environments and potential hazardous effects to humans and wildlife; however, there is still limited knowledge regarding their toxicokinetics and trophic transfer in aquatic food chains. Using a developed toxicokinetic model framework, we quantified the bioaccumulation, biotransformation and trophic transfer of tetrabromobisphenol S (TBBPS) and tetrabromobisphenol A di(allyl ether) (TBBPA-DAE) during trophic transfer from brine shrimp (Artemia salina) to zebrafish (Danio rerio). The results showed that the two TBBPA analogues could be readily accumulated by brine shrimp, and the estimated bioconcentration factor (BCF) value of TBBPS (5.68 L kg-1 ww) was higher than that of TBBPA-DAE (1.04 L kg-1 ww). The assimilation efficiency (AE) of TBBPA-DAE in zebrafish fed brine shrimp was calculated to be 16.3%, resulting in a low whole-body biomagnification factor (BMF) in fish (0.684 g g-1 ww). Based on the transformation products screened using ultra-high-performance liquid chromatograph-high resolution mass spectrometry (UPLC-HRMS), oxidative debromination and hydrolysis were identified as the major transformation pathways of TBBPS, while the biotransformation of TBBPA-DAE mainly took place through ether bond breaking and phase-II metabolism. Lower accumulation of TBBPA as a metabolite than its parent chemical was observed in both brine shrimp and zebrafish, with metabolite parent concentration factors (MPCFs) < 1. The investigated BCFs for shrimp of the two TBBPA analogues were only 3.77 × 10-10 - 5.59 × 10-3 times of the theoretical Kshrimp-water based on the polyparameter linear free energy relationships (pp-LFERs) model, and the BMF of TBBPA-DAE for fish was 0.299 times of the predicted Kshrimp-fish. Overall, these results indicated the potential of the trophic transfer in bioaccumulation of specific TBBPA analogues in higher trophic-level aquatic organisms and pointed out biotransformation as an important mechanism in regulating their bioaccumulation processes. ENVIRONMENTAL IMPLICATION: The internal concentration of a pollutant in the body determines its toxicity to organisms, while bioaccumulation and trophic transfer play important roles in elucidating its risks to ecosystems. Tetrabromobisphenol A (TBBPA) analogues have been extensively investigated for their adverse effects on humans and wildlife; however, there is still limited knowledge regarding their toxicokinetics and trophic transfer in aquatic food chains. This study investigated the bioaccumulation, biotransformation and trophic transfer of TBBPS and TBBPA-DAE in a simulated di-trophic food chain. This state-of-art study will provide a reference for further research on this kind of emerging pollutant in aquatic environments.
Assuntos
Poluentes Ambientais , Perciformes , Bifenil Polibromatos , Poluentes Químicos da Água , Animais , Humanos , Cadeia Alimentar , Bioacumulação , Ecossistema , Peixe-Zebra/metabolismo , Biotransformação , Perciformes/metabolismo , Poluentes Ambientais/análise , Éteres , Poluentes Químicos da Água/análiseRESUMO
The substantial utilization of antibiotics causes their "pseudo-persistence" in offshore environments. Published studies on antibiotic surveillance in food webs have primarily emphasized on parent forms; however, the compositions and concentrations of conjugated antibiotics in aquatic organisms remain largely unexplored. This study systematically examined the distribution characteristics and trophodynamics of free antibiotics and their conjugated forms in an estuarine food web. Total antibiotic levels differed insignificantly between the surface and bottom waters. The total mean values of free antibiotics in crabs, fish, shrimps, sea cucumbers, and snails varied from 0.77 to 1.4 ng/g (wet weight). The numbers and values of antibiotics rose in these biological samples after enzymatic hydrolysis. Conjugated antibiotics accounted for 23.8-76.9% of the total antibiotics in the biological samples, revealing that conjugated forms play a non-negligible role in aquatic organisms. More number of antibiotics exhibited bioaccumulation capabilities after enzymatic hydrolysis. In the food web, the free forms of anhydroerythromycin and conjugated forms of trimethoprim and ciprofloxacin underwent trophic dilution, whereas the free forms of trimethoprim and conjugated forms of ofloxacin underwent trophic amplification. The present work provides new insights into the bioaccumulation and trophic transfer of free and conjugated antibiotics in food webs.
Assuntos
Cadeia Alimentar , Poluentes Químicos da Água , Animais , Antibacterianos/análise , Bioacumulação , Multimídia , Poluentes Químicos da Água/análise , Organismos Aquáticos , Peixes , Trimetoprima , Monitoramento Ambiental , ChinaRESUMO
The production and use of hexabromocyclododecanes (HBCDs) have been strictly limited due to their persistence, toxicity and bioaccumulation. However, the release of HBCDs from related products and wastes would continue for a long time, which may cause many environmental problems. In this study, we investigated the occurrence and distribution of HBCDs and microplastics (MPs) in aquatic organisms inhabiting different substrates. HBCDs were measurable in the seawater, sediment, expanded polystyrene (EPS) substrates and organism samples. Mostly, the concentrations of HBCDs in organisms inhabiting EPS buoys were significantly higher than those of the same species inhabiting other substrates. Meanwhile, the diastereomeric ratio (α/γ) of HBCDs in organisms inhabiting EPS buoys was closer to that in EPS buoys. The fugacity values of HBCDs in EPS buoys were much higher than those in other media, implying that HBCDs can be transferred from EPS buoys to other media. Additionally, MPs derived from EPS buoys would be mistaken as food and ingested by aquatic organisms. The transfer of HBCDs from EPS buoys to aquatic organisms can be achieved by aqueous and dietary exposures. In combination, the contribution of MP ingestion to HBCDs for aquatic organisms should be very limited. These results supported EPS buoys as an important source of HBCDs for the aquatic ecosystem. To effectively control HBCDs pollution, it is necessary to discontinue or reduce the use of EPS buoys.
Assuntos
Hidrocarbonetos Bromados , Poluentes Químicos da Água , Poliestirenos/análise , Ecossistema , Plásticos , Monitoramento Ambiental , Hidrocarbonetos Bromados/análise , Organismos Aquáticos , Poluentes Químicos da Água/análiseRESUMO
Due to strong endocrine disrupting effects, steroids in the environment have attracted substantial attention, with studies mostly focusing on the parent steroids. Here, we conducted the first investigation on the contamination profiles, possible sources, mass inventories, and ecological risks of 27 steroids and their metabolites in 15 typical fishing ports in Southeast China. Twelve steroids were detectable in the sediment samples with the total mean concentrations of 4.6-35 ng/g. High proportions of steroid metabolites were measured in the sediments and five metabolites were newly observed. Untreated municipal sewage and aquaculture wastes constitute the possible steroid sources in the studied fishing ports. The total inventories of steroids in fishing ports ranged from 2.1-16 mg/m2, with their metabolites being important contributors. The ecological risk analysis indicated high risks across all sampling sites mainly due to the contributions of parent steroids. Furthermore, our results found that progesterone is an acceptable chemical indicator for various steroids in sediments. This study provides the first evidence of steroid metabolites in the marine environment, calling for more studies in environmental behavior and ecotoxicology of steroid metabolites.
Assuntos
Monitoramento Ambiental , Poluentes Químicos da Água , Aquicultura , China , Sedimentos Geológicos , Esteroides/análise , Poluentes Químicos da Água/análiseRESUMO
The fluorescence characteristics of dissolved organic matter (DOM) were determined in the seagrass ecosystem collected in Xincun Bay of Hainan Island in late January, 2013, using fluorescence excitation-emission matrix spectroscopy (EEMs). EEMs spectra showed 2 types of fluorescence signals in DOM samples, three hurnic-like fluorescence peaks and two protein-like fluorescence peaks, respectively. The former included UVC peak A (Ex/Em: 230/430 nm), UVA peak C (Ex/Em: 350/440 nm), and UVA peak M (Ex/Em: 300/380-400 nm), while the latter included tryptophan-like peaks R (Ex/Em: 230/355 - 375 nm) and N (Ex/Em: 280-300/365-380 nm). Peak N was more like a combination of Peak M and Peak R. Moreover, free tyrosine-like molecules in DOM from the seagrass-beds ecosystem did not exist because the tyrosine-like fluorescence was not found. There were significant positive correlations of peak N with M and R (0. 97 and 0. 54 for R2, respectively), and peak A with C (0. 86 for R2), showing their same sources and biogeochemical behaviors. The change law of mean fluorescence intensities of those fluorescence signals was R (0. 304 RU) >A (0. 194 RU) >M (0. 147 RU) >N (0. 125 RU) >C (0. 051 RU). And, higher . L-1 concentrations of all the fluorescence occurred in the coastal waters inshore, with low values in two small regions located in the southwest and southeast of the bay where the seagrasses flourished. The distributions of those fluorescence signals in Xincun Bay suggested that the dynamics responsible for the humic-like fluorescence might be the same as that responsible for the protein-like fluorescence. The high fluorescence index (FI: 1. 81), high biological index (BIX: 1. 44) and low humification index (HIXa: 4. 2 and HIXb: 0. 81) showed that the DOM from the seagrass-dominant ecosystem has a strong autochthonous contribution and poor humification degree. The results clearly suggested that the DOM in this region has a rather unique fluorescence characteristic and is quite different from other aquatic environments.
Assuntos
Ecossistema , Compostos Orgânicos/análise , Espectrometria de Fluorescência , Fluorescência , Proteínas , Análise EspectralRESUMO
The optical characteristics of chromophoric dissolved organic matter (CDOM) were determined in rain samples collected in Xiamen Island, during a rainy season in 2007, using fluorescence excitation-emission matrix spectroscopy associated with UV-Vis absorbance spectra. Results showed that the absorbance spectra of CDOM in rain samples decreased exponentially with wavelength. The absorbance coefficient at 300 nm [a(300)] ranged from 0.27 to 3.45 m(-1), which would be used as an index of CDOM abundance, and the mean value was 1.08 m(-1). The content of earlier stage of precipitation events was higher than that of later stage of precipitation events, which implied that anthropogenic sources or atmospheric pollution or air mass types were important contributors to CDOM levels in precipitation. EEMs spectra showed 4 types of fluorescence signals (2 humic-like fluorescence peaks and 2 protein-like fluorescence peaks) in rainwater samples, and there were significant positive correlations of peak A with C and peak B with S, showing their same sources or some relationship of the two humic-like substance and the two protein-like substance. The strong positive correlations of the two humic-like fluorescence peaks with a(300), suggested that the chromophores responsible for absorbance might be the same as fluorophores responsible for fluorescence. Results showed that the presence of highly absorbing and fluorescing CDOM in rainwater is of significant importance in atmospheric chemistry and might play a previously unrecognized role in the wavelength dependent spectral attenuation of solar radiation by atmospheric waters.
RESUMO
Fluorescence excitation-emission matrix spectroscopy (EEMs) was applied to study the photobleaching of chromophoric dissolved organic matter (CDOM) in two surface water samples from Xiamen Bay exposed to natural sunlight between 10:00-16:00 during September 12-18, 2007. Both samples were collected from the lower and middle salinity areas in Jiulong Estuary of Xiamen Bay, and then filtered by 0.2 microm polycarbonate filters before the photobleaching incubation experiment. The results showed that three humic-like (C, A, M) and two protein-like (T, B) fluorescence peaks were observed in both samples, and the photobleaching didn't cause obvious shift of the positions of these fluorescence peaks. The fluorescence intensities of the five peaks decreased with the increase in irradiation time and peak C demonstrated the fastest photobleaching rate. The photobleaching rate of low salinity sample was higher than that of middle salinity sample, consistent with its higher content of chromophores. All the five fluorophores could be distinguished into labile and refractory components based on their photobleaching dynamics. The increase in the intensity ratios of peak T and C (IT/IC) and peak T and C (IA/IC) after irradiation suggested that photobleaching can cause obvious change of the properties of dissolved organic matter in seawater, and it may partly account for the dominance of the protein-like fluorescence relative to the humic-like fluorescence in coastal area. The results suggest that EEMs was a useful tool to trace the transformation and removal processes of terrestrial CDOM entering the coastal regions. Keywords Chromophoric dissolved organic matter (CDOM); Photobleaching; Excitation-emission matrix spectroscopy
RESUMO
Low salinity water sample collected from Jiulong River Estuary filtered using 0.2 microm Millipore filter was exposed to natural solar radiation from 10:00 to 16:00 each day during one week period in early and late May, 2005. Photodegradation of fluorescence and absorption properties of CDOM (chromophoric dissolved organic matter) was observed. The results showed that humic-like fluorescence (lambda Ex/lambda Em = 350/450 nm), tryptophan-like fluorescence (lambda Ex/lambda Em = 225/350 nm) and absorption coefficient of CDOM can be significantly photodegraded during short-term solar exposure in early summer. These photodegradation processes followed the first-order dynamic equation. The degradation half time of humic-like fluorescence, tryptophan-like fluorescence and a (280) were calculated as 3.5-5.1 d, 3.0-4.5 d and 6.3 d. The absorption loss spectra of CDOM indicated that the solar UV radiation was responsible for the photochemical degradation of CDOM. The loss of humic-like fluorescence (70%) was obviously higher than loss of a (280) (about 40%), suggesting that photobleaching ability of CDOM fluorophores were much stronger than CDOM chromophores. However, the correlation relationship between humic-like fluorescence and absorption coefficient are still kept. A250/A350 of CDOM increased till the end of radiation experiment compared with the control group, suggesting photodegradation may decrease the average molecular size of CDOM. These findings show that terrestrial CDOM can be transformed and removed by photochemical decomposition after transport into the sea, and photodegradation might be an important sink for terrestrial CDOM.