Several regions of the world have been suffering from problems of water quality degradation caused mainly by the input of nutrients such as nitrogen and phosphorus, resulting from anthropic activities. In excess, these nutrients can be considered micropollutants that could be responsible for the blooms of aquatic plant species, algae, and potentially toxic cyanobacteria, resulting in the interference of water quality in the socio-economic and environmental sector. Biological mitigation measures using specific microorganisms have been applied for the removal of micro pollutants due to their high efficiency of nitrogen and phosphorus. The present study analyzed the efficiency of nitrifying bacteria such as N. europaea and N. winodradskyi and P. denitrificans denitrifying bacteria, individually and as a bacterial pool (formed by N. europaea, N. winodradskyi, and P. denitrificans), in removing NH₃, NO₂⁻, NO₃⁻, N, P, and PO₄³⁻, in pure water samples at times 0 to 1440 min and 0 to 7200 min. N. europaea and N. winodradskyi presented 100% removal efficiency for compounds NH₃ and NO₂⁻ respectively, and bacterial pool removed 100% of compounds NO₂⁻ and P at time 1440 min (24 h). At time 7200 min (120 h), P. denitrificans obtained 100% removal of NO₂⁻ and NO₃⁻. Over time, the bacterial pool obtained 100% removal for all compounds analyzed in the present study. This paper demonstrated the excellent performance of microorganisms in the removal of nitrogen and phosphorus compounds in pure water samples.

The concentrations of phosphorus (P) and nitrogen (N) in runoff from cropland areas may be influenced by accumulation and release of P and N by stalk residues. A laboratory study was conducted to measure the effects of time since harvest and immersion period on accumulation and release of P and N by corn, soybean, and wheat stalks. Experimental variables included type of stalk material (corn, soybean, and wheat), time since harvest (six residue collection dates over an approximate 1-year period), and stalk immersion period (25 s (0.42 min), 250 s (4.2 min), 2500 s (42 min), 25,000 s (6.9 h), and 86,400 s (24 h)). The initial concentration of each of the P and N constituents in a test solution was 6 μg mL⁻¹. The soybean, wheat, and corn residue released PO₄-P at mean rates of 40, 69, and 141 μg g⁻¹ residue, respectively. The amount of PO₄-P that was released consistently increased as immersion period became greater. Corn and wheat residue either accumulated or released NO₃-N depending on residue collection date. Soybean residue accumulated an average of 20 μg NO₃-N g⁻¹ residue. Wheat residue obtained on five of the collection dates accumulated an average of 13 μg NO₃-N g⁻¹ residue. Residue collection date also influenced accumulation of NH₄-N by soybean and wheat residue. Corn residue released an average of 77 μg NH₄-N g⁻¹ residue. The type of crop residue material, the amount of time the residue has remained in the field following harvest, and residue immersion period were found to influence nutrient concentrations of solution.

The present study was designed to investigate the nephrotoxicity of silver nanoparticles (AgNPs; 80 mg/kg; > 100 nm) and to evaluate the protective effect exercised by Beta vulgaris (beetroot) juice (RBR; 200 mg/kg) on male rats’ kidney. Serum-specific parameters (urea, creatinine, electrolytes and histopathology of kidney tissue) were examined to assess the AgNPs nephrotoxicity effect. Moreover, this study analysed oxidative stress (lipid peroxidation, glutathione, superoxide dismutase and catalase) and anti-apoptotic markers (Bcl-2). AgNPs intoxication increased kidney function marker levels and lipid peroxidation and decreased the glutathione, superoxide dismutase and catalase activities in kidney tissue. Additionally, Bcl-2 expression was downregulated following AgNPs intoxication. Moreover, AgNPs induced a significant increase in renal DNA damage displayed as an elevation in tail length, tail DNA percentage and tail moment. Interestingly, RBR post-treatment restored the biochemical and histological alterations induced by AgNPs exposure, reflecting its nephroprotective effect. Collectively, the present data suggest that RBR could be used as a potential therapeutic intervention to prevent AgNPs-induced nephrotoxicity.

A study area was selected from the industrial region of Gaoshawo Town, Yanchi County, Ningxia, to explore the level of heavy metal pollution in desert grasslands due to industrial activities. A total of 82 surface soils were collected, and the concentration of heavy metals, namely, Cu, Cd, Cr, Pb, Zn, Mn, and Co, was determined by ICP-AES (atomic emission spectrometer) (HK-8100); the average values were 21.64 ± 3.26, 0.18 ± 0.02, 44.99 ± 21.23, 87.18 ± 25.84, 86.63 ± 24.98, 570.49 ± 171.57, and 17.96 ± 9.96 mg kg⁻¹. The single-factor, Nemerow pollution, and potential ecological risk index methods were used to evaluate the status of soil heavy metal pollution and the contribution from the major sources identified by the receptor model. The results showed that 9.09% of the samples were slightly polluted, 32.47% of the samples were moderately polluted, and 58.41% of the samples were heavily polluted. The comprehensive potential ecological risk index indicated that 90.79% of the samples had moderate ecological risk. It was verified from the models and spatial distribution maps that Cr, Co, Zn, and Mn are mainly contributed by the industrial sources that account for 55.04%, 92.13%, 50.05%, and 48.77% of these heavy metals, respectively. The heavily contaminated areas are distributed around the industrial park. A total of 70.63% and 77.83% of Cu and Pb are contributed by transportation sources, respectively, with the concentrations decreasing from southwest to northeast. The contribution from agricultural activities to Cd is 77.02%, with concentrations largely distributed in the north of the highway. This study showed that the existence of the Gaoshawo Industrial Zone and the corresponding industrial and transportation activities have a significant impact on the grassland soil environment.

Atmospheric precipitation in Sri Lanka occurs mainly through rain whose terrestrial composition significantly varies based on the location as the regional geography and anthropogenic factors can largely affect environmental pollutants that are added to the atmosphere. It is therefore very important to have baseline data on the chemical composition of the atmosphere to take regulatory measures to control atmospheric pollution although very limited data available in Sri Lanka. The main objective of this study was thus to quantitatively determine selected trace metals (Al, Cr, Cu, Fe, Mn, Pb, and Zn) in bulk precipitation samples collected weekly in three sampling locations, namely the University of Peradeniya (UoP), Polgolla, and Kandy City Central (KCC), for a period of 1 year from March 2018 to March 2019. Trace metals determined using atomic emission spectrophotometry indicated that the KCC site showed the highest contamination following the sequence (with respective volume-weighted mean (VWM) concentration values) of Al (79.7 μg L⁻¹) > Fe (42.8 μg L⁻¹) > Zn (39.3 μg L⁻¹) > Mn (13.9 μg L⁻¹) > Cu (9.8 μg L⁻¹) > Cr (2.4 μg L⁻¹). The corresponding values of the Polgolla site showed the sequence Zn (64.3 μg L⁻¹) > Al (52.1 μg L⁻¹) > Fe (17.9 μg L⁻¹) > Mn (11.1 μg L⁻¹) > Cu (5.4 μg L⁻¹) > Cr (1.8 μg L⁻¹). Due to less industrialization and less traffic congestion, the UoP site showed low trace metal levels in the order Zn (29.8 μg L⁻¹) > Al (21.3 μg L⁻¹) > Fe (14.2 μg L⁻¹) > Cu (7.4 μg L⁻¹) > Mn (4.3 μg L⁻¹) > Cr (0.9 μg L⁻¹). Principal component analysis indicated that Cu, Mn, and Zn originated mainly from anthropogenic activities, such as combustion of fossil fuel and burning of municipal waste, while Al and Fe mainly originated from natural sources.

Municipal wastewater reverse osmosis concentrate (ROC) poses health and environmental risks on its disposal as it contains nutrients and harmful organic compounds at elevated concentrations. This study compared a freshwater microalga Chlorella vulgaris and a marine microalga Nannochloropsis salina in suspended and alginate-immobilised cultures for batch and semi-continuous treatment of the ROC. The immobilised algae gave comparable nutrient removal rates to the suspended cells, demonstrating immobilisation had no apparent negative impact on the photosynthetic activity of microalgae. Semi-continuous algal treatment illustrated that the microalgae could remove significant amounts of nutrients (> 50% and > 80% for TN and TP, respectively), predominantly through algal uptake (> 90%), within a short period (48 h) and generate 335–360 mg DCW L⁻¹ d⁻¹ of algal biomass. The treatment also removed a significant amount of organic matter (12.7–13.3 mg DOC L⁻¹ d⁻¹), primarily (> 65%) through the biotic pathway.

Traceability offers significant information about the quality and safety of Chinese Angelica, a medicine and food homologous substance. In this study, a systematic four-step strategy, including sample collection, specific metal element fingerprinting, multivariate statistical analysis, and benefit-risk assessment, was developed for the first time to identify Chinese Angelica based on geographical origins. Fifteen metals in fifty-six Chinese Angelica samples originated from three provinces were analyzed. The multivariate statistical analysis model established, involving hierarchical cluster analysis (HCA), principal component analysis (PCA), and self-organizing map clustering analysis was able to identify the origins of samples. Furthermore, benefit-risk assessment models were created by combinational calculation of chemical daily intake (CDI), hazard index (HI), and cancer risk (CR) levels to evaluate the potential risks of Chinese Angelica using as traditional Chinese medicine (TCM) and food, respectively. Our systematic strategy was well convinced to accurately and effectively differentiate Chinese Angelica based on geographical origins.

A dead-end ultrafiltration cup was continuously operated to investigate the underlying mechanisms of membrane fouling caused by gel layer in this paper. Anionic polyacrylamide was used as a model foulant for gel formation process in various ultrafiltration processes by two kinds of ultrafiltration membrane, e.g., polyvinylidene fluoride (PVDF) membrane (OM) and TiO₂/Al₂O₃-PVDF membrane (MM); then, a gel formation model was established and systematically assessed. The results show that the gel formation process in ultrafiltration can be divided into three stages: “slow-rapid-slow” flux decay curve. The R² value of the simulation curve was still higher than 0.90 for both OM and MM. Based on the current cognition, the proposed gel layer formation mechanism and mathematical model were feasible.

In order to unravel the cadmium (Cd) enrichment patterns in rice (Oryza sativa L.) grown under different exogenous exposure pathways, the pot experiment was conducted in a greenhouse. Cd was added to the soil-rice system via mixing soil with Cd-containing solution, irrigating the pots with Cd-containing water and leaf-spraying with Cd solution to simulate soil pollution (SPS), irrigation water pollution (IPS), and atmospheric deposit pollution sources (APS), respectively. No significant (p > 0.05) differences in plant height and rice grain yield were observed among all treatments including three different Cd pollution sources and control. The contents of Cd in rice plants significantly (p < 0.05) increased with increase in Cd concentrations in three pollution sources. The distribution pattern of Cd in the rice plant organs treated with SPS and IPS followed the order: roots > stems > leaves > husk > brown rice, while it was leaves > roots > stems > husk > brown rice treated with APS. At the same level of treatment, the highest concentration of Cd was observed in rice organs (except for middle and high concentrations treatment roots) grown under APS, followed by IPS and SPS, suggesting that the Cd bioavailability from different pollution sources followed the order of APS > IPS > SPS. It is concluded that the atmospheric pollution contributed more enrichment of rice with Cd. Therefore, in field environment, air deposits should also be analyzed for toxic metals during assessment of food chain contamination and health risk.

Anabaena flos-aquae, a typical species of cyanobacterial bloom, was employed as a useful biosorbent for uranium removal. Batch experiments were conducted to examine the effects of different parameters on the uranium uptake amount of Anabaena flos-aquae. The maximum adsorption capacity of 196.4 mg/g was obtained under the optimized experimental conditions. The calculations of kinetic and thermodynamic results proved the adsorption process was endothermic, chemisorption, and spontaneous. The adsorption of uranium onto Anabaena flos-aquae was better defined by the Langmuir model, which indicated the process was a monolayer sorption. In addition, the characterization of the biosorbent before and after uranium sorption implied that the dominant functional groups participated in the uranium adsorption process were hydroxyl, amino, and carboxyl. In conclusion, the environmentally friendly and biocompatible characteristics of Anabaena flos-aquae suggest that it can be a promising biosorbent for uranium removal.