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Heavy metal pollution in water has become a global environmental problem, threatening aquatic ecosystems and human health. Physical and chemical methods can effectively remove heavy metal pollutants, while their applications are limited due to the high costs, complex operation, and susceptibility to secondary pollution. Bioremediation is the most promising method for eliminating toxic pollutants. Microorganisms including bacteria, fungi, and algae can convert toxic heavy metals into less toxic forms, which has become an effective and environmentally friendly solution for the remediation of heavy metal pollution in water environments. This paper expounds the toxicity and mechanism of heavy metal pollution, microbial remediation mechanisms, and primary microbial remediation strategies, providing a reference for the removal or reduction of metal pollutants in water environments as well as the development of related technologies.

Concerns over the emergence of steroid hormones as pollutants in water have grown. Steroid hormone compounds present challenges in the simultaneous detection of total residual hormones owing to their analogous structures and diverse types. In this study, we established a rapid and high-throughput continuous online method based on solid phase extraction (SPE) coupled with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the simultaneous determination of 61 hormone components, including 48 glucocorticoids, 1 mineralocorticoid, 4 androgens, and 8 progesterones, in water. Various SPE columns were investigated to assess their extraction efficiency for enriching and purifying target compounds in a large sample volume (1 L). An HC-C18 SPE column was selected because of its superior performance. Acetonitrile was used as a washing solution during SPE to ensure that the majority of the tested substances achieved recoveries exceeding 70% and effectively avoid interferences from water-soluble components. Various C8 and C18 columns were tested, and the optimal HPLC conditions for hormone retention were established. We systematically evaluated different UPLC columns and mobile phases, including methanol-water and acetonitrile-water systems with 0.1% formic acid added to the aqueous phase. The optimized UPLC conditions were as follows: BEH C 18 column (100 mm×2.1 mm, 1.7 μm); column temperature, 40 ℃; flow rate, 0.3 mL/min; injection volume, 5 μL; mobile phase A: 0.1% formic acid aqueous phase; mobile phase B: acetonitrile. Gradient elution was performed as follows: 0-0.5 min, 30%B; 0.5-15.0 min, 30%B-75%B; 15.0-18.0 min, 75%B-98%B; 18.0-19.0 min, 98%B; 19.0-19.1 min, 98%B-30%B; 19.1-20.0 min, 30%B. Both positive- and negative-ion modes were explored in the UPLC-MS/MS experiment to obtain the full scan of the parent ions, and positive mode was finally selected for electrospray ionization (ESI). Two product ions exhibiting strong signals and minimal interference were selected for quantitative and qualitative ion analyses, using an external standard method for quantification. MS/MS was performed in positive-ion (ESI + ) mode with multiple reaction monitoring (MRM) scanning. The MS/MS parameters were as follows: atomizing gas pressure, 379 kPa; curtain air pressure, 241 kPa; spray voltage, 5500 V; desolvation temperature, 550 ℃; collision exit voltage (CXP), 13 V; intake voltage (EP), 10 V; and residence time of each ion pair, 0.5 ms. Other instrument settings, such as the collision energy and declustering voltage, were also optimized. The 61 hormones exhibited excellent linear relationships within their corresponding concentration ranges, with correlation coefficients greater than 0.99. The method detection limits (MDLs) were in the range of 0.05-1.50 ng/L. The average recoveries of the 61 hormones across three spiked levels ranged from 62.3% to 125.2%, with relative standard deviations (RSDs, n =6) of 1.1%-10.5%. Using this method, we successfully detected 10 hormone components (cortisone, fluticasone propionate, ciclesonide, betamethasone dipropionate, clobetasone butyrate, diflucortolone valerate, halobetasol propionate, isoflupredone, difluprednate, and hydroxyprogesterone caproate) in various surface water and groundwater samples collected from the Taihu Basin region. The SPE-UPLC-MS/MS method presented in this paper is simple, highly sensitivity, and exceptionally accurate. Thus, it exhibits promising potential for tracing targeted hormone residues in water and will be of great value in monitoring and ensuring water safety. Finally, a regional analysis was conducted on the hormone levels in water, and suggestions were made for the targeted treatment of hormone residues in future sewage treatment processes.

The revision of the national standards for drinking water quality is an important, rigorous and delicate endeavor. The paper introduced the revision of this standard, emphasizing the revision principle, overall technical considerations, and revision contents. Recommendations were also proposed for the implementation of this standard.

Through the investigation and detection of the surface water and sediments of Luoma Lake, the structure and occurrence characteristics of PFASs (perlyfluoroalkyl substances) in the two types of media were analyzed, and the principal component analysis method was used to analyze the characteristics of such substances in the surface water. The source was analyzed, and the potential health risks of such substances were evaluated using the risk quotient method. The results showed that a total of 13 PFASs were detected in the surface sediments of Luoma Lake, and one more species was detected in the surface water (PFTeA); ρ (ΣPFASs) in the surface water ranged from 46.09 to 120.34 ng·L -1 , and ω (ΣPFASs) in sediments ranged from 2.22 to 9.55 ng·g -1 . PFPeA was the major component in surface water, and the mass fraction of PFPeA was 38%. PFBA was the major component in sediment, and the mass fraction of PFPeA was 61%. The multi-media PFASs in Luoma Lake were mainly short-chain substances; the high concentration area of PFASs in the surface water of Luoma Lake was concentrated and distributed at the mouth of the northern rivers. Its concentration showed a decreasing trend from north to south, and the content of PFASs in the sediments showed a decreasing trend from southwest to northeast. The distribution of ΣPFASs, PFBA, and PFOS in the sediments of Luoma Lake and the TOC content in the sediment were related; the principal component analysis showed that the PFASs in the surface water of Luoma Lake were mainly from textile flame retardant, rubber product emulsification, food packaging processes and paper surface treatment industries, the metal electroplating industry, and leather and textile manufacturing industries. PFASs in the surface water of Luoma Lake were at a relatively low health risk level.

Due to the limitations of the treatment process of urban sewage treatment plants and the complexity of water sources, the rich inorganic nitrogen and trace persistent organic matter in the reclaimed water cause potential human health risks through lateral leakage or bioaccumulation during the replenishment process of rivers and lakes. Exploring the distribution law of different types of reclaimed water characteristic water quality factors and their formation in reclaimed water replenishment river channels is of great significance to river and lake management. This study takes the Beijing-Tianjin-Hebei section of the North Canal as the research area and explores the spatial variation characteristics of conventional physical parameters, full index, inorganic nitrogen, and salinity hydronium antibiotics in river water quality with the help of clustering, discrimination, principal components, and variance decomposition. The results showed that, although the spatial distribution patterns of different types of water quality factors were consistent, they all showed significant mid-upstream and downstream distribution; however, there were big differences in the degree of variation and the mechanism of variation. The spatial variation of inorganic nitrogen and antibiotics was the most obvious, whereas the variation in conventional physical parameters and the full index was the weakest, and the salinity hydronium showed moderate variation. The spatial variation mechanism of conventional physical parameters was mainly reflected in microbial degradation. The full index was the result of the combined effect of microorganisms, diffusion, the synergy of the two, and a certain degree of source-sink homogeneity. Diffusion was the main mechanism affecting the spatial variation in salinity hydronium. The spatial variation mechanism of inorganic nitrogen was mainly reflected in the source-sink homogenization and microbial degradation; as a secondary mechanism of the spatial variation of inorganic nitrogen, diffusion had a synergistic mode with microbial degradation. Antibiotics, which have great differences in chemical structural stability and biodegradability, showed high spatial variability and had the highest diffusion and microbial synergy mechanism. This research provides a quantitative analysis of the spatial variability mechanism of water quality based on variance decomposition, which has practical guiding significance for the causes of the spatial variability of river pollutants and river management.