PubMed · 10976690
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F I Grunder, C Bell. Proficiency Analytical Testing (PAT) Program March 2000.. https://pubmed.ncbi.nlm.nih.gov/10976690/
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Organophosphate esters (OPEs), widely used as flame retardants and plasticizers, have been increasingly detected in aquatic environments. However, investigations of their distribution in high-altitude plateau lakes remain scarce. Identifying and quantifying the sources and associated risks of OPEs are crucial for subsequent water environment management. In this study, an integrated source-risk analysis approach was employed by combining the Positive Matrix Factorization (PMF) model, the Geodetector (GD) model, and risk quotient (RQ). Analysis of 14 OPEs in surface waters of the Dianchi Lake Basin (DLB) revealed 12 detectable compounds, with total OPEs concentrations (ΣOPEs) ranging from not detected (ND)-64.6 ng/L during the wet season and ND-35.8 ng/L during the dry season. Elevated ΣOPEs were primarily observed at inflow sites in the northern part of the lake and in urban rivers. Source apportionment indicated four major contributing sources: agricultural films containing flame-retardant and plasticizer additives, traffic-related particulate emissions, releases from household and personal care products, and industrial production and applications of flame retardants in plastics, electronics, and related products (the predominant source). The ecological impact caused by OPEs ranges from no risk to low risk, with tris(2-chloroethyl) phosphate emitted from industrial source being the primary driver of potential environmental risk. These findings highlight the necessity of prioritizing industrial sources in future management strategies. Overall, this study provides a methodological framework for source apportionment and risk assessment of OPEs and offers scientific evidence to support environmental management of OPEs in the DLB.
In this study we used multidimensional solution-state NMR to elucidate the differences in the chemical composition of solid phase extracted and ultrafiltered DOM isolates. DOM was isolated from water sampled from an oligotrophic river, the River Tagliamento (Italy). The recovery of total DOM was up to 42% with both isolation techniques. In addition to 1- and 2-D solution-state NMR, we also applied 1-D solid-state 13C NMR spectroscopy for DOM characterization. 13C NMR spectroscopy only produced broad overlapping resonances, thus allowing a bulk characterization of DOM composition. However, it demonstrated that the bulk chemical composition of the two DOM fractions exhibited minor spatial-temporal changes. The 2-D experiments (TOCSY, HMQC) showed that the solid phase extracted hydrophobic DOM contained predominantly aliphatic esters, ethers, and hydroxyl groups, whereas the ultrafiltered DOM was comprised partially of peptides/protein, with further evidence for a small amount of aliphatic/fatty acid material. Sugars were present in both DOM fractions. The results show the two isolation techniques selected for different suites of compounds within the bulk DOM pool.
Humic acid was fractionated into eight different molecular size components using ultrafiltration. Solid-state CPMAS 13C NMR demonstrated that fractions larger than 100,000 Daltons were primarily aliphatic in character, while fractions smaller than 30,000 Daltons were predominantly aromatic in character. Solid-state 19F NMR examination of the sorptive uptake of hexafluorobenzene (HFB) by HA and each of the fractions gave spectroscopic evidence for the existence of at least three sorption sites in the smaller molecular size fractions, while two predominant sorption sites could be established in the larger molecular size fractions. Sorbed HFB displayed higher mobility in the smaller, more aromatic fractions while HFB in the larger, more aliphatic fractions displayed lower mobility. The relative mobilities of HFB in each sorption domain suggest that the rigid domain may be composed of aliphatic carbon rather than aromatic carbon moieties. In larger size fractions, this domain may be the result of rigid, glassy regions composed of aliphatic molecules or side chains.