Microcystin (MC) elimination is a global challenge that is necessary for the health of humans and ecosystems. Biodegradation of MC, one of the most environmental-friendly methods, had previously been focused on the aerobic condition. In this study, two enrichment cultures from Taihu sediments possessed high capacity for MC-leucine arginine (MC-LR) anaerobic biodegradation. Meanwhile, it was firstly found that MC-LR underwent similar degradation process under anaerobic conditions to that in aerobic condition. Furthermore, a novel degradation pathway, hydrolyzing of Ala-Mdha to form a new linear MC-LR intermediate, was proposed under anaerobic conditions. Combining MC-LR degradation with microbial community analysis, this study deduced that Candidatus Cloacamonas acidaminovorans str. Evry may play an important role in the degradation of MC-LR. These findings suggest an additional pathway involved in the environmental cycle of MC-LR, which implies that the biotransformation of MC-LR might play an important role in eliminating MC-LR in eutrophic lake sediments under anaerobic conditions.

The capacity of biochar to take up heavy metals from contaminated soil and water is influenced by the pyrolysis temperature. We have prepared three biochar samples from Jerusalem artichoke stalks (JAS) by pyrolysis at 300, 500 and 700 °C, denoted as JAS300, JAS500, and JAS700, respectively. A variety of synchrotron-based techniques were used to assess the effect of pyrolysis temperature on the molecular properties and copper (Cu) sorption capacity of the samples. The content of oxygen-containing functional groups in the biochar samples decreased, while that of aromatic structures and alkaline mineral components increased, with a rise in pyrolysis temperature. Scanning transmission X-ray microscopy indicated that sorbed Cu(II) was partially reduced to Cu(I), but this process was more evident with JAS300 and JAS700 than with JAS500. Carbon K-edge X-ray absorption near edge structure spectroscopy indicated that Cu(II) cations were sorbed to biochar via complexation and Cu-π bonding. With rising pyrolysis temperature, Cu(II)-complexation weakened while Cu-π bonding was enhanced. In addition, the relatively high ash content and pH of JAS500 and JAS700 facilitated Cu precipitation and the formation of langite on the surface of biochar. The results of this investigation will aid the conversion of halophyte waste to useable biochar for the effective remediation of Cu-contaminated soil and water.

That an alteration of the intestinal permeability is associated with gut barrier function has been increasingly evident, which plays an important role in human and animal health. Bisphenol A (BPA), an industrial compound used worldwide, has recently been classified as an environmental pollutant. One of our earlier studies has demonstrated that BPA disrupts the intestinal barrier function by inducing apoptosis and inhibiting cell proliferation in the human colonic epithelial cells line. In this study, we investigated the effects of dietary BPA uptake on the colonic barrier function in mice, as well as the intestinal permeability. Dietary BPA uptake was observed to destroy the morphology of the colonic epithelium and increase the pathology score. The levels of endotoxin, diamine peroxidase, D-lactate, and zonulin were found to have been significantly elevated in both plasma and colonic mucosa. A decline in the number of intestinal goblet cells and in mucin 2 gene expression was observed in the mice belonging to the BPA group. The results of immunohistochemistry revealed that the expression of tight junction proteins (ZO-1, occludin, and claudin-1) in colonic epithelium of BPA mice decreased significantly, and their gene abundance was also inhibited. Moreover, dietary BPA uptake was also found to have significantly reduced colonic microbial diversity and altered microbial structural composition. The functional profiles of colonic bacterial community exhibited adverse effects of dietary BPA intake on the endocrine and digestive systems, as well as the transport and catabolism functions. Collectively, our study highlighted that dietary BPA increased the colonic permeability, and this effect was closely related to the disruption of intestinal chemistry and physical and biological barrier functions.

Only 1% of plastic entering the ocean is found floating on its surface, with high loads in ocean accumulation zones and semi-enclosed seas, except for the Red Sea, which supports one of the lowest floating plastic loads worldwide. Given the extension of reefs in the Red Sea, we hypothesize a major role of scleractinian corals as sinks, through suspension-feeding, and assessed microplastic removal rates by three Red Sea coral species. Experimental evidence showed removal rates ranging from 0.25 × 10⁻³ to 14.8 × 10⁻³ microplastic particles polyp⁻¹ hour⁻¹, among species. However, this was only 2.2 ± 0.6% of the total removal rate, with passive removal through adhesion to the coral surface being 40 times higher than active removal through suspension-feeding. These results point at adhesion of plastic to coral reef structures as a major sink for microplastics suspended in the water column after sinking, helping explain low concentrations in Red Sea surface waters.

Roxarsone (3-nitro-4-hydroxyphenylarsonic acid, ROX) is an arsenic-containing compound widely used as a feed additive in poultry industries. ROX excreted in chicken manure can be transformed by microbes to different arsenic species in the environment. To date, most of the studies on microbial transformation of ROX have focused on anaerobic microorganisms. Here, we isolated a pure cultured aerobic ROX-transforming bacterial strain, CZ-1, from an arsenic-contaminated paddy soil. On the basis of 16S rRNA gene sequence, strain CZ-1 was classified as a member of the genus Enterobacter. During ROX biotransformation by strain CZ-1, five metabolites including arsenate (As[V]), arsenite (As[III]), N-acetyl-4-hydroxy-m-arsanilic acid (N-AHPAA), 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA) and a novel sulfur-containing arsenic species (AsC₉H₁₃N₂O₆S) were detected and identified based on high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS), HPLC-ICP-MS/electrospray ionization mass spectrometry (ESI-MS) and HPLC-electrospray ionization hybrid quadrupole time-of-flight mass spectrometry (ESI-qTOF-MS) analyses. N-AHPAA and 3-AHPAA were the main products, and 3-AHPAA could also be transformed to N-AHPAA. Based on the results, we propose a novel ROX biotransformation pathway by Enterobacter. sp CZ-1, in which the nitro group of ROX is first reduced to amino group (3-AHPAA) and then acetylated to N-AHPAA.

Application of biochar in the field has received considerable attention in recent years, but there is still little known about the fate and transport of biochar colloids (BCs) in the subsurface. Natural organic matter (NOM), which mainly consists of humic substance (HS) and proteins, is ubiquitous in the natural environment and its dissolved fraction is active and mobile. In this study, the transport of BCs in saturated porous media has been examined in the presence of two HS (humic and fulvic acids) and two proteins. Bull serum albumin (BSA) and Cytochrome c (Cyt) were selected to present the negatively and positively charged protein, respectively. At low and high salt concentration and different pH conditions, the transport of BCs was strongly promoted by HS. HS significantly increased the mobility of BCs in porous media under both low and high salt conditions due to the enhanced electrostatic repulsion and modification of surface roughness and charge heterogeneity. While BC mobility in porous media was suppressed by both BSA and Cyt in the low salt solution, the presence of BSA largely promoted and Cyt slightly enhanced the transport of BCs in high salt solutions. BSA and Cyt adsorption onto BC surface decreased the negative charge of BC and resulted in a less repulsive interaction in low salt solutions. In high salt solutions, the adsorbed BSA layers disaggregated BCs and reduced the strength of the interaction between BC and the sand. Adsorbed Cyt on BCs caused more attractive patches between BC and sand surface, and greater retention than BSA.

The effluent stream of the anaerobic digestion processes, the digestate, accommodates high residual organic content that needs to be further treated before discharge. Anaerobic treatment of digestate would not only reduce the residual organic compounds in digestate but also has a potential to capture the associated biogas. High-rate anaerobic reactor configurations can treat the waste streams using lower hydraulic retention times which requires less footprint opposed to the conventional completely stirred tank reactors. This study investigated the high-rate anaerobic treatment performance and the associated biogas capture from the digestate of a manure mixture composed of 90% laying hen and 10% cattle manures in fixed-film reactors. The results indicated that it was possible to reduce total chemical oxygen demand content of the digestate by 57–62% in 1.3–1.4 days of hydraulic retention time. The corresponding biogas yields obtained were in the range of 0.395–0.430 Lbiogas/g VSadded which were found to be comparable to many raw feedstocks. Moreover, significant total phosphorus reduction (36–47%) and greenhouse gas capture (over 14.5–18.1 tCO2e/d per m3 digestate) were also recorded in the anaerobic fixed-film reactors.

The heavy metal ion adsorption performance of birnessite (a layer-structured manganese oxide) can be enhanced by decreasing the Mn average oxidation state (Mn AOS) and dissolution−recrystallization during electrochemical redox reactions. However, the electrochemical adsorption processes of heavy metal ions by tunnel-structured manganese oxides are still enigmatic. Here, tunnel-structured manganese oxides including pyrolusite (2.3 Å × 2.3 Å tunnel), cryptomelane (4.6 Å × 4.6 Å tunnel) and todorokite (6.9 Å × 6.9 Å tunnel) were synthesized, and their electrochemical adsorptions for Cd²⁺ were performed through galvanostatic charge−discharge. The influence of both supporting ion species in the tunnel and tunnel size on the electrochemical adsorption performance was also studied. The adsorption capacity of tunnel-structured manganese oxides for Cd²⁺ was remarkably enhanced by electrochemical redox reactions. Relative to K⁺ in the tunnel of cryptomelane, the supporting ion H⁺ was more favorable to the electrochemical adsorption of Cd²⁺. With increasing initial pH and specific surface area, the electrochemical adsorption capacity of cryptomelane increased. The cryptomelane electrode could be regenerated by galvanostatic charge−discharge in Na₂SO₄ solution. Due to the differences in their tunnel size and supporting ion species, the tunnel-structured manganese oxides follow the order of cryptomelane (192.0 mg g⁻¹) > todorokite (44.8 mg g⁻¹) > pyrolusite (13.5 mg g⁻¹) in their electrochemical adsorption capacities for Cd²⁺.

Pesticides guarantee us high productivity in agriculture, but the long-term costs have proved too high. Acute and chronic intoxication of humans and animals, contamination of soil, water and food are the consequences of the current demand and sales of these products. In addition, pesticides such as glyphosate are sold in commercial formulations which have inert ingredients, substances with unknown composition and proportion. Facing this scenario, toxicological studies that investigate the interaction between the active principle and the inert ingredients are necessary. The following work proposed comparative toxicology studies between glyphosate and its commercial formulation using the alternative model Caenorhabditis elegans. Worms were exposed to different concentrations of the active ingredient (glyphosate in monoisopropylamine salt) and its commercial formulation. Reproductive capacity was evaluated through brood size, morphological analysis of oocytes and through the MD701 strain (bcIs39), which allows the visualization of germ cells in apoptosis. In addition, the metal composition in the commercial formulation was analyzed by ICP-MS. Only the commercial formulation of glyphosate showed significant negative effects on brood size, body length, oocyte size, and the number of apoptotic cells. Metal analysis showed the presence of Hg, Fe, Mn, Cu, Zn, As, Cd and Pb in the commercial formulation, which did not cause reprotoxicity at the concentrations found. However, metals can bioaccumulate in soil and water and cause environmental impacts. Finally, we demonstrated that the addition of inert ingredients increased the toxic profile of the active ingredient glyphosate in C. elegans, which reinforces the need of components description in the product labels.

Remediation of hexavalent chromium [Cr(VI)] has been widely studied for its high mobility and toxicity. As Cr(VI) migrates in natural environment, both soils and groundwater are contaminated simultaneously. In the present study, a novel reactor combining adsorption and microbial fuel cell (A-MFC) using Platanus acerifolia leaves was developed for removing Cr(VI) from groundwater and soils. When initial Cr(VI) concentration was 50 mg/L, the adsorption efficiency of A-MFC achieved 98% after 16 h. Afterwards, the leaves were used for fabricating an MFC-integrated leaching reactor. The A-MFC significantly improved the overall Cr(VI) removal efficiency through leaching and 40% of Cr(VI) in the soil column was removed. The electrical voltage and current of A-MFC reactor achieved averagely 343 mV and 141 μA to maintain the system operation without extra energy supply. This novel A-MFC reactor is an environmentally friendly technology which achieved efficient Cr(VI) removal from groundwater and soils using natural materials, proving the concept that integrated self-remediation of Cr(VI) in contaminated soil and groundwater with natural material and energy.