Nickel Pollution Research Articles

Oral supplementation of curcumin-encapsulated chitosan nanoconjugates as an innovative strategy for mitigating nickel-mediated hepatorenal toxicity in rats.

Nickel pollution adversely affects human health and causes various disorders, mainly hepatic and renal dysfunction. The present work focused on a comparative evaluation of the pure form of curcumin (CU) with curcumin-encapsulated chitosan nanoconjugates (CS/CU NCs), on mitigation of the delirious effects of Ni on hepatorenal tissue. Forty-two male rats were allocated into 6 groups (n = 7 for each) as follows: (1) control, (2) CU, (3) CS/CU NCs, (4) Ni, (5) Ni + CU, (6) Ni + CS/CU NCs. After 30days, blood and tissue (liver and kidneys) were collected to measure hepatorenal biomarkers, oxidant/antioxidant balance, inflammatory gene expression, liver and kidney histopathology, and immunohistochemistry. Results revealed disruption of hepatorenal functions, oxidative stress, and inflammatory markers at biochemical and molecular levels associated with severe hepatorenal histopathological alterations and abnormal immunohistochemical tissue expression for caspase-3 and cyclooxygenase-2. On the contrary, the treatment of Ni-intoxicated rats with CS/CU NCs markedly mitigated the adverse effect of Ni on hepatorenal tissue via regulation of oxidative stress, inflammatory, and apoptotic markers. The present study provides a novel nanoformulation for curcumin using CS NPs encapsulation that selectively targets the injured cells and improves the beneficial effect of CU via enhancing the antioxidant activity and regulating both inflammatory and apoptotic markers.

Transcriptome response in a marine copepod under multigenerational exposure to ocean warming and Ni at an environmentally realistic concentration.

Due to anthropogenic activities, coastal areas have been challenged with multi-stresses such as ocean warming and nickel (Ni) pollution. Currently, studies have concerned the combined effects of Ni and warming in marine organisms at the phenotypic level; however, the underlying molecular mechanisms are poorly known. In this study, a marine copepod Tigriopus japonicus was maintained under warming (+ 4℃) and an environmentally realistic level of Ni (20 μg/L) alone or combined for three generations (F0-F2). Transcriptome analysis was performed for the F2 individuals. We found that the gene transcripts of copepods were predominantly down-regulated after Ni and warming exposure. Based on the results of GO and KEGG analysis, chitin metabolism, detoxification, antioxidant, apoptosis, and energy metabolism were screened in this study. Among the above functions, the combined exposure enriched more differential expression genes and had a larger fold change compared to Ni exposure alone, suggesting that warming increased the negative effect of Ni on marine copepods from a molecular perspective. Specifically, the combined exposure exacerbated the down-regulation of defense, apoptosis, xenobiotic efflux, GSH system, and energy metabolism, as well as the up-regulation of detoxification and peroxidase system. Overall, this study indicates that both ocean warming and Ni pollution adversely affect the marine copepod T. japonicus from multigenerational transcriptome analysis, especially warming increased Ni toxicity to marine copepods, and our results also provide references to the mechanism concerning the effects of Ni and warming on marine copepods.

Spatial Distribution, Risk Assessment and Source Analysis of Heavy Metals in the Sediments of Jinmucuo Lake, Southern Tibetan Plateau

Sediments serve as a crucial accumulation site for pollutants, and the source and sink effects of sediment pollutants significantly influence the overlying water. In this research, the concentrations of heavy metals in the sediments of Jinmucuo Lake were investigated. The pollution levels and ecological risks of the heavy metals were assessed via the geoaccumulation index and potential ecological risk index, and the potential sources were identified via multivariate statistical methods. Results revealed that the mean concentrations of cadmium, chromium, copper, zinc, nickel, arsenic and mercury exceeded the soil background values in Tibet, and each element generally tended to increase with decreasing depth in the sediment cores. Heavy metals were mainly distributed in the estuaries of the western part of the lake. Moreover, the geoaccumulation index revealed that mercury pollution was severe, followed by nickel and copper. The potential ecological risk index revealed that Jinmucuo Lake was a highly strong ecological risk and that mercury was the most important ecological risk factor. Multivariate statistical analysis indicated that chromium and nickel pollution was influenced by natural factors and anthropogenic activities, while geothermal activity, river inputs and atmospheric transmission were the main sources of mercury and arsenic. Moreover, cadmium, lead, copper and zinc pollution was mainly affected by transportation and high background values. The results provide an important reference for the ecological and environmental protection of Jinmucuo Lake.

Microbiologically modified bioorganic fertilizer and metal-tolerant Bacillus sp. MN54 regulate the nutrient homeostasis and boost phytoextraction efficiency of mustard (Brassica juncea L.) in nickel-contaminated soil

Nickel (Ni) pollution in soil is a major environmental challenge to global food security necessitating its effective remediation. In this regard using plant growth promoting rhizobacteria (PGPR) and bioorganic fertilizers (BOF) to increase the effectiveness of Ni phytoextraction together with hyper-accumulator plants is an effective strategy. Thus, the aim of this study was to assess how BOF, alone or in combination with Bacillus sp. MN54 (herein after referred to as BS), promotes the growth and detoxifies Ni in Brassica juncea L. under both non-contaminated and Ni-contaminated soil conditions. The experimental design included both non-spiked and Ni-spiked soils (with two Ni concentrations: 50 and 100 mg kg−1), with the addition of BS and BOF at two different application rates (1% and 2%). Results showed that Ni negatively affected the growth attributes and yield of Brassica juncea but the integrated incorporation of BOF and BS significantly improved plant growth and physiological attributes. However, Ni stress increased antioxidant enzyme activities and triggered the production of reactive oxygen species in the plants. Likewise, the highest increases in Ni bioconcentration factor (19.9%, 72.83%, and 74.2%), Ni bioaccumulation concentration (30.6%, 327.4%, and 366.8%), and Ni translocation factor (22.2%, 82%, and 69%) were observed in soils supplemented with 2% BOF and BS under non-contaminated, 50 mg kg−1, and 100 mg kg−1 Ni-stressed conditions, respectively. The enhanced plant growth with BS and BOF under Ni stress suggested that both could efficiently promote Ni phytoextraction and simultaneously improve soil health in Ni-contaminated soil. This highlighted their potential as sustainable soil amendments for remediating Ni-contaminated soils, promoting resilient plant growth and supporting long-term ecosystem recovery.

Impact of Mining of Marine Gastropods Habitat: Basis for Information Education Communication(IEC) for Environmental Sustainability

An alarming socio-economic and environmental impact of mining in the Municipality of Carrascal, Surigao del Sur led to this study. It is important to assess the impact of mining on marine habitats and the diversity of gastropods in the area. The collection of gastropods is done in the selected four sampling areas, which include Brgy. Adlay, Brgy. Caglayag, Brgy. Dahican, and Brgy. Gango. Based on the sampling, 228 marine gastropod species were collected, consisting of 53 genera belonging to 10 families. The findings highlight the low diversity of the marine gastropods in the study area as the diversity index is less than 1.99. In addition, the physico-chemical parameter assessment of the study area reveals conditions ranging from slightly alkaline water with low oxygen content to very warm temperatures. These conditions suggest a delicate balance in the aquatic ecosystems, which could be sensitive to changes and affect marine gastropod populations and distributions. With regards to the average concentration of nickel (mg/kg) sediments as a result of the mining activities in the study area, the atomic absorption spectrophotometry result shows that Brgy. Gango is heavily polluted in comparison to other sampling areas. Additionally, the multiple regression analysis reveals that there is a positive and significant association between the nickel concentration and the diversity of gastropods in Brgy. Gango. This could indicate that some gastropod species, specifically those that are found in areas with high nickel concentrations, have acquired tolerance to nickel pollution. However, the regression analysis reveals that in the other sampling sites, such as Brgy. Adlay and Brgy. Caglayag, the presence of nickel sediments as a result of mining activities has a negative and significant impact on the marine habitat and diversity of gastropods. The findings suggest the importance of developing an information education and communication program addressing the negative impacts of mining and promoting environmental sustainability in the research locale.

RhoGDIβ inhibition via miR-200c/AUF1/SOX2/miR-137 axis contributed to lncRNA MEG3 downregulation-mediated malignant transformation of human bronchial epithelial cells.

Nickel pollution is a recognized factor contributing to lung cancer. Understanding the molecular mechanisms of its carcinogenic effects is crucial for lung cancer prevention and treatment. Our previous research identified the downregulation of a long noncoding RNA, maternally expressed gene 3 (MEG3), as a key factor in transforming human bronchial epithelial cells (HBECs) into malignant cells following nickel exposure. In our study, we found that deletion of MEG3 also reduced the expression of RhoGDIβ. Notably, artificially increasing RhoGDIβ levels counteracted the malignant transformation caused by MEG3 deletion in HBECs. This indicates that the reduction in RhoGDIβ contributes to the transformation of HBECs due to MEG3 deletion. Further exploration revealed that MEG3 downregulation led to enhanced c-Jun activity, which in turn promoted miR-200c transcription. High levels of miR-200c subsequently increased the translation of AUF1 protein, stabilizing SOX2 messenger RNA (mRNA). This stabilization affected the regulation of miR-137, SP-1 protein translation, and the suppression of RhoGDIβ mRNA transcription and protein expression, leading to cell transformation. Our study underscores the co-regulation of RhoGDIβ expression by long noncoding RNAMEG3, multiple microRNAs (miR-200c and miR-137), and RNA-regulated transcription factors (c-Jun, SOX2, and SP1). This intricate network of molecular events sheds light on the nature of lung tumorigenesis. These novel findings pave the way for developing targeted strategies for the prevention and treatment of human lung cancer based on the MEG3/RhoGDIβ pathway.

Optical detection strategies for Ni(II) ion using metal-organic chemosensors: from molecular design to environmental applications.

Nickel is an important element utilized in various industrial/metallurgical processes, such as surgical and dental prostheses, Ni-Cd batteries, paint pigments, electroplating, ceramics, computer magnetic tapes, catalysis, and alloy manufacturing. However, its extensive use and associated waste production have led to increased nickel pollution in soils and water bodies, which adversely affects human health, animals and plants. This issue has prompted researchers to develop various optical probes, hereafter luminescent/colorimetric sensors, for the facile, sensitive and selective detection of nickel, particularly in biological and environmental contexts. In recent years, numerous functionalized chemosensors have been reported for imaging Ni2+, both in vivo and in vitro. In this context, metal-based receptors offer clear advantages over conventional organic sensors (viz., organic ligands, polymers, and membranes) in terms of cost, durability, stability, water solubility, recyclability, chemical flexibility and scope. This review highlights recent advancements in the design and fabrication of hybrid receptors (i.e., metal complexes and MOFs) for the specific detection of Ni2+ ions in complex environmental and biological mixtures.

Heavy Metals in Urban Soils of the Volga Federal District: a Conjugate Analysis of Official Data

Based on a conjugated analysis of the official data of Roshydromet on the content of priority heavy metals (Cd, Pb, Zn, Cu, Ni) in the soils of 23 cities of the Volga Federal District, as well as Rosstat data on the socio-economic indicators of these settlements, the ecological and geochemical characteristics of urbanozems (Urbic Technosols) and with the help of multivariate statistical analyzes (cluster and factorial), possible relationships between soil pollution parameters and urban features of cities were revealed. For the soils of most cities in the region with average socioeconomic indicators, admissible levels of accumulation of Cd, Pb, Zn, and Cu have been established, which, in terms of concentrations, are close to the average abundance of urban soils in Russia. In small and medium-sized cities of the Republic of Bashkortostan, exceedances of APC Ni in soils are recorded, which reflects the presence of a regional geochemical anomaly of natural and anthropogenic nature in the eastern part of the Volga Federal District, but no correlations between nickel pollution and socio-economic indicators of settlements are revealed. The moderately hazardous level of complex pollution in urbanozems with dominant accumulation of Cd and significantly lower concentration ratios of other heavy metals (Belebey, Davlekanovo, Dzerzhinsk) shows no correlation with the demographic indicators of settlements. The more complex profile of soil pollution (Cd–Zn in Penza or Cu–Cd–Zn in Mednogorsk) shows lower values of the total fertility rate and higher values of the mortality rate (compared with the average regional indicators). In general, using the example of the cities of the Volga Federal District, it is shown that the gradients of increasing concentrations in soils of Cd, Pb, Zn, Cu and the total pollution index Zc are codirectional with an increase in the general mortality rate of the population.

Seawater warming intensifies nickel toxicity to a marine copepod: a multigenerational perspective

Due to human activities, marine organisms are frequently co-stressed with nickel (Ni) pollution and seawater warming; nevertheless, very scarce information is known about their interaction in marine biota under a multigenerational scenario. Here, after verifying the interaction of Ni and warming via a 48-h acute test, we conducted a multigenerational experiment (F0-F2), in which the marine copepod Tigriopus japonicus was exposed to Ni at environmentally realistic concentrations (0, 2, and 20 µg/L) under ambient (22℃) and predicted seawater warming (26℃) conditions. Ni accumulation and the important life history traits were analyzed for each generation. Results showed that Ni exposure caused Ni bioaccumulation and thus compromised the survivorship and egg production of T. japonicus. In particular, seawater warming significantly increased Ni accumulation, thus intensifying the negative effects of Ni on its survivorship and development. Overall, this study suggests that Ni multigenerational exposure even at environmentally realistic concentrations could produce a significant impact on marine copepod's health, and this impact would be intensified under the projected seawater warming, providing a mechanistic understanding of the interaction between warming and Ni pollution in marine organisms from a multigenerational perspective.

Copper, cadmium and nickel pollution inhibit growth and promote ascorbate catabolism in cell cultures of Arabidopsis thaliana and Zea mays

We established model systems for exploring the roles of symplastic and apoplastic ascorbate in heavy-metal-polluted dicot and monocot cells. Cell-suspension cultures of Arabidopsis and maize were treated with copper, cadmium or nickel; growth and ascorbate metabolism were measured. Growth was halved by ∼80 µM Cu2+, 90 µM Cd2+ or 1200 µM Ni2+ in Arabidopsis, and ∼90 µM Cu2+, 650 µM Cd2+ or 650 µM Ni2+ in maize. Cu2+ (128 µM) and Cd2+ (512 µM) caused partial loss of symplastic ascorbate, especially in Arabidopsis; Ni2+ (512 and 2048 µM) had moderate effects. Added apoplastic l-ascorbate (1 mM) was consumed by the cultures (half-life ∼23 and 44 min in Arabidopsis and maize, respectively), consumption rate being 3–6-fold increased by Cu2+, Cd2+ and Ni2+ in Arabidopsis, and by Cu2+ in maize; Cd2+ and Ni2+ had relatively little effect on apoplastic ascorbate consumption in maize. Radioactivity from exogenous 1 mM l-[1-14C]ascorbate remained extracellular; catabolites formed were dehydroascorbic acid, diketogulonate and oxalyl-threonates. In conclusion, suspension-cultured cells respond to heavy-metal stresses by maintaining symplastic ascorbate concentrations, which may beneficially scavenge symplastic reactive oxygen species (ROS). Apoplastic ascorbate is catabolised in metal-polluted cultures via several oxidative and non-oxidative reactions, the former potentially scavenging stress-related apoplastic ROS.

Improvement in growth and physiochemical attributes of Raphanus sativus L. through exogenous application of 28-Homobrassinolide under nickel stress

Nickel (Ni) pollution in agricultural areas is a global problem that has been steadily getting worse. Seed priming increases crop production and quality, which may be related to invoking stress memory in germinating seed under Ni stress. The objective of the current study was to comprehend the mechanism by which Raphanus sativus L. (radish) seeds primed with 28-homobrassinolide (28-HBL) could mitigate Ni stress. The R. sativus seeds primed with 0, 1, 5, and 10µmol L−1 concentrations of 28-HBL. The Ni stress caused oxidative damage in R. sativus seedlings by increased ROS biosynthesis which results in impaired morphological characteristics, photosynthetic content and gas exchange parameters. The Ni stress caused a significant decrease in protein (26%), phenolic (37%), total chlorophyll content (29%) and plant height (22%) as compared with control. Seedlings raised from 28- HBL primed seeds exhibited reduced Ni contents besides improved biosynthesis of proline content. Furthermore, 5µmol L−1 HBL enhanced shoot height (43%), no. of leaf (58%), and fresh biomass (38%) under Ni stress. Nevertheless, increased proline, DPPH activity and mineral uptake (Na, K, Mg and Zn) was obtained in 5 µmol L−1 HBL treated plants under control and Ni stress conditions. HBL2 primed seed enhanced metal tolerance index along with transpiration rate (28%), stomatal conductance (20%) and photosynthetic rate (9%) in Ni spiked soil. Briefly, the results of current study suggested that 28-HBL perhaps mitigates the deleterious effect of Ni stress and enhanced the growth of R. sativus.

Growth, Biomass and Nickel Accumulation Assessments of Amaranthus hybridus and Celosia argentea grown in Nickel Contaminated Soil

Agricultural lands used in the cultivation of vegetables are prone to contamination with heavy metals of different degrees, which could impact significantly the physiological performance of the plants, and amassing of these metals. This study was conducted at the botanical garden of the Department of Plant Biology, University of Ilorin, to appraise the effects of nickel contamination on identified growth parameters of Amaranthus hybridus and Celosia argentea, their biomass and nickel accumulated in the vegetables. The treatment comprised of varying concentrations of nickel (100, 200 and 400 mg/kg) used to pollute soil, while control soil were not contaminated. Growth parameters (stem length and girth, leaf length and breadth, number of leaves; and wet and dry weights) were evaluated. Elemental concentrations of nickel in both plants were determined using Atomic Absorption Spectrophotometer. Celosia argentea planted on soil polluted with 100 mg/kg of nickel recorded peak values for leaf length and breadth and number of leaves at 3 weeks after transplanting (WAT) (4.77 cm, 2.68 cm and 11.83) respectively. Amaranthus hybridus grown on untreated soil recorded the maximum stem length at 1, 2 and 3 WAT (3.50, 3.80 and 5.15 cm) respectively. Celosia argentea and Amaranthus hybridus grown on soil polluted with 200 and 100 mg/kg of nickel recorded the highest dry weights of 0.06 and 3.87 g respectively at 1 WAT. The highest values of nickel concentrations in Celosia argentea and Amaranthus hybridus were recorded in those planted in soil polluted with 200 mg/kg of nickel (3.90 and 3.87 mg/kg respectively). The study revealed that nickel pollution may promote the performance of Celosia argentea and Amaranthus hybridus when cultivated below the threshold of 200 mg/kg which has been established in this study to also enhance build up of nickel in the tissues of the botanicals.

Nickel in the Environment: Bioremediation Techniques for Soils with Low or Moderate Contamination in European Union

The review deals with the environmental problem caused by low or moderate nickel concentrations in soils. The main effects of this potentially toxic element on the soil biota and the most common crop species are addressed. Moreover, the paper emphasises biological remediation methods against nickel pollution in European soils. The focus is on the well-accepted phytoremediation strategy alone or in combination with other more or less innovative bioremediation approaches such as microbial bioremediation, vermiremediation and the use of amendments and sequestrants. Results acquired in real field and laboratory experiments to fight against nickel contamination are summarised and compared. The main objective was to evidence the ability of the above natural techniques to reduce the nickel concentration in contaminated sites at a not-risky level. In conclusion, the examined works agree that the efficiency of phytoremediation could be implemented with co-remediation approaches, but further studies with clear and comparable indices are strongly recommended to meet the challenges for future application at a large scale.

Nickel pollution pathways in small ecosystem, Egypt

Nickel has negative human health effects depending on dose and length of exposure; it is classified as a class 1 carcinogen. Nickel pollution threatens Saft Rashin village, Egypt. The area’s crops are highly contaminated with nickel, suggesting them as bioaccumulators. Nickel daily intake exceeds twofold the permissible limits. To fully understand the pollution process, Ni concentrations in every input/output were determined and have been normalized to grams per hectare per year (g ha−1 year−1). Geochemical mass balance (GMB) revealed that dustfall is the major Ni input (88.8%) followed by P-fertilizers (11.2% of the total inputs). Nickel in dust is mainly related to traffic emissions. On the other hand, plant uptake removes about 90% of the total nickel input. The remaining 10% accumulates in the soil with a retention rate of 44.7 g ha−1 year−1. Accordingly, using new diesel models that are more efficient and less polluting can reduce pollution levels; likewise, use eco-friendly fertilizers. Egyptian clover is recommended as a phytoremediator to remove Ni from growth media for its high efficiency and low planting cost.

Shells of Intertidal Mudflat Snails: A Promising Biomonitoring Materials of Nickel Pollution

Monitoring the level of metal pollution in a water body, especially in polluted areas, is crucial. Gastropod shells have been used as a biomonitor for metal pollution. The goal of this study was to evaluate the utilisation of the mudflat snails, Telescopium telescopium shells, as biomonitoring materials for nickel (Ni) pollution in the intertidal area. The snails and their habitat surface sediments were sampled from 17 sites in Peninsular Malaysia. Up to 21 individuals from each site were sampled and dissected. In addition to the shells, six parts of the soft tissues (cephalic tentacle, foot, gill, muscle, mantle, and remaining soft tissues) were analysed for Ni. The snail shell was found to be a potential biomonitoring material for Ni pollution based on four positive points: (i) higher value of shell/soft tissue ratios (> 1.00); (ii) categorisation as a ‘microconcentrator’ based on bioaccumulation factor; (iii) significant correlation coefficients (at least P < 0.05) and significant influential total Ni levels in the sediments to the shell Ni; and (iv) higher precision of Ni in the shells based on the lowest value of the coefficient of variation of Ni. The described results indicated that the shell of T. telescopium would be suitable for assessing Ni pollution in the intertidal areas.

Isolation and Characterization of Nickel-Tolerant Trichoderma Strains from Marine and Terrestrial Environments.

Nickel contamination is a serious environmental issue that requires immediate action. In this study, 23 strains of Trichoderma were isolated from terrestrial and marine environments and identified using a polyphasic approach of morphological characterization and ITS gene sequence analysis. The Trichoderma strains were tested for their tolerance and biosorption of nickel. Our results showed the growth of all Trichoderma strains on Trichoderma Selective Medium (TSM) with 50–1200-ppm nickel, indicating their tolerance of this heavy metal even at a relatively high concentration. Six Trichoderma strains (three isolated from terrestrial substrates and three from marine substates) had the highest radial growth on TSM with 50-ppm Ni. Among these fungal isolates, Trichoderma asperellum (S03) isolated from soil exhibited the best growth after 2 days of incubation. For the biosorption of nickel, the accumulation or uptake efficiency by the six selected Trichoderma was determined in Potato Dextrose Broth (PDB) supplemented with 50-ppm Ni using a Flame Atomic Absorption Spectrophotometer (AAS). The percent uptake efficiency of the three strains of T. asperellum (S03, S08, and LL14) was computed to be up to 66%, while Trichoderma virens (SG18 and SF22) and Trichoderma inhamatum (MW25) achieved up to 68% uptake efficiency. Observation of the Trichoderma strains with Scanning Electron Microscopy (SEM) before and after the absorption of nickel showed very minimal damage on the hyphal and conidial surface morphology, but changes in the colonial characteristics were observed. Our study highlighted the potential of terrestrial and marine strains of Trichoderma for the bioremediation of nickel pollution.

Potential of invasive alien top predator as a biomonitor of nickel deposition – the case of American mink in Iceland

American mink Neovison vison is one of the most harmful non-indigenous species in Iceland and has been proven to be a useful indirect bioindicator and biomonitor for numerous environmental pollutants. Therefore, the main objective of the study was to determine the total nickel concentration in the spleen of 35 females and 30 males obtained from Brokey archipelago and the south coast of Hvammsfjörður (Dalabyggð, Iceland) using graphite furnace atomic absorption spectroscopy. We also assessed the correlation between nickel concentration and selected anatomical and morphological parameters, hypothesising that invasive alien N. vison is a promising candidate species for biomonitoring the deposition of this trace element. The results indicated a substantial variation in nickel concentration in the spleen tissue of examined animals. For males, the maximum concentration exceeded the average level by more than 16 times, and for females by more than 7 times. The correlation coefficient between morphometric features and the level of nickel concentration in the spleen did not show a significant relationship in any of the tested combinations, for all tested animals or for each sex separately. In conclusion, American mink in Iceland can be considered a promising species for qualitative and quantitative assessment of ecosystems in terms of nickel pollution.

Spatial distribution and ecological assessment of nickel in sediments of a typical small plateau lake from Yunnan Province, China.

Nickel (Ni) in small plateau lake sediments plays an important role in influencing the quality of lake ecosystems with a high degree of endemism and toxicity. This paper focuses on the spatial distribution and ecological risks of nickel in the sediments of Jianhu Lake, a small plateau lake in China, and the influence of pH and total organic carbon (TOC) on nickel concentrations. The results showed that average total nickel concentrations were 138.99 ± 57.57 mg/kg (n = 38) and 184.31 ± 92.12 mg/kg (n = 60) in surface sediments (0-10 cm top layer) and sediment cores (0-75 cm depth), respectively, and that the residual fraction was the main form of nickel. Simultaneously, through a semivariogram model, strong spatial dependence among pH, TOC, and the oxidizable fraction was revealed, whereas total nickel, exchangeable and the weak acid soluble fraction, reducible fraction, and residual fraction showed moderate spatial dependence. The vertical distribution revealed that nickel accumulated mainly in the bottom 5 cm (70-75 cm) of the sediment layer and that the pH was higher there, whereas TOC was concentrated mainly in the top 5 cm of sediment. Using geoaccumulation and a potential ecological risk index, moderate nickel pollution and moderate risk levels were found in most surface sediments, but moderate nickel pollution and high risk levels were observed in most sediment cores. In addition, pH and TOC were found to have a strong effect on the distribution and concentration of nickel and its fractions in the small plateau lake. In summary, nickel posed a certain degree of pollution and ecological risk, which deserves attention in the sediments of small plateau lakes.

Remediation of agro-sod-podzolic soil contaminated with nickel

The results of many years field experiment on the remediation of agro-sod-podzolic loamy soil (albeluvisoils) contaminated with nickel are analyzed. Various doses of ameliorants and fertilizers were studied as ameliorative additives: limestone and phosphorite flour, superphosphate, sodium sulfide, peat and zeolite. Studies have shown that the introduction of all studied reclamation additives into contaminated soil significantly reduced the content of mobile forms of nickel in it. The highest efficiency during the entire observation period was shown by limestone flour at a dose of 12 t/ha; it reduced the degree of its mobility by 48-69%. Nickel pollution had a strong toxic effect on plants, which led to a sharp decrease in their productivity (by 76-87%) and increased accumulation of nickel in the grain. The introduction of the studied ameliorants and fertilizers significantly improved these indicators, but they still did not reach the control (without pollution), which indicates the presence of a very serious problem of crop production on land contaminated with nickel.

Calculation of the Soil Risk Control Value through a Hydrus-1D Model for Groundwater Protection

A combined Hydrus-1D and groundwater dilution model was employed to determine the risk control value and risk control volume of soil in correspondence of an electroplating workshop located in the Pearl River Delta. In particular, we considered the risk control value and risk control volume of soil in relation to characteristic chromium (Ⅵ) and nickel pollutants, which can affect the quality of groundwater. Based on the absorption of pollutants by the soil in the vadose zone, we obtained soil risk control values of 41.6 mg·kg-1 and 619.1 mg·kg-1 for chromium (Ⅵ) and nickel, respectively. These values were 10 and 45 times greater than those obtained from theoretical calculations (based on the soil/water partition equation combined with the groundwater dilution model), while the soil risk control volumes of chromium (Ⅵ) and nickel were 1804 m3 and 44590 m3, respectively. The soil risk control values calculated through the soil/water partition equation combined with the groundwater dilution model tend to be excessively conservative for the contaminated sites of the Pearl River Delta (characterized by a shallow buried depth of the underground water level and a close hydraulic connection); hence, it is necessary to carry out further hydrogeological surveys and fully consider the migration process of pollutants in the vadose zone. We conclude that the combined Hydrus-1D and groundwater dilution model for groundwater protection can be used to determine the soil risk control value, potentially saving the costs involved in later remediation and risk control.