Artisanal and small-scale gold mining (ASGM) accounts for almost half of anthropogenic mercury (Hg) emissions worldwide and causes widespread water pollution. In Indonesia, several studies have identified harmful levels of Hg in areas affected by ASGM. While most of these studies focus on mining areas with thousands of miners, water contamination in smaller ASGM areas is less understood. We evaluated Hg contamination in four ASGM areas in Central Java of varying scale (from 30 to 3000 amalgamator barrels at each area), including Jatiroto, Kebonsari, Gumelar, and Kulon Progo. At each location, we collected water samples along river transects upstream and downstream of ASGM areas during the dry season (June–July 2017). Total Hg (THg) concentrations in stream water increased by orders of magnitude from upstream to downstream of ASGM activities at Jatiroto (1.35–4730 ng/L), with smaller observed increases at the other locations. Dissolved THg concentrations exceeded USEPA criteria for aquatic life (12 ng/L) at two of the four ASGM areas. THg concentrations in tailings exceeded 150,000 ng/L. Notably, THg concentrations in stream water were not directly related to the scale of mining, with Jatiroto having the highest concentrations as second smallest mining areas of the four in this study. Downstream of the mining areas, the fraction of dissolved methyl Hg to dissolved THg reached 20%, indicating that active Hg methylation occurs in the watersheds. Further study is needed to investigate Hg transport in the wet season when rainfall and high stream discharge may mobilize contaminated sediment near mining areas.

This study investigates levels of bacteria through population indicators as well as the levels of antibiotic-resistance bacteria in dairy manure. Although overall bacteria levels may be reduced during manure processing, it is of interest whether changes in management practices could lead to increased levels of antibiotic-resistance bacteria, which are becoming more prevalent in agricultural soils, groundwater, and surface water. Appropriate manure treatments are needed not only to reduce the potential risk of exporting antibiotic-resistant bacteria to an environment, but also reduce antibiotic-resistant bacteria exposure to animals if processed water is recycled. Results from this research revealed manure separation under relatively low speed centrifuge with 100 ppm polyacrylamide (PAM) emulsion addition reduced bacteria indicators population such as total coliforms and Escherichia coli (E. coli) significantly in the liquid stream compared to no PAM added. However, the percentages of antibiotic-resistant isolates in liquid stream after centrifuge with PAM were higher compared to raw manure and no PAM added. Antibiotic resistance (cephalosporin, florfenicol, penicillin, or tetracycline) was observed or 65.38% of bacterial isolates in manure from a large dairy farm in Wisconsin and 39.29% of isolates demonstrated multidrug resistance. The results from this study strongly suggest that appropriate manure treatment is essential in order to help minimize the abundance of antibiotic resistance in our water environment.

Accurate determination of emerging contaminants in drinking water constitutes a major environmental challenge for which highly sensitive analytical methods are needed. This work details the development of a novel highly sensitive solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) method for simultaneous determination of a diverse panel of widely used trace contaminants, including two pharmaceuticals (fluoxetine and gemfibrozil), three pesticides (3-hydroxycarbofuran, azinphos-methyl, and chlorpyrifos), and two hormones (testosterone and progesterone) in water. The method is highly reproducible and sensitive with detection limits at subnanogram per liter level (0.05–0.5 ng/L). It was used to monitor the occurrence of these contaminants in source and drinking water across 18 drinking water treatment facilities in Missouri, USA in 1 year including cold winter and hot summer seasons. The experiment results indicated that all of the monitored contaminant concentrations are very low, lower than or close to the method detection limits, in the selected water treatment facilities. Pesticide concentrations were slightly elevated in some source waters during hot season, whereas slightly higher pharmaceuticals were observed during cold season. The concentrations of two hormones were lower than the limits of detection in all the water samples. These contaminants were present, if any, at below detection limits in all treated drinking water samples analyzed, suggesting that treatment processes effectively removed the contaminants studied herein. Graphical Abstract

Sunflower stalk–derived biochars (BC) were prepared at various temperatures (i.e., 500, 650, and 1000 °C) and demonstrated as a highly efficient catalyst in persulfate (PS) activation for the oxidation of p-nitrophenol (PNP) at 60 °C. The apparent PNP oxidation rate constant in the BC500 (0.1543 L mol⁻¹ S⁻¹), BC650 (0.6062 L mol⁻¹ S⁻¹), or BC1000 (2.1379 L mol⁻¹ S⁻¹) containing PS system was about 2, 8 and 28 times higher than that in PS/PNP (0.0751 L mol⁻¹ S⁻¹) system, respectively. The effect of reaction temperature on PNP oxidation was also investigated. Furthermore, the radical quenching tests and electron paramagnetic resonance spectroscopy (EPR) were employed to investigate the sulfate and hydroxyl radicals for PNP oxidation. The Raman results suggested that the defective sites on biochars possess vital role for oxidation of PNP in PS system. The possible activation pathway of PS/BC was proposed that the defective sites on BC were involved for weakening the O–O bond in PS and subsequently cleaving O–O bond by heat to generate sulfate radical. The oxidation of PNP at low concentration (below 100 μg L⁻¹) was completely removed in urban wastewater by PS/BC system within 30 min. This work would provide new insights into PS activation by BC catalyst and afford a promising method for organic pollutant removal in high-temperature wastewater.

The purpose of this study is to explore the empirical relationship between foreign direct investment (FDI), population, energy production, and water resources in South Asia. The newly developed approach dynamic common correlated effects (DCCE) by Chudik and Pesaran (Journal of Econometrics 188:393–420, 2015a) for measuring co-integration has been applied in the present study. This procedure provides significant robust outcomes in the presence of cross-sectional dependence among the cross-sectional units. The findings confirmed that earlier models, such as mean group (MG), pooled mean group (PMG), and augmented mean group (AMG), which have been used in the literature for long data, provide misleading results in the presence of cross-sectional dependence among the cross-sectional units. A statistically significant and negative result has been observed between FDI, population, energy production, and water resources in South Asia. The governments of South Asian economies must encourage green FDI initiatives for water management, ensuring water security, securing natural resources for enhancing the sustainable development of regional economies.

As potassium ferrate(VI) is an important kind of water treatment agent which has a high efficiency in algal removal, its effects on the cell substance are rarely discussed. The changing of the protein and enzyme was analyzed here to deeply understand the oxidation of Fe on the protein in the algae. The result of the research showed the inactivation on growth and the biochemical process of the algal cell were all inhibited by Fe, including the function of the photosynthesis system. During the process, SOD (superoxide dismutase), CAT (catalase), POD (peroxidase), and GST (glutathione S-transferase) played cooperative roles to prevent the injury on the cells from destructive oxidation stress. The lipid peroxidation strengthened the defense system. The damage was intensified with the increase of ferrate concentration.

Fungi are one of the bioaerosols in indoor air of hospitals. They have adverse effects on staff and patients. The aim of this study was to investigate the effects of three incubation temperature on the density and composition of airborne fungi in an indoor and outdoor space of hospital. Sabouraud dextrose agar was used for culture the fungi. For improvement of aseptic properties, chloramphenicol was added to this medium. The density of airborne fungi was less than 282 CFU/m³. The highest density was detected in emergency room and the lowest of them was in neonatal intensive care unit (NICU) and operation room (OR). Results showed that fungi levels at 25 °C were higher than 37 and 15 °C (p = 0.006). In addition, ten different genera of fungi were identified in all departments. The predominant fungi were Fusarium spp., Penicillium spp., Paecilomyces spp., and Aspergillus niger. Moreover, the density and trend of distribution of Fusaruim spp. in the indoor space was directivity to outdoor space by ventilation system. The present study has provided that incubation temperature had effect on airborne fungi remarkably. We are suggested that more studies would be conducted on incubation temperature and other ambient factors on airborne fungi.

Phosphogypsum (PG), the waste byproduct resulting from wet process phosphoric acid production, is employed as a selective and effective adsorbent for total rare earth elements (REEs) from aqueous solution and leach liquor. The elaboration of PG adsorbent complemented after some physical treatments. Adsorption and elution studies carried out in experimental batches, including the effect of pH, adsorbent dose, initial REE concentration, and equilibrium time. Adsorption of REEs onto PG fitted well with Langmuir isotherm with a theoretical capacity surpassed 357 mg/g. REEs were effectively eluted from loaded PG with 2 mol L⁻¹ HCl acid with an efficiency of 94%. PG showed an outstanding selectivity towards REEs in the presence of many cations and anions, for instance (Fe³⁺, UO₂²⁺, Ca²⁺, SO₄²⁻, NO₃⁻). Different qualitative techniques such as EDS, SEM, and FTIR used to emphasize the adsorption of REEs onto PG. The film diffusion model was the preponderant adsorption mechanism for REEs; also, the adsorption process has a good accordance with pseudo-second-order kinetic model.

Despite the widespread use of the insecticide imidacloprid (IMI), a neonicotinoid, there is an urgent need for documenting information related to its acute toxicity. Therefore, this study aims to explore the markers of IMI acute toxicity in the testes of the red palm weevil (Rhynchophorus ferrugineus). The LC₅₀ of IMI was determined at 15.7 ppm for male R. ferrugineus. We assessed biochemical alterations in the testes resulting from treatment with four IMI concentrations (10, 15, 20, and 30 ppm). A reduction in glutathione content and acetylcholine esterase activity followed the IMI concentration in a dependent manner. Catalase activity was inhibited only at 20 ppm, while it increased significantly at 30 ppm. Lipid peroxidation increased steadily as the IMI concentrations increased. Based on ultrastructural analyses of spermiogenic stages, acute IMI toxicity produced swelling and degeneration of spermatid mitochondria indicating structural imbalances in their membranes. Further, abnormal chromatin condensation in nuclei and even loss of sperm were also apparent. This study provides biochemical and ultrastructural indicators for acute toxicity resulting from IMI.

Nanofiltration polyamide membranes naturally tend towards biofouling, due to their surface physicochemistries. Nisin, a type of short cationic amphiphilic peptide with antimicrobial properties, has been recognized as a safe antimicrobial for food biopreservation and biomedical applications. This study investigates the impact of nisin on the initial bacterial attachment to membranes, its anti-biofouling properties, and characterizes a non-monotonic correlation between nisin concentration and biofilm inhibition. Nisin was found to inhibit B. subtilis (G+) and P. aeruginosa (G−) attachment to both the nanofiltration membrane and the PES membrane. To determine the mechanism of action, we investigated the polysaccharides, protein, and eDNA as target components. We found that the quantities of polysaccharides and eDNA were significantly changed, resulting in bacterial death and anti-adhesion to membrane. However, there were no discernable impacts on protein. We postulated that nisin could prevent irreversible biofouling by decreasing adhesion, killing bacteria, and reducing biofilm formation. We examined membrane flux behavior through bench-scale cross-flow experiments at a set concentration of nisin (100 μg mL⁻¹), with membrane behavior being confirmed using CLSM images. Results showed that nisin could enhance anti-biofouling properties through both anti-adhesive and anti-bacterial effects, and therefore could be a novel strategy against biofouling of membranes.