Recognition and Prioritization of Chemical Mixtures and Transformation Products in Chinese Estuarine Waters by Suspect Screening Analysis

Abstract

Chemical mixtures in surface waters could have significant impacts on exposure risks to human beings and pollution stress to aquatic system. By suspect screening analysis of high-resolution mass spectrometry data, occurrence, and compositions of ToxCast chemicals were investigated in grab estuarine water samples from a combination of 20 rivers that represents approximately 70% of the total river flow discharge along the east coast of China. In total, 59 ToxCast chemicals in seven use categories were identified, in which pesticides, intermediates, and pharmaceuticals were the abundant analogues. Significant differences in pollutant composition profiles were noticed, which possibly reflected singular release pattern and geographical-relevant usage preference (especially for herbicides and fungicides in the pesticide category). With the aid of tentative quantitative/semiquantitative measurement, essential contributors to the cumulative pollutant mass discharges and aquatic acute toxicity potentials were focused onto few particular chemicals. Existence of transformation products was further explored, which indicated that the fates of the selected parent ToxCast chemicals could be influenced by dominating transformation reactions (e.g., N-dealkylation and hydroxylation) and possible environmental factors (i.e., microbial activity). The results emphasize the necessity of suspect screening analysis for assessing the influence of terrestrial emissions of pollutants to the surrounding environment.

Occurrence and Ecological Impact of Chemical Mixtures in a Semiclosed Sea by Suspect Screening Analysis

“…In detail, among the 18 herbicides with DF over 50%, prometryn, atrazine, simetryn, and ametryn were the predominant compounds with IRs of 3–149 folds higher than the other compounds in this subcategory. These observations were consistent with our previous study, showing that triazine analogues were the main contributors to herbicide residue levels in the surrounding rivers of the Bohai Sea, which is related to cropland distribution patterns . The consistency implied that terrestrial emissions potentially affected the composition and distribution of pollutants in the Bohai Sea.…”

“…These observations were consistent with our previous study, showing that triazine analogues were the main contributors to herbicide residue levels in the surrounding rivers of the Bohai Sea, which is related to cropland distribution patterns. 16 The consistency implied that terrestrial emissions potentially affected the composition and distribution of pollutants in the Bohai Sea. Fungicides are widely used in comparable masses compared with the herbicides and insecticides globally; nevertheless, less attention has been received to the ecological exposure.…”

“…Without the need of reference standards or a priori knowledge of sample constituents, analytical strategies such as suspect and non-target screening could be used to cover a broad range of pollutant candidates, simultaneously. Integrated technical approaches, − which generally include sample pretreatment, data acquisition and processing, statistical analysis, and structure identification, are indispensable for translating mass spectrometry data into elemental compositions, compound structure, and instrumental abundances. Analogous methods have successfully characterized the composition profiles of pollutant mixtures in stormwater, airborne particulate matter, soil, and biological tissues .…”

“…Nevertheless, the lack of authentic standards still hinders accurate quantitative measurement of residue levels for a majority part of the identified chemicals, which is also detrimental to the prioritization of pollutants contributing to the ecological risks. To address the challenge, previous attempts have been made by limiting the range of substances to be evaluated to those with commercial standards available, or using additional substances with similar ionization efficiencies for preliminary semiquantitative analysis of particular groups of pollutants . Alternatively, the concept of relative ranking of chemicals was proposed in toxicity testing by introducing multiple domains of variables in a weight-of-evidence ranking framework, such as toxicological priority index (ToxPi), which might also be utilized to pave the road-linking environmental exposure to biological effects and ecological risks.…”

Persistent Organic Pollutants (POPs) and Related Chemicals in the Global Environment: Some Personal Reflections

“…Such schemes can use an array of approaches, such as: physico-chemical property measurement and estimation; in-silico prediction and computational machine learning to design and 'categorise' compounds and identify problems and unintended consequences early; inventories; non-target screening of compounds in environmental and biological indicator sample; targeted screening; bio-toxicity assays; read-across methods; modelling; hazard ranking; and risk assessment. 144,[158][159][160] These are all vitally important endeavours and will keep us all busy far into the future.…”