Single and mixture toxicity of cadmium and copper to swim bladder in early life stages of Japanese medaka (Oryzias latipes).

Toxicity observed in aquatic ecosystems often cannot be explained by the action of a single pollutant. Likewise, evaluation standards formulated by a single effect cannot truly reflect the environmental quality requirements. The study of mixtures is needed to provide environmental relevance and knowledge of combined toxicity. In this study, the embryos of Japanese medaka (Oryzias latipes) were treated with individual and binary mixture of copper (Cu) and cadmium (Cd) until 12 days post-fertilization (dpf). Hatching, mortality, development, histology and gene expression were assessed. Our results showed that the highest concentration mixture of Cd (10 mg/L) and Cu (1 mg/L) affected survival, hatching time and hatching success. Occurrence of uninflated swim bladder was the highest (value) with exposure to 10 mg/L Cd. Swim bladder was commonly over-inflated in a mixture (0.1 mg/L Cd + 1.0 mg/L Cu) exposure. Individuals exposed to the mixture (0.1 Cd + 1.0 Cu mg/L) showed up to a 7.69% increase in swim bladder area compared to the control group. The mixtures containing 0.1 or 10 mg/L Cd, each with 1.0 mg/L Cu resulted in significantly increased of Pbx1b expression, higher than any Cd or Cu alone (p < 0.01). In the co-exposure group (0.1/10 Cd + 1.0 Cu mg/L), Pbx1b expression was found at 12 dpf but not 7 dpf in controls. Higher concentrations of Cd may progressively reduce Pbx1b expression, potentially explaining why 75% of individuals in the 10 mg/L Cd group failed to inflate their swim bladders. Additionally, the swim bladder proved to be a valuable bio-indicator for biological evaluation.

Soil aggregate-driven changes in nutrient redistribution and microbial communities after 10-year organic fertilization.

Research studies on nutrient content and microbial communities after the application of organic manure have been reported, while available information about multi-interaction mechanisms of nutrient stoichiometry and microbial succession in soil aggregates remains limited. This work conducted a 10-year field experiment amended with cow manure (1.5 t/ha), during which the application of organic manure stimulated the fragmentation of soil macro-aggregates (>5 mm) and the agglomeration of soil micro-aggregates (<0.25 mm). Hence, the proportion of medium-size aggregates (0.25-5 mm) was increased in bulk soil, and there was an insignificant difference in the stability of soil aggregates. Meanwhile, the application of organic manure increased soil organic carbon (SOC), total nitrogen (TN) and phosphorus (TP) in all soil aggregate fractions. SOC, TN and TP were higher in micro-aggregates (<0.25 mm) after the application of organic manure, thus the dominating phylum of bacteria and fungi was more abundance in micro-aggregates due to the increase in nutrient level. During the organic fertilization process, fungal communities significantly changed because the variation of carbon-to-nitrogen ratio (C:N) in soil aggregates. Cultivated farmland in Northeast China showed a considerable capacity to sequestrate SOC during the organic fertilization process, but nitrogen may be a primary macro-element limiting soil productivity. Theoretically, organic manure amended with nitrogen fertilizer could be an effective measure to maintain microbial diversity and crop productivity in agro-ecosystems in Northeast China.

Removal of microcystin (MC-LR) in constructed wetlands integrated with microbial fuel cells: Efficiency, bioelectricity generation and microbial response.

Microcystins (MCs) pollution caused by cyanobacteria harmful blooms (CHBs) has posed short- and long-term risks to aquatic ecosystems and public health. Constructed wetlands (CWs) have been verified as an effective technology for eutrophication but the removal performance for MCs did not achieve an acceptable level. CWs integrated with microbial fuel cell (MFC-CWs) were developed to intensify the nutrient and Microcystin-LR (MC-LR) removal efficiencies in this study. The results indicated that closed-circuit MFC-CWs (T1) exhibited a better NO3--N, NH4+-N, TP and MC-LR removal efficiency compared to that of open-circuit MFC-CWs (CK, i.e., traditional CWs). Therein, a MC-LR removal efficiency of greater than 95% was observed in both trials in T1. The addition of sponge iron to the anode layer of MFC-CWs (T2) improved only the NO3--N removal and efficiency bioelectricity generation performance compared to T1, and the average effluent MC-LR concentration of T2 (1.14 µg/L) was still higher than the provisional limit concentration (1.0 µg/L). The microbial community diversity of T1 and T2 was simplified compared to CK. The relative abundance of Sphingomonadaceae possessing the degradation capability for MCs increased in T1, which contributed to the higher MC-LR removal efficiency compared to CK and T2. While the relative abundance of electrochemically active bacteria (EAB) (i.e., Desulfuromonadaceae and Desulfomicrobiaceae) in the anode of T2 was promoted by the addition of sponge iron. Overall, this study suggests that integrating MFC into CWs provides a feasible intensification strategy for eutrophication and MCs pollution control.

Potential health risks of metals in skin care products used by Chinese consumers aged 19-29 years.

Metal contamination of skin care products that occurs during their production poses potential health risks, which are of increasing concern, to consumers. Here, we collected 570 responses to an online survey to analyze the usage pattern of skin care products across China. Then a total of 30 commonly used skin care products with various prices and applications were purchased. The concentrations of metals (Al, Zn, Cu, Ni, Cr, Pb, Hg, and Cd) and metalloid As, were determined. Next, we improved the frequency calculation method and used the weighted exposure frequency to calculate the dermal absorption dose (DAD). The amounts of Zn, Cr, and Al that were assimilated by the human body via uptake were approximately 2 orders of magnitude greater than those of Pb, Hg, Cd, Ni and metalloid As. In addition, younger consumers were at higher risk of metals exposure than older consumers because of their higher frequency of use of skin care products. Al and Zn posed higher risk to consumers because of its high DAD. There was no significant chronic non-carcinogenic health risk (hazard index < 1) posed by skincare product use.

Metallic elements in human hair from residents in smelting districts in northeast China: Environmental factors and differences in ingestion media.

The health of residents in Huludao City is affected by the emissions of heavy metals from smelting, diet and atmospheric precipitation. This study investigated the concentrations of Hg, Cd, Pb, Cu and Zn in scalp hair samples from 259 residents of different ages and genders from five districts in Huludao City and examined the main factors for heavy metal exposure. Cd and Pb concentrations in hair samples exceeded the normal concentration ranges for human hair (Cd < 0.3 mg/kg; Pb < 9.3 mg/kg), and the highest Pb concentrations were found in subjects in the age range 0-15 years. Samples from men were higher in Cd and Pb compared to those for women. Workers from the Huludao zinc plant (HZP) had higher concentrations of all metals in their hair relative to other occupations except for Cu. Geographically, the highest Cd and Pb concentrations in hair were found for residents living in Daochi district (DCD) and the Zn plant district (ZPD), respectively. In smelting regions, the effects of dust ingestion on heavy metal exposure were more important than in non-smelting regions.

Health risk assessment of heavy metals in street dust around a zinc smelting plant in China based on bioavailability and bioaccessibility.

In order to investigate pollution level, chemical speciation and health risk of exposure to heavy metals in street dust from smelting district, we carried the following studies: (a). the differences in the morphology of street dust in smelting and non-smelting districts using a scanning electron microscope; (b). the chemical speciation and bioavailability of heavy metals in <100 µm and <63 µm particles near a smelting district using a modified three-stage BCR sequential extraction procedure and in vitro digestion test, respectively; (c). the evaluation of the non-carcinogenic risk of children and adults exposure to dust based on bioaccessibility. The results showed that most of the dust particles near Huludao Zinc Plant (HZP) were relatively solid with less porosity, which might originate from incompletely burned mineral particles from the smelting process. The concentrations of Pb, Cd and Cu were much higher than the background levels: 1560, 178.5 and 917.9 mg kg-1 in <100 µm dust samples, and 2099, 198.4, 1038 mg kg-1 in <63 µm dust samples, respectively. Pb was mostly present in the reducible fraction and the acid exchangeable fraction, while Cd and Cu were the most common heavy metals in the acid exchangeable fraction and oxidizable fraction, respectively. The rank order of bioaccessibility for the gastric and intestinal phase was Cd (58.13%) > Pb (50.00%) > Cu (19.19%) and Cd (20.36%) > Cu (15.67%) > Pb (5.08%), respectively. Hand-to-mouth ingestion poses the greatest non-carcinogenic exposure risk compared with other exposure pathways. When bioavailability is taken into account, children experienced higher non-carcinogenic and carcinogenic risks of dust exposure compared with adults, and the <63 µm particles posed greater risks than <100 µm particles.

Physiological and genetic effects of cadmium and copper mixtures on carrot under greenhouse cultivation.

The exposure to combinations of heavy metals can affect the genes of vegetables and heavy metals would accumulate in vegetables and thereby indirectly affecting human health. Exploring the links between genetic changes and phenotypic changes of carrot under the combined pollution of Cd and Cu is of great significance for studying the mechanism of heavy metal pollution. Therefore, this study examined the effects of mixtures of cadmium (Cd) and copper (Cu) on physiological measures (malondialdehyde (MDA), proline, and antioxidant enzyme) and expression of growth-related genes (gibberellin gene, carotene gene, and glycogene) in carrot under greenhouse cultivation. The results showed in the additions with mixtures of Cd and Cu at higher concentration, the MDA content increased significantly (p < 0.05), whereas the proline content was not significantly different from those in the control. In the mixed treatments with high Cd concentrations, the activity of superoxide dismutase (SOD) was significantly lower than that in the control (p < 0.05); whereas the activity of peroxidase (POD) increased to different degrees compared to the control. In the additions with mixtures of Cd and Cu, compared with the control, the expression of the gibberellin gene was downregulated from 1.97 to 20.35 times (not including the 0.2 mg kg-1 Cd and 20 mg kg-1 Cu mixture, the expression of gibberellin gene in this treatment was upregulated 1.29 times), which lead to decreases in the length and dry weight of carrots. The expression of the carotene gene in mixed treatments downregulated more than that in single treatments, which could reduce the ability of carrots to resist oxidative damage, as suggested by the significant increase in the MDA content. In the addition with mixtures of Cd and Cu, compared with the control, the expression of the glycogene was downregulated by 1.42-59.40 times, which can cause a significant reduction in the sugar content in carrots and possibly further reduce their ability to resist heavy metal damage. A cluster analysis showed that in the additions with mixtures of Cd and Cu, the plant phenotype was affected first, and then with increases in the added concentration, the expression of genes was also affected. In summary, in the additions with mixtures of Cd and Cu, plants were damaged as Cd and Cu concentrations increased.

Contamination assessment and health risk of arsenic exposure to stairway dust in the zinc smelting district, Northeast China.

Stairway dust samples were collected from residential communities in Huludao city to investigate population health risk of arsenic (As) exposure through stairway dust. ArcGIS software was used to analyze As spatial distribution in Huludao city. Hazard index was applied to assess health risk due to exposure to As in stairway dust. The results were that As concentrations ranged from 13.26 to 237.58 mg kg-1, and the mean value was 59.64 mg kg-1, which was seven times as high as the background value of Liaoning Province. The pattern of spatial distribution was concentric rings as the center of Huludao zinc plant, with the extension to the northeast and southwest. The average value of Igeo was 2.176, which fell into moderately polluted level. For non-carcinogenic risk, the hazard indexes were less than 1, indicating that there was almost no health risk for residents exposed to stairway dust. But population risk exposure to dust would increase rapidly with exposure time in stairway. The highest contribution to the overall figure of non-carcinogenic risk and carcinogenic risk appeared to be ingestion of substrate particles followed by inhalation pathway and dermal absorption of As in dust samples. And for carcinogenic risk, the risk values were lower than the threshold range of EPA's safe limits (1 × 10-6 and 1 × 10-4), suggesting that potential cancer risk of As due to exposure to stairway dust can be acceptable.

Effect of soil pH and organic matter content on heavy metals availability in maize (Zea mays L.) rhizospheric soil of non-ferrous metals smelting area.

Maize plant tissues and rhizosphere soil were collected from an agricultural area around the Huludao Zinc Plant in Liaoning Province, China, to investigate the effects of soil pH and organic matter content on heavy metal concentration and accumulation in different types of maize tissues. The mean pH of the soil samples was 7.02 (range 5.74-7.86), and the mean organic matter content was 31.03 g kg-1 (range 18.80-52.20 g kg-1). The average Cu, Zn, Pb, and Cd contents in soil were 2.92, 6.72, 7.95, and 16.28 times greater than the corresponding background values, respectively. The geo-accumulation index indicated that the soils were uncontaminated to moderately contaminated by Cu, moderately to strongly contaminated by Pb and Zn, and strongly contaminated by Cd. The average available Cu, Pb, Zn, and Cd contents in the soil samples were 16.34, 6.997, 69.77, and 0.190 mg kg-1, respectively, while their bioavailability coefficients were 28.53%, 1.65%, 40.44%, and 10.83%, respectively. The respective mean Pb and Cd concentrations in grain samples were 0.341 and 0.342 mg kg-1, which exceeded the maximum concentrations permitted by the Chinese National Standard. Thus, the maize grain is not safe for consumption and poses potential risks to human health. With the exception of Cu, the combined effect of pH and organic matter content had a stronger influence on the availability of heavy metals in soil compared with either factor alone. Cd uptake in maize plant tissues was affected by the combination of soil pH, organic matter content, and bioavailable Cd content in soil; however, the combination of these three factors had only slight effects on Cu, Zn, and Pb absorption in maize tissues.

The Toxicological Effects of Mercury Exposure in Marine Fish.

Since the Minamata incident in Japan, the public have become increasingly aware of the negative health effects caused by mercury pollution in the ocean. Consequently, there has been significant interest in the health of humans eating fish exposed to mercury (Hg). However, the toxicity of mercury to the marine fish themselves has received far less attention. In this review, we summarize mercury accumulation in marine fish and the toxicological effects of mercury exposure. Results showed that the bioaccumulation of mercury in marine fish was highly variable, and its concentration was affected by the specific physiological and ecological characteristics of different fish species. Mercury exposure can produce teratogenic, neurotoxic effects, and reproductive toxicity. These effects can then cause harm to cells, tissues, proteins and genes, and ultimately, the survival, growth, and behavior of marine fish. Future studies should afford more attention to the toxicological effect of mercury exposure upon marine fish.

Effects of cadmium and copper mixtures to carrot and pakchoi under greenhouse cultivation condition.

A pot experiment was undertaken to investigate the effects of Cd and Cu mixtures to growth and nutrients (sugar, carotene or vitamin C) of carrot and pakchoi under greenhouse cultivation condition. The study included: (a) physical-chemical properties of soil and soil animals in response to Cd and Cu stress; (b) bioaccumulation of heavy metals, length, biomass, contents of sugar and carotene (vitamin C) of carrot and pakchoi; (c) estimation the effects of Cd and Cu mixtures by multivariate regression analysis. The results implied that heavy metals impacted negative influence on soil animals' abundance. The metals contents in plants increased obviously with Cd and Cu contamination in soil. The biomass production and nutrients declined with Cd and Cu contents increasing. Cd (20 mg kg-1) treatment caused maximum reduction of sugar content (45.29%) in carrot root; maximum reduction in carotene content (75.73%) in carrot, 75.1% sugar content reduction and 70.58% vitamin C content reduction in pakchoi shoots were observed with addition of Cd (20 mg kg-1) and Cu (400 mg kg-1) mixture. The results of multivariate regression analysis indicated that combination of Cd and Cu exerts negative effects to both carrot and pakchoi, and both growth and nutrients were negatively correlated with metals concentrations. It is concluded that the Cd and Cu mixtures caused toxic damage to vegetable plants as Cd and Cu gradient concentrations increased.

Greenhouse gases emissions and carbon budget estimation in horizontal subsurface flow constructed wetlands with different plant species.

Constructed wetlands (CWs) are pivotal for wastewater treatment due to their high efficiency and numerous advantages. The impact of plant species and diversity on greenhouse gas (GHG) emissions from CWs requires a more comprehensive evaluation. Moreover, controversial perspectives persist about whether CWs function as carbon sinks or sources. In this study, horizontal subsurface flow (HSSF) CWs vegetated with Cyperus alternifolius, Typhae latifolia, Acorus calamus, and the mixture of these three species were constructed to evaluate pollutant removal efficiencies and GHG emissions, and estimate carbon budgets. Polyculture CWs can stably remove COD (86.79 %), NH4+-N (97.41 %), NO3--N (98.55 %), and TP (98.48 %). They also mitigated global warming potential (GWP) by suppressing N2O emissions compared with monoculture CWs. The highest abundance of the Pseudogulbenkiania genus, crucial for denitrification, was observed in polyculture CWs, indicating that denitrification dominated in nitrogen removal. While the highest nosZ copy numbers were observed in CWs vegetated with Cyperus alternifolius, suggesting its facilitation of denitrification-related microbes. Selecting Cyperus alternifolius to increase species diversity is proposed for simultaneously maintaining the water purification capacity and reducing GHG emissions. Carbon budget estimations revealed that all four types of HSSF CWs were carbon sinks after six months of operation, with carbon accumulation capacity of 4.90 ± 1.50 (Cyperus alternifolius), 3.31 ± 2.01 (Typhae latifola), 1.78 ± 1.30 (Acorus calamus), and 2.12 ± 0.88 (polyculture) kg C/m2/yr. This study implies that under these operation conditions, CWs function as carbon sinks rather than sources, aligning with carbon peak and neutrality objectives and presenting significant potential for carbon reduction efforts.

Soil amendments reduce CH4 and CO2 but increase N2O and NH3 emissions in saline-alkali paddy fields.

Limited research has been conducted on ammonia (NH3) volatilization and greenhouse gases (GHGs) emissions in saline-alkali paddy fields, along with complex interaction involving various genes (16sRNA, amoA, narG, nirK, nosZ, and nifH). This study employed mesocosm-scale experiment to investigate NH3 volatilization and GHGs emissions, focusing on bacterial communities and genic abundance, in saline-alkali paddy fields with desulfurized gypsum (DG) and organic fertilizer (OF) amendments. Compared to the control (CK) treatment, DG and OF treatments reduced methane (CH4) and carbon dioxide (CO2) emissions by 78.05 % and 26.18 %, and 65.84 % and 11.62 %, respectively. However, these treatments increased NH3 volatilization by 26.26 % and 45.23 %, and nitrous oxide (N2O) emission by 41.00 % and 12.31 %. Notably, NH3 volatilization primarily stemmed from ammonia nitrogen (NH4+-N), rather than total nitrogen (TN) in soil and water. N2O was mainly produced from nitrate nitrogen (NO3--N) in soil and water, as well as NH4+-N in water. The increase in NH3 volatilization and N2O emission in DG and OF treatments, was attributed to the reduced competition among bacterial communities, rather than the increased bacterial activity and genic copies. These findings offer valuable insights for managing nutrient loss and gaseous emissions in saline-alkali paddy fields.

Layered double hydroxides, an effective nanomaterial to remove phosphorus from wastewater: Performance, mechanism, factors and reusability.

Systematic understanding of phosphorus adsorption performance, mechanism, factors and reusability of layered double hydroxides (LDH) remains limited. Thus, iron (Fe), calcium (Ca) and magnesium (Mg)-based LDH (FeCa-LDH and FeMg-LDH), were synthesized with a co-precipitation method to improve phosphorus removal efficiency during the wastewater treatment process. Both FeCa-LDH and FeMg-LDH showed a considerable ability to remove phosphorus in wastewater. When the phosphorus concentration was 10 mg/L, the removal efficiency reached 99 % (FeCa-LDH: 1 min) and 82 % (FeMg-LDH: 10 min), respectively. The phosphorus removal mechanism was observed to be electrostatic adsorption, coordination reaction and anionic exchange, which was more evident at pH = 10 for FeCa-LDH. Co-occurrence anions that affected phosphorus removal efficiency, were observed in the following order: HCO3- > CO32- ≈ NO3- > SO42-. After five adsorption-desorption cycles, phosphorus removal efficiency was still up to 85 % (FeCa-LDH) and 42 % (FeMg-LDH), respectively. Together, the present findings suggest that LDHs were high-performance, strongly-stable and reusable phosphorus adsorbents.

Factors Influencing Gaseous Emissions in Constructed Wetlands: A Meta-Analysis and Systematic Review.

Constructed wetlands (CWs) are an eco-technology for wastewater treatment and are applied worldwide. Due to the regular influx of pollutants, CWs can release considerable quantities of greenhouse gases (GHGs), ammonia (NH3), and other atmospheric pollutants, such as volatile organic compounds (VOCs) and hydrogen sulfide (H2S), etc., which will aggravate global warming, degrade air quality and even threaten human health. However, there is a lack of systematic understanding of factors affecting the emission of these gases in CWs. In this study, we applied meta-analysis to quantitatively review the main influencing factors of GHG emission from CWs; meanwhile, the emissions of NH3, VOCs, and H2S were qualitatively assessed. Meta-analysis indicates that horizontal subsurface flow (HSSF) CWs emit less CH4 and N2O than free water surface flow (FWS) CWs. The addition of biochar can mitigate N2O emission compared to gravel-based CWs but has the risk of increasing CH4 emission. Polyculture CWs stimulate CH4 emission but pose no influence on N2O emission compared to monoculture CWs. The influent wastewater characteristics (e.g., C/N ratio, salinity) and environmental conditions (e.g., temperature) can also impact GHG emission. The NH3 volatilization from CWs is positively related to the influent nitrogen concentration and pH value. High plant species richness tends to reduce NH3 volatilization and plant composition showed greater effects than species richness. Though VOCs and H2S emissions from CWs do not always occur, it should be a concern when using CWs to treat wastewater containing hydrocarbon and acid. This study provides solid references for simultaneously achieving pollutant removal and reducing gaseous emission from CWs, which avoids the transformation of water pollution into air contamination.

FeCa-based layered double hydroxide, a high-performance phosphorus adsorbent in constructed wetlands and ecological dams - A pilot scale study.

Research studies have modified traditional substances to seek fast-acting removal of phosphorus in constructed wetlands (CWs) and ecological dams, rather than develop a brand-new nano-adsorbent. This work synthesized FeCa-based layered double hydroxide (FeCa-LDH) with a chemical co-precipitation method, and the performance, mechanism and factors of phosphorus removal were investigated. FeCa-LDH showed a marked ability to adsorb phosphorus from waste water, with a removal efficiency of 94.4% and 98.2% in CWs and ecological dams, respectively. Both FTIR and XPS spectrum evidenced that FeCa-LDH removed phosphorus via electrostatic and hydrogen-bonding adsorption, as well as a coordination reaction and interlayer anion exchange. FeCa-LDH showed a higher capacity to remove phosphorus in alkaline and neutral waste water than in acid conditions. Co-occurrence anions, which influenced the efficiency of the phosphorus removal capacity are considered in the sequence below: CO32- ≈ HCO3- > SO42- > NO3-. Innovatively, FeCa-LDH was not affected by the low-temperature limitation for CWs, and phosphorus removal efficiency at 5 °C was almost equal to that at 25 °C. These results cast a new idea on the construction, application and phosphorus removal performance of CWs and ecological dams.

Integration of MFC reduces CH4, N2O and NH3 emissions in batch-fed wetland systems.

The combination of microbial fuel cells (MFCs) with constructed wetlands (CWs) for enhancing water purification efficiency and generating bioelectricity has attracted extensive attention. However, the other benefits of MFC-CWs are seldom reported, especially the potential for controlling gaseous emissions. In this study, we have quantitatively compared the pollutant removal efficiency and the emission of multiple gases between MFC-CWs and batch-fed wetland systems (BF CWs). MFC-CWs exhibited significantly (p < 0.01) higher COD, NH4+-N, TN, and TP removal efficiencies and significantly (p < 0.01) lower global warming potential (GWP) than BF CWs. The integration of MFC decreased GWP by 23.88% due to the reduction of CH4 and N2O fluxes, whereas the CO2 fluxes were slightly promoted. The quantitative PCR results indicate that the reduced N2O fluxes in MFC-CWs were driven by the reduced transcription of the nosZ gene and enhanced the ratio of nosZ/(nirS + nirK); the reduced CH4 fluxes were related to pomA and mcrA. Additionally, the NH3 fluxes were reduced by 52.20% in MFC-CWs compared to BF CWs. The integration of MFC promoted the diversity of microbial community, especially Anaerolineaceae, Saprospiraceae and Clostridiacea. This study highlights a further benefit of MFC-CWs and provides a new strategy for simultaneously removing pollutants and abating multiple gas emissions in BF CWs.

Biochar-amended constructed wetlands for eutrophication control and microcystin (MC-LR) removal.

Microcystins (MCs) pollution caused by eutrophication and climate change has posed a serious threat to ecosystems and human health. Constructed wetlands (CWs) with biochar addition volume ratios of 0% (BC0-CWs), 10% (BC10-CWs), 20% (BC20-CWs) and 50% (BC50-CWs) were set up to evaluate the efficiency of biochar-amended CWs for eutrophication and MCs pollution control. The results illustrated that removal efficiencies of both NH4+-N and NO3--N were enhanced by biochar addition to varying degrees. The average TP and MC-LR removal efficiencies increased with increasing biochar addition ratios, and the average TP and MC-LR removal efficiencies in biochar-amended CWs were significantly (p < 0.05) improved by 5.64-9.58% and 10.74-14.52%, respectively, compared to that of BC0-CWs. Biochar addition changed the microbial community diversity and structure of CWs. The relative abundance of functional microorganisms such as Burkholderiaceae, Nitrospiraceae, Micrococcaceae, Sphingomonadaceae and Xanthomonadaceae was promoted by biochar addition regardless of addition ratios. The higher relative abundance of the above microorganisms in BC20-CWs and BC50-CWs may contribute to their better removal performance compared to other CWs. The concentrations of extracellular polymeric substance (EPS) in biochar-amended CWs were significantly (p < 0.05) lower than that in BC0-CWs, which can reduce the risk of system clogging. This study demonstrated that biochar addition may be a potential intensification strategy for eutrophication and MCs pollution control by CWs. Considering both the removal performance and economic cost, a biochar addition ratio of 20% was recommended as an optimal addition ratio in practical application.

Inhalation Bioaccessibility and Risk Assessment of Metals in PM2.5 Based on a Multiple-Path Particle Dosimetry Model in the Smelting District of Northeast China.

PM2.5 can deposit and partially dissolve in the pulmonary region. In order to be consistent with the reality of the pulmonary region and avoid overestimating the inhalation human health risk, the bioaccessibility of PM2.5 heavy metals and the deposition fraction (DF) urgently needs to be considered. This paper simulates the bioaccessibility of PM2.5 heavy metals in acidic intracellular and neutral extracellular deposition environments by simulating lung fluid. The multipath particle dosimetry model was used to simulate DF of PM2.5. According to the exposure assessment method of the U.S. Environmental Protection Agency, the inhalation exposure dose threshold was calculated, and the human health risk with different inhalation exposure doses was compared. The bioaccessibility of heavy metals is 12.1−36.2%. The total DF of PM2.5 in adults was higher than that in children, and children were higher than adults in the pulmonary region, and gradually decreased with age. The inhalation exposure dose threshold is 0.04−14.2 mg·kg−1·day−1 for the non-carcinogenic exposure dose and 0.007−0.043 mg·kg−1·day−1 for the carcinogenic exposure dose. Cd and Pb in PM2.5 in the study area have a non-carcinogenic risk to human health (hazard index < 1), and Cd has no or a potential carcinogenic risk to human health. A revised inhalation health risk assessment may avoid overestimation.

Room temperature synthesis of 2D CuO nanoleaves in aqueous solution.

A simple room temperature method was reported for the synthesis of CuO nanocrystals in aqueous solution through the sequence of Cu(2+) → Cu(OA)2 → Cu(OH)2 → Cu(OH)(2-)4 → CuO. Sodium oleate (SOA) was used as the surfactant and shape controller. The as-prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectroscopy (UV-vis) and differential thermal analysis (DTA). It can be seen that 1D Cu(OH)(2) nanowires were first obtained from Cu(OA)(2) and, at room temperature, converted into 2D CuO nanoleaves (CuO NLs) in a short time under a weakly basic environment. On prolonging the reaction time, the top part of these 2D nanoleaves branched and separated along the long axis to form 1D rod-like nano-CuO because of the assistance of SOA. A possible transformation mechanism of Cu(OH)(2) to CuO nanostructures at room temperature in aqueous solution is discussed. The transformation velocity can be controlled by changing the pH value of the system. The prepared CuO NLs were used to construct an enzyme-free glucose sensor. The detecting results showed that the designed sensor exhibited good amperometric responses towards glucose with good anti-interferent ability.