Extracellular Polymeric Substances (EPS) influenced Poly Cyclic Aromatic Hydrocarbons (PAHs) degrading Klebsiella pneumoniae was isolated from the marine environment. To increase the EPS production by Klebsiella pneumoniae, several physicochemical parameters were tweaked such as different carbon sources (arabinose, glucose, glycerol, lactose, lactic acid, mannitol, sodium acetate, starch, and sucrose at 20 g/L), nitrogen sources (ammonium chloride, ammonium sulphate, glycine, potassium nitrate, protease peptone and urea at 2 g/L), different pH, carbon/nitrogen ratio, temperature, and salt concentration were examined. Maximum EPS growth and biodegradation of Anthracene (74.31%), Acenaphthene (67.28%), Fluorene (62.48%), Naphthalene (57.84%), and mixed PAHs (55.85%) were obtained using optimized conditions such as glucose (10 g/L) as carbon source, potassium nitrate (2 g/L) as the nitrogen source at pH 8, growth temperature of 37 °C, 3% NaCl concentration and 72 h incubation period. The Klebsiella pneumoniae biofilm architecture was studied by confocal laser scanning microscopy (CLSM) and scanning electron microscope (SEM). The present study demonstrates the EPS influenced PAHs degradation of Klebsiella pneumoniae.

Developing low-cost and high-performance biosorbent for water purification continues drawing more and more attention. In this study, cellulose-chitosan composite hydrogels were fabricated via a co-dissolution and regeneration process using a molten salt hydrate (a 60 wt% aqueous solution of LiBr) as a solvent. The addition of chitosan not only introduced functionality for metal adsorption but also increased the specific surface area and improved the mechanical strength of the composite hydrogel, compared to pure cellulose hydrogel. Batch adsorption experiments indicated that the composite hydrogel with 37% cellulose and 63% chitosan exhibited an adsorption capacity of 94.3 mg/g (1.49 mmol/g) toward Cu²⁺ at 23 °C, pH 5, and initial metal concentration of 1500 mg/L, which was 10 times greater than the adsorption capacity of pure cellulose hydrogel. Competitive adsorption from a mixed metals solution revealed that the cellulose-chitosan composite hydrogel exhibited selective adsorption of the metals in the order of Cu²⁺ > Zn²⁺ > Co²⁺. This study successfully demonstrated an innovative method to fabricate biosorbents from abundant and renewable natural polymers (cellulose and chitosan) for removing metal ions from water.

The feasibility and effectiveness of iron turning waste as low cost and sustainable permeable reactive barrier (PRB) media for remediating dieldrin, endrin, dichlorodiphenyltrichloroethane (DDT), and lindane individually (batch system) and combined (continuous flow column) in water were investigated. After 10 min of reaction in a batch system, removal of endrin, dieldrin, and DDT was higher (86–91 %) than lindane (41 %) using 1 g of iron turning waste in 200 mL of pesticide solution (20 μg/L for each pesticide). Among the studied pesticides, only lindane removal decreased substantially in the presence of nitrate (37 %) and magnesium (18 %). Acidic water environment (pH = 4) favored the pesticide removal than neutral and basic environments. For the column experiments, sand alone as PRB media was ineffective for remediating the pesticides in water. When only iron turning was used, the removal efficiencies of lindane, endrin, and dieldrin were 83–88 % and remained stable during 60 min of the experiments. DDT removal was less than other pesticides (58 %). Sandwiching the iron turning waste media between two sand layers improved DDT removal (79 %) as well as limited the iron content below a permissible level in product water. In a long-term PRB column performance evaluation, iron turning waste (150 g) removed all pesticides in water (initial concentration of each pesticide = 2 μg/L) effectively (≥94 %) at a hydraulic retention time of 1.6 h. Iron turning waste, which was mainly in the form of zerovalent iron (Fe⁰), was oxidized to ferrous (Fe²⁺) and ferric (Fe³⁺) iron during its reaction with pesticides, and electrons donated by Fe⁰ and Fe²⁺ were responsible for complete dechlorination of all the pesticides. Therefore, it can be used as inexpensive and sustainable PRB media for groundwater remediation especially in developing countries where groundwater contamination with pesticides is more prevalent.

The unified bioaccessibility method (UBM) was harnessed to assess in vitro oral bioaccessibility pools of dialkyl phthalate congeners (with methyl, –ethyl, –butylbenzyl, –n-butyl, –2-ethylhexyl, and –n-octyl moieties) and bisphenol A at the 17 μg g⁻¹ level in beach sand contaminated with polyethylene microplastics. A variety of sample preparation approaches prior to the analysis of the UBM gastrointestinal extracts, including traditional methods (protein precipitation, liquid-liquid extraction, and solid-phase extraction) and dispersive liquid-liquid microextraction (DLLME) were comprehensively evaluated for clean-up and analyte enrichment. DLLME was chosen among all tested approaches on account of the high extraction efficiency (73–95%, excluding bis(2-ethylhexyl)phthalate and di-n-octyl phthalate), high sample throughput (∼7 min per set of samples), and environmental friendliness as demonstrated by the analytical eco-scale score of 83, and the green analytical procedure index pictogram with green/yellow labeling. The release of the less hydrophobic plastic-laden compounds (dimethyl phthalate, diethyl phthalate and bisphenol A) from the contaminated sample into the body fluids was significant, with bioaccessibility values ranging from 30 to 70%, and from 43 to 74% in gastric and gastrointestinal fluids, respectively, and with relative standard deviation < 17% in all cases. The majority of the compounds were leached during gastric digestion, likely as the combined action of the low pH and the gastric enzymes. The risk exposure analysis revealed that accumulation/concentration in the body fluids is potentially relevant for dimethyl phthalate, diethyl phthalate and bisphenol A, with relative accumulation ratios ranging from 1.1 ± 0.1 to 2.6 ± 0.4. The average daily intake values for the suite of compounds, corrected with the bioaccessibility fraction, ranged from 60 to 430 ng kg of body weight⁻¹·day⁻¹, in all cases, far below the tolerable daily intakes, thus indicating the lack of children health risk by ingestion of microplastic-laden sand with elevated concentrations of plasticizers.

Microbial selenite reduction has increasingly attracted attention from the scientific community because it allows the separation of toxic Se from waste sources with the concurrent recovery of Se nanoparticles, a multifunctional material in nanotechnology industries. In this study, four selenite-reducing bacteria, isolated from a river water sample, were found to reduce selenite by > 85% within 3 d of incubation, at ambient temperature. Among them, strain NDSe-7, belonging to genus Lysinibacillus, can reduce selenite and produce Se nanospheres in alkaline conditions, up to pH 10.0, and in salinity of up to 7.0%. This strain can reduce 80 mg/L of selenite to elemental Se within 24 h at pH 6.0–8.0, at a temperature of 30–40 °C, and salinity of 0.1–3.5%. Strain NDSe-7 exhibited potential for use in Se removal and recovery from industrial saline wastewater with high alkalinity. This study indicates that extremophilic microorganisms for environmental remediation can be found in a conventional environment.

Surface modified lipopeptide biosurfactant (BS) with enhancement of amino acids was produced using Bacillus Malacitensis. The aromatic hydrocarbons from contaminated soil were removed by BS soil washing process and bioremediation using activated functionalized carbon-BS matrix (AFC-BS). The Central Composite Design (CCD) showed the optimum time100 h; pH 7; temperature 30°C on maximum yield of BS. The amino acid profiling of BS reveals the enhancement of amino acids especially polar amino acids and its importance in the formation of micellar structure for the tight packing of aromatic hydrocarbons from industrial contaminated soil. AFC-BS matrix was implanted directly into the contaminated soil for 28 days and found 61.80 % of Total Petroleum Hydrocarbon (TPH) removal efficiency which is high compared to the AFC treated soil. The compounds were extracted from contaminated soil and AFC-BS matrix, found similar peaks in high performance liquid chromatography, which reveals the ability of BS to remove aromatic contaminants. The soil toxicity was also analyzed by seed germination and found improvement in the growth of seeds. The germination of seeds increased from 60 % to 100 % and the phytotoxicity of root and shoot was reduced from 89.50 %, 88.45 % to12.55 %, 11.87 % respectively.

As a common natural phenomenon, corpse decomposition may lead to serious environmental pollution such as nitrogen pollution. However, less is known about antibiotic resistance genes (ARGs), an emerging contaminant, during corpse degradation. Here, ARGs and microbiome in three soil types (black, red and yellow soil) have been investigated between experimental and control groups based on next-generation sequencing and high-throughput quantitative PCR techniques. We found that the absolute abundance of total ARGs and mobile genetic elements (MGEs) in the experimental groups were respectively enriched 536.96 and 240.60 times in different soil types, and the number of ARGs in experimental groups was 7–25 more than that in control groups. For experimental groups, the distribution of ARGs was distinct in different soil types, but sulfonamide resistance genes were always enriched. Corpse decomposition was a primary determinant for ARGs profiles. Microbiome, NH₄⁺ concentrates and pH also significantly affected ARGs profiles. Nevertheless, soil types had few effects on ARGs. For soil microbiome, some genera were elevated in experimental groups such as the Ignatzschineria and Myroides. The alpha diversity is decreased in experimental groups and microbial community structures are different between treatments. Additionally, the Escherichia and Neisseria were potential pathogens elevated in experimental groups. Network analysis indicated that most of ARGs like sulfonamide and multidrug resistance genes presented strong positively correlations with NH₄⁺ concentrates and pH, and some genera like Ignatzschineria and Dysgonomonas were positively correlated with several ARGs such as aminoglycoside and sulfonamide resistance genes. Our study reveals a law of ARGs’ enrichment markedly during corpse decomposing in different soil types, and these ARGs contaminant maintaining in environment may pose a potential threat to environmental safety and human health.

Fungicide application for controlling fungal diseases can increase copper (Cu) accumulation in soil. More urgently, Cu released from fungicides can associate with soil clay and favour the mutual aggregation of Cu and soil clay, thereby potentially intensifying the accumulation of Cu. We investigated the effects of Cu salt and six common Cu-based fungicides on colloidal dynamics of a clay fraction from citrus cultivated soil. Batch experiments were carried out to provide the loading capacity of the clay fraction for Cu. The colloidal dynamic experiments were performed over a pH range from 3 to 8 following a test tube method, while surface charge, the key electrochemical factor of the solid-liquid interface, was quantified by a particle charge detector. It was found that all the studied fungicides, via releasing Cu²⁺, acted to effectively favour clay aggregation. The dissolved organic matter obtained from the dissolution of polymers in fungicides can theoretically stimulate clay dispersion. However, their effects were obscured due to the overwhelming effect of Cu²⁺. Therefore, Cu²⁺ appears as the most active agent in the fungicides that intensifies clay aggregation. These findings imply that the intensive application of fungicides for plant protection purposes can inadvertently reduce clay mobility, favour the co-aggregation of clay and fungicides, and hence potentially exacerbate the contamination of the citrus soil.

Rising of temperature in conjunction with acidification due to the anthropogenic climates has tremendously affected all aquatic life. Small changes in the surrounding environment could lead to physiological constraint in the individual. Therefore, this study was designed to investigate the effects of warm water temperature (32 °C) and low pH (pH 6) on physiological responses and growth of hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) juveniles for 25 days. Growth performance was significantly affected under warm water temperature and low-pH conditions. Surprisingly, the positive effect on growth was observed under the interactive effects of warm water and low pH exposure. Hybrid grouper exposed to the interactive stressor of warm temperature and low pH exhibited higher living cost, where HSI content was greatly depleted to about 2.3-folds than in normal circumstances. Overall, challenge to warm temperature and low pH induced protein mobilization as an energy source followed by glycogen and lipid to support basal metabolic needs.

Enhanced release of phosphorus (P) from soils with snowmelt flooding poses a threat of eutrophication to waterbodies in cold climatic regions. Reductions in P losses with various soil amendments has been reported, however effectiveness of MgSO₄ has not been studied under snowmelt flooding. This study examined (a) the P release enhancement with flooding in relation to initial soil P status and (b) the effectiveness of MgSO₄ at two rates in reducing P release to floodwater under simulated snowmelt flooding. Intact soil monoliths were collected from eight agricultural fields from Southern Manitoba, Canada. Unamended and MgSO₄ surface-amended monoliths (2.5 and 5.0 Mg ha⁻¹) in triplicates were pre-incubated for 7 days, then flooded and incubated (4 °C) for 56 days. Pore water and floodwater samples collected at 7-day intervals were analyzed for dissolved reactive P (DRP), pH, Ca, Mg, Fe and Mn. Redox potential (Eh) was measured on each day of sampling. Representative soil samples collected from each field were analyzed for Olsen and Mehlich 3-P. Simulated snowmelt flooding enhanced the mobility of soil P with approximately 1.2–1.6 -fold increase in pore water DRP concentration from 0 to 21 days after flooding. Mehlich-3 P content showed a strong relationship with the pore water DRP concentrations suggesting its potential as a predictor of P loss risk during prolonged flooding. Surface application of MgSO₄ reduced the P release to pore water and floodwater. The 2.5 Mg ha⁻¹ rate was more effective than the higher rate with a 21–75% reduction in average pore water DRP, across soils. Soil monoliths amended with MgSO₄ maintained a higher Eh, and had greater pore water Ca and Mg concentrations, which may have reduced redox-induced P release and favored re-precipitation of P with Ca and Mg, thus decreasing DRP concentrations in pore water and floodwater.