环境科学与技术最新文献

Wildfires remarkably alter the quantity and quality of dissolved organic matter (DOM) that regulates postfire biogeochemical processes and environmental quality. However, it remains unclear how the heating-induced percent changes (%HIC) in DOM quantity and quality differ among soil types on a wide geographic scale. Here, we used dissolved organic carbon (DOC) quantification, absorption, and fluorescence spectroscopies, and Fourier transform ion cyclotron resonance mass spectrometry to investigate the variations in %HIC in DOM quantity and quality of Chinese soil reference materials after heating at 250 and 400 °C. Our results reveal that as soil pH increased, %HIC in DOC content increased, while %HIC in aromaticity-related indices of DOM decreased for both heating temperatures. Moreover, the %HIC in DOM biolability and contents of aliphatics increased with soil pH for 250 °C heating but remained relatively stable for 400 °C heating. Results suggest that compared to those in acidic soil-dominated forests, wildfires in alkaline soil-dominated forests may cause greater DOM content and biolability in soils, which may facilitate postfire microbial recovery. These findings deepen our understanding of the site-specific impacts of wildfires on DOM and the subsequent implications for biogeochemical cycling and environmental quality across different geographic regions.

The transformation pathways and risks of emerging contaminants (ECs) in wastewater remain unclear due to the limited throughput of nontarget screening. In this study, an improved method called entropy similarity-driven transformation reaction molecular networking (ESTRMN) was developed to identify transformation products (TPs) in wastewater. In detail, entropy similarity was the most effective algorithm for identifying parent-product spectrum pairs and a threshold of 0.5 for it was determined with the guarantee of high specificity. Additionally, a TP structure database predicted according to known structures and reactions was established to assist in identification. Sartan is one of the most commonly used angiotensin II receptor blocker antihypertensive drugs. Take sartans as an example, 69 TPs of sartans with confidence levels above 3 were identified by ESTRMN, 43 of which were newly discovered. The most common reactions included hydroxylation, hydrolysis, and oxidation, resulting in the majority of sartan TPs exhibiting higher persistence, mobility, and toxicity (PMT) than their parents. The concentration of 75% sartans and TPs increased after treatment in a WWTP, and the overall risk has not been effectively mitigated. This study emphasizes the role of ESTRMN in incorporating TPs of ECs into environmental monitoring protocols and risk assessment frameworks for wastewater management.

Chlorinated persistent organic pollutants (Cl-POPs) are highly hydrophobic and are easily adsorbed to solid particulate matter after being released into the water column, thus affecting the transformation process and environmental fate. This study investigated the photodegradation behavior of 16 Cl-POPs in the Pearl River suspended particulate matter (SPM)-water system. The photodegradation rates of polychlorinated biphenyls (PCBs) were generally higher than those of dioxins and increased with substitution numbers of Cl atoms. A QSAR model correlating photodegradation rate constants of Cl-POPs and their structural parameters was established by using multiple linear regression (MLR) analysis and machine learning. The model results showed that soil-water partition coefficient (K_OC), morgan fingerprint (mf_1747), and nucleophilicity index (NI) were the main factors affecting the photodegradation of Cl-POPs, confirming that the photodegradation of Cl-POPs with higher hydrophobicity and larger nucleophilic reactivity proceeded faster. According to the quenching experiment and theoretical calculation results, ^•O₂^- in the hydrophobic region contributed more to the strongly hydrophobic Cl-POPs, while the contribution of ^•OH was mainly concentrated in the weakly hydrophobic Cl-POPs. This study provided valuable insights into photolysis-related environmental persistence and fate of Cl-POPs in the SPM-water system.