Shengxing Long

The partitioning behavior of perfluoroalkyl acids (PFAAs) between water and suspended particulate matter (SPM) can significantly influence their migration and fate in aquatic environments, yet the role of natural organic matter, including dissolved organic matter (DOM) and particulate organic matter (POM), in this process has rarely been explored. This study investigated the potential influences of DOM and POM on multiphase distribution process and migration of PFAAs. Results indicated that the origin and humification degree of DOM and POM were different, leading to distinct effects on the partitioning and migration of PFAAs. Overall, DOM inhibited adsorption of PFAAs to SPM, while POM promoted it, with protein-like components playing a more significant role than humus-like components. As the humification degree of DOM increases, its inhibiting effect decreases due to a reduced affinity of DOM components for PFAAs. In contrast, this effect is less pronounced in POM due to its higher humification degree. Furthermore, during the sedimentation of particulate PFAAs, wind can shift their pollution hotspots away from the emission source, probably increasing the spread of ecological risks. These findings indicate that DOM and POM may alter the fate of PFAAs by changing their partitioning, highlighting the need for strategies to prevent potential risks in practice.

In recent years, mangrove restoration has gained significant attention due to its carbon storage capacity, role as a pollution sink, and ecological and economic benefits. Moreover, the United Nations Sustainable Development Goals’ strategies include mangrove restoration. This review investigates the status of mangrove restoration research and the influence of restoration on trace metal accumulation, speciation, and associated risks in mangrove sediments. Our analysis reveals that research on mangrove restoration is increasing globally, with a notable surge in publications after 2017. However, fewer than 25 articles published between 2007 and 2024 address trace metals in restored mangroves, indicating limited focus from researchers on this topic. Research shows that mangrove restoration can quickly alter sediment properties, such as texture, salinity, and pH. As a result, restored sediments tend to accumulate higher organic carbon content than barren areas. Most studies also suggest that trace metal accumulation is higher in restored sites than in non-restored areas. However, metal speciation varies considerably between sites due to local environmental factors. Furthermore, many studies suggest that restoration may increase the risks posed by trace metals to aquatic biota. The challenges of mangrove restoration research include short study timeframes, low success rates, poorly defined targets, small-scale efforts, conflicts with local communities over resources and benefits, insufficient government funding, and a lack of historical data on community health and pollution status.

The water quality has degraded with economic development globally. However, the relationship between food-web structure and nitrogen and phosphorus is of rare concern. To study food chain in this ecosystem, we measured the concentrations of stable isotope value δ13C and δ15N in aquatic matter and organisms in Pearl River. The δ13C and δ15N concentrations ranged from −41.2‰ to −19.4‰ and from 0.81‰ to 25.4‰, respectively. The δ13C concentrations in consumers were significantly higher than the particulate organic matter (POM), periphyton, phytoplankton, and higher aquatic plants. The δ13C of POM was likely derived from phytoplankton and exogenous organic detritus entering from a tributary, rather than from endogenous phytoplankton in the main river channel. The δ13C of phytoplankton was derived from eutrophic water with high nitrogen and phosphorus concentrations. Total δ13C was significantly higher in fish than in POM, phytoplankton, higher aquatic plants, and zooplankton, indicating that those components were the main carbon sources for fish. The carbon sources tended to be the same for different fish species in the same season at the same site, but different for a given fish species among seasons and sampling sites. This finding suggested that the feeding habits of different fish species converge as an adaptation to change environment. The food chain was longer (trophic level = 4.4) in river subsections with more carnivorous fish, such as Erythroculter pseudobrevicauda and Coilia grayii, and shorter in areas with more omnivorous fish. The total nitrogen and total phosphorus concentrations in the water were negatively correlated with food-chain length (R2 = 0.67, P<0.05; R2 = 0.40, P<0.05). These results suggested that limiting nitrogen and phosphorus inputs into the water body would reduce the ecological risk in this area.

Crystal violet (CV), a triphenylmethane dye, is widely used in the textile, printing, paper, leather, and cosmetics industries. However, due to its higher chemical stability and lower biodegradability, CV has teratogenic and carcinogenic toxic effects on animals and humans. Therefore, the objective of the present study was to investigate whether or not the as-prepared nZVI supported on an ordered mesoporous Zr-Ce-SBA-15 composite (nZVI/Zr-Ce-SBA-15) had more potential for CV removal from simulated wastewater in comparison with Zr-Ce-SBA-15. Meanwhile, the parameters of CV adsorption onto nZVI/Zr-Ce-SBA-15 composites were optimized by a response surface methodology (RSM) and an artificial neural network combined with particle swarm optimization (ANN–PSO). According to XRD, FTIR, SEM, and TEM, N₂ adsorption, and thermogravimetric analyses, nZVI was supported successfully on Zr-Ce-SBA-15 composites, becoming an ordered mesoporous material. The results of RSM indicated that the order of the effects of the four parameters on CV removal was, successively, initial pH, contact time, temperature, and initial CV concentration. ANN–PSO was more suitable, in comparison to RSM, to optimize the experimental parameters for CV removal from simulated wastewater using ordered mesoporous nZVI/Zr-Ce-SBA-15 composites. The optimized removal rate of CV was 93.87% under an initial pH of 3.00, a contact time of 20.00 min, an initial CV concentration of 261.00 mg/L, and a temperature of 45. Pseudo-second-order kinetics can better describe the behavior of CV adsorption onto nZVI/Zr-Ce-SBA-15 composites. The process of CV adsorption onto Zr-Ce-SBA-15 composites was followed by the Langmuir model, and its maximum adsorption capacity was 105 mg/g in 213 K. It was indirectly confirmed that the maximum adsorption capacity of nZVI/Zr-Ce-SBA-15 exceeded this value because the removal efficiency of CV using nZVI/Zr-Ce-SBA-15 was obviously higher than that of using Zr-Ce-SBA-15. The thermodynamics results indicated that CV adsorption onto nZVI/Zr-Ce-SBA-15 was a spontaneous, endothermic, and entropy-driven process. The dissolution of Fe ions and light/dark experiments confirmed nZVI/Zr-Ce-SBA-15 was simultaneously of adsorption and catalysis in the process of CV removal. The effect of removal CV was still maintained in the first four experiments (removal rate > 78%), and our suggestion is that nZVI/Zr-Ce-SBA-15 is a potential adsorbent for CV remediation from wastewater compared to Zr-Ce-SBA-15 and other adsorbents.

Antibiotic (Σsulfonamide, Σfluoroquinolone, Σtetracycline and Σmacrolide) contamination in aquatic systems has remained a global concern in recent years. In this study, fourteen antibiotics, sulfadiazine (SDZ), sulphapyridine (SPD), sulfacetamide (SCT), sulfamethoxazole (SMX), sulfamethazine (SMZ), trimethoprim (TMP), ofloxacin (OFX), lomefloxacin (LFX), ciprofloxacin (CFX), norfloxacin (NFX), oxytetracycline (OTC), tetracycline (TC), dehydroerythromycin (ETM-H2O) and roxithromycin (RTM), were analysed in zooplankton collected from the Yelang Lake Reservoir between May 2016 and Mar. 2017. Our results demonstrated that the antibiotic TC (mean 95.80 ng g-1), OTC (mean 167.0 ng g-1) and RTM (mean 151.80 ng g-1) concentrations were significantly higher in zooplankton than the other antibiotics. TC, OTC and RTM accumulated intensively in zooplankton, and the BAFs of OTC, RTM and TC were significantly higher, with mean BAF values of 78.43, 108.4 and 110.1, respectively. Antibiotic concentrations were strongly correlated with zooplankton phytoplankton biomass, OTC, RTM and SMX concentrations in zooplankton were significantly positively correlated with bacillariophyte biomass, and SDZ and SMZ concentrations in zooplankton were significantly positively correlated with T. brevifurcatus, T. mongolicus, and D. pulex biomass. SPD with P. tunguidus, C. cornuta, TMP, ETM and OFX with P. tunguidus, C. cornuta, M. leuckarti, C. vicinus vicinus, CFX with D. pulex, LFX with T. brevifurcatus, T. mongolicus, Bosmina longirostris, and D. dubium were significantly positively correlated. These results show that bioaccumulation or scavenging of antibiotics across trophic levels is a fundamental and complex component of antibiotic cycling in aquatic environments.

Biochar can have multiple benefits, such as solid waste recycling, water pollution treatment, carbon fixation and sustainability, and it is green, friendly, inexpensive and highly efficient. Therefore, the present study aimed to investigate Cd(II) removal from aqueous solutions using pomelo peel derived biochar combined with a permeable reactive barrier (PRB). Meanwhile, the materials were characterized using SEM, FIIR, XRD, N₂ adsorption, Zeta potential, TGA and XPS. The removal conditions were optimized by a response surface methodology (RSM) and a back propagation combined with genetic algorithm (BP-GA). The results show that there were slight changes in the structure of the pomelo peel derived biochar before and after activation, while the variation was not significant. The specific surface areas of the not activated and activated pomelo peel derived biochars were 3.207 m² g⁻¹ and 6.855 m² g⁻¹, respectively. The pore diameter of the former was 4.165 nm and that of the latter was 4.425 nm, indicating that the two materials are mainly mesoporous. BP-GA is more suitable than RSM for optimizing the removal conditions of Cd(II) using the prepared materials combined with PRB. The maximum removal efficiency of Cd(II) was 90.31% at biochar dosage = 4.84, reaction time = 53.75 min, initial Cd(II) concentration = 19.36 mg l⁻¹ and initial pH = 6.07. The verification experiment was 88.74% under these experimental conditions, and the absolute error was 1.57%. The saturated adsorption capacity of quartz sand for Cd(II) is approximately 0.08 mg g⁻¹ when reaching equilibrium. The saturated adsorption capacity of biochar for Cd(II) is approximately 29.76 mg g⁻¹. Pseudo second order kinetics and Langmuir isotherm adsorption were more suitable for describing the Cd(II) adsorbed from an aqueous solution by activated pomelo peel derived biochar. The adsorption process of Cd(II) by the prepared biochar was spontaneous, endothermic and entropy driven. Our results suggest that the modified pomelo peel derived biochar can be regenerated within the fourth cycle and that it has application prospects as a useful adsorbent for water treatment in PRB systems. This finding provides a reference for relieving Cd pollution and for its large scale removal from wastewater when combined with a PRB system.

Spinacia oleracea L., as the most widely cultivated green leafy vegetable in China, can threaten human health in cases of its excessive heavy metal content, especially in mining areas of karst landforms. Therefore, the present study mainly investigates whether biochar is useful for remediating heavy metal pollution in soil and S. oleracea and the degree of this improvement in karst areas. The effects of heavy metal exposure on the health of children and adults in S. oleracea and rhizosphere lime soil with six biochar levels are evaluated by a health risk assessment, namely, 4000 g of lime soil (C-0), 160 g of biochar + 3840 g of lime soil (C-160), 240 g of biochar + 3760 g of lime soil (C-240), 320 g of biochar + 3680 g of lime soil (C-320), 400 g of biochar + 3600 g of lime soil (C-400) and 800 g of biochar + 3200 g of lime soil (C-800). The results show that the pH values of the lime soil were positively correlated with Pb, P and K contents and negatively correlated with As, Cr, Hg, Cd and N contents in S. oleracea. The assessments of the potential ecological risk index show that the soil samples for the C-0 and C-160 levels pose moderate ecological hazards, while the soil samples for the C-320, C-800, C-400 and C-240 levels constitute mild ecological hazards. The single noncarcinogenic risks, total noncarcinogenic risk indexes, single carcinogenic risks and total carcinogenic risks values indicate that exposure to heavy metals in lime soil and S. oleracea poses a serious threat to human health. It also presents an unacceptable cancer risk and children are more threatened than adults. Our results suggest that heavy metal pollution of S. oleracea and its rhizosphere lime soil in karst areas still poses a threat to human health after adding biochar, and the relevant local departments need to implement more active measures to solve the excessive heavy metal contents in the local soil and vegetables of this karst regions.