Spatiotemporal variation and source apportionment of organotin compounds in sediments in the Yangtze Estuary

Abstract

Background: The Yangtze Estuary is a vital habitat and breeding ground for many rare species (e.g., Chinese sturgeon, Chinese paddlefish). From the view of marine ecosystem health, organotin compounds (OTCs) should be of great concern in this area based on their broad applications and potential threats. At present study, five OTC species were determined in 28 and 26 surface sediments from the Yangtze Estuary (including the Nearshore area, Estuarine Turbidity Maxima (ETM) zone and Plume zone) in 2015 and 2016, respectively. Meanwhile, four sludge samples were collected from the adjacent Shidongkou Wastewater Treatment Plant to perform a source apportionment. Results: The sum of OTCs presented a decreasing trend towards the open sea, averaging 4.8 ± 6.0 ng Sn g −1 dw in the Plume zone. While OTC levels in the Nearshore area (2.9-34.6 ng Sn g −1 dw) were similar with those in the ETM zone (5.6-36.0 ng Sn g −1 dw), and the sites belonging to the Deepwater Navigation Channel showed heavier contamination in the ETM zone than the Nearshore area. There are abundant suspended particles and organic matters in the ETM zone that can effectively capture the hydrophobic compounds. Besides, OTC contamination in shoreside zone was more serious than those in channel center. High OTC loads (average 633 ± 124 ng Sn g −1 dw) were also found in sludge samples from adjacent wastewater treatment plant. Conclusion: Land-based sources (e.g. sewage discharge, runoff) are probably one of the predominant pathways of OTCs entering the ocean. Combining with previous observation in 2014, OTC contamination in the same ten sites varied slightly with years. Risk assessment indicated that the concentrations of tributyltin (TBT) are sufficient to pose ecosystem threats especially in the ETM zone. Hence, OTC contamination issues in the Yangtze Estuary still can not be neglected.

Coupling between Increased Amounts of Microplastics and Dissolved Organic Compounds in Water

“…Besides leaching artificial additives (i.e., plasticizers, colorants, and flame retardants), MPs can also leach absorbed organic compounds into the environment. After irradiation with UV and visible light, Chen et al ( 2019) detected the release of organotin compounds (OTCs) from PVC microplastics (MPs) [86]. Four types of OTC, namely dimethyltin (DMT), monomethyltin (MMT), dibutyltin (DBT), and monobutyltin (MBT), were observed to be released from PVC in the dark.…”

“…The reason for this is that changes in salinity can alter the water and compound chemistry, affecting the pH, ionic strength, polarity, and other parameters [19]. found that the release of organotin compounds from PVC particles was inhibited under high-salinity conditions, probably due to organotin's re-adsorption on PVC [86].…”

Integrated assessment of biomarker responses and comparative toxicity pathway in snails Bellamya aeruginosa exposed to tributyltin and triphenyltin in sediments

“…In costal systems, sedimentary concentration levels of TBT were reported as ranging from 9 to 469 ng/g dw from Jinhae Bay in Korea [8], and from 0.3 to 174.7 ng/g dw at the ports of Xiamen, Shantou and Huiyang in China [9]. Chen et al [10] found that sediment samples from the Estuarine Turbidity Maxima zone of the Yangtze Estuary had the TBT levels above 10 ng/g dw, which are sufficient to bring harmful effects to benthic organisms and pose serious ecological risks. The organotin compounds' contamination was demonstrated to vary slightly during the year 2014-2016 in the Yangtze Estuary [10].…”

“…Chen et al [10] found that sediment samples from the Estuarine Turbidity Maxima zone of the Yangtze Estuary had the TBT levels above 10 ng/g dw, which are sufficient to bring harmful effects to benthic organisms and pose serious ecological risks. The organotin compounds' contamination was demonstrated to vary slightly during the year 2014-2016 in the Yangtze Estuary [10]. It is expected that the TBT and TPT effects will be present in marine environments and freshwater ecosystems for some years ahead [11].…”