Springer Science and Business Media LLC

Persulfate (PS)-based in situ chemical oxidation (ISCO) has been widely used for pollutant remediation in soil and groundwater. However, the underlying mechanism of interactions between mineral and PS was not fully explored. In this study, several soil model minerals including goethite, hematite, magnetite, pyrolusite, kaolin, montmorillonite, and nontronite were selected to investigate their potential effects on PS decomposition and free radical evolution. It was found the decomposition efficiency of PS by these minerals varied significantly, and both the radical and non-radical decomposition processes were included. Pyrolusite has the highest reactivity for PS decomposition. However, PS decomposition is prone to form SO42− through non-radical pathway, and thus, the amounts of free radicals (e.g., •OH and SO4•−) produced are relatively limited. However, PS mainly decomposed to produce free radicals in the presence of goethite and hematite. In the presence of magnetite, kaolin, montmorillonite, and nontronite, PS both decomposed to produce SO42− and free radicals. Furthermore, the radical process exhibited the high degradation performance for model pollutant such as phenol with relatively high utilization efficiency of PS, while non-radical decomposition has limited contribution to phenol degradation with extremely low utilization efficiency of PS. This study deepened the understanding of interactions between PS and minerals during the PS-based ISCO in soil remediation.

Cirrhinus mrigala, Labeo rohita, and Catla catla are economically important fish for human consumption in Pakistan, but industrial and sewage pollution has drastically reduced their population in the River Chenab. Statistics are an important tool to analyze and interpret comet assay results. The specific aims of the study were to determine the DNA damage in Cirrhinus mrigala, Labeo rohita, and Catla catla due to chemical pollution and to assess the validity of statistical analyses to determine the viability of the comet assay for a possible use with these freshwater fish species as a good indicator of pollution load and habitat degradation. Comet assay results indicated a significant (P < 0.05) degree of DNA fragmentation in Cirrhinus mrigala followed by Labeo rohita and Catla catla in respect to comet head diameter, comet tail length, and % DNA damage. Regression analysis and correlation matrices conducted among the parameters of the comet assay affirmed the precision and the legitimacy of the results. The present study, therefore, strongly recommends that genotoxicological studies conduct appropriate analysis of the various components of comet assays to offer better interpretation of the assay data.

Plastic is a broad name given to the different types of organic polymers having high molecular weight and is commonly derived from different petrochemicals. Plastics are generally not biodegradable or few are degradable but in a very slow rate. Day by day, the global demand of these polymers is sharply increasing; however, considering their abundance and potentiality in causing different environmental hazards, there is a great concern in the possible methods of degradation of plastics. Recently, there have been some debates at the world stage about the potential degradation procedures of these synthetic polymers and microbial degradation has emerged as one of the potential alternative ways of degradation of plastics. Alternatively, some scientists have also reported many adverse effects of these polymers in human health, and thus, there is an immediate need of a potential screening of some potential microbes to degrade these synthetic polymers. In this review, we have taken an attempt to accumulate all information regarding the chemical nature along with some potential microbes and their enzymatic nature of biodegradation of plastics along with some key factors that affect their biodegradability.

Water quality and quantity should be paid more attention in regions with arid climate and thick vadose zones since the limited groundwater cannot be replenished rapidly once polluted. This study focused on the Loess Plateau of China to investigate the geochemical mechanism affecting groundwater chemistry and to calculate contribution rates of multiple sources to groundwater solutes. We employed multiple methods (diagrams, bivariate analyses, hierarchical cluster analysis (HCA), sodium adsorption ratio (SAR), water quality index (WQI), correlation analysis, and forward model) for the above purposes. We collected 64 groundwater samples in the thick loess deposits in June 2018 (flood season) and April 2019 (dry season). The average concentrations of cation were in the order of Ca2+ > Na+ > Mg2+ > K+ in the flood season, and Na+ > Ca2+ > Mg2+ > K+ in the dry season. The order of anions contents in the flood season and the dry season were HCO3- > SO42- > Cl- > NO3-. The major hydrochemical facies were Ca-HCO3 and Ca·Mg-HCO3 in the flood season and Na·Ca-HCO3·SO4 and Na-HCO3 in the dry season, respectively. Most of the groundwater (95% in the flood season and 96% in the dry season) was suitable for drinking, and the overall water quality was acceptable for irrigation. Mineral dissolution and cation exchange were important natural processes affecting groundwater chemistry. The forward model showed that the contribution of atmospheric input, anthropogenic input, evaporite dissolution, silicate weathering, and carbonate weathering to solutes in groundwater was 2.3±1.5%, 5.0±7.1%, 19.3±21.4%, 42.8±27.3%, and 30.6±27.1% in the flood season, and 9.1±6.4%, 3.4±5.2%, 20.3±15.9, 56.6±23.2%, and 10.7±15.4% in the dry season, respectively. Obviously, silicate and carbonate weathering contribute the most to groundwater chemistry in the flood season, while silicate weathering and evaporite dissolution contribute the most in the dry season. Although the overall contribution of anthropogenic inputs was insignificant, it was the dominant source of solutes for local groundwater. This study provides fundamental information for water management in arid areas.

Two polypropylene HVAC electret filters: a regular filter and an antimicrobial filter containing zinc pyrithione (ZPT), were compared for filtration performance. The study was conducted over 7 months in realistic conditions with semi-urban outdoor air. Several parameters were monitored over the study period: the average temperature was about 20 °C and relative humidity about 60%, the average inlet concentration of cultivable microorganisms was 50 CFU m−3, the average inlet concentration of particles was 10 μg m−3, the filter pressure drop increased moderately by about 30 Pa, and the particle collection efficiency of soda fluorescein (median diameter 0.35 μm) decreased in the first half of the study period by about 30% and then stabilized. The microbial concentration on the filters was quantified every 2 months using an innovative methodology based on media coupons in conjunction with microorganism quantification by CFU counting, with 5 culture media favorable to bacteria and/or fungi growth. The microbial concentrations on the filters were between 100 and 2000 CFU cm−2. The antimicrobial effect of zinc pyrithione was confirmed by the fungi cultivated with DRBC agar: no effects in the level of filter clogging were revealed in the range studied. The high statistical deviation in the results regarding the inhibiting effect of zinc pyrithione on bacteria prevents any conclusion.

Emerging demand for humic substances escalated the short supply of coal-related resources from which humic substances are extracted in large quantities for various applications. Production of humic-like substances from lignocellulosic waste materials similar in structural and functional properties to humic substances has gained interest recently. Tea waste is a by-product from tea manufacturing factories enriched in lignocellulose is used to extract two types of humic fractions. One fraction has purified humic-like acid (HLA), and the other has unpurified humic and fulvic acids called as humic-like substances (HLS). Elemental composition, spectroscopic (13C CPMAS NMR and FTIR) properties, and biological activity of tea waste derived humic-like substances (TWDHLS) were compared with commercially available humic acid (CHA) extracted from lignite. Elemental analysis and FTIR characterization showed slight differences between HLA and HLS, while NMR results revealed that both have similar carbon distribution and are abundant in cellulosic polysaccharides and lignin derivatives. The presence of more stable compounds in TWDHLS contribute to its recalcitrant nature. NMR spectra of CHA significantly varied with TWDHLS and were rich in aliphatic compounds. The biological activity of TWDHLS and CHA was studied at five different concentrations (0, 20, 40, 80, and 160 mg L−1). The results show that soil application TWDHLS at 80 mg L−1 concentration showed better results on the growth of tea nursery plants similar to CHA, contrasting to the variation in their structural properties. Our findings revealed that TWDHLS could be used not only as a potential plant biostimulant but also as a better substitute for humic substances.

Achieving the carbon neutrality in China has great impact on alleviating global warming. Compost application, an important measure to promote soil organic carbon (SOC) sequestration, has been practiced in China since 2015. However, it is still unclear how much carbon can be fixed by cropland soil under compost application in the whole China. China has pledged to strive for the goal of carbon neutrality by 2060, which brought two issues: whether compost application can consistently promote SOC sequestration until 2060, and how much contribution it can make to the carbon neutrality. In the present study, we analyzed the results from 93 literatures to determine the SOC sequestration under compost application in the different agricultural divisions of China. Results showed that there were regional differences in the effect of compost application on SOC sequestration. The annual SOC sequestration in Northern China (NC) and Gansu + Xinjiang (GX) was significantly high than other regions. In addition, the annual SOC sequestration was negatively related to the duration of the experiment, while the accumulative SOC sequestration during the experimental period increased with the increase of the duration. According to our results, the total SOC sequestration in topsoil of Chinese cropland was 85 Tg C year−1 under compost application, which will make a 4.4% contribution to carbon neutrality during 2021–2060. In conclusion, cropland soil in China can still sequester carbon for more than 35 years under compost application. Thus, abidingly promoting compost application in China is crucial to accomplishing the carbon neutrality goal.