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Understanding the mechanisms on how water management can minimize the concentrations of heavy metals in rice grains is important. Two water managements were concerned in our studies, including continuously flooding and alternate wetting and drying (AWD). Compared to AWD, a continuously flooded culture reduces the concentration of cadmium and other metals in the rice grains by reducing the root-to-shoot translocation and the availability of metals in rhizosphere. In a flooded environment, the rice rhizosphere was characterized by an increased soil pH, reduced fluorescein diacetate (FDA) activity, and lower metal bioavailability. In addition, flooding significantly decreased the iron plaque on the root surface and reduced the affinity for metals in rhizosphere. Water managements significantly changed soil microbial diversity, especially the proportion of anaerobic bacteria, including the iron-reducing bacteria Latescibacteria , Desulfuromonadales, and Geobacteraceae. Interestingly, these bacteria exhibited a significant correlation with cadmium that was adsorbed on the root. This study revealed that continuously flooded culture is a valuable strategy for minimizing heavy metal accumulation in rice grains. By increasing the abundance of unique bacterial community, iron plaque formation and the affinity of metals in rhizosphere were reduced, and the uptake and accumulation of heavy metals in rice plants was finally mitigated. Unlabelled Image • Flooding decreased rice grain metals through reducing root-to-shoot translocation and availability of metals in rhizosphere. • Flooding inhibited the iron plaque formation and reduced Cd contents on the root surface. • Cd adsorbed in iron plaque negatively correlated with the unique bacterial communities in flooded condition. [ABSTRACT FROM AUTHOR]

Endocrine-disrupting chemicals (EDCs), which can threaten ecological safety and be harmful to human beings, have been cause for wide concern. There is a high demand for efficient methodologies for evaluating potential EDCs in the environment. Herein an evaluation platform was developed using novel and statistically robust ternary models via different machine learning models ( i . e ., linear discriminant analysis, classification and regression tree, and support vector machines). The platform is aimed at effectively classifying chemicals with agonistic, antagonistic, or no estrogen receptor (ER) activities. A total of 440 chemicals from the literature were selected to derive and optimize the three-class model. One hundred and nine new chemicals appeared on the 2014 EPA list for EDC screening, which were used to assess the predictive performances by comparing the E -screen results with the predicted results of the classification models. The best model was obtained using support vector machines (SVM) which recognized agonists and antagonists with accuracies of 76.6% and 75.0%, respectively, on the test set (with an overall predictive accuracy of 75.2%), and achieved a 10-fold cross-validation (CV) of 73.4%. The external predicted accuracy validated by the E -screen assay was 87.5%, which demonstrated the application value for a virtual alert for EDCs with ER agonistic or antagonistic activities. It was demonstrated that the ternary computational model could be used as a faster and less expensive method to identify EDCs that act through nuclear receptors, and to classify these chemicals into different mechanism groups. [ABSTRACT FROM AUTHOR]

Harmful algal blooms (HABs) have been emerging as a worldwide issue due to their detrimental effect to water quality and the threat to ecological health. However, there were scarcely reports on whether existing agrochemicals such as herbicides have potential effects on Microcystis aeruginosa ( M. aeruginosa ) which may form large surface blooms. In this study, we aimed to demonstrate the effects of glufosinate, a widely use herbicide in the world, on the growth of M. aeruginosa . The change of the content of intracellular (intra-) and extracellular (extra-) levels of microcystin-LR (MC-LR) were also determined by HPLC. The mRNA level of mcy A, mcy D, mcy H related to the production of MC-LR was detected after 48 h exposure to glufosinate. Our results revealed that low concentrations of glufosinate exposure (0.5 mg/L, 1 mg/L) would promote the growth of M. aeruginosa. It was worth noting intra-MC-LR contents of algal cells were also significantly increased at low concentrations of glufosinate exposure (1 mg/L). While at high concentrations (5 mg/L, 10 mg/L), glufosinate could induce the MDA level and inhibit the growth of M. aeruginosa that would limit the production of MC-LR to the water body. At last, the transcription levels of algae toxin synthesis related genes mcy A and mcy D were increased significantly at environmentally relevant concentrations of glufosinate, which may affect the MC production. This study not only illuminated effects of glufosinate on growth of and MC-LR synthesis of M. aeruginosa at environmentally relevant concentrations, but also reminding us the potential risk caused by herbicide use should arouse concerns. [ABSTRACT FROM AUTHOR]

The preservation of anammox granules is of great significance for the rapid start-up of the anammox process and improvement of performance stability. Therefore, it is necessary to explore an economical and stable preservation strategy. Exogenous extracellular polymeric substances (EPS) were used as protective agents for the preservation of anammox granules in this study. In brief, EPS from anammox sludge (A-EPS) and denitrifying sludge (D-EPS) were added to preserve anammox sludge at 4 °C and room temperature (15–20 °C). The results showed that A-EPS addition at 4 °C was the optimal condition for the preservation of anammox granules. After 90 days of preservation, the specific anammox activity (SAA) of the anammox granules remained at 92.7 ± 2.2 mg N g−1 VSS day−1 (remaining ratio of 33.4%), while that of the sludge with D-EPS addition at the same temperature was only 77.1 ± 3.2 mg N g−1 VSS day−1 (remaining ratio of 27.8%). The nitrogen removal efficiency of the experimental group with D-EPS at room temperature was 85.9%, and that of the A-EPS group reached 90.6% under the same temperature conditions. The abundance of the functional genes hzs A, hdh and nir S of the sludge (4 °C; A-EPS addition) after recovery were 138.5%, 317.1%, and 375.9%, respectively, of those of sludge from the D-EPS-added group at the same temperature. RDA revealed the contribution of proteins to the preservation process. Overall, this study provides an economical and robust strategy for the preservation of anammox granules. Unlabelled Image • Exogenous EPS was used as protective agents for the anammox sludge preservation. • Addition of exogenous EPS significantly increased anammox activity in short term. • Adding A-EPS at 4 °C led to the optimal recovery performance. • The protein in EPS is a potential factor in optimizing preservation performance. [ABSTRACT FROM AUTHOR]

• Mostly elevated-Mn groundwater occurs in granular aquifers in the Pearl River Delta. • Elevated-Mn groundwater in urbanized areas was more than that in non-urbanized areas. • Urbanization enhanced elevated-Mn groundwater in urbanized and peri-urban areas. • Acid precipitation from industry enhanced elevated-Mn groundwater in peri-urban areas. • Mn-rich surface water, an important source for groundwater Mn in river network areas. High concentration of manganese (Mn) in groundwater is a major concern because of its harmful to human health, and the origin of which in urbanized areas is often complicated. The present study aims to delineate spatial distributions of groundwater Mn in various aquifers and in areas with different urbanization levels in the Pearl River Delta (PRD), and to identify the origins of groundwater Mn in this region. Nearly 400 groundwater samples collected, and 14 chemicals were analyzed. The results show that approximately 20% groundwater in granular aquifers showed elevated-Mn (>0.4 mg/L), and was more than two times of that in fissured aquifers, while that in karst aquifers was absent. The proportions of elevated-Mn groundwater in urbanized areas and peri-urban areas were higher than that in non-urbanized areas. The decomposition of organic matter and reduction of Fe (hydr)oxides in sediments with reducing condition was likely to be the main factor controlling elevated-Mn groundwater in granular aquifers at a regional scale. By contrast, elevated-Mn groundwater in fissured aquifers was likely mainly affected by the urbanization accompanied with the leakage of low-oxygen domestic sewage and the industrialization accompanied by the leakage of industrial wastewater. In addition, Mn-rich surface water was also probably an important source for groundwater Mn in river network areas. Therefore, it is necessary to make a long-term monitoring for groundwater Mn in granular aquifers, especially in urbanized areas and river network areas, because of the high proportion of elevated-Mn. [ABSTRACT FROM AUTHOR]

Investigations on environmental behaviors of SVOCs have recently received great attention. However, the SVOC occurrence and influence of pipe materials on SVOC levels in the tap water have received little attention. Herein, we collected tap water samples from 25 households constructed at different ages in Hangzhou, China. Concentrations of 61 SVOCs, including phthalate esters (PAEs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs), were simultaneously determined in these collected samples. The potential human exposure risks were evaluated via the hazard index calculation. Our results showed that the total concentration of detected SVOCs (∑SVOCs) ranged from 110 to 289 μg/L (mean, 179 μg/L), and the SVOCs were dominated by PAHs (mean, 116 ng/L) and PAEs (mean, 55 ng/L) in Hangzhou tap water. 12 PCB congeners were detected in Hangzhou tap water samples, with hepta-CBs (68% of samples) as the most frequently detected PCBs. Nearly all tap water samples contained measurable o, p' -DDE, p, p' -DDT, and p, p' -DDD, and ∑DDTs had significantly (p < 0.05) higher concentrations than ∑HCHs. All target PAHs had high detection frequencies (>72%) in tap water samples, with their mean concentrations in the range of 2.1–41 ng/L. Tap water from steel pipes had relatively lower SVOC concentrations than that from either reinforced concrete, gray cast iron, or ductile iron pipes. Although no carcinogenic risks originating from exposure to SVOCs through ingestion and bathing were observed, the tap water from steel pipes showed relatively low exposure risks than that from other materials. Data provided here, for the first, are helpful in understanding the influence of pipe materials on human SVOC exposure risks through tap water intake. Unlabelled Image • Occurrence of 61 SVOCs in Hangzhou tap water was firstly reported. • SVOCs detected in tap samples were dominated by PAHs and PAEs. • Tap water from steel pipes had relatively lower SVOC concentrations. • Human SVOC exposure risks through tap water from different pipes were estimated. [ABSTRACT FROM AUTHOR]

Abstract Both nickel and salinity are often detected in the environment. Especially electroplating wastewater contains some salt and nickel, which affects microbial activity in biological wastewater treatment process. In this study, the effects of sustaining addition of a high-concentration salinity and Ni(II) on the anaerobic ammonium oxidation (anammox) process were examined. The results indicated that the anammox system had an acclimation ability to <0.2 mg L−1 Ni(II) and 20 g L−1 NaCl. After a recovery phase of approximately 70 days, the nitrogen removal efficiency and rate reached at 77.1% and 1.18 kg N m−3 d−1, respectively. The three-dimensional excitation-emission matrix fluorescence and Fourier transform infrared spectra results showed that the introduction of NaCl and Ni(II) caused a substantial variation in the quantity and composition of the bound EPS in the surface of anammox granules. The present study is the first to document the long-term effect of co-existence of salinity and Ni(II) on the performance of the freshwater-derived anammox bacteria in the upflow anaerobic sludge blanket reactor and to provide a reference for the stable operation of anammox bioreactors for the treatment of sulfonamide-containing wastewater. Graphical abstract Unlabelled Image Highlights • Long-term exposure to NaCl and Ni(II) resulted in co-inhibition on the anammox UASB system. • The sludge characteristics changed after chronic exposure to NaCl and Ni(II). • 3D-EEM analyses showed a change in organic compositions in B-EPS. • FTIR analyses suggested a shift in functional groups in B-EPS. • The deleterious impact of NaCl and Ni(II) was reversible. [ABSTRACT FROM AUTHOR]

Abstract Organophosphate flame retardants (OPFRs) are frequently found in the environment and could be adversely affecting organisms. In fact, nine OPFRs have been shown to cause endocrine disruptions, but information on the metabolism-perturbing properties of these OPFRs remains unclear. In this study, the 1H-nuclear magnetic resonance (NMR) based metabolomic method was applied to evaluate the metabolic disturbances caused by these nine OPFRs. From the analysis of the metabolic phenotypes, we found that TDBPP, TMPP and TPHP could be clustered into one group; TBOEP, TCIPP, TCEP and TEHP could be clustered into another group; and the residual OPFRs could be clustered into another. The classification results agree with the antagonistic activities of glucocorticoid and mineralocorticoid receptors. Then, we found that when HepG2 cells were exposed to TMPP, TPHP and TDBPP, the main metabolic sub-network disturbances focused on metabolism linked with oxidative stress, osmotic pressure equilibrium, and glucocorticoid and mineralocorticoid receptor antagonist activities; this was also true for TNBP and TDCIPP. Meanwhile, the other OPFRs mainly affected oxidative stress and amino acid metabolism. With multivariate statistical analysis, we found many differential metabolites in each group. Notably, Trimethylamine‑N‑oxide (TMAO) was the differential metabolite in six of the tested OPFRs, excluding TMPP, TPHP and TDBPP, and was one of the potential cardiovascular biomarkers. The data provided here could be helpful in gaining a more in-depth understanding of the metabolic disturbances of these nine OPFRs and may offer a new perspective for understanding potential pollutants with endocrine-disrupting effects on host metabolism. Graphical abstract Unlabelled Image Highlights • OPFRs could change the metabolic phenotypes of HepG2 cells at low concentration. • The metabolic phenotypes agreed with antagonistic activities of GR and MR. • A list disturbed sub-networks were proposed as potential risk of OPFRs of effects. [ABSTRACT FROM AUTHOR]

The sustainable management and recirculation of phosphorus resources are essential to our human lives. In this work, phosphorus removal and recovery from secondary effluent were achieved using municipal wastewater-derived materials as adsorbents. Through modification with 0.5 M NaOH for 30 min, iron containing sludge that originated from the coagulation pretreatment of municipal wastewater was successfully converted to phosphorus adsorbent. The maximal adsorption capacity of the prepared adsorbent was estimated to be 22 mg-P/g, and the adsorption performance remained stable in the pH range of 5–8. FeO(OH) was identified as the key adsorption site, and the ligand exchange mediated chemical adsorption was the main mechanism for phosphorus removal by the prepared material. Moreover, a laboratory-scale continuous-flow adsorption column experiment showed that the surplus phosphorus in secondary effluent could be readily reduced to <0.1 mg/L. By pyrolysis of P-laden alkali-treated iron sludge under oxygen limited conditions, the phosphorus was recovered and successfully applied to support wheat growth. This work provides valuable information for both the sustainable management of phosphorus streams in wastewater and cyclic utilization of waste sludge. Unlabelled Image • Iron enriched sludge was successfully converted into phosphorus absorbent. • Phosphorus in secondary biological effluent was readily reduced to <0.1 mg/L. • The potential of reusing adsorbed phosphorus as fertilizer was evaluated. [ABSTRACT FROM AUTHOR]