Possible Risk Factors and Their Potential Associations with Combined Heavy Metal Exposures in Pregnant Women in the Republic of Suriname.

Background: The exposure of pregnant women to multiple environmental pollutants may be more disadvantageous to birth outcomes when compared to single-compound contaminations. Objective: This study investigated the mixed exposures to mercury, manganese, or lead in 380 pregnant Surinamese women. The factors that might be associated with the heavy metal exposures and the relative risk of the potential factors to cause the mixed exposures were explored. The influencing factors of exposures to mixed contaminants assessed were living in Suriname's rural regions, several parts of which are contaminated with heavy metals emitted from artisanal and small-scale gold mining and agricultural activities; the consumption of potentially contaminated foods; advanced maternal age; as well as a relatively low formal educational level and monthly household income. Methods: Descriptive statistics were used to calculate frequency distributions and χ2-contingency analyses to calculate associations and relative risks (RR) with 95% confidence intervals (CI). Findings: Blood levels of two or three of the heavy metals above public health limits were observed in 36% of the women. These women were more often residing in the rural regions, primarily consumed potentially contaminated food items, were 35 years or older, were lower educated, and more often had a lower household income. However, only living in the rural regions (RR = 1.48; 95% CI 1.23-1.77) and a low household income (RR = 1.38; 95% CI 1.15-1.66) significantly increased the risk of exposure exceeding levels of concern to two or three of the heavy metals (by 48% and 38%, respectively). Conclusion: More comprehensive pharmacological, ecological, and epidemiological studies about exposures to mixed heavy metal contaminations in pregnant women are warranted.

[Pollution Characteristics, Source, and Health Risk Assessment of Metal Elements in PM2.5 Between Winter and Spring in Zhengzhou].

A total of 18 metal elements in ambient PM2.5 in Zhengzhou were continuously determined using an online heavy metal observation instrument in January and April, 2021, and the changes in element concentrations were analyzed. Metal elements were traced via enrichment factors, positive matrix factorization (PMF), and a characteristic radar chart. The US EPA health risk assessment model was used to assess the health risks of heavy metals, and the backward trajectory method and the concentration-weighted trajectory (CWT) method were used to evaluate the potential source regions of health risks. The results showed that the element concentrations were higher in spring, and the sum of Fe, Ca, Si, and Al concentrations accounted for 89.8% and 87.5% of the total element concentrations in winter and spring, respectively. Cd was enriched significantly, which was related to human activities. The concentrations of Pb, Se, Zn, Ni, Sb, and K in winter and Cr, Ni, Fe, Mn, V, Ba, Ca, K, Si, and Al in spring increased with the increasing pollution level. The results of PMF and the characteristic radar chart showed that the main sources of metal elements in winter and spring were industry, crust, motor vehicles, and mixed combustion, with industry and mixed combustion pollution occurring more often in winter and crust pollution occurring more often in spring. Significant non-carcinogenic risks existed in both winter and spring with more severe health risks in winter, and Mn caused significant non-carcinogenic risks. The health risks in winter were mainly influenced by Zhengzhou and surrounding cities and long-distance transport in the northwest, and the health risks in spring were mainly influenced by Zhengzhou and surrounding cities.

[Bacterial Community Structure of Typical Lake Sediments in Yinchuan City and Its Response to Heavy Metals].

Lake wetlands are extremely important and special ecosystems, which are important for regional water resource storage, environmental protection, and biodiversity maintenance. Sediment bacteria are an important component of lake ecosystems and are a major driver of biogeochemical cycling in lakes. In order to investigate the community structure of bacteria in typical lake sediments in Yinchuan City and their influencing factors, three typical lakes in Yinchuan City (Yuehai Lake, Mingcui Lake, and Xiniu Lake) were selected for the study and surface sediments were collected in January, April, July, and October 2021. The composition of the sediment bacterial community was examined using 16S rDNA high-throughput sequencing technology, and the response relationships between them and heavy metals were explored. The results showed that the ecological hazard coefficient for heavy metals in the sediments of three typical lakes in Yinchuan City was far less than 40, and the ecological hazard index was far less than 150, all of which indicated a minor ecological hazard. There were no significant differences in bacterial community diversity among the three lakes, but there were significant variations in diversity among the lakes in different seasons and significant differences in community composition. The dominant phyla (top three in terms of relative abundance) in Yuehai Lake, Mingcui Lake, and Xiniu Lake were Proteobacteria, Bacteroidetes, and Chloroflexi. The dominant lower orders were Gammaproteobacteria, Alphaproteobacteria, and Deltaproteobacteria. The main divergent species that occurred at the phylum level in typical lakes in Yinchuan were Proteobacteria, Bacteroidetes, Euryarchaeota, Firmicutes, Actinobacteria, and Acidobacteria. The sediment bacterial community structure of Yuehai Lake was significantly correlated with Cu, Fe, Mn, Zn, As, and Pb; the sediment bacterial community structure of Lake Mingcui was significantly correlated with Fe, Pb, and Cr; and the sediment bacterial community structure of Xiniu Lake was not significantly correlated with heavy metals. The types and contents of sediment heavy metals had a significant effect on the bacterial community structure of sediments in Yinchuan Yuehai Lake and Mingcui Lake and were important environmental factors that caused changes in the bacterial community structure of lake sediments.

[Analysis and Evaluation of Heavy Metal Pollution in Farmland Soil in China：A Meta-analysis].

In this study, a Meta-analysis was used to investigate the pollution status of eight farmland soil heavy metal elements (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in China. Meanwhile, their spatiotemporal changes and differences between different types of cultivated land were explored. The research data were chosen from 449 relevant literature data collected by CNKI and Web of Science from 2005 to 2021, and the Meta-analysis used a weighted method based on "sampling numbers", "study area", and "standard deviation". The results showed that the national average values of the eight heavy metal elements in Chinese farmland soil were ω(As)11.00 mg·kg-1, ω(Cd)0.350 2 mg·kg-1, ω(Cr)62.91 mg·kg-1, ω(Cu)28.87 mg·kg-1, ω(Hg)0.135 1 mg·kg-1, ω(Ni)28.91 mg·kg-1, ω(Pb)34.67 mg·kg-1,and ω(Zn)90.24 mg·kg-1. Compared with their background values, all elements except As accumulated to some extent, and Cd and Hg accumulated the most, exceeding their background values by 177.9% and 340.3%, respectively. The research results indicated that Cd and Hg were the main pollution elements in farmland soil in China, and their accumulation was mainly influenced by human activities. In terms of their temporal and spatial changes, the Yunnan-Guizhou Plateau and the eastern coast were the most concentrated areas of pollution cases, and the pollution center shifted from the middle reaches of the Yangtze River to the southwest over time. The accumulation of heavy metals in farmland soil was affected by crop planting types, and the accumulation of heavy metals in vegetable and paddy soil was significantly greater than that in other cultivated land types.

[Health Risk Assessment of Heavy Metals in Soils of a City in Guangdong Province Based on Source Oriented and Monte Carlo Models].

Taking a city in Guangdong Province as the research area, the concentration and spatial distribution characteristics of heavy metals in the surface soil were studied to clarify the situation of soil heavy metal pollution and priority control factors, providing basic data for the prevention and control of soil heavy metal pollution in the city. The content characteristics of heavy metals in 221 soil samples in the city were analyzed, and the potential health risk assessment and source analysis were carried out through the Monte Carlo model, the potential health risk assessment (HRA) model, and the PMF receptor model. It was found that heavy metals ω(As), ω(Hg), ω(Cd), ω(Pb), ω(Cr), ω(Cu), ω(Ni), and ω(Zn) in the soil of the city were 18.16, 0.43, 1.46, 68.57, 98.34, 64.19, 26.53, and 257.32 mg·kg-1, respectively, with a moderate to high degree of variation. Except for Ni concentration, the soil concentrations of other heavy metal elements exceeded the background values of soil in Guangdong Province to a certain extent, and the concentrations of Cd and Zn exceeded the national secondary standards, resulting in severe heavy metal pollution; the main sources of heavy metals were industrial sources, and natural parent materials, lead battery manufacturing, transportation, artificial cultivation, and pesticide and fertilizer inputs also had an undeniable impact on the accumulation of heavy metals in the soil. Heavy metals in the soil had a certain degree of tolerable carcinogenic health risk for both children and adults, whereas non-carcinogenic risks could be ignored. The potential health risk of children was greater than that of adults, and the main exposure route was through oral intake. The input sources of pesticides and fertilizers and As should be the main controlling factors for the health risks of heavy metals in the city's soil, followed by mixed sources and Cr. There were differences in the spatial distribution characteristics and relative pollution levels of heavy metals, and it is necessary to deepen zoning monitoring and control, strengthen soil pollution prevention and control, and reduce human input of heavy metals in soil.

[Effects of Vermicomposting on Compost Quality and Heavy Metals：A Meta-analysis].

In order to comprehensively evaluate the effects of vermicomposting on compost quality and the conversion of heavy metals under different control conditions, 109 studies were reviewed. The effects of earthworm species, pre-compost time, ventilation methods, initial C/N, initial pH, and initial moisture of the raw materials on compost quality and the heavy metal toxicity were quantitatively discussed during the vermicomposting process through Meta-analysis. The results showed that the six subgroups of factors all showed obvious influences on the compost quality and heavy metal toxicity. After vermicomposting, the contents of NO3--N (116.2%), TN (29.1%), TP (31.2%), and TK (15.0%) were significantly increased, whereas NH4+-N (-14.8%) and C/N (-36.3%) were significantly decreased. Meanwhile, the total amount of Cu and Cr of the final compost and their bioavailability were significantly reduced. Considering the influences of grouping factors on compost quality and heavy metals, it is recommended to adjust the initial moisture of pile materials to 70%-80%, C/N to 30-85, and pH to 6-7 and to conduct pre-composting for 0-15 d; additionally, vermicomposting should be naturally placed when the composting is aimed at promoting the compost quality. If the main purpose is to weaken the perniciousness of heavy metals in the raw material, it is recommended to adjust the initial moisture of the material to 50%-60%, C/N to less than 30, and pH to 7-8; to conduct no pre-compost; regularly turn the piles; and use the earthworm Eudrilus eugeniae for vermicomposting.

Growth-dependent cr(VI) reduction by Alteromonas sp. ORB2 under haloalkaline conditions: toxicity, removal mechanism and effect of heavy metals.

Bacterial reduction of hexavalent chromium (VI) to chromium (III) is a sustainable bioremediation approach. However, the Cr(VI) containing wastewaters are often characterized with complex conditions such as high salt, alkaline pH and heavy metals which severely impact the growth and Cr(VI) reduction potential of microorganisms. This study investigated Cr(VI) reduction under complex haloalkaline conditions by an Alteromonas sp. ORB2 isolated from aerobic granular sludge cultivated from the seawater-microbiome. Optimum growth of Alteromonas sp. ORB2 was observed under haloalkaline conditions at 3.5-9.5% NaCl and pH 7-11. The bacterial growth in normal culture conditions (3.5% NaCl; pH 7.6) was not inhibited by 100 mg/l Cr(VI)/ As(V)/ Pb(II), 50 mg/l Cu(II) or 5 mg/l Cd(II). Near complete reduction of 100 mg/l Cr(VI) was achieved within 24 h at 3.5-7.5% NaCl and pH 8-11. Cr(VI) reduction by Alteromonas sp. ORB2 was not inhibited by 100 mg/L As(V), 100 mg/L Pb(II), 50 mg/L Cu(II) or 5 mg/L Cd(II). The bacterial cells grew in the medium with 100 mg/l Cr(VI) contained lower esterase activity and higher reactive oxygen species levels indicating toxicity and oxidative stress. In-spite of toxicity, the cells grew and reduced 100 mg/l Cr(VI) completely within 24 h. Cr(VI) removal from the medium was driven by bacterial reduction to Cr(III) which remained in the complex medium. Cr(VI) reduction was strongly linked to aerobic growth of Alteromonas sp. The Cr(VI) reductase activity of cytosolic protein fraction was pronounced by supplementing with NADPH in vitro assays. This study demonstrated a growth-dependent aerobic Cr(VI) reduction by Alteromonas sp. ORB2 under complex haloalkaline conditions akin to wastewaters.

Evaluation of soil pollution by heavy metal using index calculations and multivariate statistical analysis.

This study aims to assess the extent of heavy metals (HMs) pollution in soil and identify its potential sources using single and integrated pollution index calculations, and multivariate statistical analysis. The HM concentrations of soil samples were analyzed using ICP-MS. The concentrations (mg/kg) of arsenic (As) ranged from 2.8 to 208.1, cadmium (Cd) from 0.1 to 0.3, cobalt (Co) from 1.9 to 20.5, copper (Cu) from 3.7 to 17.7, nickel (Ni) from 14.7 to 110.6, and lead (Pb) from 6.7 to 37.3. High levels of As contents and physicochemical parameters were found in the northeastern parts of the study area, while levels of other HMs were high in the remaining parts. The HM contents of some soil samples exceeded the average values of basalt and limestone in the study area, as well as the upper, bulk, and lower continental crusts, shale, and soil (worldwide). Multiple index methods were used to assess the pollution risk, and it was determined that some soil samples were moderately to considerably contaminated with varying levels of As, Cd, Co, Ni, and Pb. Multivariate statistical analyses provided that the source of HMs contamination in the soil was a result of geogenic and/or anthropogenic activities. Geogenic sources were associated with weathering rock units, while anthropogenic sources were linked to industrial activities, traffic emissions, and agricultural applications. The findings are useful for detecting contamination by HMs in soil, and they could contribute to future monitoring programs to prevent soil contamination and protect the health of living organisms.

Mitigating heavy metal accumulation in tobacco: Strategies, mechanisms, and global initiatives.

The threat of heavy metal (HM) pollution looms large over plant growth and human health, with tobacco emerging as a highly vulnerable plant due to its exceptional absorption capacity. The widespread cultivation of tobacco intensifies these concerns, posing increased risks to human health as HMs become more pervasive in tobacco-growing soils globally. The absorption of these metals not only impedes tobacco growth and quality but also amplifies health hazards through smoking. Implementing proactive strategies to minimize HM absorption in tobacco is of paramount importance. Various approaches, encompassing chemical immobilization, transgenic modification, agronomic adjustments, and microbial interventions, have proven effective in curbing HM accumulation and mitigating associated adverse effects. However, a comprehensive review elucidating these control strategies and their mechanisms remains notably absent. This paper seeks to fill this void by examining the deleterious effects of HM exposure on tobacco plants and human health through tobacco consumption. Additionally, it provides a thorough exploration of the mechanisms responsible for reducing HM content in tobacco. The review consolidates and synthesizes recent domestic and international initiatives aimed at mitigating HM content in tobacco, delivering a comprehensive overview of their current status, benefits, and limitations.

Occurrence, distribution, and ecological risk assessment of heavy metals in Chao Phraya River, Thailand.

Understanding heavy metals in rivers is crucial, as their presence and distribution impact water quality, ecosystem health, and human well-being. This study examined the presence and levels of nine heavy metals (Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) in 16 surface water samples along the Chao Phraya River, identifying Fe, Mn, Zn, and Cr as predominant metals. Although average concentrations in both rainy and dry seasons generally adhered to WHO guidelines, Mn exceeded these limits yet remained within Thailand's acceptable standards. Seasonal variations were observed in the Chao Phraya River, and Spearman's correlation coefficient analysis established significant associations between season and concentrations of heavy metals. The water quality index (WQI) demonstrated varied water quality statuses at each sampling point along the Chao Phraya River, indicating poor conditions during the rainy season, further deteriorating to very poor conditions in the dry season. The hazard potential index (HPI) was employed to assess heavy metal contamination, revealing that during the dry season in the estuary area, the HPI value exceeded the critical threshold index, indicating the presence of heavy metal pollution in the water and unsuitable for consumption. Using the species sensitivity distribution model, an ecological risk assessment ranked the heavy metals' HC5 values as Pb > Zn > Cr > Cu > Hg > Cd > Ni, identifying nickel as the most detrimental and lead as the least toxic. Despite Cr and Zn showing a moderate risk, and Cu and Ni posing a high risk to aquatic organisms, the main contributors to ecological risk were identified as Cu, Ni, and Zn, suggesting a significant potential ecological risk in the Chao Phraya River's surface water. The results of this study provide fundamental insights that can direct future actions in preventing and managing heavy metal pollution in the river ecosystem.

The role of microbial partners in heavy metal metabolism in plants: a review.

Heavy metal pollution threatens plant growth and development as well as ecological stability. Here, we synthesize current research on the interplay between plants and their microbial symbionts under heavy metal stress, highlighting the mechanisms employed by microbes to enhance plant tolerance and resilience. Several key strategies such as bioavailability alteration, chelation, detoxification, induced systemic tolerance, horizontal gene transfer, and methylation and demethylation, are examined, alongside the genetic and molecular basis governing these plant-microbe interactions. However, the complexity of plant-microbe interactions, coupled with our limited understanding of the associated mechanisms, presents challenges in their practical application. Thus, this review underscores the necessity of a more detailed understanding of how plants and microbes interact and the importance of using a combined approach from different scientific fields to maximize the benefits of these microbial processes. By advancing our knowledge of plant-microbe synergies in the metabolism of heavy metals, we can develop more effective bioremediation strategies to combat the contamination of soil by heavy metals.

Emission characteristics of condensable particulate matter during the production of solid waste-based sulfoaluminate cement: Compositions, heavy metals, and preparation impacts.

Recycling solid waste for preparing sulfoaluminate cementitious materials (SACM) represents a promising approach for low-carbon development. There are drastic physical-chemical reactions during SACM calcination. However, there is a lack of research on the flue gas pollutants emissions from this process. Condensable particulate matter (CPM) has been found to constitute the majority of the primary PM emitted from various fuel combustion. In this study, the emission characteristics of CPM during the calcination of SACM were determined using tests in both a real-operated kiln and laboratory experiments. The mass concentration of CPM reached 96.6 mg/Nm3 and occupied 87% of total PM emission from the SACM kiln. Additionally, the mass proportion of SO42- in the CPM reached 93.8%, thus indicating that large quantities of sulfuric acid mist or SO3 were emitted. CaSO4 was one key component for the formation of main mineral ye'elimite (3CaO·3Al2O3·CaSO4), and its decomposition probably led to the high SO42- emission. Furthermore, the use of CaSO4 as a calcium source led to SO42- emission factor much higher than conventional calcium sources. Higher calcination temperature and more residence time also increased SO42- emission. The most abundant heavy metal in kiln flue gas and CPM was Zn. However, the total condensation ratio of heavy metals detected was only 40.5%. CPM particles with diameters below 2.5 µm and 4-20 µm were both clearly observed, and components such as Na2SO4 and NaCl were conformed. This work contributes to the understanding of CPM emissions and the establishment of pollutant reduction strategies for waste collaborative disposal in cement industry.

Electrochemical processes for the treatment of contaminant-rich wastewater: A comprehensive review.

Global water demand and environmental concerns related to climate change require industries to develop high-efficiency wastewater treatment methods to remove pollutants. Likewise, toxic pollutants present in wastewater negatively affect the environment and human health, requiring effective treatment. Although conventional treatment processes remove carbon and nutrients, they are insufficient to remove pharmaceuticals, pesticides, and plasticizers. Electrochemical processes effectively remove pollutants from wastewater through the mineralization of non-biodegradable pollutants with consequent conversion into biodegradable compounds. Its advantages include easy operation, versatility, and short reaction time. In this way, this review initially provides a global water scenario with a view to the future. It comprises global demand, treatment methods, and pollution of water resources, addressing various contaminants such as heavy metals, nutrients, organic compounds, and emerging contaminants. Subsequently, the fundamentals of electrochemical treatments are presented as well as electrochemical treatments, highlighting the latest studies involving electrocoagulation, electroflocculation, electroflotation, capacitive deionization and its derivatives, eletrodeionization, and electrochemical advanced oxidation process. Finally, the challenges and perspectives were discussed. In this context, electrochemical processes have proven promising and effective for the treatment of water and wastewater, allowing safe reuse practices and purification with high contaminant removal.

Spatiotemporal variations, health risk assessment, and sources of potentially toxic elements in potamic water of the Anday Stream Basin (Türkiye), Black Sea Region.

Monitoring and protecting freshwater habitats are paramount for a sustainable water management perspective. This study investigated potentially toxic elements (PTEs) in the potamic water of the Anday Stream Basin (Türkiye), Black Sea Region, for a hydrological year (from May 2020 to April 2021). Among PTEs, the highest average values were recorded for sodium (Na) at 41.3 mg/L and the lowest for mercury (Hg) at 0.009 µg/L and noted under quality guidelines. The stream was found to be at the level of "Low Heavy Metal Pollution" and "Low Contamination" based on the ecotoxicological risk indices. The highest calculated hazard quotient (HQ) value of 1.21E-02 for Cd was noted in the children via the dermal pathway and the lowest of 6.91E-06 for Fe in adults via the ingestion pathway. Results revealed a higher hazard index (HI) value of 1.50E-02 for Cd to children and the lowest of 1.98E-05 for Fe to adults. As a result of applying agricultural risk indices, the stream showed sodium adsorption ratio values less than 6 and was found to be "Excellent" for agriculture. However, the sodium percentage values were less than 20 and found "Permissible" and the magnesium hazard > 50 and noted as "Unsuitable" for agriculture. Statistical analysis revealed that natural factors mainly attributed to PTE contamination of the Anday Stream Basin.

Health risk assessment of heavy metals in some vegetables-Erbil City-Kurdistan Region of Iraq.

Heavy metals can have significant impacts on human health due to their toxicity and potential to accumulate in the body over time. Some heavy metals, such as lead, cadmium, mercury, and arsenic, are particularly harmful even at low concentrations. The estimation of hazards of vegetable intake to human health as well as explore the of heavy metals accumulation in different vegetables (cucumbers, tomato, eggplant, and bell peppers) collected in Erbil city from different source locally and imported from nearby country are conducted. The heavy metals concentration (cooper, zinc, lead and cadmium) was measured and analyzed by inductively coupled plasma-optical emission spectrophotometry. The maximum concentration of Pb was 27.95 mg/kg and the minimum was 6.49 mg/kg; for Cd, the concentration was 1.43 and 0.99 mg/kg, 74.94 and 5.14 mg/kg for Zn; and for Cu, the result was 56.25 and 8.2 mg/kg for the maximum and minimum, which they are within limits described by Food Agricultural Organization, but more than health limits and health risks calculated by mean of hazard quotient (HQ) techniques for Cu and Pb which they are more than 1. The local sample that collected in Erbil city show less concentration of heavy metals and low HQ in comparison with imported samples. The carcinogenic risk study shows elevated risk of accumulative consuming of edible part of those plant which they exceed the permissible limit that is 10-6.

Change in water quality in an Amazonian microbasin: ecological and human health implications.

The decline in the quality of water resources in the Amazon is very rapid in cities suffering from unplanned urban growth. The region has two defined seasons, winter (wet) and summer (dry), which directly affect the behavior of contaminants in aquatic ecosystems. The aim of this study was to assess the ecological and human health risks associated with the use of the watershed. In addition, an ecological index was proposed: the Quality Index for Aquatic Life, for the risk of contaminants to aquatic life. Sampling was carried out at six points in the Juá watershed. Physicochemical parameters, major anions, metals and total phosphorus were analyzed at both stations between 2020 and 2021. The highest concentrations of contaminants were found in the rainy season, due to the washing away of the banks. In this sense, Cl presented a concentration more than 307 times higher than that permitted by Brazilian legislation (wet). The ecological index showed that the watershed has a high risk of metals such as Cr III and Cr VI for the biota. The human health risk analysis showed a low risk; however, the lack of basic sanitation in the city indicates that monitoring of urban water resources is necessary.

The impact of recycling polyaluminium chloride and anionic polyacrylamide water treatment residuals on heavy metal adsorption in soils: implications for stormwater bioretention systems.

Despite the high adsorption capacity of polyaluminum chloride and anionic polyacrylamide water treatment residuals (PAC-APAM WTRs) for Pb2+, Cd2+, Cu2+, and Zn2+, their influence on the adsorption behavior of heavy metals in traditional bioretention soil media remains unclear. This study investigated the impact of PAC-APAM WTRs at a 20% weight ratio on the adsorption removal of Pb2+, Cd2+, Cu2+, and Zn2+ in three types of soils. The results demonstrated improved heavy metal adsorption in the presence of PAC-APAM WTRs, with enhanced removal observed at higher pH levels and temperatures. The addition of PAC-APAM WTRs augmented the maximum adsorption capacity for Pb2+ (from 0.98 to 3.98%), Cd2+ (from 0.52 to 10.99%), Cu2+ (from 3.69 to 36.79%), and Zn2+ (from 2.63 to 13.46%). The Langmuir model better described the data in soils with and without PAC-APAM WTRs. The pseudo-second-order model more accurately described the adsorption process, revealing an irreversible chemical process, although qe demonstrated improvement with the addition of PAC-APAM WTRs. This study affirms the potential of PAC-APAM WTRs as an amendment for mitigating heavy metal pollution in stormwater bioretention systems. Further exploration of the engineering application of PAC-APAM WTRs, particularly in field conditions for the removal of dissolved heavy metals, is recommended.

Extraction of heavy metals from copper tailings by ryegrass (Lolium perenne L.) with the assistance of degradable chelating agents.

Heavy metal contamination is an urgent ecological governance problem in mining areas. In order to seek for a green and environmentally friendly reagent with better plant restoration effect to solve the problem of low efficiency in plant restoration in heavy metal pollution soil. In this study, we evaluated the effects of three biodegradable chelating agents, namely citric acid (CA), fulvic acid (FA) and polyaspartic acid (PASP), on the physicochemical properties of copper tailings, growth of ryegrass (Lolium perenne L.) and heavy metal accumulation therein. The results showed that the chelating agent application improved the physicochemical properties of copper tailings, increased the biomass of ryegrass and enriched more Cu and Cd in copper tailings. In the control group, the main existing forms of Cu and Cd were oxidizable state, followed by residual, weak acid soluble and reducible states. After the CA, FA or PASP application, Cu and Cd were converted from the residual and oxidizable states to the reducible and weak acid soluble states, whose bioavailability in copper tailings were thus enhanced. Besides, the chelating agent incorporation improved the Cu and Cd extraction efficiencies of ryegrass from copper tailings, as manifested by increased root and stem contents of Cu and Cd by 30.29-103.42%, 11.43-74.29%, 2.98-110.98% and 11.11-111.11%, respectively, in comparison with the control group. In the presence of multiple heavy metals, CA, FA or PASP showed selectivity regarding the ryegrass extraction of heavy metals from copper tailings. PCA analysis revealed that the CA-4 and PASP-7 treatment had great remediation potentials against Cu and Cd in copper tailings, respectively, as manifested by increases in Cu and Cd contents in ryegrass by 90.98% and 74.29% compared to the CK group.

Heavy metal association with chronic kidney disease of unknown cause in central India-results from a case-control study.

BACKGROUND: Chronic Kidney Disease of unknown cause (CKDu) a disease of exclusion, and remains unexplained in various parts of the world, including India. Previous studies have reported mixed findings about the role of heavy metals or agrochemicals in CKDu. These studies compared CKDu with healthy controls but lacked subjects with CKD as controls. The purpose of this study was to test the hypothesis whether heavy metals, i.e. Arsenic (As), Cadmium (Cd), Lead (Pb), and Chromium (Cr) are associated with CKDu, in central India. METHODS: The study was conducted in a case-control manner at a tertiary care hospital. CKDu cases (n = 60) were compared with CKD (n = 62) and healthy subjects (n = 54). Blood and urine levels of As, Cd, Pb, and Cr were measured by Inductively Coupled Plasma- Optical Emission Spectrometry. Pesticide use, painkillers, smoking, and alcohol addiction were also evaluated. The median blood and urine metal levels were compared among the groups by the Kruskal-Wallis rank sum test. RESULTS: CKDu had significantly higher pesticide and surface water usage as a source of drinking water. Blood As levels (median, IQR) were significantly higher in CKDu 91.97 (1.3-132.7) µg/L compared to CKD 4.5 (0.0-58.8) µg/L and healthy subjects 39.01 (4.8-67.4) µg/L (p < 0.001) On multinominal regression age and sex adjusted blood As was independently associated with CKDu[ OR 1.013 (95%CI 1.003-1.024) P < .05].Blood and urinary Cd, Pb, and Cr were higher in CKD compared to CKDu (p > .05). Urinary Cd, Pb and Cr were undetectable in healthy subjects and were significantly higher in CKDu and CKD compared to healthy subjects (P = < 0.001). There was a significant correlation of Cd, Pb and Cr in blood and urine with each other in CKDu and CKD subjects as compared to healthy subjects. Surface water use also associated with CKDu [OR 3.178 (95%CI 1.029-9.818) p < .05). CONCLUSION: The study showed an independent association of age and sex adjusted blood As with CKDu in this Indian cohort. Subjects with renal dysfunction (CKDu and CKD) were found to have significantly higher metal burden of Pb, Cd, As, and Cr as compared to healthy controls. CKDu subjects had significantly higher pesticide and surface water usage, which may be the source of differential As exposure in these subjects.

Effects of cadmium and zinc interactions on the physiological biochemistry and enrichment characteristics of Iris pseudacorus.

Compound pollution with cadmium (Cd) and zinc (Zn) is common in nature. The effects of compounded Cd and Zn on the growth and development of Iris pseudacorus in the environment and the plant's potential to remediate heavy metals in the environment remain unclear. In this study, the effects of single and combined Cd and Zn stress on I. pseudacorus growth and the enrichment of heavy metals in I. pseudacorus seedlings were investigated. The results showed that under Cd (160 µM) and Zn (800 µM) stress, plant growth was significantly inhibited and photosynthetic performance was affected. Cd+Zn200 (160 µM + 200 µM) reduced the levels of malondialdehyde, hydrogen peroxide, and non-protein thiols by 31.29%, 53.20%, and 13.29%, respectively, in the aboveground tissues compared with levels in the single Cd treatment. However, Cd+Zn800 (160 µM + 800 µM) had no effect. Cd and Zn800 inhibited the absorption of mineral elements, while Zn200 had little effect on plants. Compared with that for Cd treatment alone, Cd + Zn200 and Cd+Zn800 reduced the Cd content in aboveground tissues by 54.15% and 49.92%, respectively, but had no significant effect on Cd in the root system. Zn significantly reduced the Cd content in subcellular components and limited the content and proportion of Cd extracted using water and ethanol. These results suggest that a low supply of Zn reduces Cd accumulation in aboveground tissues by promoting antioxidant substances and heavy metal chelating agents, thus protecting the photosynthetic systems. The addition of Zn also reduced the mobility and bioavailability of Cd to alleviate its toxicity in I. pseudacorus.