Geo-Accumulation Indices of Heavy Metals in Soil and Groundwater of Kanpur, India Under Long Term Irrigation of Tannery Effluent

Contamination characteristics of heavy metals in a small-scale tanning area of southern China and their source analysis

Tanning industry has been identified as a significant source of heavy metals; however, heavy metals contamination in farmland soil due to small-scale tanning activities remains unstudied. Here, samples from topsoil, profile soil, water and sediments in the vicinity of a small-scale tanning area in Nanning, Guangxi Zhuang Autonomous Region, southern China, were collected to explore the contamination characteristics and source apportionment of Cd, Cr, Hg, As, Cu, Pb, Ni and Zn. The results show that the farmland soil was mainly contaminated by Cr and its content was 33.40-3830.00 mg kg-1. The highest level of Cr, Cd and Hg was above their thresholds, while the average contents of Cd, Cr, Pb and Hg exceeded the corresponding background levels. Moreover, enrichment of Cr in soil profiles and stream sediments were also observed, whose concentrations varied from 11.50 to 2590.00 mg kg-1 and 738.00 to 11,200.00 mg kg-1, respectively. Concentrations of Cr in top soils and soil profiles from farmland surrounding the stream were significantly higher than those from other areas, and the soils surrounding the stream were moderately to heavily polluted. The multivariate statistical analysis indicated that the heavy metals originated from traffic (Cu, Ni, Zn, Hg, and Pb), agriculture (Cr and Cd) and nature (As). Source apportionment with PMF model results showed that the relative contribution rates of heavy metals by traffic, tanning, agriculture, other industrial activities and natural sources were 16.00%, 18.88%, 20.88%, 22.04% and 22.20%, respectively. These findings indicate that small-scale tanning activities could also lead to heavy metal accumulation in the surrounding environment, which requires decision-makers to pay more attention and to develop effective remediation procedures.

Evaluation of heavy metals contamination in cereals, vegetables and fruits with probabilistic health hazard in a highly polluted megacity

Heavy metals (HMs) contamination in foodstuffs could pose serious health issues for public health and humans are continually exposed to HMs through the consumption of cereals, fruits, and vegetables. The present study was conducted to assess 11 HMs in foodstuffs to investigate pollution levels and health risks to children and adults. The mean contents of Cd, Cr, Cu, Ni, Zn, Fe, Pb, Co, As, Mn and Ba in foodstuffs were 0.69, 2.73, 10.56, 6.60, 14.50, 9.63, 2.75, 0.50, 0.94, 15.39 and 0.43 mg/kg, respectively and the concentration of Cd, Cr, Cu, Ni and Pb were higher than maximum permissible concentrations (MPCs) showing that these foods may be contaminated with metals and constitute a danger to consumers. Vegetables had relatively higher metal contents followed by cereals and fruits. The average value of the Nemerrow composite pollution index (NCPI) for cereals, fruits, and vegetables were 3.99, 6.53, and 11.34, respectively indicating cereal and fruits were moderately contaminated whereas vegetables were heavily contaminated by the studied metals. The total estimated daily and weekly intakes for all studied metals were higher than the maximum tolerable daily intake (MTDI) and provisional tolerance weekly intake (PTWI) recommended by FAO/WHO. The target hazard quotients and hazard index of all studied metals exceeded the standard limit for adults and children suggesting significant non-carcinogenic health hazards. The total cancer risk value of Cd, Cr, Ni, Pb, and As from food intake exceeded the threshold range (1.0E-04), suggesting potential carcinogenic risks. Based on practical and sensible evaluation techniques, the current work will assist policymakers in controlling metal contamination in foodstuffs.

Management of acid and alkaline phosphatase, dehydrogenase activities by sugarcane industry waste under lead contamination- A case study of Indian Vertisol

Soil fertility management and crop productivity both are inter-related need extensive attention for sustainability. Industries are being built, which over time produces a lot of effluents containing heavy metal(s), which is then dumped on healthy soils and water bodies. Long-term discharge of lead (Pb)-containing wastewater resulted in significant Pb buildup as well as a decrease in soil biological activity. In this experiment, graded dose of Pb, i.e. 0, 100, 150 and 300 mg/kg and pressmud (PM) (0, 2.5, 5, 10 g/kg) were applied to monitor the Pb toxic effect on soil acid and alkaline phosphatase, dehydrogenase activity. Different treatment combinations were formulated and the experiment was conducted in a completely randomized design (CRD) with three replications. In this experiment, spinach crop was used as a test crop. According to the findings, increased Pb levels in the soil lowered dehydrogenase activity (DHA), acid and alkaline phosphatase. The addition of PM enhanced enzymatic activities by decreasing the labile fraction of Pb in the soil. Incorporation of PM improved the soil enzymatic activities as alkaline phosphatase activity > DHA > acid phosphatase activity in the study. This study suggested that the addition of 10 g/kg PM reduced Pb toxicity (contamination level 300 mg/kg) and improved the soil microbial properties in black soil. These findings are very useful for the remediation of Pb contaminated soil with the help of PM, particularly in peri-urban Pb effluent irrigated areas.

Analysis of heavy metals and toxicity level in the tannery effluent and the environs

Heavy metals have found a large number of applications in the recent times. These heavy metals are being continuously added to our environment through various natural and anthropogenic activities. Industries employ heavy metals to process raw materials into final products. Effluents from these industries carry heavy metals. Atomic absorption spectrophotometer and ICP-MS (inductively coupled plasma-mass spectrometer) are of great help in detecting various elements in the effluent. They have been extensively applied to solve problems related to environmental monitoring and assessment. Heavy metals like Cu, Cd, Ni, Pb, and Cr can be easily detected using both the techniques. Some of these heavy metals are toxic to both humans and animals. They can have significant related health effects. Presence of heavy metals in the industrial effluent has gained varied attention in the recent times and it has become one of the major causes of water and soil pollution. Significant contributions can be linked with the leather tanning industry. As the effluent from the tanning industry has been found to contain a large number of heavy metals in many studies. Continuous monitoring and treatment of the effluent is necessary to keep a check on the concentration of heavy metals in these effluents. This study focuses on the analysis of the various studies available on tannery effluents, methods used for heavy metal analysis, toxicity of these heavy metals, and the related major health effects. Data for heavy metals in the tannery effluent from different studies in last two decades has been collected and analysed. The data from various studies indicates that Cr, Cd, Pb, Zn, Cu, Fe, and Ni are the most commonly found heavy metals released from the tanning industry. Proper management of the tannery effluent is thus very essential for saving the environment.

Bacteriophages diversity in India's major river Ganga: a repository to regulate pathogenic bacteria in the aquatic environment

Bacteriophages are key viruses that can kill thousands of harmful microbes generally present at polluted sites. Such bacteriophages are abundantly present in the river Ganga, where millions of people in India and abroad drink its water and take baths every day for spiritual reasons. Besides bacteriophages, several pathogenic and zoonotic microbes are present in the river Ganga. It is interesting to study the diversity and abundance of bacteria and their respective phages present in polluted or non-polluted sites. Thus, the metagenomics study was carried out at the most polluted sites of river Ganga near Kanpur and non-polluted sites at Farakka, which harbors several harmful bacteria and their phages. The results revealed a significantly higher percentage of Microviridae phage family, ssDNA viruses, and Mimiviridae virus family near Kanpur than Farakka. In addition, compared to Kanpur, Farakka has a more significant percentage of Myoviridae, an unidentified phage family, and Retroviridae viral families. Despite heavy drainage of untreated and contaminated effluents from the leather industry, pesticide industry, paper mills, metropolitan cities, and other sources, the vast number of said phages kills several harmful pathogenic microbes in polluted sites to maintain the Ganga water's healing power or natural sterility. In a polluted aquatic environment, the varieties of bacteriophages were identified in the Ganga and their interaction with the microbial host. The taxonomic diversity of several bacteriophages found in pathogenic host systems was investigated to get exceptional knowledge of these small viruses in the aquatic environment.

Toxic and carcinogenic effects of hexavalent chromium in mammalian cells in vivo and in vitro: a recent update

Chromium VI (Cr (VI)) can cross cell membranes readily and causes the formation of Cr-DNA adducts, genomic damages, elevation of reactive oxygen species (ROS) and alteration of survival signaling pathways, as evidenced by the modulation in p53 signaling pathway. Mammals, including humans are exposed to Cr, including Cr (VI), frequently through inhalation, drinking water, and food. Several studies demonstrated that Cr (VI) induces cellular death through apoptosis and autophagy, genotoxicity, functional alteration of mitochondria, endocrine and reproductive impairments. In the present review, studies on deleterious effects of Cr (VI) exposure to mammalian cells (in vivo and in vitro) have been documented. Special attention is paid to the underlying molecular mechanism of Cr (VI) toxicity.

Can Application of Pressmud Mediated Plant Nutrient Dynamics Under Lead Contaminated Soils of Indian Vertisol?

Long- term application of marginal quality water accumulated significant amount of pollutant into the soil. It reduces soil health parameters, and crop yield and their quality. In this regards, graded application of pressmud (PM), i.e. 0, 2.5, 5 and 10 g/kg was applied on lead (Pb) contamination level (0, 100, 150, 300 mg/kg) and evaluated interaction effect on plant nutrients uptake by spinach. Analytical data showed that increasing the PM levels enhanced the macro (phosphorus, potassium, sulphur) and micro-nutrient (zinc, copper, manganese, iron) concentration into the soil. Whereas, increasing the level of Pb significantly (p ≤ 0.05) reduced the P, K and S nutrient concentration and uptake pattern by spinach crop. Increasing PM levels (control to 10 g/kg soil) improved P, K and S by 46.99, 98.96 and 76.79%, respectively in soil. This study is useful to formulate management strategies for minimizing Pb contamination in the food chain by the application of PM mostly in peri-urban areas.

Immobilization of chromium bioavailability through application of organic waste to Indian mustard (Brassica juncea) under chromium-contaminated Indian soils

Industrialization results in production of large volume of wastewaters, and disposing of them become a serious problem. The wastewaters may have range of heavy metals, which have an impact on soil and plant health. The objective was to evaluate the influence of farm yard manure (FYM) and pressmud (PM) applications on Indian mustard growth and chromium (Cr) uptake in tannery effluent irrigated Cr-contaminated soil. Soil was collected from the tannery effluent irrigated fields (chromium contaminated) of Shekhpura village of Kanpur, India. A pot culture experiment was carried out by growing Indian mustard (Brassica juncea) var. RH 749 on the Cr-contaminated soil with application of different levels and combinations of FYM and PM (at 0, 2.5, and 5 g kg^-1 each). Biomass yield, Cr uptake, bioconcentration factor (BCF), transfer factor (TF), transfer efficiency (TE), and Cr removal indices were examined. Higher doses of FYM and PM resulted in reduction of Cr concentrations in shoot (6.60 to 2.50 µg g^-1) and root (27.27 to 9.43 µg g^-1); and absorption in plant tissues and had improved total dry matter yield (14.56 to 30.94 g pot^-1). The use of FYM and PM had a substantial (p ≤ 0.05) impact on phytoremediation parameters like BCF (0.128 to 0.045), TE (59.61 to 64.51%), and Cr removal (0.65 to 0.51%). Combined application of FYM (5 g kg^-1) and PM (5 g kg^-1) had enhanced the dry matter yield of shoot (12.51 to 26.40 g pot^-1) and root (2.05 to 4.54 g pot^-1) and reduced the Cr uptake (138.54 to 108.79 mg pot^-1) than the individual amendment addition of FYM (138.52 to 135.89 mg pot^-1) and PM (126.02 to 130.52 mg pot^-1). Combined application of FYM (5 g kg^-1) and PM (5 g kg^-1) could be beneficial for remediation of Cr-contaminated areas for cultivation of crops.

Tanneries impact on groundwater quality: a case study of Kasur city in Pakistan

Leather industry is the second largest export-earning sector of Pakistan. However, because of poor waste management, this industry has been continuously polluting the environment. In this paper, the impact of tanneries on the groundwater quality of Kasur city (i.e., the second largest leather producing city) is examined. The study is conducted in the following three phases: (I) water samples collection, (II) determination of physio-chemical properties, and (III) application of data mining techniques. In phase I, groundwater samples were collected from various sources such as hand pumps, motor pumps, and tube wells. In phase II, several physio-chemical properties such as (i) total dissolved solids (TDS), (ii) pH, (iii) turbidity, (iv) electrical conductivity (EC), (v) total hardness (TH), (vi) total alkalinity (TA), (vii) nitrates, (viii) chromium, (ix) fluoride, and (x) chloride were estimated. The estimated values of all these foregoing parameters are then compared with the Punjab Environmental Quality Standards for Drinking Water (PEQSDW). In phase III, principle component analysis and cluster analysis of the estimated parameters were performed to elucidate the relation between various parameters and to highlight the highly vulnerable sites, respectively. The results exhibit that most of the sampling collections sites are at the threshold of losing quality water. Moreover, it is also found that Mangal Mandi carries the worst groundwater quality among all sampling locations. Overall, it is concluded that serious attention is due from the water and wastewater authorities to further investigate and monitor the groundwater quality of Kasur before the country strikes with another pandemic after COVID-19.

Reuse of poor-quality water for sustainable crop production in the changing scenario of climate

The availability of freshwater is limited for agriculture systems across the globe. A fast-growing population demands need to enhance the food grain production from a limited natural resources. Therefore, researchers and policymakers have been emphasized on the production potential of agricultural crops in a sustainable manner. On the challenging side, freshwater bodies are shrinking with the pace of time further limiting crop production. Poor-quality water may be a good alternative for fresh water in water scarce areas. It should not contain toxic pollutants beyond certain critical levels. Unfortunately, such critical limits for different pollutants as well as permissible quality parameters for different wastewater types are lacking or poorly addressed. Marginal quality water and industrial effluent used in crop production should be treated prior to application in crop field. Hence, safe reuse of wastewater for cultivation of food material is necessary to fulfil the demands of growing population across the globe in the changing scenario of climate.

Nickel-mediated lead dynamics and their interactive effect on lead partitioning and phytoremediation indices in spinach

A greenhouse research was conducted to monitor lead (Pb) translocation dynamics in spinach (Spinacia oleracea L.) mediated by nickel (Ni) application. Each of the four levels of Pb (0, 100, 150, and 300 mg/kg) and Ni (0, 100, 150, and 300 mg/kg) was applied in different combinations in the pot experiment. A fully matured spinach crop was harvested and divided into biomass samples from the roots and above ground. ICP-OES was used to determine the concentrations of Pb and Ni in the samples. The increase in Pb application rate in soil resulted in a decrease in dry matter yield of plant roots and above-ground biomass, according to the findings. Pb accumulation was also found in significant amounts in roots and above-ground biomass. Pb was accumulated in greater quantities in the spinach roots than in the above-ground biomass. Pb uptake in spinach roots and above-ground biomass decreased when high dose of Ni was applied. The Ni application in spinach crop had a negative impact on various parameters of Pb uptake, including translocation factor, bioconcentration factor, translocation efficiency, and crop removal of Pb. Pb toxicity was reduced when higher doses of Ni (100 to 300 mg/kg) were applied to Pb-contaminated soil. The findings of this study could help researchers better understand how Pb and Ni interact, as well as how to treat soil that has been contaminated by industrial wastewater containing nickel and lead.

Impact of wastewater discharge on the plant diversity, community structure and heavy metal pollution of range plants in eastern Saudi Arabia

The main objectives of this study were to determine the floristic composition of the vegetation cover and to find the effects of wastewater pollution on the plant community structure in eastern Saudi Arabia. 28 stands which were distributed among polluted and unpolluted sites, were chosen for this study. A total of 42 plant species were recorded (14 in the polluted and 28 in the unpolluted sites). The recorded plants comprised of 13 perennial plant species and 29 annual plant species. Seven vegetation communities were determined using TWINSPAN and DCA classification and ordination techniques. Three in the polluted sites, two in the unpolluted sites and the remaining two were mixed communities. The (Sarcopoterium spinosum – Pistacia len‐tiscus) community in the polluted sites, had the highest values of soil moisture, salinity, sulphate, calcium and potassium. On the other hand, Juniperus phoenicea – Olea europaea community in the unpolluted site, had the lowest value of organic matter, salinity and magnesium. In respect of genetic diversity, the community of Foeniculum vulgare - Nicotiana glauca in the unpolluted site, was the most diverse, while Ricinus communis - Chrysanthemum coronarium in the polluted sites was the least one. Both soil and wastewater heavy metal analysis indicated that Pb, Cd, Cr, Cu and Ni concentrations in the polluted sites were significantly higher than those in the unpolluted ones. The impact of wastewater discharge led to the appearance of new invasive plant species that may significantly affect plant diversity and community structure in eastern Saudi Arabia. Finally wastewater discharge in open rangelands could adversely affect the growth of plant species in the rangelands and thus adversely affect plant community structure and diversity.

Maturity indices as an index to evaluate the quality of sulphur enriched municipal solid waste compost using variable byproduct of sulphur

The aim of this study was to assess the maturity indicators of municipal solid waste compost (MSWC) enrichment with different byproduct of (sugar and fertilizer industry) sulphur (S). The concentration of total S (TS), water-soluble S (WSS), HCl extractable S and available S were significantly different in composts prepared through different byproduct of S with MSW. WSS varied from 4.6 to 5.9% of TS after 120 days of the composting period, whereas, available S varied from 14.5 - 8.6% of TS. S enriched MSW compost had lower C/N, C/S ratio and higher nitrification index as well as lower phyto-toxicity, demonstrating that composts are properly matured and stabilised. Highest compost quality index (0.97) was recorded with S1 compost. Arylsulphatase activity significantly increased with compost maturity. Results stated that all S enriched products maintained a superior amount of plant nutrients and quality indices, indicating that S enriched compost could be a possible substitute for expensive fertilizers.

Impact of arsenic-polluted groundwater on soil and produce quality: a food chain study

The experiment was conducted to assess the impact of arsenic (As)-contaminated groundwater irrigation on soil health and crop quality. Geo-referenced groundwater, soil, and crop produce samples were collected from the middle Gangetic plains of Maner block of Patna and were analyzed for As content. The result showed that long-term application of As-contaminated groundwater (0.017 to 0.677 mg L^-1) buildup significant amount of As in the soil (0.41 to 8.66 mg kg^-1). A significant correlation (r² = 0.922) was also observed between As content in groundwater and the soil. The content of As in groundwater also affected crop quality and accumulated metal content in different crop parts. Total As content in crop samples ranged from 0.010 to 0.963 μg g^-1 of dry weight. The average As content in crop followed order: oilseeds > cereals > vegetables > pulses. Therefore, produce quality should be monitored frequently for As uptake as there is a great chance of As accumulation in food crops. Hence, these approaches are useful for the formulation of policy guidelines for the management of As-containing groundwater and routine risk assessment of As-contaminated soils.

Urban kitchen gardens: Effect of the soil contamination and parameters on the trace element accumulation in vegetables - A review

Trace element contaminants in kitchen garden soils can contribute to human exposure through the consumption of homegrown vegetables. In urban areas, these soils can be contaminated to various degrees by trace element (TE). They are characterized by a great variability in their physicochemical parameters due to the high anthropization level, the wide variety and combination of disturbance sources, as well as the diversity of cultivation practices and the large range of contamination levels. Pollutants can be taken up by vegetables cultivated in these soils and be concentrated in their edible parts. In this review, the behavior of vegetables cultivated in contaminated kitchen gardens is assessed through six examples of the most widely cultivated vegetables (lettuce, tomato, bean, carrot, radish, potato). The role of soil parameters that could influence the uptake of As, Cd, Cr, Ni, Pb, and Zn by these vegetables is also discussed.

Pollution and Ecological Risk Evaluation of Heavy Metals in the Soil and Sediment around the HTM Tailings Pond, Northeastern China

Tailings ponds are a main heavy metal pollution source in mining areas. In this study, the geo-accumulation index (Igeo) and the potential ecological risk index (RI) are used to evaluate the environmental impact of Hongtou Mountain (HTM) tailings pond on the surrounding area. Farmland soil, surface water, and sediment samples in the Hun River around the HTM tailings pond were collected. Heavy metal contents in the samples were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results show that Cu, Zn, and Cd content in the farmland soil and sediment around the lower reaches of the Hun River (HTM tailings pond section) are obviously higher than the upper reaches. The Igeo values show that the farmland soil near the outlet of the tailings pond is the most polluted area. Cu was classified as moderate-strongly pollution, Zn was moderately pollution, and Cd was strongly pollution. Cd is the major pollutant in farmland soil, the monomial ecological risk (Eri) for Cd is a very high potential ecological risk. The potential ecological risk of sediment in the dry season is more serious than in the raining season. In the dry season, the Igeo index shows strong pollution for Cu and Cd at the confluence of the Hun River and the tributary from the HTM tailings pond, and a moderate-strongly pollution for Zn. Whereas, the Eri index shows that the monomial ecological risk for Zn at H3 is low, and Cu is moderate. The potential ecological risk at H3 is high, and Cd is the main source of the ecological risk around the HTM tailings pond.

Effect of passive ventilation on the performance of unplanted sludge treatment wetlands: heavy metal removal and microbial community variation

Sludge treatment wetlands (STWs) have been applied worldwide to treat excess sludge; however, the performance of STWs is generally limited by weather partly due to the plants vegetated on the STWs. In this study, ventilation is suggested to assist unvegetated STWs. Solid samples from different depths were analysed. Additionally, the variation of microbial community in STW unit was analysed and the fate of heavy metals in the sludge was determined. Results indicate that the STW unit with suitable parameters has better performance in stabilising and maturing the sludge than planted STW, which may contribute to the variation of the microbial community; additionally, ventilation exerts a positive influence on these bacteria during the variation of microbial community and on heavy metal removal through the substrate and positively impacts the Cd and Pb in reduction state. Furthermore, ventilation decreases the bioavailability of Cr. With ventilation in STWs, Bacillus and Streptomyces play a necessary role in enhancing the possibility of sludge to be used as microbial inoculants.

Microbial and plant-assisted heavy metal remediation in aquatic ecosystems: a comprehensive review

Heavy metal (HM) pollution in aquatic ecosystems has an adverse effect on both aquatic life forms as well as terrestrial living beings, including humans. Since HMs are recalcitrant, they accumulate in the environment and are subsequently biomagnified through the food chain. Conventional physical and chemical methods used to remove the HMs from aquatic habitats are usually expensive, slow, non-environment friendly, and mostly inefficient. On the contrary, phytoremediation and microbe-assisted remediation technologies have attracted immense attention in recent years and offer a better solution to the problem. These newly emerged remediation technologies are eco-friendly, efficient and cost-effective. Both phytoremediation and microbe-assisted remediation technologies adopt different mechanisms for HM bioremediation in aquatic ecosystems. Recent advancement of molecular tools has contributed significantly to better understand the mechanisms of metal adsorption, translocation, sequestration, and tolerance in plants and microbes. Albeit immense possibilities to use such bioremediation as a successful environmental clean-up technology, it is yet to be successfully implemented in the field conditions. This review article comprehensively discusses HM accumulation in Indian aquatic environments. Furthermore, it describes the effect of HMs accumulation in the aquatic environment and the role of phytoremediation as well as microbe-assisted remediation in mitigation of the HM toxicity. Finally, the review concludes with a note on the challenges, opportunities and future directions for bioremediation in the aquatic ecosystems.

Health risks of heavy metal exposure and microbial contamination through consumption of vegetables irrigated with treated wastewater at Dubai, UAE

The shortage of fresh water is a major problem throughout the world, but the situation is worst in the arid and semiarid regions. Therefore, reuse of nonconventional water resources such as treated wastewater (TWW) is a common practice to irrigate field crops, vegetables, and forestry sectors. The present study was conducted to evaluate the significant impact of different heavy metals such as copper (Cu), iron (Fe), chromium (Cr), and zinc (Zn) on the soil and leafy, root, and fruit vegetables following irrigation with TWW through subsurface drip irrigation. Our results indicate that iron (Fe) was highest in lettuce followed by spinach, and Zn and Cr were second and third most abundant element in the different vegetables. Eggplant and radish showed the lowest concentrations of various heavy metals. A significant difference was observed in transfer factor (TF) among vegetables, and highest TF_soil-veg was observed for Fe in lettuce and the lowest for Cr in eggplant. Estimated daily intake (EDI) was the lowest in adults and highest in children. Target hazard quotient (THQ) of Cu, Zn, and Fe being < 1.0 appears relatively safe in all the tested vegetables. Risk index (RI) values showed that heavy metals were lower than 1.0 and hence lower risk for human. The combined HI values for Cu, Zn, Cd, Cr, and Pb were substaintionaly higher 12.8 and 9.21 after consumption of lettuce and carrot. So, consumption of these vegetables should be avoided after irrigation with TWW. Spinach exhibited maximum total coliform loading, while ecological risk was negligible due to sandy nature of soil type. Health risks to human could be reduced through proper selection of suitable vegetables, time of maturity, and consumed organs (leaf, fruit, or root part). Appropriate should be followed to decontaminate the microbial load in order to avoid any risks to human health (both adults and children).

Reducing chromium uptake through application of calcium and sodium in spinach

In peri-urban areas, the use of wastewater for crop production is a common practice due to water scarcity. Moreover, in the recent years, large quantity of wastewater generation and discharge as industrial effluent in water resources is another issue for reduction of water quality. The leather industries are significantly contributing chromium (Cr) in effluent, whereas, other industries may have salt and cationic load in their discharges are mixed up. Therefore, it is mandatory to study the interactive effect of different effluent constituents on crop plants. In this connection, a pot culture experiment was conducted at the ICAR-Indian Institute of Soil Science, Bhopal to compute the effect of application of calcium (Ca) and sodium (Na) ions on Cr uptake by spinach crop in Vertisol of central India. Three levels of Cr (0, 50, 100 mg kg^-1), calcium (0, 2, 4 mM), and sodium (0, 40, 80 mM) were applied in combinations. The spinach variety All Green was used as a test crop and harvested at full maturity. Results showed that application of Ca and Na reduced the Cr uptake in spinach crop. The reduction of Cr uptake was more in the root than shoot. Applied calcium acted as an essential plant nutrient and enhanced the crop biomass. Sole applications of Na adversely affected the crop biomass and Cr uptake in both root and shoot of spinach. In conclusion, application of Ca fertilizers reduced the Cr toxicity in spinach and could be used as a strategy for the safe utilization of tannery industrial effluents for crop production.

Chromium toxicity mediated by application of chloride and sulfate ions in Vertisol of Central India

Chromium (Cr) is one of the toxic metals adversely affecting organisms including humans in the ecosystems, and it is present in considerable concentration in the tannery industrial effluent. Toxicity expression of Cr is suspected to be influenced considerably by other accompanying ions present in the effluent used for irrigation. In a screen house experiment, interactive effects of chloride and sulfate ions in a Vertisol on uptake of Cr by spinach crop were investigated and treatments imposed were three levels each of Cr (0, 50, 100 mg kg^-1), chloride (Cl^-) (0, 25, 50 mM kg^-1), and sulfur (S) (0, 4, 8 mM kg^-1) in possible combinations. Plant growth parameters and leaf Cr concentrations were recorded to find out the effect of anions on Cr dynamics in the plant. Increasing the concentration of Cl^- ions in soil reduced the Cr concentration in both root and shoot. Similarly, increasing the concentration of S from 4 to 8 mM kg^-1 also reduced the concentration and uptake of Cr. Application of sulfate ions augmented the plant growth and counters the negative effect of Cl^- ions and Cr. Thus, the study revealed that the addition of S fertilizers could minimize the Cr toxicity in high Cr contaminated soils.

Impact of Long-Term Application of Sewage on Soil and Crop Quality in Vertisols of Central India

Shortfall of rain and the decreased groundwater level force farmers to use poor quality water for crop production in developing countries. In this study, the quality of agricultural produce and soil health affected by sewage water (Patranala) irrigation was evaluated. Sewage sediment, soil and crop samples were analyzed for physico-chemical properties. Sewage water found to contain trace concentration of heavy metals. However, long-term application of this water for crop production could build up a significant amount of trace metals in both soil and sediments. The DTPA extractable heavy metals ranged Cu 2.7-7.59, Cd 0.04-0.06, Pb 1.29-2.05, Cr 0.01-0.04, Ni 0.24-1.03 and Zn 0.63-2.59 mg kg^-1 soil. The heavy metal risk assessment (hazard quotient, HQ) was calculated and found that HQ for these metals in the crops under study was in safe limits. From the study, it is concluded that growing vegetables using sewage water of Patranala is safe, but periodic monitoring to be carried out to avoid food chain contamination.

Assessment of Cadmium Scavenging Potential of Canna indica L

The aquatic plant, Canna indica L. (Indian shoot) of Cannaceae family was investigated to assess cadmium scavenging potential at 5, 10, 25, 50, 100 and 150 mg Cd L^-1 exposers. The results showed that Canna has considerable potential of cadmium accumulation, which was up to 58.69 and 10.13 mg Cd kg^-1 dry weight in root and shoot of Canna, respectively. The effects of different cadmium levels on biomass production of plant tissues were significantly (p = 0.05) showed negative relation due to cadmium toxicity. The root concentration factor was higher than the bioconcentration factor which indicated the lower translocation factor of Canna. Considering the high root concentration factor, average bioconcentration factor, rapid growth and optimum adaptive properties up to 100 mg Cd L^-1 level, the Canna could be employed as an eco-friendly and efficient aquatic plant for cadmium scavenging. This study plays a potential role in remediation of cadmium contaminated wastewater.

Soil Enzymatic Activities as Influenced by Lead and Nickel Concentrations in a Vertisol of Central India

A pot-culture was conducted in Completely Randomized Design with three replicates to study the effect of Pb and Ni on enzymatic activities in a Vertisols. Results indicated that increasing in the levels of Pb from 0, 100, 150 and 300 mg kg^-1 soil significantly reduced the dehydrogenase activity (DHA) 38.9, 32.1, 30.9, 18.1 µg triphenylformazan g^-1 soil 24 h^-1; acid phosphatase activities 73, 61, 58, 55 µg PNP g^-1 soil h^-1 and alkaline phosphatase activities 80.7, 69.4, 66.2 and 64.0 µg PNP g^-1 soil h^-1, respectively. Application of Ni up to 100 mg kg^-1 had significantly improved the soil enzymatic activities and thereafter there was no such change up to the highest level (300 mg Ni kg^-1). Among soil enzymatic activities, DHA was more sensitive to Pb application. The findings generated through this study can be useful for managing waste water for safe disposal as well as sustainable crop production.