Role of organic and inorganic amendments on physiological attributes of germinating pea seedlings under arsenic stress.

There are scarce data regarding the effects of soil amendments on biophysicochemical responses of plants at the early stages of growth/germination. This study critically compares the effects of ethylene-diamine-tetra-acetic-acid (EDTA) and calcium (Ca) on biophysicochemical responses of germinating pea seedlings under varied arsenic levels (As, 25, 125, 250 µM). Arsenic alone enhanced hydrogen peroxide (H2O2) level in pea roots (176%) and shoot (89%), which significantly reduced seed germination percentage, pigment contents, and growth parameters. Presence of EDTA and Ca in growth culture minimized the toxic effects of As on pea seedlings, EDTA being more pertinent than Ca. Both the amendments decreased H2O2 levels in pea tissues (16% in shoot and 13% in roots by EDTA, and 7% by Ca in shoot), and maintained seed germination, pigment contents, and growth parameters of peas close to those of the control treatment. The effects of all As-treatments were more pronounced in the pea roots than in the shoot. The presence of organic and inorganic amendments can play a useful role in alleviating As toxicity at the early stages of pea growth. The scarcity of data demands comparing plant biophysicochemical responses at different stages of plant growth (germinating vs mature) in future studies.

Till date, abundant research has focused on plant biophysicochemical responses to different types of pollutants. However, the majority of these studies dealt with pollutant exposure to mature plants (generally after a vegetative growth period of 1­2 weeks). Despite significant research, there are still limited data regarding the biophysicochemical responses of plants at their early stages of germination and growth. In fact, stresses at germination or at an early stage of growth can be highly fatal and may significantly affect the ultimate plant growth and potential to remediate the contaminated sites. Therefore, the current study deals with the exposure of germinating pea seedlings to arsenic (As) stress under varied amendments. This experimental plan helped to understand the initial biophysicochemical changes induced in pea plants under As stress.

Magnetic nanocomposite of maize offal biomass for effective sequestration of Congo red and methyl orange dyes from contaminated water: modeling, kinetics and reusability.

The current study aims to use a facile and novel method to remove Congo red (CR) and Methyl Orange (MO) dyes from contaminated water with Maize offal biomass (MOB) and its nanocomposite with magnetic nanoparticles (MOB/MNPs). The MOB and MOB/MNPs were characterized with Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), BET, XRD and point of zero charge (pHPZC). The influence of initial CR and MO levels (20-320 mg/L), adsorbent dosage (1-3 g/L), pH (3-9), co-exiting ions, temperature (25-45 °C) and time (15-180 min) was estimated. The findings demonstrated that MOB/MNPs exhibited excellent adsorption of 114.75 and 29.0 mg/g for CR and MO dyes, respectively while MOB exhibited 81.35 and 23.02 mg/g adsorption for CR and MO dyes, respectively at optimum pH-5, and dose 2 g/L. Initially, there was rapid dye removal which slowed down until equilibrium was reached. The interfering/competing ions in contaminated water and elevated temperature favored the dyes sequestration. The MOB/MNPs exhibited tremendous reusability and stability. The dyes adsorption was spontaneous, and exothermic with enhanced randomness. The adsorption effects were well explained with Freundlich model, pseudo second order and Elovich models. It is concluded that MOB/MNPs showed excellent, eco-friendly, and cost-effective potential to decontaminate the water.

Nanocomposite of Maize offal biomass demonstrated higher dyes removal.FTIR, SEM, BET, XRD and pH_PZC provided vital evidence for dyes adsorption.MOB/MNPs displayed excellent stability and reusability for dyes adsorption.Groundwater samples exposed a higher dyes removal.Results were validated with equilibrium and kinetic adsorption models.

Iron enriched quinoa biochar enhances Nickel phytoremediation potential of Helianthus annuus L. by its immobilization and attenuation of oxidative stress: implications for human health.

The present study was performed to assess Ni-immobilization and the phytoremediation potential of sunflower by the application of quinoa stalks biochar (QSB) and its magnetic nanocomposite (MQSB). The QSB and MQSB were characterized with FTIR, SEM, EDX, and XRD to get an insight of their surface properties. Three-week-old seedlings of sunflower were transplanted to soil spiked with Ni (0, 15, 30, 60, 90 mg kg-1), QSB and MQSB (0, 1, and 2%) in the wire house under natural conditions. The results showed that increasing Ni levels inhibited sunflower growth and yield due to the high production of reactive oxygen species (ROS) and lipid peroxidation. Enzyme activities like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POX) also increased as Ni levels increased. However, the application of QSB and MQSB reduced Ni uptake, root-shoot, and shoot-seed translocation and decreased the generation of ROS, and lowered the activity of SOD, CAT, APX, and POX, leading to improved growth and yield, especially with MQSB. This was verified through SEM, EDX, XRD, and FTIR. It can be concluded that QSB and MQSB can effectively enhance Ni-tolerance in sunflowers and mitigate oxidative stress and human health risks.

The article focuses on enhancing the phytoremediation remediation potential of Helianthus annuus by using the quinoa stalks biochar (QSB) and magnetic quinoa stalks biochar (MQSB) by immobilization of Ni in soil and ultimately attenuation of oxidative stress in plants and human health risk. Iron enrichment of biochar improves the surface characteristics (surface area, functional groups, porosity, etc.) which help to immobilize metals ions. To the best of our knowledge, QSB and MQSB has never been used before to study the Ni dynamics and for enhancing sunflower phytoremediation potential.

Spatial distribution, health risk assessment, and public perception of groundwater in Bahawalnagar, Punjab, Pakistan: a multivariate analysis.

The current study investigated the hydrogeochemical behavior of groundwater quality attributes including arsenic (As) and their associated health risks in unexplored groundwater aquifers of Bahawalnagar, Punjab, Pakistan. The groundwater samples were collected from 40 colonies of Bahawalnagar city from electric/hand pumps, tube wells and turbines installed at varying depth (20 to > 100 m). The groundwater possessed the highest concentrations of PO4 (0.5 mg/L), HCO3 (425 mg/L), Cl (623 mg/L), NO3 (136.68 mg/L) and SO4 (749.7 mg/L) concentrations. There was no difference in concentration of As in shallow and deep aquifers. Interestingly, none of the water samples showed As concentration higher than the WHO limit of 10 µg/L for drinking water with groundwater As concentration spanning from 2.5 to 7.9 µg/L. The HQ values for As were less than 1 and there was no apparent non-carcinogenic risk from the long-term consumption of As contaminated water. The questionnaire survey indicated that 82% respondents believe that drinking water quality affects human health and 55% of respondents considered that groundwater in the area is not suitable for drinking. Survey results revealed that 29.11, 22.78, 17.08, 15.19, 7.59, 5.06 and 3.16% respondents/family members suffered from hepatitis, skin problems, diabetes, tuberculosis, kidney disorders, muscular weakness and gastro, respectively. However, the data cannot be correlated with As contamination and disease burden in the local community and it can be anticipated that the groundwater may contain other potentially toxic ions that are deteriorating the water quality and compromising human health. The hydrogeochemical analysis revealed Na-Cl/SO4, K-SO4 type of groundwater suggesting the potential role of sulfate containing minerals in releasing As in the groundwater aquifers.

A critical analysis of wastewater use in agriculture and associated health risks in Pakistan.

Freshwater shortage and its contamination with various types of pollutants are becoming the most alarming issues worldwide due to impacts on socioeconomic values. Considering an increasing freshwater scarcity, it is imperative for the growers, particularly in semiarid and arid areas, to use wastewater for crop production. Wastewaters generally contain numerous essential inorganic and organic nutrients which are considered necessary for plant metabolism. Besides, this practice provokes various hygienic, ecological and health concerns due to the occurrence of toxic substances such as heavy metals. Pakistan nowadays faces a severe freshwater scarcity. Consequently, untreated wastewater is used routinely in the agriculture sector. In this review, we have highlighted the negative and positive affectivity of wastewater on the chemical characteristics of the soil. This review critically delineates toxic metal accumulation in soil and their possible soil-plant-human transfer. We have also estimated and deliberated possible health hazards linked with the utilization of untreated city waste effluents for the cultivation of food/vegetable crops. Moreover, we carried out a multivariate analysis of data (144 studies of wastewater crop irrigation in Pakistan) to trace out common trends in published data. We have also compared the limit values of toxic metals in irrigation water, soil and plants. Furthermore, some viable solutions and future viewpoints are anticipated taking into account the on-ground situation in Pakistan-such as planning and sanitary matters, remedial/management technologies, awareness among local habitants (especially farmers) and the role of the government, NGOs and pertinent stakeholders. The data are supported by 13 tables and 7 figures.

Arsenic level in groundwater and biological samples in Khanewal, Pakistan.

Groundwater is the most valuable natural source in our earth's planet, being contaminated in various regions worldwide. Despite considerable research, there are scarce data regarding arsenic (As) levels in groundwater and its build-up in biological samples in Pakistan. The current investigation analyzed As contamination in four tehsils of District Khanewal (Kabirwala tehsil, Jahaniyan tehsil, Mian Channu tehsil, and Khanewal tehsil). For that, 123 groundwater samples, 19 animal milk samples, 20 human nails, and 20 human hair samples were collected from the study area. Arsenic concentration in groundwater was up to 51.8 µg/L with an average value of 7.2 µg/L. About 28 water samples (23%) had As contents > WHO limit and 38 samples (31%) > DEP-NJ limit. Low levels of As were detected in biological samples. Average As levels were 23 µg/L in the milk samples and 298 µg/kg in human hair. Arsenic contents were not detected in nail samples, except in one sample from Kabirwala tehsil. The maximum values of hazard quotient and cancer risk in District Khanewal were 4.9 and 0.0022, respectively. It is anticipated that long-term use of As-containing water may led to poisoning of humans in the study area, especially in Kabirwala. Therefore, it is necessary to monitor As contamination in the groundwater of Kabirwala tehsil to reduce the potential health hazards.

Nickel toxicity pretreatment attenuates salt stress by activating antioxidative system and ion homeostasis in tomato (Solanum lycopersicon L.): an interplay from mild to severe stress.

Plants antioxidative system is the first line of defense against oxidative stress caused secondarily by toxic ions under salinity. Plants with pre-activated antioxidative system can better adapt to salinity and can result in higher growth and yield. The current experiment was conducted to assess the adaptation of two tomato genotypes (Riogrande and Green Gold) with pre-activated antioxidative enzymes against salt stress. Tomato seedlings were exposed to mild stress (Ni: 0, 15 and 30 mg L-1) for three weeks to activate the antioxidative enzymes. The seedlings with pre-activated antioxidative enzymes were then grown under severe stress in hydroponics (0, 75 and 150 mM NaCl) and soil (control, 7.5 and 15 dS m-1) to check the adaptation, growth and yield. The results showed that Ni toxicity significantly enhanced activities of antioxidant enzymes (SOD, CAT, APX and POX) in both the genotypes and reduced growth with higher values in genotype Riogrande than Green Gold. The seedlings with pre-activated antioxidant enzymes showed better growth, low Na+ and high K+ uptake and maintained higher antioxidative enzymes activity than non-treated seedlings after four weeks of salt stress treatment in hydroponics. Similarly, the results in soil salinity treatment of the Ni pretreated seedlings showed higher yield characteristics (fruit yield per plant, average fruit weight and fruit diameter) than non-treated seedlings. However, Ni pretreatment had nonsignificant effect on tomato fruit quality characteristics like fruit dry matter percentage, total soluble solids, fruit juice pH and titratable acidity. The genotype Riogrande showed better growth, yield and fruit quality than Green Gold due to higher activity of antioxidant enzymes and better ion homeostasis as a result of Ni pretreatment. The results suggest that pre-activation antioxidant enzymes by Ni treatment proved to be an effective strategy to attenuate salt stress for better growth and yield of tomato plants.

Biowaste-based sorbents for arsenic removal from aqueous medium and risk assessment.

Water contamination by arsenic (As) is widespread and is posing serious health threats globally. Hence, As removal techniques/adsorbents need to be explored to minimize potentials hazards of drinking As-contaminated waters. A column scale sorption experiment was performed to assess the potential of three biosorbents (tea waste, wheat straw and peanut shells) to remove As (50, 100, 200 and 400 µg L-1) from aqueous medium at a pH range of 5-8. The efficiency of agricultural biosorbents to remove As varies greatly regarding their type, initial As concentration in water and solution pH. It was observed that all of the biosorbents efficiently removed As from water samples. The maximum As removal (up to 92%) was observed for 400 µg L-1 initial As concentration. Noticeably, at high initial As concentrations (200 and 400 µg L-1), low pH (5 and 6) facilitates As removal. Among the three biosorbents, tea waste biosorbent showed substantial ability to minimize health risks by removing As (up to 92%) compared to peanut shells (89%) and wheat straw (88%). Likewise, the values of evaluated risk parameters (carcinogenic and non-carcinogenic risk) were significantly decreased (7-92%: average 66%) after biosorption experiment. The scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray and X-ray diffraction analyses confirmed the potential of biosorbents to remediate As via successful loading of As on their surfaces. Hence, it can be concluded that synthesized biosorbents exhibit efficient and ecofriendly potential for As removal from contaminated water to minimize human health risk.

Chromium removal from aqueous solution using bimetallic Bi0/Cu0-based nanocomposite biochar.

Chromium (Cr), due to its greater contamination in aquifers and distinct eco-toxic impacts, is of greater environmental concern. This study aimed to synthesize nanocomposites of almond shells biochar (BC) with zerovalent bismuth and/or copper (Bi0/BC, Cu0/BC, and Bi0-Cu0/BC) for the removal of Cr from aqueous solution. The synthesized nanocomposites were investigated using various characterization techniques such as XRD, FTIR spectroscopy, SEM, and EDX. The Cr removal potential by the nanocomposites was explored under different Cr concentrations (25-100 mg/L), adsorbent doses (0.5-2.0 g/L), solution pH (2-8), and contact time (10-160 min). The above-mentioned advanced techniques verified successful formation of Bi0/Cu0 and their composite with BC. The synthesized nanocomposites were highly effective in the removal of Cr. The Bi0-Cu0/BC nano-biocomposites showed higher Cr removal efficiency (92%) compared to Cu0/BC (85%), Bi0/BC (76%), and BC (67%). The prepared nanocomposites led to effective Cr removal at lower Cr concentrations (25 mg/L) and acidic pH (4.0). The Cr solubility changes with pH, resulting in different degrees of Cr removal by Bi0-Cu0/BC, with Cr(VI) being more soluble and easier to adsorb at low pH levels and Cr(III) being less soluble and more difficult to adsorb at high pH levels. The experimental Cr adsorption well fitted with the Freundlich adsorption isotherm model (R2 > 0.99) and pseudo-second-order kinetic model. Among the prepared nanocomposites, the Bi0-Cu0/BC showed greater stability and reusability. It was established that the as-synthesized Bi0-Cu0/BC nano-biocomposite showed excellent adsorption potential for practical Cr removal from contaminated water.

Comparison of As removal efficiency and health risks from aqueous solution using as-synthesized Fe0 and Cu0: modelling, kinetics and reusability.

Batch scale removal of arsenic (As) from aqueous media was explored using nano-zero valent iron (Fe0) and copper (Cu0) particles. The synthesized particles were characterized using a Brunauer-Emmett-Teller (BET) surface area analyzer, a scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). The BET result showed that the surface area (31.5 m2/g) and pore volume (0.0415 cm3/g) of synthesized Fe0 were higher than the surface area (17.56 m2/g) and pore volume (0.0287 cm3/g) of Cu0. The SEM results showed that the morphology of the Fe0 and Cu0 was flowery microspheres and highly agglomerated with thin flakes. The FTIR spectra for Fe0 showed broad and intense peaks as compared to Cu0. The effects of the adsorbent dose (1-4 g/L), initial concentration of As (2 mg/L to 10 mg/L) and solution pH (2-12) were evaluated on the removal of As. Results revealed that effective removal of As was obtained at pH 4 with Fe0 (94.95%) and Cu0 (74.86%). When the dosage increased from 1 to 4 g L-1, the As removal increased from 70.59 to 93.02% with Fe0 and from 67 to 70.59% with Cu0. However, increasing the initial As concentration decreased the As removal significantly. Health risk indices, including estimated daily intake (EDI), hazard quotient (HQ), and cancer risk (CR) were employed and a significant decline (up to 99%) in risk indices was observed in As-treated water using Fe0/Cu0. Among the adsorption isotherm models, the values of R2 showed that isothermal As adsorption by Fe0 and Cu0 was well explained by the Freundlich adsorption isotherm model (R2 > 0.98) while the kinetic experimental data was well-fitted with the Pseudo second order model. The Fe0 showed excellent stability and reusability over five sorption cycles, and it was concluded that, compared to the Cu0, the Fe0 could be a promising technology for remediating As-contaminated groundwater.

Effect of freshwater and wastewater irrigation on buildup of toxic elements in soil and maize crop.

Untreated wastewater is routinely used for agricultural activities in water-stressed regions, thereby causing severe ecological risks by various pollutants. Hence, management strategies are needed to cope with the environmental issues related to wastewater use in agriculture. This pot study evaluates the effect of mixing either freshwater (FW) or groundwater (GW) with sewage water (SW) on the buildup of potentially toxic elements (PTEs) in soil and maize crop. Results revealed that SW of Vehari contains high levels of Cd (0.08 mg L-1) and Cr (2.3 mg L-1). Mixing of FW and GW with SW increased soil contents of As (22%) and decreased Cd (1%), Cu (1%), Fe (3%), Mn (9%), Ni (9%), Pb (10%), and Zn (4%) than SW "alone" treatment. Risk indices showed high-degree of soil-contamination and very-high ecological risks. Maize accumulated considerable concentrations of PTEs in roots and shoot with bioconcentration factor > 1 for Cd, Cu, and Pb and transfer factor > 1 for As, Fe, Mn, and Ni. Overall, mixed treatments increased plant contents of As (118%), Cu (7%), Mn (8%), Ni (55%), and Zn (1%), while decreased those of Cd (7%), Fe (5%), and Pb (1%) compared to SW "alone" treatments. Risk indices predicted possible carcinogenic risks to cow (CR 0.003 > 0.0001) and sheep (CR 0.0121 > 0.0001) due to consumption of maize fodder containing PTEs. Hence, to minimize possible environmental/health hazards, mixing of FW and GW with SW can be an effective strategy. However, the recommendation greatly depends on the composition of mixing waters.

Accumulation pattern and risk assessment of potentially toxic elements in selected wastewater-irrigated soils and plants in Vehari, Pakistan.

There are scarce data about the accumulation pattern and risk assessment of potentially toxic elements (PTEs) in soil and associated potential ecological risks, especially in less-developed countries. This study aims to assess the pollution levels and potential ecological risks of PTEs (As, Cr, Cd, Cu, Ni, Mn, Pb and Zn) in wastewater-irrigated arable soils and different edible-grown plants in selected areas of Vehari, Pakistan. The results revealed that the values of PTEs in soil samples were higher than their respective limit values by 20% for As, 87% for Cd, 15% for Cu, 2% for Cr, 83% for Mn, 98% for Fe, and 7% for Zn. The values of soil risk indices such as the potential ecological risk (PERI >380 for all samples), pollution load index (PLI >4 for 94% of studied samples), and degree of contamination (Dc > 24 for all samples) showed severe soil contamination in the study area. Some vegetables exhibited a high metal accumulation index (e.g., 8.1 for onion), signifying potential associated health hazards. Thus, long-term wastewater irrigation has led to severe soil contamination, which can pose potential ecological risks via PTE accumulation in crops, particularly Cd. Therefore, to ensure food safety, frequent wastewater irrigation practices need to be minimized and managed in the study area.

Assessment of cadmium and lead tolerance potential of quinoa (Chenopodium quinoa Willd) and its implications for phytoremediation and human health.

Soil contamination with Cd and Pb is a worldwide problem which not only degrades the environment but also poses a serious threat for human and animal health. Phytoremediation of these contaminated soils using halophytic plants like quinoa presents an opportunity to clean the soils and use them for crop production. The current experiment was performed to evaluate the Cd and Pb tolerance potential of quinoa and subsequently its implications for human health. Three weeks old quinoa seedlings were exposed to Cd (30, 60 and 90 mg kg-1) and Pb (50, 100 and 150 mg kg-1) levels along with a control. The results revealed that plant height decreased at highest levels of soil Cd and Pb. Shoot, root and seed dry weight decreased with increasing levels of soil Cd and Pb. Tissue Cd and Pb concentrations increased with increasing levels of Cd and Pb in soil, the highest Cd was found in roots while the lowest in seeds. The highest Pb concentration was found in shoots at low Pb level, while in roots at high level of Pb. Increasing levels of Cd and Pb stimulated the activities of measured antioxidant enzymes and decreased membrane stability index. The health risk assessments of Cd and Pb revealed that hazard quotient was < 1 for both the metals. However, the results of total hazard quotient showed that value was < 1 for Pb and 1.19 for Cd showing potential carcinogenicity. This study demonstrates that quinoa has good phytoremediation potential for Cd and Pb however, the risk of Cd toxicity is challenging for human health.

Multivariate analysis of accumulation and critical risk analysis of potentially hazardous elements in forage crops.

Potentially hazardous element (PHE) contamination of aquifers is an issue of global concern, as this not only affects soil and plants but also exerts a negative impact on livestock. The current study assessed the extent of PHE (cadmium, copper, nickel, and lead) contamination of groundwater, soil, and forage crops in Shorkot, Punjab, Pakistan. Low concentrations of PHEs, particularly Cd and Cu, were found in drinking water which remained below detection limits. The concentrations of Ni and Pb in water samples were 0.1 and 0.06 mg L-1, respectively. Calculated risk indices showed that there was a high carcinogenic and non-carcinogenic risk to livestock (sheep and cow/buffalo) from the ingestion of Ni- and Pb-contaminated water. Soil irrigation with contaminated water resulted in PHE accumulation (Cd: 0.4 mg kg-1, Cu: 16.8 mg kg-1, Ni: 17.6 mg kg-1, Pb: 7.7 mg kg-1) in soil and transfer to forage crops. The potential impact of PHE contamination of the groundwater on fodder plants was estimated for animal health by calculating the average daily dose (ADD), the hazard quotient (HQ), and the cancer risk (CR). While none of the PHEs in forage plants showed any carcinogenic or non-carcinogenic risk to livestock, a high exposure risk occurred from contaminated water (HQ: 12.9, CR: 0.02). This study provides baseline data for future research on the risks of PHE accumulation in livestock and their food products. Moreover, future research is warranted to fully understand the transfer of PHEs from livestock products to humans.

Bioassimilation of lead and zinc in rabbits fed on spinach grown on contaminated soil.

Accumulation of heavy metals in the environment can pose a potential risk to living organisms. Ingestion of leafy vegetables, containing heavy metals, is one of the main routes through which these elements enter the human body. The present study was conducted to assess the accumulation of lead (Pb) and zinc (Zn) in spinach grown on metal contaminated soil, and to examine the bioassimilation of these metals in spinach-fed rabbits. Spinach grown in the fields spiked with Pb (1000 mg kg-1 soil) and Zn (150 mg kg-1 soil), was fed to the rabbits for 14 days. Concentrations of Pb and Zn in the leaves of spinach were 39.1 and 113 mg kg-1, respectively. For the assessment of Pb and Zn concentration, blood samples were collected after 24 h, 7 days and 14 days of feeding, while the essential organs, i.e. liver and kidneys of rabbits were collected at the end of feeding trials. Concentrations (mg L-1) of Pb (3.28) and Zn (7.10) increased in blood after 24 h compared to control treatment and then decreased (Pb 1.12; Zn 3.32) to a steady state with the passage of time after 7 days. A significant increase in the concentrations of Pb (1.20%, 3.95% and 5.58%) and Zn (10.7%, 6.89% and 18.4%) as compared to control treatment was also found in liver, kidney and bones of the rabbits, respectively, which was further confirmed by multivariate analysis. The highest significant values of correlation coefficient (r) were observed for blood and bones, i.e. 0.992 followed by blood and liver, i.e. 0.989. The bioassimilation of Pb in the body of rabbits was in the order of bone > kidney > liver > blood, while for Zn the order was bone > liver > kidney > blood. The bioassimilation of Pb and Zn in the blood, essential organs and bones depicted the serious health risks associated by consuming the metal contaminated vegetable.

Hydrogeochemical and health risk investigation of potentially toxic elements in groundwater along River Sutlej floodplain in Punjab, Pakistan.

Understanding groundwater quality and hydrogeochemical behavior is important because consumption of the potentially toxic elements (PTEs)-contaminated drinking water may induce several health problems for humans and animals. In the current study, we examined the potential groundwater contamination with various PTEs (arsenic, As; cadmium, Cd; copper, Cu; manganese; Mn) and the PTEs-induced health risk. Groundwater (n = 111) was characterized for total As, Cd, Cu, and Mn concentrations and other water quality attributes along the River Sutlej floodplain of Punjab, Pakistan. Results revealed that groundwater, which is used for drinking purpose, contained high concentrations of As and Cd (mean As: 33 µg/L, mean Cd: 3 µg/L), exceeding 100% and 32% than the World Health Organization's safe limits (10 and 3 µg/L, respectively) in drinking water. The other water quality attributes (i.e., EC, HCO3, Cl and SO4) were also found above their safe limits in most of the wells. Hydrogeochemical data showed that groundwater was dominated with Na-SO4, Na-Cl, Ca/Mg-CO3 type saline water. The hazard quotient and cancer risk indices values calculated for As and Cd indicated potential threat (carcinogenic risk > 0.0001 and non-carcinogenic risk > 1.0) of drinking groundwater in the study area. This study shows that the groundwater along River Sutlej floodplain poses a health threat to the communities relying on it for drinking and irrigation due to high concentrations of As and Cd in water. Moreover, it is important to monitor groundwater quality in the adjacent areas along River Sutlej floodplain and initiate suitable mitigation and remediation programs for the safety of people's health in Punjab, Pakistan.

Distribution and health risk assessment of trace elements in ground/surface water of Kot Addu, Punjab, Pakistan: a multivariate analysis.

Water is a key component for living beings to sustain life and for socio-economic development. Anthropogenic activities contribute significantly to ground/surface water contamination particularly with trace elements. The present study was designed to evaluate distribution and health risk assessment of trace elements in ground/surface water of the previously unexplored area, Tehsil Kot Addu, Southern-Punjab, Pakistan. Ground/surface water samples (n = 120) were collected from rural and urban areas of Kot Addu. The samples were analyzed for physicochemical characteristics: total dissolved solids (TDS), pH, and EC (electrical conductivity), cations, anions, and trace elements particularly arsenic (As), lead (Pb), cadmium (Cd), and zinc (Zn). All of the water characteristics were evaluated based on the water quality standards set by World Health Organization (WHO). Results revealed the suitability of water for drinking purpose with respect to physicochemical attributes. However, the alarming levels of trace elements especially As, Cd, and Pb make it unfit for drinking purpose. Noticeably, 23, 96, and 98% of water samples showed As, Cd, and Pb concentrations higher than the permissible limits. Overall, the estimated carcinogenic and non-carcinogenic risk to the exposed community was higher than the safety level of USEPA, suggesting the probability of cancer and other diseases through long-term exposure via ingestion routes. Therefore, this study demonstrated an urgent need for water filtration/purification techniques, and some quality control measures are warranted to protect the health of the exposed community in Tehsil Kot Addu.

Comparative physiological and biochemical evaluation of salt and nickel tolerance mechanisms in two contrasting tomato genotypes.

Plant tolerance against a combination of abiotic stresses is a complex phenomenon, which involves various mechanisms. Physiological and biochemical analyses of salinity (NaCl) and nickel (Ni) tolerance in two contrasting tomato genotypes were performed in a hydroponics experiment. The tomato genotypes selected were proved to be tolerant (Naqeeb) and sensitive (Nadir) to both salinity and Ni stress in our previous experiment. The tomato genotypes were exposed to combinations of NaCl (0, 75 and 150 mM) and Ni (0, 15, and 20 mg l-1 ) for 28 days. The results revealed that the tolerant and sensitive tomato genotypes showed similar response to NaCl and Ni stress; however, the level of response was significantly different in both genotypes. The tolerant tomato genotype showed less reduction in growth than the sensitive genotype against both NaCl and Ni stress. Root and shoot ionic analysis showed a decrease in Na and increase in K concentration by increasing Ni levels in the growth medium. Moreover, accumulation of Na and Ni in tissues showed a decrease in membrane stability index and an increase in malondialdehyde contents. The activity of superoxide dismutase, catalase, peroxidase and glutathione reductase under NaCl and Ni stress was significantly higher in the tolerant compared to the sensitive genotype. Enhanced activity of many antioxidant enzymes in Naqeeb under stress conditions is among the other mechanisms that enabled the genotype to better detoxify reactive oxygen species and therefore Naqeeb tolerated the stresses better than Nadir.

Acid treated biochar enhances cadmium tolerance by restricting its uptake and improving physio-chemical attributes in quinoa (Chenopodium quinoa Willd.).

Heavy metals contamination of soil especially with cadmium (Cd) is a serious environmental concern in the current industrial era. Biochar serves as an excellent ameliorating agent depending upon its properties and application rates. In the pot scale study, effect of acid treated (AWSB) and untreated wheat straw biochar (WSB) was studied on physiology, grain yield, Cd accumulation, and tolerance of quinoa with possible health risks. Different levels of Cd (0, 25, 50 and 75 mg kg-1), AWSB and WSB (1% and 2% (w/w)) were applied in soil. Accumulation of Cd in control plant tissues led to oxidative stress which was shown in terms of increased lipid peroxidation. While biochar application relieved the oxidative damage as confirmed by the low production of H2O2 and TBARS contents. Application of AWSB improved plant growth, pigment contents and gas exchange attributes by limiting the accumulation of Cd in root, shoot and grain of quinoa. Results revealed a significant improvement in the activity of superoxide (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) with biochar at elevated levels of Cd in soil. Target Hazard Quotient (THQ) remained < 1 in the quinoa grains with WSB and AWSB under Cd stress. These results revealed that AWSB most effectively alleviated Cd toxicity in quinoa thereby decreasing Cd accumulation and regulation of Cd induced oxidative stress triggered by the antioxidant enzymatic system.

A multivariate analysis of comparative effects of heavy metals on cellular biomarkers of phytoremediation using Brassica oleracea.

The biochemical/physiological variations in plant responses to heavy metals stress govern plant's ability to phytoremediate/tolerate metals. So, the comparative effects of different types of heavy metals on various plant responses can better elucidate the mechanisms of metal toxicity and detoxification. This study compared the physiological modifications, photosynthetic performance and detoxification potential of Brassica oleracea under different levels of chromium (Cr), nickel (Ni) and selenium (Se). All the heavy metals induced a severe phytotoxicity to B. oleracea in terms of chlorophyll contents, Ni being the most toxic (76% decrease). Brassica oleracea showed high lipid oxidation: 87% and 273%, respectively in leaves and roots. Furthermore, all the metals increased the activities of catalase and peroxidase, while decreased superoxide dismutase and ascorbate peroxidase. Interestingly, heavy metals decreased hydrogen peroxide contents perhaps due to their possible transformation to another form of reactive oxygen species such as hydroxyl radical. Among the three metals, Ni was more phytotoxic than Cr and Se. Moreover, the phytoremediation/tolerance potential of B. oleracea to Ni, Cr and Se stress varied with the type of metal, their applied levels, response variables and plant organ type (root/shoot). The multivariate analysis separated different plant response variables and heavy metal treatments into different groups based on their correlations.