Garden pruning waste is becoming a problem that intensifies the garbage siege. It is of great significance to purify polluted water using biochar prepared from garden pruning waste. Herein, the interaction mechanism between BPS and oriental plane tree biochar (TBC) with different surface functional groups was investigated by adsorption experiments, spectroscopic analysis and theoretical calculations. Adsorption kinetics and isotherm of BPS on TBC can be satisfactorily fitted into pseudo-second-order kinetic and Langmuir models, respectively. A rapid adsorption kinetic toward BPS was achieved by TBC in 15 min. As compared with TBC prepared at low temperature (300 °C) (LTBC), the maximum adsorption capacity of TBC prepared at high temperature (600 °C) (HTBC) can be significantly improved from 46.7 mg g⁻¹ to 72.9 mg g⁻¹. Besides, the microstructure and surface functional groups of HTBC were characterized using SEM, BET-N₂, and XPS analysis. According to density functional theory (DFT) theoretical calculations, the higher adsorption energy of HTBC for BPS was mainly attributed to π-π interaction rather than hydrogen bonding, which was further supported by the analysis of FTIR and Raman spectra as well as the adsorption thermodynamic parameters. These findings suggested that by improving π-π interaction through high pyrolysis temperature, BPS could be removed and adsorbed by biochar with high efficacy, cost-efficiency, easy availability, and carbon-negative in nature, contributing to global carbon neutrality.

Herein, polyethylenimine (PEI)-grafted nitrogen (N)-doping magnetic biochar (PEIMW@MNBCBM) was synthesized, and characterization results showed that the microwave-assisted PEI grafting and ball milling-assisted N doping introduced abundant amino, pyridine N and pyrrole N structures onto biochar, which possessed high affinity to Cr(VI) in the anion form. The as-prepared PEIMW@MNBCBM displayed pH-dependence adsorption performance and high tolerance to co-existing ions with maximum uptake capacity of Cr(VI) identified as 183.02 mg/g. Furthermore, PEIMW@MNBCBM could bind Cr(VI) through electrostatic attraction, complexion, precipitation, reduction and pore filling. Especially, effective reduction of Cr(VI) was ascribed to cooperative electron transfer of partial oxygen-containing functional groups, intramolecular pyridine/pyrrole N, protonated amino and Fe²⁺ on the adsorbent, while oxygen-containing and amino functional groups from N-doping biochar and PEI synergistically complexed Cr(III) via providing lone pair electrons to form coordinate bonds. Furthermore, the stable precipitation was formed between Fe³⁺ and Cr(III). Additionally, the Cr(VI) elimination efficiency could maintain 95.83% even after four adsorption-desorption cycles, suggesting PEIMW@MNBCBM as a high-performance adsorbent for Cr(VI) contaminated water remediation.

River floodplain ecosystems host one of the highest freshwater molluscan biodiversity on Earth. However, multiple human disturbances, such as loss of hydrological connectivity and deterioration of water quality, are seriously threatening most floodplain lakes throughout the world. Given the high imperilment rate of freshwater molluscs but the scarcity of studies examining the anthropogenic effects on this fauna, we test the response of mollusc assemblages to river-lake disconnection and eutrophication in 30 lakes in the Yangtze River floodplain, China. The species richness of entire Mollusca, Gastropoda and Bivalvia and 6 dominant families were all much lower at disconnected lakes than that in connected lakes, and decreased with increasing water eutrophication. The assemblage structure differed significantly among four lake groups for datasets based on entire Mollusca, Gastropoda and Bivalvia, indicating the serious impacts of hydrological disconnection and eutrophication. Moreover, the connected lakes showed significantly lower values of average taxonomic distinctness (Δ⁺) but higher values of variation in taxonomic distinctness (Λ⁺) than disconnected lakes. Such variations were triggered by the extirpation of congeneric and endemic species (mainly from families Unionidae and Viviparidae), which giving a waring of the loss of mollusc endemism in this region. In general, the present study showed that river-lake disconnection and deterioration of water quality resulted in serious biodiversity declines of both gastropods and bivalves in the Yangtze River floodplain lakes. A systematic approach including restoration of river-lake connectivity and habitats and improvement of water quality should be implemented in the conservation planning in this large river floodplain.

Legionella species are the etiological agent of Legionnaires' disease, a pathology easily contracted from water circuits and by the inhalation of aerosol droplets. This bacterium mainly proliferates in water: Legionella pneumophila is the most commonly isolated specie in water environments and consequently in water system, although further Legionella species have frequently been isolated, including Legionella dumoffii. The simultaneous presence of the two species in the water system can therefore lead to the simultaneous infection of several people, giving rise to harmful outbreaks. Ultraviolet inactivation of waterborne microorganisms offers a rapid and effective treatment technique and recently is getting more attention mostly to eliminate unsafe level of contamination. To tackle the issue, the inactivation of the two species of Legionella spp., namely L. pneumophila and L. dumoffii, by means of UV-A light emitting diodes (UV-A LED) system is explored. We used a commercially available UV-A LED at 365 nm wavelength, and the UV-A dose is given incrementally to the Legionellae with a concentration of 10⁶ CFU/mL in 0.9% NaCl (aq) solution. In this study, with a UV-A-dose of 1700 mJ/cm², the log-reduction of 3-log (99.9% inactivation) for L. pneumophila and 2.1-log (99.1% inactivation) for L. dumoffii of the contaminated water are achieved. The Electrical Energy per Order (EEO) is evaluated and showed this system is more economic and efficient in comparison with UV-C and UV-B LEDs. Following the support of this preliminary study with additional tests, aiming to validate the technology, we expect this device may be installed in water plants such as cooling systems or any water purification station in either industrial or home scales to reduce the risk of this infectious disease, preventing consumers' health.

Distillery sludge is a major source of aquatic pollution, but little is known about their microbial community and their association with the organic and metal pollutants. Sugarcane molasses-based distillery is an important industry in India, although the waste is usually treated prior to disposal, the treatment is often inadequate. The adverse effects of the organic and metal pollutants in sugarcane molasses-based distillery sludge on the microbial biodiversity and abundance in the disposal site have not been elucidated. This study aims to address this gap of knowledge. Samples were collected from the discharge point, 1 and 2 km downstream (D1, D2, and D3, respectively) of a sugarcane distillery in Uttar Pradesh, India, and their physico-chemical properties characterised. Using QIIME, taxonomic assignment for the V3 and V4 hypervariable regions of 16 S rRNA was performed. The phyla Proteobacteria (28–39%), Firmicutes (20–28%), Bacteriodetes (9–10%), Actinobacteria (5–10%), Tenericutes (1–9%) and Patescibacteria (2%) were the predominant bacteria in all three sites. Euryechaeota, were detected in sites D1 and D2 (1–2%) but absent in D3. Spirochaetes (5%), Sinergistetes (2%) and Cloacimonetes (1%) were only detected in samples from site D1. Shannon, Simpson, Chao1, and Observed-species indices indicated that site D1 (10.18, 0.0013, 36706.55 and 45653.84, respectively) has higher bacterial diversity and richness than D2 (6.66, 0.0001, 25987.71 and 49655.89, respectively) and D3 (8.31, 0.002, 30345.53 and 30654.88, respectively), suggesting the organic and metal pollutants provided the stressors to favour the survival of microbial community that can biodegrade and detoxify them in the distillery sludge. This study confirmed that the treatment of the distillery waste was not sufficiently effective and provided new metagenomic information on its impact on the surrounding microbial community. It also offered new insights into potential bioremediation candidates.

The effectiveness and feasibility of the three biochar materials for remediation of arsenic (As) and lead (Pb) contaminated soil were explored in this study. Significant reduction of bioaccessibility and migration risks of both heavy metals have been explained mechanistically by incubation, column experiments and numerical simulation. Langmuir equation fitted As and Pb sorption isotherms better in the control and biochar (BC) amended soils, while Freundlich model was more suitable for iron modified biochar (Fe-BC) and sulfur/iron modified biochar (S/Fe-BC) amended soils, indicating that modified biochar promoted chemical adsorption process for As and Pb. For the three biochar materials, S/Fe-BC showed the best effects on reducing the bioavailability of As and Pb, with a decrease of 40.42%–64.21%. The reduction in bioaccessibility by metal portioning into available and non-available fractions was better for illustrating the mechanisms including adsorption, precipitation/coprecipitation and As(III) oxidation behind S/Fe-BC efficacy. Moreover, S/Fe-BC can effectively inhibit the leaching behavior of As and Pb under acid rain, which increased by 99.89% and 90.18%, respectively, compared with the control. The HYDRUS-1D modeling indicated that S/Fe-BC could continuously treat As (100 mg/L) and Pb (1000 mg/L) contaminated water for 16.22 years and 40.86 years, respectively, and ensure the groundwater quality criteria being met. Based on these insights, we believe that our study will provide meaningful information about the potentials of biochar derived materials for soil heavy metals’ remediation.

Quinolone antibiotics (QNs) pollution in lake environments is increasingly raising public concern due to their potential combined toxicity and associated risks. However, the spatiotemporal distribution and trophodynamics of QNs in transit-station lakes for water diversion are not well documented or understood. In this study, a comprehensive investigation of QNs in water, sediment, and aquatic fauna, including norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR), and ofloxacin (OFL), was conducted in Luoma Lake, a major transit station for the eastern route of the South-to-North Water Diversion Project in China. The target QNs were widely distributed in the water (∑QNs: 70.12 ± 62.79 ng/L) and sediment samples (∑QNs: 13.35 ± 10.78 ng/g dw) in both the non-diversion period (NDP) and the diversion period (DP), where NOR and ENR were predominant. All the QNs were detected in all biotic samples in DP (∑QNs: 80.04 ± 20.59 ng/g dw). The concentration of ∑QNs in the water in NDP was significantly higher than those in DP, whereas the concentration in the sediments in NDP was comparable to those in DP. ∑QNs in the water-sediment system exhibited decreasing trends from northwest (NW) to southeast (SE) in both periods; however, the Kₒc (organic carbon normalized partition coefficients) of individual QNs in DP sharply rose compared with those in NDP, which indicated that water diversion would alter the environmental fate of QNs in Luoma Lake. In DP, all QNs, excluding NOR, were all biodiluted across the food web; whereas their bioaccumulation potentials in the SE subregion were higher than those in the NW subregion, which was in contrast to the spatial distribution of their exposure concentrations. The estimated daily QN intakes via drinking water and aquatic products suggested that residents in the SE side were exposed to greater health risks, despite less aquatic pollution in the region.

Water pollution is an urgent problem that needs to be controlled via green transformation and the development of the Yangtze River Economic Belt (YREB). Based on the water pollutant discharge and socio-economic database of prefecture-level cities in the YREB from 2011 to 2015, this study explores the spatiotemporal variations in water pollutant discharge in the YREB via two main indicators: chemical oxygen demand (COD) and ammonia nitrogen (NH₃–N). Further, the spatial effects and determinants of water pollutant discharge are quantitatively estimated. The results show that (1) the water pollutant discharge in the YREB has decreased significantly, with the COD and NH₃–N discharge reduced by 10.46% and 10.79%, respectively, and the discharge reduction in the lower reaches was the most prominent; (2) the spatial pattern of water pollutant discharge in the YREB was generally stable and partially improved, and cities with a high rate of water pollutant reduction in the YREB were distributed in the main stream region of the Yangtze River and the intersection of the main stream and tributaries; (3) spatial effects had a significant impact on water pollutant discharge in the YREB, with regional cooperation and economic radiation through environmental management and control initially showing a combined reduction trend in regional water pollutants; and (4) determinants of population size and agricultural economic share declined to varying degrees at the end of the study period, although the urbanization level continued to increase, indicating that urbanization in the YREB occurred too quickly and that water pollutant discharge reduction was limited. However, economic development leading to the deterioration of the water environment was alleviated. In addition, foreign direct investment (FDI) inflows and rapid industrialization processes must be monitored to increase the reduction in characteristic water pollutants.

Excessive nutrient discharges have resulted in pervasive water pollution and aquatic eutrophication. China has made massive efforts to improve water quality since 2000. However, how long-term policy interventions govern external and internal fluxes as well as nitrogen (N) concentrations is not well known. Here we examined the historical N concentration change and its key drivers in eutrophic Lake Dianchi (southwest China) over the period 2002–2018, based on monthly observations of water quality and external N fluxes, local surveys of mitigation measures, and process-based model simulations of internal N fluxes. Our data indicated that N concentrations peaked at 3.0 mg L⁻¹ in 2007–2010 but afterwards declined down to 1.2 mg L⁻¹ in 2018. Compared with 2010, the decline in lake N concentrations was attributed to reduced riverine N inflow decreasing by 0.20 g N m⁻³ month⁻¹ and the water-sediment exchange flux decreasing by 0.07 g N m⁻³ month⁻¹ from 2010 to 2018. Adoptions of wastewater treatment, pollution interception, and transboundary water transfer dominated the changes in external and internal fluxes of N and thereby the decline of lake N concentrations. These findings underscore the priority of reducing external discharge for historical lake water quality improvement and the need of enhancing internal N removal for future lake ecosystem restoration.

Excess of water irrigation and fertilizer consumption by crops has resulted in high soil nitrogen (N) losses and underground water contamination not only in China but worldwide. This study explored the effects of soil N input, soil N output, as well as the effect of different irrigation and N- fertilizer managements on residual N. For this, two consecutive years of winter wheat (Triticum aestivum L.) –summer maize (Zea mays L.) rotation was conducted with: N applied at 0 kg N ha⁻¹ yr⁻¹, 420 kg N ha⁻¹ yr⁻¹ and 600 kg N ha⁻¹ yr⁻¹ under fertigation (DN0, DN420, DN600), and N applied at 0 kg N ha⁻¹ yr⁻¹ and 600 kg N ha⁻¹ yr⁻¹ under flood irrigation (FN0, FN600). The results demonstrated that low irrigation water consumption resulted in a 57.2% lower of irrigation-N input (p < 0.05) in DN600 when compared to FN600, especially in a rainy year like 2015–2016. For N output, no significant difference was found with all N treatments. Soil gaseous N losses were highly correlated with fertilization (p < 0.001) and were reduced by 23.6%–41.7% when fertilizer N was decreased by 30%. Soil N leaching was highly affected by irrigation and a higher reduction was observed under saving irrigation (reduced by 33.9%–57.3%) than under optimized fertilization (reduced by 23.6%–50.7%). The net N surplus was significantly increased with N application rate but was not affected by irrigation treatments. Under the same N level (600 kg N ha⁻¹ yr⁻¹), fertigation increased the Total Nitrogen (TN) stock by 17.5% (0–100 cm) as compared to flood irrigation. These results highlighted the importance to further reduction of soil N losses under optimized fertilization and irrigation combined with N stabilizers or balanced- N fertilization for future agriculture development.