The uptake, transportation, and chemical speciation of Sb(III) and Sb(V) by wetland plants Arundinoideae (Phragmites australis) and Potamogetonaceae (Potamogeton crispus).

Antimony (Sb) is increasingly released and poses a risk to the environment and human health. Antimonite (Sb(III)) oxidation can decrease Sb toxicity, but the current knowledge regarding the effects of Sb(III) and antimonate (Sb(V)) exposure is limited to wetland plants, especially the Sb speciation in plants. In this study, Phragmites australis and Potamogeton crispus were exposed to 10 and 30 mg/L Sb(III) or Sb(V) for 20 days. The total concentration, subcellular distribution, and concentration in the iron plaque of Sb were determined. The Sb speciation in plants was analyzed by HPLC-ICP-MS. It illustrated that Sb(III) exposure led to more Sb accumulation in plants than Sb(V) treatments, with the highest Sb concentration of 405.35 and 3218 mg/kg in Phragmites australis and Potamogeton crispus, respectively. In the subcellular distribution of Sb, accumulation of Sb mainly occurred in cell walls and cell cytosol. In Phragmites australis, the transport factor in the Sb(V) treatments was about 3 times higher than the Sb(III) treatments, however, it was lower in the Sb(V) treatments than Sb(III) treatments for Potamogeton crispus. Sb(V) was detected in the plants of Sb(III) treatments with different Sb(V)-total Sb vitro (Phragmites australis: 34 % and, Potamogeton crispus: 15 %), moreover, Sb(V) was also detected in the nutrient solution of Sb(III) treatments. Antimony exposure caused a reduction of the iron plaque formation, at the same time, the root aerenchyma formation was disrupted, and this phenomenon is more pronounced in the Sb(III) treatments. Moreover, the iron plaque has a higher sorption potential to Sb under Sb(III) exposure than that under Sb(V) exposure. The results can fill the gap for antinomy speciation in wetland plants and expand the current knowledge regarding the Sb translocation in wetland systems.

Sulfur-manganese carbonate composite autotrophic denitrification: nitrogen removal performance and biochemistry mechanism.

A novel composite sulfur-manganese carbonate autotrophic denitrification (SMAD) system was developed to reduce sulfate production and provide pH buffer function while improving denitrification efficiency without external organics. The average removal efficiency of total nitrogen (TN) was 98.09% and 96.29%, and that of NO3--N was 99.53% and 97.77%, respectively, in the SMAD system with a hydraulic retention time (HRT) of 6 h and 3 h. They were significantly higher than that in the controls (quartz sand, manganese carbonate ore, and sulfur systems). The H+ produced by the sulfur autotrophic denitrification (SAD) process promoted the release of Mn2+ in the SMAD system. And this system had a stable pH with no accumulation of NO2--N. The decrease of sulfate and formation of Mn oxides through Mn2+ electron donation confirmed the presence of the manganese autotrophic denitrification (MAD) process in the SMAD system. Dominant functional bacteria in the SMAD system were Thiobacillus, Chlorobium, and Sulfurimonas, which were linked to nitrogen, sulfur, and manganese conversion and promoted denitrification. Meanwhile, Flavobacterium participating in Mn2+ oxidation was found only in the SMAD system. The SMAD system provided a new strategy for advanced tailwater treatment.

The function and keystone microbiota in typical habitats under the influence of anthropogenic activities in Baiyangdian Lake.

Microbe is an essential driver in regulating the biochemical cycles of carbon, nitrogen, and sulfur. In freshwater lake, microbial communities and functions are influenced by multiple factors, especially anthropogenic activities. Baiyangdian Lake consisted of various habitats, and was frequently interfered with human activities. In this study, 16 S rRNA sequencing and metagenomic sequencing were performed to characterize the microbial communities, determine keystone taxa and reveal dominated metabolic functions in typical habitats in Baiyangdian Lake. The results showed that the diversity of microbial community was significantly higher in sediment compared with corresponding water sample. Microbial community showed strong spatial heterogeneity in sediment, and temporal heterogeneity in water. As for different habitats, significantly higher alpha diversity was observed in ecotone, where the interference of human activities was relatively weak. The shared OTUs were distinguished from the keystone taxa, which indicated the uniqueness of microbiota in different ecological habitat. Moreover, the interactions of microbial in ecological restoration area (abandoned fish pond) were relatively simple, suggesting that this ecosystem was relatively fragile compared with others. Based on the metagenomic sequencing, we recognized that the canal, open water, and abandoned fish pond were beneficial for methanogenic and the ecotone might be a hot zone for the oxidation of methane. Notably, most of the microbes that participated in these predominant metabolisms were unclassified, which indicated the hug potential for exploring functional microorganisms in Baiyangdian Lake. This study provided a comprehensive understanding of the ecology characteristics of microbiota in habitats undergoing various human interference in Baiyangdian Lake.

Potential functions of engineered nanomaterials in cadmium remediation in soil-plant system: A review.

Soil cadmium (Cd) contamination is a global environmental issue facing agriculture. Under certain conditions, the stable Cd that bound to soil particles tend to be remobilized and absorbed into plants, which is seriously toxic to plant growth and threat food safety. Engineering nanomaterials (ENMs) has attracted increasing attentions in the remediation of Cd pollution in soil-plant system due to their excellent properties with nano-scale size. Herein, this article firstly systematically summarized Cd transformation in soil, transport in soil-plant system, and the toxic effects in plants, following which the functions of ENMs in these processes to remediate Cd pollution are comprehensively reviewed, including immobilization of Cd in soil, inhibition in Cd uptake, transport, and accumulation, as well as physiological detoxication to Cd stress. Finally, some issues to be further studied were raised to promote nano-remediation technology in the environment. This review provides a significant reference for the practical application of ENMs in remediation of Cd pollution in soil, and contributes to sustainable development of agriculture.

Immobilization and phytoavailability of antimony (Sb) in contaminated agricultural soils amended with composted manure.

A pot experiment was conducted to assess the Sb phytoavailability and its accumulation in the wheat before and after remediation, using the composted manure of poultry and sheep, and a chemical amendment (limestone). The present study evaluates the effects of amendments on Sb bioavailability in different soils and investigates the relationship between bioaccumulated Sb and its availability in spiked soils using two different single extraction methods. Furthermore, a sequential extraction procedure was used to measure different fractions of Sb in soil, in order to assess the effect of remediation. The results revealed that bioavailability of Sb were highly affected by the three soil amendments on plant height, uptake of Sb by wheat. Poultry compost (Pc) and Sheep compost (Sc) increased the residual fraction of Sb in soils, and decreased the Sb uptake by wheat, enhanced the height, biomass and dry yield of the wheat crop. While the residual fraction of Sb in soils didn't obviously increased by adding Chemical (limestone) in the four soils. It is concluded that uptake of Sb in the soils significantly decreased with the addition of amended materials in the Sb spiked soils, and poultry compost is the most effective. In the lower level of Sb contaminated soils remediated by poultry compost (Pc), the uptake of Sb in wheat decreased 63.1-74.4 %, 68.7-79.0 %, 68.9-76.9 % and 66.3-82.6 % in S1, S2, S3, S4, compared to the contaminated soils without amendments, respectively.

Maternal essential metals, thyroid hormones, and fetal growth: Association and mediation analyses in Chinese pregnant women.

BACKGROUND: Essential metals play critical roles in fetal growth and development, but results from human studies are inconsistent. Additionally, whether maternal thyroid hormone (TH) levels mediate the associations between essential metals and fetal growth remains unknown. METHODS: Data for analysis were extracted from the Information System of Guangdong Women and Children Hospital between January 2017 and December 2019. Maternal levels of essential metals [copper (Cu), zinc (Zn), magnesium (Mg), and iron (Fe)] and THs were measured at the second trimester. Multivariate linear models were introduced to evaluate the potential associations between maternal essential metals, thyroid functions, and fetal growth, and the possible mediation effects of thyroid functions were explored in the median analyses. RESULTS: A total of 4186 mother-infant pairs were included in the present study. Maternal Fe levels were found to significantly increase birth weight in 272.91 g (95 % CI: 15.59, 530.22) among anemia group. Maternal Cu levels were positively associated with increased free triiodothyronine/free thyroxine ratio (FT3/FT4). Negative associations of Fe and Mg levels with thyroid-stimulating hormone (TSH) concentrations were observed, accompanied with the positive associations in relation to FT3, FT4 and FT3/FT4 ratio. Mediation analyses suggested that 72.01 % of the associations between Fe levels and birth length might be mediated by FT3 levels. Additionally, 25.85 % of the Cu-birth length association and 44.53 % of the Fe-birth length association could be explained by FT3/FT4 ratio. CONCLUSION: Our findings suggest that maternal Cu, Mg, and Fe levels can alter TH concentrations, and maternal FT3 and FT3/FT4 ratio might be potential mediators on the developmental effects of Cu and Fe levels.

Toxicity and bioavailability of antimony in edible amaranth (Amaranthus tricolor Linn.) cultivated in two agricultural soil types.

Although elevated levels of antimony (Sb) in agricultural soil and plant systems can have harmful effects on human health and ecosystems, little is known about the toxicity of Sb to plants and its mechanism. The assessment of Sb bioavailability is essential for understanding its potential risks and toxicity. In this study, we used pot experiments with two agricultural soil types spiked with Sb to investigate the dose-effect relationship between exposure to Sb and toxic effects (growth and bioaccumulation) on edible amaranth (Amaranthus tricolor Linn.). Soil solution (pore water) and seven single extractants were used to assess the bioavailability of Sb. Different toxic effects of Sb to amaranth cultivated in two types of soils (alkaline and acid soil) were observed. In alkaline soil (chestnut soil, pH 8.39), antimony is more easily absorbed by root and transported to shoot by plants, leading to more adverse effects, than in acid soil (pH 4.91) under the same exposure level. Our findings also highlight the need for more attention on asymptomatic accumulation of Sb in plants, especially for agricultural products cultivated in contaminated areas. The extraction efficiency of Sb was various in different extractants and soil types, Mehlich 3, NaHCO3 and Na2HPO4 for Sb were more efficient than other extractants in both tested alkaline and acid soil. Based on the extractability and correlation coefficients of toxic effects on amaranth and extractable Sb, we found that 0.1 M Na2HPO4 is the best extractant to predict the bioavailability of Sb in soil, and M3 is a suitable alternative. Antimony concentration in soil solution can also be used as an alternative indicator of the bioavailability of Sb.

Uptake, translocation and phytotoxicity of antimonite in wheat (Triticum aestivum).

Antimony (Sb) contamination of soils and its potential negative impact on crop yields have been recently recognized. To explore the effects of Sb(III) on wheat, responses of physical growth properties, enzyme activities and gene expression were examined. The root length was the most relevant indicator to exposure concentration, the root fresh weight was the most sensitive endpoint according to the comparison of the EC50 (50% inhibitory effect concentration) values, and NRAMP1 gene expression at 1 mg L-1 was more sensitive than other genes. The genes HMA2 and IRT1 were upregulated but less sensitive than NRAMP1. Additionally, the antioxidant enzyme response was examined to explore Sb toxicity toward wheat. The glutathione (GSH) content in roots exposed to high concentrations of Sb(III) was higher than that in the control group, which indicated that GSH is involved in protecting wheat against the effects of Sb(III). Comparing the different antioxidant responses and correlations with malondialdehyde (MDA) in different tissues, super oxide dismutase (SOD) exhibited the main contribution to defense Sb(III) in roots; SOD and peroxidase (POD) were the major antioxidants in shoots. Gene expression of transporter proteins was a highly sensitive indicator of Sb toxicity in wheat and allowed for understanding the defense mechanism in wheat. The upregulation of HMA2 under Sb(III) expression was one kind of defense mechanism, which can induce efflux of heavy metals into the apoplast or vacuoles. Biomass and plant height results suggested that wheat may grow better than other crops under similar exposure due to the lower degree of Sb uptake. This work is the first to provide a wheat uptake model of Sb(III) under a wide concentration range as well as a perspective on the response to this stress at the molecular level.

Antimony speciation in the environment: Recent advances in understanding the biogeochemical processes and ecological effects.

Antimony (Sb) is a toxic metalloid, and its pollution has become a global environmental problem as a result of its extensive use and corresponding Sb-mining activities. The toxicity and mobility of Sb strongly depend on its chemical speciation. In this review, we summarize the current knowledge on the biogeochemical processes (including emission, distribution, speciation, redox, metabolism and toxicity) that trigger the mobilization and transformation of Sb from pollution sources to the surrounding environment. Natural phenomena such as weathering, biological activity and volcanic activity, together with anthropogenic inputs, are responsible for the emission of Sb into the environment. Sb emitted in the environment can adsorb and undergo redox reactions on organic or inorganic environmental media, thus changing its existing form and exerting toxic effects on the ecosystem. This review is based on a careful and systematic collection of the latest papers during 2010-2017 and our research results, and it illustrates the fate and ecological effects of Sb in the environment.

Effect of Sodium Fluoride on the Proliferation and Gene Differential Expression in Human RPMI8226 Cells.

Although fluoride is known to reduce the incidence of caries, chronic excessive fluoride exposure can impair human health, even resulting in fluorosis. Now the underlying mechanisms of fluoride-induced toxicity are not fully understood. So, we conducted this study with the purpose of investigating the effect of sodium fluoride (NaF) in human RPMI8226 cells. In this experiment, human RPMI8226 cells were cultured with varied doses of fluoride (10, 20, 40, 80, 160, 320 µM). After 48 h exposure, the change of cell viability was examined by CCK-8 assay, and also the messenger RNA (mRNA) expression of relevant genes was assessed by QRT-PCR. Compared to the control group, fluoride exposure increased the human RPMI8226 cells viability at relatively lower levels (10-160 µM); however, when the concentration reached to 320 µM, the cell proliferation was significantly inhibited (p < 0.05). In addition, the genes mRNA expression, including ANKRD1, CRSP6, KLF2, SBNO2, ZNF649, FANCM, PDGFA, RNF152, CDK10, and CETN2 changed in a concentration-dependent manner and increased with fluoride exposure concentration. The results suggest that overexposure to fluoride (160-320 µM) can induce cytotoxicity and regulate relevant genes expression. Our findings provide novel insights into the mechanisms of action of fluoride-induced toxicity.

Study on changes of clinical indicators and key proteins from fluoride exposure.

Few studies have evaluated the biomarker changes of fluoride exposure. In order to explore early and sensitive indicators, animal experiment was designed. Ninety-six healthy SD rats (48 males and 48 females) weighing approximately 60 g were randomly divided into six groups of 16 animals each by gender average. Control animals were supplied with distilled water only as group 1. Exposure groups' animals were treated with 2, 4, 8, 16, and 32 mg NaF/kg bw, respectively, as groups 2, 3, 4, 5, and 6. Our study found that contents of white blood cell (WBC), lymphocyte percentage (LYMPH%), lymphocyte (LYM), mean platelet volume (MPV), and platelet distribution width (PDW) increased significantly in high-fluoride-exposure groups (p < 0.05), which revealed that immune system may be interfered by high fluoride. Meanwhile, levels of alanine aminotransaminase (ALT), aspartate aminotransaminase (AST), and ALT/AST in groups 5 and 6 decreased significantly compared to those in control group (p < 0.05), as well as the concentration of uric acid (UA) in groups 3, 4, 5, and 6 exhibited the same trends (p < 0.05). On the contrary, the level of blood B2 microglobulin (BB2MG) increased significantly (p < 0.05) in groups 4, 5, and 6. Changes of ALT, AST, UA, and BB2MG suggested the functions of the liver and kidney be altered by fluoride exposure. At the same time, the ATF4 content decreased gradually with the increase of fluoride concentration; furthermore, a highly significant (r = -0.586, p < 0.01) negative relationship between ATF4 content and fluoride exposure level was found. Results meant that clinical indicators cannot act as indicators of high fluoride exposure, and it also suggested that protein ATF4 might be the early and sensitive indicator in epidemiologic study of high fluoride exposure.