Amino accelerators and antioxidants in sediments from the Dong Nai River System, Vietnam: Distribution and influential factors

摘要

Amino accelerators and antioxidants (AAL/Os) have become a suite of contaminants of emerging concern recently due to the accumulating evidence for their environmental occurrence and associated toxic potential. Nevertheless, data on sedimentary deposition of AAL/Os has remained scarce, particularly for regions beyond the North America. In the present study, we elucidated spatial distribution of fifteen AAL/Os and five AAO trans-formation products (AAOTPs) in seventy-seven sediments from the Dong Nai River System (DNRS), Vietnam. Total concentrations of AAL/Os ( n-ary sumation AAL/Os) ranged from 0.377 to 51.4 ng/g (median: 5.01 ng/g). 1,3-Diphenyl-guanidine and 4,4 '-bis(1,1-dimethylbenzyl) diphenylamine were the two most prevalent congeners, both with detection frequencies >80%. Additionally, AAOTPs were quantifiable in 79% of the DNRS sediments with a median n-ary sumation AAOTPs at 2.19 ng/g, dominated by N, N '-diphenylbenzidine and 2-nitrodiphenylamine. Higher sediment-associated levels of AAL/Os and AAOTPs were spotted in downstream and the primary tributary of the DNRS compared to the upstream, implying their cumulative sedimentation towards the estuarine region. The distribution patterns of AAL/Os and AAOTPs across individual transects also demonstrated the influence of human activities (e.g., urbanization and agriculture), hydrodynamics, and decontamination by mangrove re-serves. Meanwhile, characteristics of sediments, i.e., total organic carbon (TOC) content and grain sizes, exhibited significant correlations with the burdens of these compounds, indicating their preferential partitioning into the fine and TOC-rich matter. This research sheds light on environmental behavior of AAL/Os and AAOTPs beneath Asian aquatic system, and highlights the need for further evaluation of their impacts on the wildlife and public health.

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