Organotin compounds in surface sediments from selected fishing ports along the Chinese coast

Tetrabromobisphenol A and hexabromocyclododecanes in sediments from fishing ports along the coast of South China: Occurrence, distribution and ecological risk

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDDs) have attracted extensive attention due to their strong persistence and toxicity. However, little has been known about their pollution status in fishing ports, which are typical sinks of land-sourced pollutants. In this study, we investigated the occurrence, distribution and ecological risk of TBBPA and HBCDDs in sediments from fishing ports along the coast of South China. The concentrations of TBBPA and ΣHBCDD (sum of α-, β-, and γ-HBCDD) in the fishing-port sediments were in the ranges of 0.02-21.5 ng/g dw and 1.06-14.1 ng/g dw, respectively. γ-HBCDD was the predominant diastereoisomer in most fishing-port sediments. The enantiomeric analysis indicated a preferential enrichment of (-)-enantiomers for α-, β-, and γ-HBCDD. The geographical location of fishing ports is a significant determinant of distribution for TBBPA and HBBCDs. The concentrations of TBBPA and HBCDDs in fishing-port sediments were strongly associated with local population density, but weakly correlated with total organic carbon content of the sediment. The mass inventories of TBBPA and ΣHBCDD were estimated to be 77.0 ng/cm² and 141 ng/cm², respectively. The ecological risk assessment demonstrated that TBBPA and HBCDDs in fishing-port sediments exhibited low risks to marine organisms. This study contributes to the understanding pollution situation of fishing ports, and provides a reference for environmental safety assessment and environmental pollution control.

Butyltin Contamination in Fishing Port Sediments after the Ban of Tributyltin Antifouling Paint: A Case of Qianzhen Fishing Port in Taiwan

This study investigated the concentrations of monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) in the sediments of the Qianzhen Fishing Port (Taiwan) in 2020. Further, the pollution status, composition, and potential ecotoxicity of BTs were evaluated. This case study provides a reference for the benefits of the ban of TBT-based antifouling paint to date. Results showed that the total butyltin (ΣBTs, sum of TBT, DBT, and MBT) concentrations measured in the sediments of the Qianzhen Fishing Port ranged between 14.2–807 ngSn·g−1 dw, with an average of 356 ± 305 ngSn·g−1 dw. TBT was the most dominant species, with an average concentration of 303 ± 287 ngSn·g−1 dw. This average TBT concentration is about 4.3 times lower than in 2003, showing the progress of gradual degradation of TBT in the sediments. Still, the degradation is rather slow, with a half-life of about 8.09 years. An analysis of the effects of TBT on organisms in the sediments of the Qianzhen Fishing Port was carried out according to the TBT toxicity guidelines of the US Environmental Protection Agency and the assessment class criterion for imposex (ACCI) of the Oslo and Paris Commission (OSPAR). The results showed that TBT levels in 80% of the sediments may pose negative effects on sensitive gastropods, and half of the sediments may even have an impact on gastropod reproduction. These show that marine life is still affected and threatened by TBT compounds, despite the decline of TBT concentrations since the ban of TBT-containing antifouling paints on ships in 2008. Therefore, it is necessary to continue paying attention to the changes of TBT concentrations and their potential ecological risks in the marine environment, and to formulate TBT management plans and strategies to mitigate their impacts in marine ecosystems.

Fabrication of a honeycomb-like bimetallic SERS substrate for the detection of triphenyltin chloride

Triphenyltin chloride (TPhT) is an organotin compound that causes intensive toxicological risk to the environment and humans. A detection method with high sensitivity and stability is therefore desired to better detect TPhT. In this study, a novel SERS substrate was prepared by sputtering an ultra-thin Au layer on a honeycomb-like silver nanoarray fabricated via the nanosphere lithography method. The ultra-thin Au layer was formed by sputtering the intermittent Au nanoparticles on the silver nanoarray, resulting in bimetallic coupling with dramatically increased hotspots and extremely high SERS enhancement with an analytical enhancement factor (AEF) of 6.08 × 10⁹ using Rhodamine 6G (R6G) as the probe molecule. Based on density functional theory (DFT) simulations, the Raman characteristic peaks of TPhT at 999 cm^-1 and 655 cm^-1 were selected for TPhT detection. The AEF of the SERS substrate HC5-AgAu was calculated to be 3.38 × 10⁶ with the detection concentration of TPhT down to 10^-10 M. The as-prepared honeycomb-like silver-gold bimetallic SERS substrate demonstrated great stability and sensitivity for TPhT detection, which might also be applied in monitoring many other environmental pollutants.

Phthalates, organotin compounds and per-polyfluoroalkyl substances in semiconfined areas of the Spanish coast: Occurrence, sources and risk assessment

In this work two sensitive areas of the Spanish coast located in the Atlantic (Ria de Vigo) and Mediterranean (Mar Menor lagoon) have been studied regarding their contamination by phthalates, organotin compounds and per-polyfluoroalkyl substances (seawater and sediments) in two different campaigns (spring and autumn in 2015). PFAS and OTCs were detected in seawater and sediments at low concentrations (few ng L^-1 or ng g^-1), whereas PAEs were detected at levels two orders of magnitude higher, particularly in Mar Menor lagoon due to its semi-confined characteristics. However, PAEs and OTCs concentration in sediments were higher in Ría de Vigo than in Mar Menor lagoon as a consequence of the influence of the important urban nuclei and port in that area. The ecological risk assessment revealed that in both areas tributyltin, dibutyltin and diethylphthalate pose a significant risk in sediments, whereas in seawater tributyltin in both areas resulted in a high risk.

Development and Application of a Novel QuEChERS Method for Monitoring of Tributyltin and Triphenyltin in Bottom Sediments of the Odra River Estuary, North Westernmost Part of Poland

A Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction method combined with Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) for determination of organotin compounds (OTC) has been newly developed. The novel analytical method was validated and the quality of the results was tested by the use of certificate reference material of freshwater sediment BCR 646. The method was applied in determination of OTC concentration in real samples of bottom sediments collected from the Polish part of Odra River Estuary. The samples came from locations with different anthropogenic impact. Additionally, the extraction recovery of OTC and matrix effect on MS signal response was investigated based on those real environmental samples. It was found that organic compounds and anthropogenic contaminations present in bottom sediments may affect extraction efficiency of the organotin compounds (OTC) and change the matrix effect on MS signal response. The highest concentrations of tributyltin were found in bottom sediments collected from locations in vicinity of the Szczecin harbor and shipyards. The presence of triphenyltin above limit of detection (5 ng TPhT/g of sediment) was observed only in two samples and its concentration was several times lower compared to concentration of tributyltin (from 58 ng/g to 5263 ng/g). In spite of the fact that, the application of TBT-based paints on hull of vessel entering EU ports has been banned by European Commission regulation No. 782/2003 since 2008, the OTC compounds are still present in bottom sediment and pose significant threat to the environment. This threat should be taken into account during dredging of waterways and other hydrotechnical works.

Concentration of Organotin and Booster Biocides in Sediments of Seagrass Area from Sungai Pulai Estuary, South of Johor, Malaysia

Antifouling compounds are widely used in paints applied on ship hulls to prevent attachment of fouling organisms. However, a certain amount of these chemicals could leach from the painted surface, enter seawater, and pose deleterious effects on various marine biotas. The present study aimed to determine the concentration of organotin (OT) compounds and booster biocides in sediments collected from the seagrass area of Sungai Pulai estuary, Malaysia. The sediment samples were collected from three points on the seagrass bed, brought back to the laboratory, extracted using standard extraction procedure, and the analytes were analysed using gas chromatography-mass spectrometry (GC-MS) method. The results showed that tributyltin (TBT) concentrations in sediments were within the range of 8.1 ± 0.4 to 10.6 ± 0.5 µg/kg, whereas the values of triphenyltin (TPT) were between 17.1 ± 0.9 and 19.4 ± 1.0 µg/kg. The range of concentration of booster biocides, namely diuron, dichlofluanid chlorothalonil, Irgarol 1051, M1, and Sea-Nine 211, were from <0.1 to 22.9 ± 1.1, 48.7 ± 2.4 to 800 ± 40, <0.1 to 6.2 ± 0.3, <0.1 to 1.4 ± 0.1, 44 ± 2.2 to 877 ± 44, and 9.1 ± 0.5 to 170 ± 8.5 µg/kg, respectively. The concentration of organotin was much lower than the previous study conducted in southern Johor. Meanwhile, the increased concentration of booster biocides proves the use of these compounds as antifouling paints in shipping systems nowadays.

Organotins in the aquatic media of secondary anabranches in the Three Gorges Reservoir Region, China

The Three Gorges Reservoir Region (TGRR) is one of the most sensitive areas of ecological environment in China. As vital backwater areas, the secondary anabranches of the TGRR were prone to eutrophication in Spring which would affect the distribution and transfer of organotins (OTs) among aquatic media. This study quantified the concentrations of butyltins (BTs) and phenyltins (PhTs) in water columns and aquatic media of two anabranches of the TGRR, the Daning River (DR) and the Xiaojiang River (XR) during the state of eutrophication. Our results showed that the average concentrations of BTs and PhTs in surface water are 43.91, 81.25 ng Sn L^-1 in the DR, and 63.49, 69.21 ng Sn L^-1 in the XR, respectively, and there were no obvious differences in the concentrations of BTs and PhTs across the water columns in the DR and XR. PhTs, especially monophenyltin (MPhT), are predominated in the dissolved phase, whereas BTs, especially dibutyltin (DBT), are predominated in both suspended particulate matter (SPM) and the sediment. Shipping and agricultural activity were likely the sources of OTs in both the DR and XR. High concentrations of tributyltin (TBT) and triphenyltin (TPhT) are still present in the aquatic media of the TGRR, and pose a significant risk to aquatic organisms due to the potential for bioaccumulation. Therefore, it is necessary to further monitor and assess OTs especially PhTs in surface water, and to continue to restrict the use of OTs to protect the aquatic environment of the TGRR.

Fast and Feasible Ultrasound-Assisted Pretreatment for the Determination of Organotin Compounds in Environmental Samples

The goal of this study was to improve an already established reference method, such as the one devoted to organotin compounds determination (Reference Method for Marine Pollution Studies, No. 59, UNEP). The proposed upgrade consists of replacing the mechanical shaking by ultrasound energy and applying low temperature throughout the whole procedure. The optimization of the new operational conditions was performed by using a factorial design. Quality control was performed using a certified sediment reference material (PACS-2) for sediments (82.5-97% of recovery) and recoveries on spiked samples for suspended particulate matter (SPM) and mussels (94-100%). The proposed procedure was applied to surface sediment samples, SPM, and native bivalve mollusks (Brachidontes rodriguezii) collected in Bahia Blanca estuary, a very industrialized zone. The relative standard deviation (RSD %) of the environmental samples were less than 7.9%. It is important to note that the proposed procedure reduced the sample pretreatment time about seven times.

Occurrence of organotins in the aquatic environment during an operating cycle of the Three Gorges Reservoir, China

Organotins (OTs) pollution in the aquatic environment of the Three Gorges Reservoir (TGR) was assessed during the reservoir's operating cycle. Butyltins (BTs) and phenyltins (PhTs) in the water phase and suspended particulate matter (SPM) at different water levels were analysed. It was found that the distribution of OTs in the surface and bottom water phases were similar, with the dominant OTs being BTs at the low water level and PhTs at the high water level. The detection rates and concentrations of OTs in the water phase at the high water level were both higher than those at the low water level, with most OTs being monobutyltin (MBT) at the low water level and monophenyltin (MPhT) at the high water level. The concentrations of OTs in SPM at the low water level were higher than those at the high water level, and BTs, especially dibutyltin (DBT) and tributyltin (TBT), were the predominant OTs whether surface or bottom layer at each water level. The BTs and SPM concentrations had a significant positive relationship in all samples, indicating that the SPM concentration would determine the distribution of BTs in the aquatic environment of the TGR region (TGRR). The difference in the distribution of OTs at the different water levels indicated that the hydrological and hydraulic behaviour of the TGR influences OTs transport in the aquatic environment of the TGRR.

Tributyltin disrupts feeding and energy metabolism in the goldfish (Carassius auratus)

Tributyltin (TBT) can induce obesogen response. However, little is known about the adverse effects of TBT on food intake and energy metabolism. The present study was designed to investigate the effects of TBT, at environmental concentrations of 2.44 and 24.4 ng/L (1 and 10 ng/L as Sn), on feeding and energy metabolism in goldfish (Carassius auratus). After exposure for 54 d, TBT increased the weight gain and food intake in fish. The patterns of brain neuropeptide genes expression were in line with potential orexigenic effects, with increased expression of neuropeptide Y and apelin, and decreased expression of pro-opiomelanocortin, ghrelin, cocaine and amphetamine-regulated transcript, and corticotropin-releasing factor. Interestingly, the energy metabolism indicators (oxygen consumption, ammonia exertion and swimming activity) and the serum thyroid hormones were all significantly increased at the 2.44 ng/L TBT group in fish. However, no changes of energy metabolism indicators or a decrease of thyroid hormones was found at the 24.4 ng/L TBT group, which indicated a complex disrupting effect on metabolism of TBT. In short, TBT can alter feeding and energy metabolism in fish, which might promote the obesogenic responses.

Occurrence of organotin compounds in river sediments under the dynamic water level conditions in the Three Gorges Reservoir Area, China

The Three Gorges Project is the largest hydro project in the world, and the water level of the Three Gorges Reservoir (TGR) is dynamic and adjustable with the aim of flood control and electrical power generation. It is necessary to investigate the pollutants and their underlying contamination processes under dynamic water levels to determine their environmental behaviors in the Three Gorges Reservoir Area (TGRA). Here, we report the assessment of organotin compounds (OTs) pollution in the river sediments of the TGRA. Surface sediment samples were collected in the TGRA at low and high water levels. Tributyltin (TBT), triphenyltin (TPhT), and their degradation products in sediments were quantified by gas chromatography-mass spectrometry. Butyltins (BTs) and phenyltins (PhTs) were detected in sediments, and BTs predominated over PhTs in the whole study area under dynamic water level conditions. The concentrations of OTs in sediments varied markedly among locations, and significant concentrations were found in river areas with high levels of boat traffic and wastewater discharge. Sediments at all stations except Cuntan were lightly contaminated with TBT, and total organic carbon (TOC) was a significant factor affecting the fate of TBT in the TGRA. The butyltin and phenyltin degradation indices showed no recent inputs of TBT or TPhT into this region, with the exception of fresh TPhT input at Xiakou Town. Shipping activity, wastewater discharge, and agriculture are the most likely sources of OTs in the TGRA.