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The aim of the present study was to define potentially toxic element (PTE) concentrations, their pollution levels, their ecological risks, and the human health risks of Çoruh River sediments in Bayburt (NE Turkey). The sediment samples were analyzed through inductively coupled plasma mass spectroscopy (ICP-MS). The concentrations (mg/kg) of Ni, Cu, Zn, As, Pb, Cr, and Hg varied within 243.6–1134.3, 23.7–178.6, 33.0–52.0, 8.5–38.8, 4.0–7.7, 1.27–7.17, and 0.02–0.10 in the sediments, respectively. According to various geochemical indices, such as the geo-accumulation index, pollution index, pollution load index, and enrichment factor, the sediments were unpolluted by Cr, Zn, Pb, and Hg, and these elements were not enriched in the sediments. By contrast, the sediments were generally moderately polluted—very strongly polluted by Cu, As, and Ni, and these elements were moderately enriched—extremely enriched in the sediments. The results of the ecological risk factor for Ni, As, Cu, and Hg ranged from a low to a high potential ecological risk (RI). The RI values revealed that the investigated area was in a high-risk condition because the corresponding RI value was greater than 150. The outcomes of the modified hazardous quotients demonstrated that Ni, As, and Cu would pose an important health risk if humans were exposed to the sediments and could be hazardous to aquatic animals in Çoruh River. The hazard quotient for ingestion and the hazard index of As for children more than a year old in the high-intensity residential area indicated that As would pose an important health risk if children were exposed to the sediments. Pearson's correlation matrix and principal component analyses showed that the accumulation of PTEs in Çoruh River's sediments was related to anthropogenic and geological sources. [ABSTRACT FROM AUTHOR]

The use of chelators with high biodegradability is a promising strategy to remove potentially toxic elements (PTEs) from soils by washing. The current study investigated the potential of nitrilotriacetic acid (NTA) to remove Cd from Cd-contaminated soil from Iran (calcareous soil, ICd) and Belgium (acidic soil, BCd). Washing tests were carried out with soils artificially contaminated with 2 levels of Cd (20 and 40 mg kg−1), 4 levels of NTA (0, 2, 5, and 15 mmol L−1), different pHs (4, 7, and 10), and different contact times (20, 40, and 60 min). The results showed that the optimal concentrations of NTA were 5 and 2 mmol L−1 for ICd and BCd, respectively. After using NTA5 compared to NTA0, Cd removal at pH 4, 7, and 10 increased by 1, 76, and 80% in ICd20 and 1, 77, and 81% in ICd40, respectively. These values were 46, 53, and 52% in BCd20 and 32, 64, and 62% in BCd40, respectively, after using NTA2. Also, in the first 20 min of the experiment, 95–100% and 75–80% of the maximum extractable Cd were removed from ICd and BCd, respectively. Moreover, NTA extracted a higher percentage of Ca, Fe, Al, Zn, and Cu from BCd compared to ICd (as an exception, the percentage of Ca extracted at pH 4 was higher in ICd compared to BCd). The results showed that the physical/chemical properties of soils affect the washing efficiency and should be taken into account before selecting the type and dose of chelate to remove metals in a given soil. [ABSTRACT FROM AUTHOR]

Various techniques are employed nowadays to lessen the harmful consequences of high soil concentrations of heavy metals (HMs). In this instance, a relatively novel technique to lessen the toxicity of HMs is the use of biochar. In this study, in order to investigate the effect of sugarcane bagasse biochar on improving the growth of corn (Zea mays L.) in Cadmium (Cd) and lead (Pb) contaminated soil; a pot experiment was conducted in a randomized complete block design. The variables included planting maize, which was done in two independent experiments for Cd and Pb, three levels of Cd (0, 40, and 80 mg kg-1 of soil from CdSO4.8H2O), three levels of Pb (0, 400, and 800 mg kg-1 of soil from PbSO4), and two levels of sugarcane bagasse biochar (0 and 5% by weight). The results showed that increasing Cd and Pb treatments significantly increased the concentrations of these two elements in the maize shoots and roots and markedly decreased the dry weight of the shoots and roots by 35 to 45% and between 55 and 65%, respectively. A rise in Cd and Pb content was also accompanied by a notable decrease in the chlorophyll index, leaf area, plant height, and dry weight of roots and shoots. However, the use of sugarcane bagasse biochar increased the chlorophyll index, leaf area, plant height, and dry weight of the roots and shoots as a result of a considerable decrease in the concentration of Cd and Pb in the roots and shoots. In compared to the control, the translocation coefficient and bioconcentration factor reduced after the application of 5% sugarcane bagasse biochar. According to the findings, sugarcane bagasse biochar may stabilize and adsorb Pb and Cd from soil. It follows that adding sugarcane bagasse biochar to HM-contaminated soils is an appropriate remedial treatment that will promote plant development. [ABSTRACT FROM AUTHOR]

Environmental contamination due to mines disturbs biological and physio-chemical properties of the soil. Literature available discussing environmental contamination and physical disturbances (waste dumps, loss of vegetation, and quarry sites) due to mines was critically evaluated to understand the implication of mines on soil organic matter. The factors responsible for organic matter (OM) degradation are divided into two categories, i.e., major (direct) and minor (indirect). The impacts due to major factors (decrease in OM at the quarry and waste dumping sites) in OM degradation are easy to quantify and directly caused by mines. The conversion of fertile land into quarry and waste dumping sites lead to loss of soil carbon and imbalances the ecosystem structure. The lack of nutrients and organic matter hinders the revegetation process of waste dump sites. The role of minor factors is not easy to quantify (reduction of OM due to land use and land cover change, depletion of water resources, heavy metal contamination, etc.) and indirectly impacts the OM degradation. The heavy metal contamination of neighboring soil retards the growth of plants and decreases the OM turnover. The soil erosion, loss of agricultural lands, deforestation, loss of soil moisture, depletion of water resources, decrease in microbial activities, and land subsidence in the mining region indirectly contribute to OM degradation. The degradation or release of carbon stored in the soil increases CO2 in the atmosphere contributing significantly to climate change. Mines spread in 57,277 km2 across the world and in India mine wasteland covers 2256 km2 of area. The wider spread of mines suggests that the degradation of OM and its contribution to climate change is in significant quantity at the global level. Further research on the degradation of organic carbon in the vicinity of mines and its contribution to climate change is recommended. [ABSTRACT FROM AUTHOR]

Crop coefficients are important to determine crop evapotranspiration (ETc), seasonal crop water requirement, and irrigation water depth. Similarities between the curve of crop coefficient and remote sensing-based vegetation indices of a crop during its growth period suggested the possibility of modeling crop coefficient (Kc) as a function of vegetation indices. In this study, high-resolution multispectral (MS) images of a rice crop acquired using a quadcopter unmanned aerial vehicle (UAV) were processed to generate Kc maps. Lysimeter experiments were conducted for estimating daily ETc of rice using the water balance concept for conventionally irrigated paddy during kharif (monsoon) 2018/2019, rabi 2018/2019 (non-monsoon), and kharif (monsoon) 2019/2020 seasons. The average lysimeter-based crop coefficients for all three seasons were observed to be 1.04, 1.24, 1.36, and 1.18 for initial, crop development, reproductive, and late growth stages of the rice crop season, respectively. The mean Kc was significantly different for the growth stage, but it was not significantly different for the season. Among the eight vegetation indices tested, the ratio vegetation index (RVI) and normalized difference red edge (NDRE) were found to be correlated well with the lysimeter-based Kc for the kharif 2019/2020 season. The developed linear regression equations (RVI vs. Kc; NDRE vs. Kc) were tested using kharif 2018/2019 and rabi 2018/2019 seasons and found acceptable levels of different performance indices. These regression models will be helpful in generating Kc maps and estimating irrigation water requirement of paddy crop (MTU 1010 variety) in the sub-humid subtropical region. [ABSTRACT FROM AUTHOR]

Experiment was conducted to assess the effect of combined application of biochar and organic manure amendment in an acidic hilly soil on grain quality, nutrient contents, biomolecular composition and biochemical response, and energy budgeting as well as soil quality under maize-black gram cropping system. Our results suggested that biochar application increased protein content. Lysine content decreased with manures addition and increase in biochar application rate. Hydration index, swelling index, water absorption capacity, and water uptake ratio increased in both the manures without biochar and manures with biochar. The seed density, foaming capacity, and foam stability increased significantly with addition of both manures without biochar and manures with biochar. Biochar application increased the nitrogenase activity. Manures without biochar application increased nodule relative water content and manures with biochar addition decreased nodule relative water content. Biochar application significantly decreased number of nodules per plant. Results revealed that protein, ash, tannin, C, N, P, K, Zn, Fe, Cu, Mn, and B content significantly increased and enhanced by both the manures without biochar and manures with biochar. The nodule soluble sugars were increased by manures and biochar application. Both the manures and biochar significantly enhanced all the energy related terminology in maize and black gram crop. Results suggest that biochar application may affect the grain quality in maize and black gram adversely and nutritional imbalance in grains might occur. [ABSTRACT FROM AUTHOR]

The study was conducted to analyse the potentially toxic elements (PTEs) (Fe, Cu, Co, Mn, Zn, Ni, Cr, Se, Cd, As and Pb), and pH, phosphorus and organic carbon in roadside soils of the Punjab state, India. The results showed that Fe concentration recorded maximum, while Co concentration was found lowest among the analysed PTEs. Enrichment factor exhibits very high enrichment of PTEs suggesting their anthropogenic addition. The ecological risk assessment results revealed that study area was moderate to highly contaminated by the PTEs, while Cd is the main element responsible for contamination in the area. The non-carcinogenic health risk method recommended by the U.S. Environmental Protection Agency signifies that average hazard indices were less than 1, implying no significant threat of non-carcinogenic perils to both children and adults. The carcinogenic results indicated that As, Cr and Pb showed high threat by ingestion route in contrast with the inhalation route. [ABSTRACT FROM AUTHOR]

Soil contamination with cadmium (Cd) is problem nowadays due to industrialization. A pot experiment was conducted to assess the exogenous effect of calcium nitrate (CaNO3) on morphological traits, photosynthetic efficiency, oxidative stress indicators, secondary metabolites and enzymatic antioxidative capacity in two chickpea (chickpea-brittle and chickpea-2008) cultivars under Cd stress (0 and 200 μM). Results revealed that the Cd stress caused a significant (p < 0.05) reduction in biomass production, photosynthetic pigments, flavonoids and phenolics whereas increase in the activities of various antioxidative enzymes like superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) as well as malondialdehyde (MDA) and H2O2 content. Cd-administered plants accumulated proline and total soluble proteins in substantial amount. However, results also show that chickpea-brittle showed more tolerance to the chickpea-2008 under the same levels of Cd in the soil. The leaves may be treated with Ca(NO3)2 to reduce toxic effects of Cd, which enhances biomass through increased plant growth along elevated pigments of photosynthetic, activities of antioxidant enzymes and levels of secondary metabolites, in comparison to untreated plants. Additionally, fortifying the Ca(NO3)2 application also decreases the levels of oxidative damaged to membrane-bounded organelles in the plants. Our findings suggested that Ca(NO3)2 spray can mitigate Cd toxicity and leads to increased chickpea growth and yield under Cd-contaminated conditions depicting by decreasing oxidative stress within cell. It was concluded that foliar application of Ca(NO3)2 may alleviate toxic effects of Cd in studied chickpea cultivars through enhanced plant growth, high content of photosynthetic pigments and low oxidative stress under Cd treatments. [ABSTRACT FROM AUTHOR]

During a landfill's service, a large amount of methane will be produced and released attributable to microbial degradation of organic matter; this methane escapes into the atmosphere even with gas traps in place. Methane is a flammable and explosive greenhouse gas. When the concentration of methane in the landfill reaches a certain limit, it can cause explosions, fires, and other accidents, and its potential global greenhouse effect is approximately 25 times higher than that of carbon dioxide. Therefore, because the emission of methane from landfills into the atmosphere aggravates the greenhouse effect, for the sake of safety and environmental protection, it is urgent to take measures to reduce the ability of methane to escape through the landfill cover. Methanotrophs are microorganisms that use methane as their sole carbon and energy source and have a strong ability to oxidize methane biologically. In this paper, methanotrophs' methane removal efficiency in an inorganic salt culture medium was studied. It was found that the methane removal efficiency in the inorganic salt culture medium increased first and then decreased as the pH or initial methane concentration increased. Methanotrophs' methane removal efficiency in this study was highest when the pH was equal to 7, or the initial methane concentration was equal to 2%. Biochar is an economic and environment-friendly "green material" with a porous structure, high specific surface area, and high ion exchange capacity. It can adsorb escaped methane and can provide a good habitat for methanotrophs. In this paper, biochar-methanotroph-amended clay was taken as the research target, and the effects of the presence or absence of methanotrophs, the amount of biochar, and the compactness of soil on the removal of methane were analyzed, and the methane removal efficiency of biochar-clay mixture with methanotrophs was studied. The above experiments were conducted under laboratory-scale conditions, and the methane concentration, pH, and dry density were set with reference to the measured data in the cover of the landfill in order to expect the closest possible approximation to the actual landfill cover experimental environment. The results showed that the efficiency of methane removal increased first and then decreased as the biochar content and compaction increase. Furthermore, the efficiency of methane removal was strongest when the biochar content was 15% or the dry density was 1.2 g/cm3. [ABSTRACT FROM AUTHOR]

In this study, arsenic (As) adsorption in 2 calcareous soils with different properties (A and B) under amendment with sewage sludge (SS) and its biochar was investigated. The spectroscopic analysis showed that SS and its biochar have a rough surface and several organic functional groups. The kinetic study demonstrated a rapid initial uptake rate of As in the first 4 h, followed by a slower adsorption rate that reached equilibrium after 16–64 h in different treatments. When SS, native biochar, and modified biochar were added to soil A, which had a lower organic matter and cation exchange capacity (0.64% and 12 Cmolc kg−1, respectively), the percent of As adsorption after 88 h was 13.16, 13.74, and 15.12, respectively while the corresponding values for soil B, which had a higher organic matter and cation exchange capacity (3.52% and 16.9 Cmolc kg−1, respectively), were 14.76, 17.36, and 24.00, respectively. The cumulative As adsorbed (qe, ex) was in the range of 56.7–120.0 mg kg−1 with an average of 76.9 mg kg−1, while the predicted amounts by pseudo-second-order equation (qe, cal) were in the range of 59.0–120.6 mg kg−1 with an average of 78.0 mg kg−1. This indicates that the pseudo-second-order equation describes the kinetic adsorption of As in control and amended soils well. The distribution coefficient (Kd) values of As adsorption varied from 1.65 l kg−1 in the control soil A to 6.14 l kg−1 in soil B amended with modified biochar. According to maximum adsorption (Qmax) predicted by the Langmuir equation, soil B amended with modified biochar had the highest capacity for As adsorption (177.03 mg kg−1). Modification of the biochar increased the As adsorption in soils A and B from 87.45 to 98.30 mg kg−1 and from 119.3 to 177.03 mg kg−1, respectively. High capacity of soils in As adsorption could be due to the presence of iron oxides in the SS. The main innovative aspect of this study is application of SS biochar as a soil amendment in As-affected lands. The findings of this research can be useful for farmers and environmental organizations. [ABSTRACT FROM AUTHOR]

Biochar is an organic and pyrogenic material produced by pyrolysis of animal or plant-based feedstocks. In recent days, biochar has gained much attention due to its unique physiochemical properties and distinct role in improving the soil biological and physiochemical properties, carbon sequestration and remediation of organic and inorganic pollutants. However, performance of biochar in a specific role is largely dependent on its physiochemical properties which are influenced by biochar preparation conditions. The specific aim of this review paper is to highlight the impact of different biochar preparation conditions including pyrolysis temperature, type of feedstock and acid modifications on physiochemical properties of biochar such as pH value, pore volume, cation exchange capacity (CEC), volatile matter, specific surface area (SSA), carbon and ash contents. Biochar produced at higher pyrolysis temperature contains high pH, carbon and ash contents, high porosity and specific surface area but with lower volatile matter and cation exchange capacity values. The aforementioned changes occurred due to substantial decomposition of organic materials at high pyrolysis temperature. Biochar obtained from solid waste and animal manure feedstocks contains lower volatile matter, carbon contents and specific surface area but higher cation exchange capacity than biochar derived from wood and crop residue feedstocks. These changes are mainly attributed to profound variations in moisture, cellulose and lignin contents of feedstocks. Acid modification of biochar with oxalic acid, citric acid, sulphuric acid, phosphoric acid and hydrochloric acid increases surface functional groups (hydroxyl, carbonyl and carboxyl), specific surface area and porosity while pH value is decreased. The findings of this review paper suggest that a cost-effective and specific type of biochar with desirable physiochemical attributes can be prepared based on biochar preparation conditions, to solve specific environment or agriculture-related problems. [ABSTRACT FROM AUTHOR]

Wheat straw biochar (WSB) and lignite are counted as soil conditioners which used to improve soil properties and promote plant growth. Astragalus podolobus Boiss. & Hohen is a palatable species from Fabaceae family that is used for restoring of rangelands and fodder production as well as soil conservation against erosion. In this experiment, we studied the influence of WSB and lignite on soil properties and the plant traits of A. podolobus. For this purpose, the WSB and lignite were incorporated at levels of 0%, 1.25%, 2.5%, and 3.75% (w/w) in six repetitions. For this purpose, the experiment was done in pots at greenhouse condition. Data were analyzed statistically by one-way analysis of variance in SPSS21 software. The results demonstrated that WSB and lignite addition improve the soil microbial biomass (SMB) and chemical properties, e.g., electrical conductivity (EC), soil organic carbon (SOC), total N, phosphorus, and magnesium, but A. podolobus did not respond positively to these amendments. Also, lignite 3.75% (w/w) is the most effective treatment on improving soil properties. The SOC (g.kg−1) varied from 1.9 in the control to 4.6 and 6.5 by WSB and lignite at 3.75% (w/w), respectively. On the other hand, SMB (µg100gr−1 of soil) was significantly increased from 5.52 in the control to 11.5 and 11.67 by lignite and WSB 3.75% (w/w), respectively. The highest plant biomass (10.50 g) and the lowest roots dry weight (3.01 and 2.69 g) were observed in soil receiving lignite at 2.5% (w/w) and 1.25% (w/w), respectively. The amendment of WSB and lignite strongly enhance the properties of clay loam solonchak rangeland soil. It is suggested to add lignite soil conditioner at level 3.75%w/w in plantation the degraded rangelands but the response of other species must be tested to rate species that responds positively to the soil properties enhancement. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) toxicity in paddy soil and its accumulation in rice has caused widespread concern due to its negative health effects. Biochar (BC) and traditional manures (farmyard manure and press-mud) are well-known to improve plant growth by decreasing the uptake of toxic heavy metals. However, the impact of various organic amendments on Cd and the accumulation of major mineral nutrients in rice have been less understood. Therefore, in the present study, wheat straw biochar (WSB), sugarcane straw biochar (SSB), press-mud (PRM), and farmyard manure (FYM) at the rate of 1% (w/w) were evaluated for Cd immobilization in soil and to enhance nutrient uptake in rice plants grown in Cd contaminated soil (6.0 mg kg−1). Before 18 days of rice nursery transplanting, the amendments were applied to Cd contaminated soil, and rice plants were harvested at maturity after 120 days of transplanting. Results depicted that the use of WSB significantly enhanced the number of grains panicle−1, straw, and paddy yield by 35, 96, and 76% as compared to the control without any amendment under Cd stress. Cd uptake was reduced by 12, 25, 58, and 44% in rice straw, and paddy yield increased by 38, 45, 76, and 66% with the use of FYM, PRM, WSB, and SSB respectively. The application of WSB and SSB caused an increase of 191 and 158% in N uptake in rice straw compared to control, respectively. Similarly, FYM and PRM improved P uptake in paddy by 118 and 136%, respectively over the control. The maximum Zn uptake in rice grains and straw was noted with the application of WSB which was around 261 and 346% higher than in control. In conclusion, BC proved more effective in soil Cd immobilization and reduction of Cd uptake in straw and paddy compared to traditional manures. [ABSTRACT FROM AUTHOR]

The aim of the present research was to investigate the removal of a specific fraction, namely, neutral dissolved organic matter (NDOM) from aqueous solutions, using commercial activated carbon as an adsorbent. The NDOM from two Algerian dams (Koudiet Lamdaouar and Beni Haroun) was isolated and concentrated using a mixed bed ion exchange resin and a reverse osmosis membrane, respectively. The results of the concentration step showed that the recovery efficiency reached more than 70% in terms of chemical oxygen demand (COD) and 74% in terms of absorbance at the wavelength 254 nm (UV254) for both dams. The results of the adsorption process show significant removal yields of 77% in terms of COD and 78% in terms of UV254 for the Koudiet Lamdaouar dam, 70% in terms of COD, and 76% in terms of UV254 for the Beni Haroun dam. Equilibrium adsorption data were fitted to the isotherm models. Langmuir isotherm best fitted the adsorption equilibrium for both dams with adsorption capacities of 286 and 288 mg/g for the Koudiet Lamdaouar and Beni Haroun dams, respectively. The kinetic study showed a pseudo-second-order kinetic model for both dams. The results of this study show that the adsorption process onto the activated carbon is a suitable treatment for the removal of NDMO from aqueous solutions. To the best of our knowledge, no study has so far been reported on the treatment of this new specific fraction using activated carbon. [ABSTRACT FROM AUTHOR]

Biochar, as soil amendment, can control the bioavailability of heavy metals in contaminated soils and reduce the risk of transferring heavy metals to the food chain. The objective of the study was to investigate the impacts of biochar derived from various wastes (apple pruning (AB), grape pruning (GB), or wheat straw (SB)) at 0%, 2%, and 5% w/w affecting lettuce growth and lead (Pb) phytoavailability in a Pb-contaminated calcareous soil. The plants were harvested 60 days after seeding and plant dry weight, Pb concentration, transfer factor (TF), biological concentration factor of shoot and root (BCF), and soil Pb phytoavailability were measured. At the highest Pb spiking, NH4NO3-extractable Pb was reduced by 24.6% and 51.8% at biochar rates of 2% and 5%, respectively, compared to the control. Application of biochar decreased Pb concentration in lettuce shoots, with the most significant reduction occurring by 5% of AB (44.0%), GB (30.5%), and SB (23.8%) at the highest level of Pb. The present findings provide novel evidence on the beneficial effects of the tested biochars, especially SB, on lettuce growth in a Pb-contaminated calcareous soil. Biochars could be used as an eco-friendly and cost-effective strategy for improving lettuce growth in metal-contaminated soils. [ABSTRACT FROM AUTHOR]

Mercury is a pollutant that is used everywhere, is harmful, and has a global impact. The ambient Total Gaseous Mercury (TGM) concentrations in the Chennai metropolis areas were measured in this study. Because of various anthropogenic source pollutants, studies of atmospheric mercury in this city are extremely significant. The measurement was conducted using a high-resolution mercury vapor analyzer (Tekran 2537B) instrument in February and March 2016. The annual mean concentration of TGM in the Chennai metropolis was 8.89 mg m−3 and 8.01 mg m−3, respectively. The extreme aggregate recurrence between the directions is WNW to NNW and NNE to ENE, and TGM was released about 39% in this region, according to this research. We performed statistical studies, and the results of the principal component analysis and conditional probability function suggest that mercury sources are equivalent to other atmospheric pollutants such as SO2, CO, NO2, and PM2.5, which are predominantly emitted by urban and industrial combustion plants. The meteorological parameters and TGM concentration have a direct relationship, according to continuous measurements of TGM in the air and dendrogram maps, and they have been essentially controlled by sunlight-based radiation. Some estimates of atmospheric mercury focuses have been conducted in the urban region; however, as far as we know, our findings are the essentials that unveiled concerning environmental aggregate vaporous mercury observed in a necessary industrialized metropolitan zone in India. This research will aid in the development of more effective management measures to reduce the effects of atmospheric mercury in the urban environment and public safety in a megacity, as well as those who may be harmed by the long-distance transit of TGM. The assessment of mercury emissions and the effectiveness of Chennai's mercury control policies is warranted by long-term observations of mercury in the city—and background regions in Chennai. [ABSTRACT FROM AUTHOR]

Salinity considers a restricting agent for plant production in arid and semiarid regions of the world. A lysimeter experiment was carried out in the 2018–2019 growing season for faba bean in saline-sodic soil, to study the effects of different levels of nano-ZnO as a foliar application under the addition of sulfur (S) alone or combined with rice straw compost (C) on the chemical properties of the saline-sodic soil and faba bean (Vicia faba L.) productivity. The results indicated that the application of S alone or combined with C significantly increased removal sodium efficiency (RSE), exchangeable Ca, availability of nutrients (NPK), organic matter (OM), and faba bean yield as compared to control. A total yield of faba bean was increased by about 39.7% in the plots treated with the nano-ZnO foliar application at 2% as compared with the control. The decrease in soil ESP and EC under the S+C with nano-ZnO at 2 g·L−1 was 44.95% and 22.13% greater than the control treatment. The mixtures of S+C with nano-ZnO foliar application gave better results in increasing the plant height and total yield, especially the rate of 2% of nano-ZnO as compared to adding them individually. The experimental results concluded that the integration effect of nano-ZnO as a foliar application with organic fertilizer and sulfur as amendments to reclaim saline-sodic soil can be used as a promising strategy to improve its properties and increase the bean yield. [ABSTRACT FROM AUTHOR]

Tarabalo geothermal area is one of the eight geothermal areas existing in the Indian state of Odisha. The present study aims to (i) understand the influence of thermal spring water and agricultural activities on the spatial distribution of trace elements in the soil, (ii) delineate the contamination of heavy metals, and (iii) identify the possible sources of trace elements in the soil. For these purposes, thermal spring water samples were collected from 9 locations and twenty soil samples were collected in a gridded pattern from the geothermal area. Trace elements such as As, Ba, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Pb, Sb, Se, Th, Tl, U, V, and Zn are considered in this study. The trace element concentrations in the soil show wide variation ranging from 0.02 (Be) to 931.4 mg/kg (Mn). The contribution from thermal spring water is considered to have a limited effect on the accumulation and distribution of trace elements. The values obtained from Igeo, EF, and ERF to delineate contamination of heavy metals in the soil show that it is enriched with heavy metals such as As and Pb. Based on ERI values, the ecological risk caused by the concentration of heavy metals in the study area is low. Trace element concentrations in the soil are considered to be significantly from geogenic source and moderately from anthropogenic activities. [ABSTRACT FROM AUTHOR]

Nile Delta represents 63% of Egypt's fertile agricultural land. Unfortunately, food chain contamination with potentially toxic elements (PTEs) was recorded along Cairo- Alexandria Highway within Nile Delta. This paper aims to identify pollution sources of PTEs (Cd, Pb, Co, Ni, Zn, Cu, Cr, and Mn), using multivariate statistics. Generally, the studied soil is alkaline loam with about 3.69% CaCO3 and 1.97% organic matter. Pollution levels varied widely from uncontaminated to highly contaminated soil. Cd, Pb, Co, and Ni showed spatial variability, relatively high enrichment, reflecting their anthropogenic sources. Mn and Cr show more uniform distribution, reflecting their natural source from the geologic parent material of Egyptian soil. Surprisingly, no significant road traffic impact was observed at the sampling sites. Multivariate analysis indicates P-fertilizer is the main pollution source rather than traffic in roadside soils. The prevailing of fertilizers as a pollution source may be referred to the expansion in the use of unleaded fuel and the continuous increase in the annual fertilization rate. [ABSTRACT FROM AUTHOR]

Understanding the impact of physiographic position and agricultural practices on Mn forms is an important option to improve current Mn management. This work mainly aimed to investigate the effects of land physiographic position and agricultural practices on Mn forms in soils under long-term continuous wheat (Triticum aestivum L.) cultivation. In this regard, the changes and distribution of total Mn (Mnt), DTPA-extractable Mn (MnDTPA), free Mn (Mnd), crystalline Mn (Mnc), poor crystalline Mn (Mno), and organic complex Mn (Mnp) were determined in the agricultural soils (under wheat cultivation) developed on different physiographic positions. These units included piedmont alluvial plain (PA), river alluvial plain (RA), plateau (PL), and lowland (LO). In addition, the geoaccumulation index (Igeo), enrichment factor (CF), and bio-concentration factor (BCF) of Mn in the soil-wheat system was investigated. The results show that agricultural practices have resulted in remarkable changes in the level and pattern of different forms of Mn, the indices of metal accumulation, and wheat yield components into physiographic positions. A considerable variation was recorded in Mnt (206–1006 mg kg-1), MnDTPA (1.9–11 mg kg-1), Mnd (32–250 mg kg-1), Mnc (3–135 mg kg-1), Mno (34–240 mg kg-1), and Mnp (7–66 mg kg-1). Factor analysis, supported by correlation analysis, shows that particle-size distribution, organic carbon, calcium carbonate, SiO2, Al2O3, and Fe2O3 have the predominant influence on the distribution of Mn forms. All soil samples were not contaminated to moderately contaminated by Mn using the geoaccumulation index (Igeo) and enrichment factor (EF). The BCF values were also < 1, showing the inability of wheat to bioaccumulate Mn. Data show evidence concerning the effect of agricultural practices and physiographic position on Mn forms, allowing commendations for improving the management of the soil-wheat system in a semi-arid region. All soil sites can be considered safe for the production of healthy crops regarding soil-wheat pollution with Mn. [ABSTRACT FROM AUTHOR]

The study examines about the red sand dune deposit locally designated as teri deposits; it is an omnipresent geomorphologic feature present in the coastal region of Thoothukudi and Ramanathapuram districts of Tamil Nadu, India. One of the inland teri sand dune outcrops is located around the Kuthiraimozhi village of Thoothukudi district in Tamil Nadu, India. Textural, mineralogical and geochemical studies were carried out in the teri sediments and its compact sandstone outcrops. The sediments are moderately sorted to well-sorted and finely skewed nature which indicates that fluvio-marine depositional environment. Geochemical analysis results of major, trace and rare earth elements for teri deposits help to predict the provenance, weathering status, depositional environment and climate. The geochemical study reveals that the sediments were derived from marine and non-marine sources. Teri sediments are geochemically classified as lithic arenite or wacke. Petrography and X-ray diffraction analysis reveal the predominance of quartz and feldspars along with the accessory minerals like ilmenite, rutile, garnet, magnetite, hematite, zircon, diopside, hypersthenes and biotite. Mineralogical observation illustrates that the teri sediments have originated from the weathering of felsic and mafic source rocks. The Chemical Index of Alteration (CIA) values of sediments represent moderate to the high status of weathering conditions in the source area. The depositional environment indicates that the sediments are fine-grained with high maturity index. Despite that the sediments are formed by fluvio-marine sources, the reddening character in the teri deposits is due to oxidation and leaching of iron-bearing minerals by percolating surface water from high rainfall and groundwater fluctuation of the aquifer under arid and semi-arid climate conditions. [ABSTRACT FROM AUTHOR]

In fly ash–contaminated soils, metal buildup and translocation and their subsequent uptake in different parts of naturally growing plants were studied. The mean metal levels in soil and plants at uncontaminated site were significantly (p < 0.01) lower than the contaminated site. In polluted soils, metal enrichment factor (EF) was observed in order of Cd > Fe> Cr > Zn > Pb > Cu > Ni > Mn. The shoot enrichment factor (SEF) of Pithecellobium dulce (P. dulce) was Cd > Fe > Zn > Cr > Ni > Cu > Mn > Pb, whereas for Azadirachta indica (A. Indica) and Cassia fistula (C. fistula), the SEF was of the order Fe > Cd > Cr > Zn> Ni > Mn > Cu > Pb, respectively. Root enrichment factor (REF) for P. dulce was Cd > Fe > Zn > Ni > Cu > Cr = Mn > Pb, but in A. indica, the REF was Fe > Cd > Zn > Ni > Mn > Pb > Cu > Cr, and in C. fistula, this order was Fe > Cd > Zn > Ni > Cr > Cu > Mn > Pb. Metal mobilization ratio in plants at both sites were below 1, except Mn and Fe at contaminated site. Single and combined element pollution indexes (SEPI and CPI) and shoot contamination factor (SCF) at contaminated soil were higher than uncontaminated, but root contamination factor (RCF) between sites shows a variable response. From ANOVA results, metal concentration showed significant variation due to site, plants, location, and season interactions. [ABSTRACT FROM AUTHOR]

The cadmium (Cd) uptake and accumulation in the cereal crops like wheat and rice are a serious concern in recent years. Application of various organic amendments in Cd-contaminated soil is an effective technique in management of crop growth and health as organic amendments not only promote plant's growth but also check Cd translocation in plants. For this purpose, 3 organic amendments (wheat straw biochar (WSB), cotton stick biochar (CSB), and compost comp) were applied @ 0.5% (under randomized complete block design with 4 replicates) in sewage water fed Cd-contaminated soil for effective locking of Cd in soil being cultivated with wheat and rice. The experiment was completed in almost 1 year (December 2014 to November 2015). Our results revealed that all amendments can enhance plant growth and physiology and decrease soil bioavailable Cd contents, but WSB was most prominent among 3 applied. Our results conclude that WSB can enhance straw yield (29.20 and 26.78% for wheat and rice) and grain yield (22.69% and 26.70%) and boast all physiological attributes (chlorophyll contents, stomatal/substomatal conductance, photosynthetic and transpiration rate). Application of WSB decreased post-harvest bioavailable soil Cd contents after wheat and rice crops to 56.37, 48.99% and 7.63, 26.78% in 0–15-cm and 15–30-cm soil depths, respectively. The WSB also decreased Cd translocation in grain, thus helping in decreasing the health risk index (HRI) associated with Cd-contaminated grain consumptions. For economics, amendment application in wheat crops increases its cost, so the benefit–cost ratio was observed to be less than 1. But for upcoming cropping seasons, residues of amendments will still be actively influencing plant growth and yield, so we expect a net higher benefit–cost ratio proving long-lasting use of amendments (especially WSB) a net beneficial approach. [ABSTRACT FROM AUTHOR]

Hydrochar is a carbon-rich material produced by the hydrothermal carbonization (HTC) of biomass. As a new concept, hydrochar has generated much research interest due to its ability to employ wet and dry biomass as feedstocks and its application in the agronomical, environmental, and energy sectors. This review considers the developments made with hydrochar as a soil amendment in terms of soil fertility, carbon sequestration, and fate of pollutants based on the available data. Moreover, the economic feasibility using a life cycle assessment of hydrochar has also been discussed. This review assessed that the hydrochar is an environmentally friendly soil amendments for plant growth by slow release of nutrients and carbon sequestration. Hydrochar application to the soil may increase the soil's water-holding capacity but decreases the bulk density, although the water-holding capacity of hydrochar depends on the reaction temperature and particle size of the materials. Furthermore, the hydrochar may exert a positive effect on growth and abundance of different soil microbes. This paper not only summarizes the recent advances made in developing hydrochar as a soil amendment, it also discusses the challenges and limitations of hydrochar in a wider context. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the performance of nonlinear (NL) and linearized Langmuir models to fit the experimental data of cadmium (Cd) sorption to soils. Cd-sorption data, collected from 19 soils, were fitted to the NL and four linearized Langmuir models. Functional evaluation of the models was provided to compare Cd transport simulated by HYDRUS-1D. Furthermore, it was determined if sorption parameter values obtained either by NL fitting of the Langmuir model or by linearized alternatives would affect simulation of Cd transport in soil.The NL fit of the Langmuir model performed best. The best linearized model was subjective, either depending on the similarity between obtained sorption parameter values compared with the NL model or the variations in the prediction error in Cd sorbed to the soils. The magnitude of error varied at different concentrations, and the best model in terms of its prediction accuracy was dependent on the concentration (C) at which was needed to estimate the Cd sorption to the soil (S). The simulation of Cd transport in soil, using the values of sorption parameters obtained via either fitting the NL or linearized Langmuir models, showed that at a specific soil extract concentration, 1.24 mg Cd L−1, a linearized model demonstrated simulations most like that of the NL model. The linearized model with the lower prediction error was different from the linearized models that were most similar to the NL model to simulate Cd transport in soil. Furthermore, the linearized model with the most comparable parameter values to the NL model did not demonstrate a lower prediction error. The findings suggest that it is vital to generate sorption data over the concentration range of interest for specific applications. [ABSTRACT FROM AUTHOR]

This study introduced modified biochar to enhance the adesorption isotherms of hexavalent chromium in a calcareous soil. Almond soft husk and rice husk biochars as precursor reagents were applied to prepare the modified biochars with abundant amino groups for heavy metal removal. For this purpose, biochars included levels zero (without biochar or control) and 4 wt% (unmodified biochar and modified biochar). Biochars were modified separately with Fe3O4, NaOH, KOH, H2SO4, and HNO3 and four levels of potassium dichromate (0–150 mg/kg soil) were used. Sampling from the treated soil was carried out 5 months after the contamination of soil with chromium. All treatments (5 g) were extracted with 25 mL of a 0.01 M EDTA solutions. The suspensions were shaken for different time periods (5 to 2880 min) at 150 rpm. Concentration of Cr was analyzed in each extract by atomic absorption spectrophotometer. The results indicated that adding rice husk and almond soft husk biochars to the soil resulted in a decrease in Cr uptake at all extraction times compared to control, whereas the rice husk biochar showed a lower reduction in Cr removal than the control compared to the almond soft husk biochar. Based on the determination coefficient and standard error, the best two-constant rate equations are considered the best predictor of the chromium release kinetics trend in the studied soil. [ABSTRACT FROM AUTHOR]

The potentially bio-available heavy metals were assessed in the bulk and the three fine fraction sediments (Ø3, Ø4, and Ø5) from 24 stations across Lake Burullus. We found the same pattern of metal contents in all fractions with the sequence: Fe > Mn > Zn > Cu ≥ Ni > Pb > Cd. The recorded concentrations of Cu, Zn, Ni, Mn, and Fe in Burullus were higher than the coastal area outside the lagoon. Some metals showed trend of different spatial distribution inside the lake; the highest Cu (40.7–82.2 μg/g) and Mn (495.6–690.7 μg/g) was recorded in the middle sector and Fe (1912.6–2017.4 μg/g) recorded in the western sector of the lake. The concentrations of Cu in Ø4 (41.4–82.2 μg/g) and Ø5 (28.2–76.2 μg/g) were relatively higher than in the total sediments (5.8–44.8 μg/g); meanwhile, Fe and Mn in fine fractions reached 1.2–1.5 times higher than bulk sediments. Correlation coefficient and principal component analysis (PCA) showed strong association between Cu, Zn, and Ni. On the other hand, there was partial association of Mn with Fe indicating anthropogenic sources from the industrial and agriculture drains. The calculated environmental and biological indices pointed out that the leachable metals in Lake Burullus were classified between unpolluted and moderately polluted. The potential biological adverse effects were in minimum susceptibility because the levels of metals were predominantly below the sediments severe effect levels (SEL) quality guidelines. [ABSTRACT FROM AUTHOR]

The ecological importance of Musa fjord has made it one of the remarkable marine ecosystems in southwestern of Iran. The fast development in terms of industrialization has exposed the Musa fjord to a serious threat from the effect of pollutants including heavy metals. This study aims to assess the temporal trend of heavy metal content in Musa fjord sediments and highlighting hot spot zones, the zones with high levels of heavy metals, based on the processing of the previous published data. The results showed an increasing temporal trend for Cu, Zn, Ni, Pb, Cd, and Hg (7.20, 3.36, 3.32, 0.44, 0.34, and 0.29 mg kg−1 year−1 respectively). The highest concentrations of Hg, Cd, and Cu were found in Pet Zone, which can be due to discharging petrochemical industries and chloralkali plants sewages and painting ships. The highest concentration of Pb was observed in Mouth, which is probably due to the shipping routes. The highest concentrations of Zn in Zangi might be attributed to nearing the jetties for loading mineral materials. And the highest concentrations of Ni in Ghazale might be explained by loading and unloading petroleum. Hg and Ni were the most critical pollutants in this area and have frequently adverse biological effects on aquatic organisms. Ghanam, Ghazale, Pet Zone, and Mouth accounted for the highest values of PLI, mCd, RI, M-ERM-Q, and STd indexes. Results from cluster analysis and principal component analysis indicated that Zn originated from natural sources; Cu, Ni, and Pb originated from anthropogenic sources; and Cd and Hg also derived from other human activities while implied a unique source. [ABSTRACT FROM AUTHOR]

Numerous physical and chemical approaches are existing for metal elimination from the soil; nonetheless, phytoremediation is regarded as one of the paramount effective and cost-friendly approach. However, ample work has been done all over the world to appraise phytoremediation capability of plants in controlled conditions; only limited studies are existing on metal uptake abilities of plants cultivated under natural conditions. So, the present work estimates the phytoremediation potential of rice, imperative food crop cultivated in agricultural soils of Punjab with key objective to appraise the accretion and transport of metals (Zn, Cu, Mn, Cr, Cd, Ni, As and Pb) in roots, stems and leaves. Data was analysed by using Pearson's correlation analysis and heatmap analysis. Correlation analysis exhibited strong relationship among metals in soil and different tissues of rice. pH, soil organic carbon and phosphorus showed significant correlation with studied metal(loid)s in the soils affecting their availability and retention. In soil, highest and lowest concentrations of Zn and Pb were found for different sites, respectively. In rice among all the metals, Ni was found maximum in roots and stems, while Zn content was recorded maximum in leaves. The results of bioaccumulation factor and translocation factor were obtained above one for Zn, Mn, Ni, Cr, Cd and Pb, signifying the phytoremediation potential of rice in natural conditions. [ABSTRACT FROM AUTHOR]

In the current study, the variations of soil classes at the first and second levels of WRB (World Reference Base for soil resource) soil classification system were investigated by two machine learning including multinomial logistic regression (MLR) and random forest (RF) models in an arid floodplain which covers an area approximately 600 km2 located in Sistan region, Iran. The model's performance was tested using 10-fold cross-validation by calculation of overall model accuracy and the kappa statistic. Three main Reference Soil Groups (RSGs) including Cambisols, Fluvisols, and Solonchaks at the first level, and 18 WRB soil groups at the second level were identified. Results showed that the overall accuracy at the first level of WRB was 53% and 49% with a kappa of 0.26 and 0.19 for MLR and RF models, respectively. At the second level of WRB, the overall accuracy was 11% and 21% with a kappa of 0 and 0.09 for MLR and RF models, respectively. Also, results showed that the MLR model had better performance (overall accuracy = 53%) at the first level of WRB, but the RF model showed better prediction (overall accuracy = 21%) at the second level of WRB. Multiresolution Valley Bottom Flatness Index (MrVBF), Normalized Difference Salinity Index (NDSI), Multiresolution of Ridge Top Flatness Index (MrRTF), convergence index, and channel network base level were among top covariates used for prediction at two levels of WRB. Results revealed the complexity of soil variations in this floodplain. Using other covariates such as soil texture and salinity maps can improve the prediction power. Increasing the size of sampling is recommended to improve the accuracy of the models in predicting the second level of WRB in this area. [ABSTRACT FROM AUTHOR]

Coarse textured soils with water scarcity significantly restrict the productivity and sustainability of agriculture, particularly in arid regions. The effects of the partial root zone drying irrigation strategy (PRD) and different organic soil amendments on sweet pepper growth, yield, and water-use efficiency (WUE) in sandy soil were surveyed. PRD consisted of two treatments: IR1 (80% ETc) and IR2 (100% ETc). Amendments consisted of biochar (BC), compost (Comp), and their mixture. The results showed that a reduction in the water supply (IR1) caused significant decreases in the morphological traits of pepper plants during flowering, fruit setting, and vigorous fruit-bearing stages. However, vegetative growth stage is not sensitive to such treatment. Plants under IR1 had higher reductions in fresh and dry weight partitioning of all plant parts (root, stem, leaf, and fruit), fruit number, and total yield compared to those under IR2. However, the WUE value was 21.6% higher than those under IR2. Integrated application of BC 2% + Comp 2% showed clear and positive effects on plant growth (plant height, stem diameter, and number of leaves), yield, and WUE, followed by Comp 4%. On the other hand, amending plants with BC 2% + Comp 2% under the full water level (IR2) generated the greatest yield improvement (70.4%). However, such treatment under IR1 gave a moderate improvement (39.9%) in yield with a higher WUE (103.8%) than the control (no organic applying under IR2). Thus, the application of BC 2% + Comp 2% with PRD (80% ETc) could be a good management strategy to enhance the productivity of sweet pepper, while saving approximately 22.0% of applied water. Information from such studies will help vegetable producers make proper decisions about increasing productivity or saving water to be allocated for greenhouse production of pepper in arid regions under water scarcity conditions. [ABSTRACT FROM AUTHOR]

The question if biochar is a suitable soil nutrient amendment for potato cultivation in the Atlantic Canada is yet to be answered. The objective of this study was to answer this question. Three replicates of twelve lysimeters, each 8000 cm2, were packed with an Atlantic Canada representative soil to cultivate potatoes with four treatments of soil amendments (T1 = control [no added nutrients], T2 = B [biochar], T3 = F [synthetic fertilizer @ recommended NPK], and T4 = B + F [biochar + recommended NPK]) under a completely randomized block design with factorial arrangements. Chemical analyses of soils were conducted for physical, hydrological, and chemical (including concentration of macro- and micro-nutrients) prior to and after the completion experiments to evaluate soil fertility and its resulting effects on crop yield. The biochar amendment improved soil micro- and macro-nutrients. Soil organic matter, pH, and cation exchange capacity (ECE) significantly increased by application of biochar. The maximum potato yield of 30,467.4 kg h−1 was achieved by the combined application of biochar and synthetic fertilizer as this combination resulted in the maximum net benefit ($4433.98 ha−1) in comparison with control treatment that had net loss of $– 2621.49 ha−1. It is therefore concluded that biochar amendment of soils resembling to that of the Atlantic Canada representative soil used in this study, with a mix of recommended NPK for, can formulate a smart precision farming nutrient management technique for this region subject to the field trials and replicate experimental treatments for more than three times. [ABSTRACT FROM AUTHOR]

Zinc (Zn) deficiency is widespread in the calcareous soils which needs correction in a sustainable way. An open-air incubation study was conducted to observe the effects of biochar (BC), farmyard manure (FYM) and poultry manure (PM) on ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extractable Zn in high-limed (16.6% CCE) and low-limed (6.6% CCE) calcareous soils. Both soils were treated with10 g kg−1 (equivalent to 20 t ha−1) of BC, FYM and PM and three levels of Zn (as ZnSO4), i.e. 0, 1.5 and 3 mg kg−1 soil. The AB-DTPA-extractable Zn and soil pH was determined at 0, 7, 14, 28, 56 and 84 days of incubation. Results revealed that more extractable Zn was recorded in the low-limed soil as compared with high-limed soil. Further, more extractable Zn was detected in both soils when treated with PM (84.62%), followed by FYM (69.23%) and BC (52.56%) during 0–28 days as compared with control. But after 56 days and later, BC alone or in combination with external Zn produced more extractable Zn. Increase in extractable Zn, upon Zn external application, was dose dependent (highest with 3 mg Zn kg−1 soil) in both soils. Moreover, high-limed soil (0.73–1.28 mg kg−1) had significantly lower AB-DTPA-extractable Zn than low-limed soil (1.28–1.45 mg kg−1) at each incubation interval, irrespective of applied Zn levels. Data of combined application of organic amendments with external Zn showed that PM + Zn treatment had more extractable Zn (1.23–1.44 mg kg−1) than FYM + Zn treatment (1.08–1.32 mg kg−1) in both soils in earlier incubation intervals, but later, more extractable Zn was recorded in BC + Zn treatment (1.39–1.49 mg kg−1) at 84th day of incubation. Further, pH of high- and low-limed soils was decreased with PM, FYM and BC, applied either alone or in combination with external Zn. Thus, organic amendments applied with mineral Zn may improve Zn pools and productivity of calcareous soils in a sustainable way. [ABSTRACT FROM AUTHOR]

The present work deals with a geobiological assessment of metal pollution in the abandoned Fej Lahdoum mine in Northwest Tunisia. The geological part of the assessment deals with the petrographic, mineralogical, and geochemical study of wastes, soils, and water collected from the mine. The biological part of the assessment investigated the metal presence within leaves and roots of Ampelodesmos mauritanicus and Typhonium flagelliforme species. Waste characterization revealed the presence of potentially toxic elements (PTEs) mainly Pb and Zn (46,040 and 17,650 mg kg−1, respectively, as average value). Anomalous contents in metals exceeding the geochemical background and global range specified for calcic soils are found with average concentrations up to 10,313 mg kg−1 for Pb and 5282 mg kg−1 for Zn, maximum levels are detected in soils in the immediate vicinity of the dumps particularly in the upper horizons but also in depth resulting from plowing and mud cracks which facilitated the incorporation and vertical migration of the pollutants. Enrichment factor (EF) and geoacumulation index (Igeo) indicated different classes of contamination of Fej Lahdoum soils. Metal concentration in plants and water is not very high compared to soils and does not exceed the maximum recommended concentrations, thus, not currently presenting a risk of contamination of the food chain. Nonetheless, further erosion and leaching would have relevant damage on water and plants. [ABSTRACT FROM AUTHOR]

The management of polluted soils is a major challenge for global environmental engineering. An incubation pot trial was conducted to assess the effectiveness of pumice (P), leca (LE), bentonite (BE), zeolite (Z), biochar 640 °C (BI1), and biochar 420 °C (BI2) as soil amendments to remediate a cadmium (Cd) and lead (Pb)-polluted soil. The DTPA- and EDTA-extractable Cd and Pb concentrations were measured to estimate the potential bioavailability of Cd and Pb in the calcareous soil. Additionally, Tessier's fractionation procedure was used to determine various forms of Cd and Pb in non-amended and amended soils. Application of the amendments reduced the DTPA-extractable Cd by 51–68% and Pb by 12–32% compared with the control. The EDTA-extractable concentrations were decreased by 102–81 mg kg−1 (Cd) and 1202–792 mg kg−1 (Pb). All amendments decreased exchangeable fraction (F1) of Cd and Pb compared with the non-amended soil. Although the BI1 and BI2 exhibited the highest reducing rate of exchangeable fraction (F1) of Cd and Pb, respectively, they increased the oxide (F3) and organic (F4) fractions, which may be due to O-containing functional groups and high alkalinity leading to an enhance in the linking of Cd and Pb to organic compounds and mineral oxides. [ABSTRACT FROM AUTHOR]

The contamination of arsenic (As) in soil and groundwater has posed serious hazards to food chain and ecosystem. The aim of the present study was to assess the impacts of different biochar (rice husk biochar and plant biowaste biochar at 10 and 20 t ha−1) on the retention and immobilization of As in wheat. For this purpose, soil and herbage samples were collected in the vicinity of Gujranwala, Pakistan, and characterized for different physicochemical parameters. Pot experiment was carried out on wheat plant to check the effect and uptake of As (at two concentrations, i.e., 10 and 15 mg L−1) from irrigation water as affected by biochar. The results of the collected samples showed a minimum concentration of As and maximum concentration of lead (Pb) in Gujranwala City. Moreover, iron (Fe), chromium (Cr), and manganese (Mn) were the dominant elements in the sampling area. The application of biochar increased the plant biomass of wheat as compared to control. Among the studied biochars, the application of plant biowaste biochar significant increased the retention and immobilization of As at a higher level (15 mg L−1). However, the rich husk performs better at lower As level (10 mg L−1). Both the studied amendments increased the immobilization of As but plant biowaste biochar was more effective. The plant waste biochar could be used to improve agricultural production in polluted soil by minimizing the risk of food chain contamination. [ABSTRACT FROM AUTHOR]

Arsenic pollution in groundwater is the most serious geo-environmental problem posing a threat to the health of millions of people in the densely populated area of interfluvial region of Bhagirathi-Hugli and the Jalangi-Ichamati Rivers. The present paper focuses on arsenic vulnerability assessment at the mouza level (smallest revenue unit) in Beldanga II block of Murshidabad district of West Bengal in India. A number of indicators (e.g., arsenic concentration in groundwater, population density, well depth, and seasonal fluctuation of water level) have been incorporated, and weighted linear combination method was adopted into this model to develop a composite vulnerability index. The results reveal that about 15 and 10 % of the total mouzas are respectively high and extreme vulnerable, found in the eastern part of block, where 34 % people are potentially vulnerable due to arsenic pollution. This study reveals a multi-parametric spatial model for micro level arsenic vulnerability assessment, may be further improved if more relevant parameters are incorporated into this model, and it can facilitate as a basis for directing policy interventions. [ABSTRACT FROM AUTHOR]

Oil shales are sedimentary rocks that contain organic material in its inorganic matrix. The oil shale deposits of Jordan have been investigated since the 1960s. An extensive investigation studies have been commenced to evaluate the quality and quantity of these resources. In 2006, the government of Jordan invited pioneer companies in oil shale field to submit their proposal to utilize and develop the oil shale of Jordan using different extraction technologies. Jordan is considered one of the driest countries in the world, which poses an additional challenge for oil shale development, because a vast quantity of water is needed for this process. El-Lajjun study area is located in central Jordan; the oil shale in the study area was deposited in marine environment; it comprises massive beds of brown-black, kerogen-rich, bituminous chalky marl. Ten representative oil shale rock samples were collected for risk assessment investigations from different localities of oil shale exposures. A standardized laboratory Fischer assay test delivered oil shale characteristics. Sequential extraction was used to evaluate mobility and distribution of the trace elements Ti, V, Cr, Co, Zn, As, Zr, Cd, Pb, and U. Column leaching experiments were performed to simulate the leaching behavior of the above elements from oil shale and spent shale to evaluate the possible negative impact on groundwater in the study area. Results of sequential extraction indicate that concentration of trace elements and trace elements are richer in oil shale and in the spent shale compared to most rocks and soils. The concentrations in the leachate were below the maximum contaminant levels of the Environmental Protection Agency (EPA) and the Jordanian standards for drinking water. The significance of this study lies in that its utilizes for the first time the sequential extraction and column leaching techniques to investigate the Jordanian oil shale rocks. [ABSTRACT FROM AUTHOR]

In the present study, efficiency of different biochars (BCs) on cadmium (Cd) immobilization and its bioavailability to spinach were investigated. In the first experiment, Cd-spiked soil was amended with treatments (T1 = control, T2 and T3 = cotton stalk biochar (CBC) 2% and 5%, T4 and T5 = rice straw biochar 2% and 5%) and incubated for 120 days. In the second experiment, spinach was grown in pots using three soils (a normal soil, a Cd-spiked soil, and a sewage-irrigated soil) after application of CBC and rice straw biochar (RBC) (2% w/w each) in each soil. In the field experiments, spinach was grown at two sites with six treatments including T0 = control, T1 and T2 (RBC 5 and 10 ton ha−1), T3 and T4 (CBC 5 and 10 ton ha−1). The results of our experiments showed a significant impact of BCs on soil pH, EC, soil organic matter, and Cd bioavailability. The plant growth parameters were also influenced positively by application of BC in both pot and field experiments. In field experiments, plant population and fresh biomass at different sites varied significantly. The Cd concentration in plants was lower when grown in treated soils. Moreover, there was a significant increase in soluble Si and phosphorus concentrations in plants and this had significant correlation with Cd concentration in plants. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) toxicity is among the most prominent issues regarding land degradation. Traditional approaches for soil remediation are not effective. However, phytoremediation is described as the most efficient, economical, and sustainable approach to combat with terrestrial heavy metal pollution. Moreover, if phytoremediation is used in combination with soil amendment, its effectiveness can be increased several folds. Among soil amendments, biochar is considered the best amendment due to its potential for remediation and plant growth. The objective of this study was to determine the phytoremediation potential of Albizia lebbeck in Cd-contaminated and biochar-amended soils. A pot experiment was planned to test the ecophysiological response and Cd uptake of 3-month-old uniform-sized Albizia lebbeck seedlings. Cadmium was induced in soil through irrigational water at the rate of 25 mg/L. Two concentrations of biochar were used: B1 (3%) and B2 (6%). A total of six treatments were applied: Cd0B0 (T1), Cd0B1 (T2), Cd0B2 (T3), Cd1B0 (T4), Cd1B1 (T5), and Cd1B2 (T6), where, Cd0 and B0 designate the control treatment. The plants were harvested after 4 months of growth in the soil with amendments. The maximum growth and gas exchange characteristics were showed by the plant of T3. Cadmium toxicity reduced the growth and gas exchange characteristics to a great extent. Plants of T4 showed the minimum growth compared to the other amendments. The addition of 6% biochar in Cd-contaminated soil (T6) resulted in the decent increase in the growth of plants. The maximum root length (67.18 cm) and shoot length (80.06 cm) were observed in the plants of T3, whereas, the minimum root length (13.94 cm) and shoot length (35.03 cm) were observed in the plants of T4. This study suggests that biochar can be used to enhance the growth of agroforestry tree species like Albizzia lebbek in Cd-contaminated soils. [ABSTRACT FROM AUTHOR]

Application of silicon (Si) in agriculture, especially in degraded soils, is a promising, sustainable, and agro-environment compatible strategy. However, dilemma is the poor availability of monosilicic acid (SA) in soil solution due to intensive polymerization. Commercial silicates have severe limitations due to low solubility, inaccessibility, and high prices. Thus, identification of cheaper, soluble, and sustainable Si sources is an exigent requisite for utter and cost-effective remediation. Presence of high quantities of soluble Si in Si hyperaccumulating plants and industrial by-products provides an enticing choice. Therefore, chemical characteristics of 28 amendments were explored. Investigated amendments were plant residues, ashes, biochars (BCs), and industrial by-products. Our findings declared that total Si contents (TSi) were higher in BCs (5.7-71.6%) > ashes (49.5-53.6%) > plant residues (13-5%) > biosolids (3.6-41%) > by-products (15.9-36.8%). The phyto-available Si (PASi) was also highest in BCs (0.82-34.7%) > ashes (23.5-28.7%) > plant residues (6.2-26.9%) > by-products (4.8-13.3%) > biosolids (1.8-12%). Overall, the water-soluble Si (WSi) ranged from 0.04 to 1.09%. The carbon (C) contents ranged from 14.2 to 67.4% among amendments. BCs also showed higher pH (7.0 to 12.7). Pearson correlation and path analysis indicated that strong relationship existed among chemical properties. Rice residue-based amendments showed promising characteristics with high contents of TSi, PASi, WSi, and other essential nutrients. [ABSTRACT FROM AUTHOR]

Chromium (Cr) pollution in soil has the greatest threat to human beings as it has a potential to enter into the food chain through contaminated soil. Chromium has no defined role in plant biology and has detrimental effects on plants. Biochar used as soil amendment has been demonstrated to diminish the bioavailability of trace elements. The current study investigated the effect of poultry litter biochar (PLB) on Cr bioavailability and its accumulation in spinach grown on Cr-contaminated soil. Data showed significant decline in bioavailable Cr concentration (DTPA-extraction) with an increasing biochar concentration, especially at 5% application rate in soil. With the 3% and 5% application of PLB, Cr concentration in shoots significantly (P < 0.05) decreased by 32% and 49%, respectively, over the control. The results showed that PLB significantly enhanced the plant growth and biomass over the control. Under Cr stress, the PLB addition increased the catalase and superoxide dismutase activities while decreased malondialdehyde and hydrogen peroxide concentrations as compared to control. Overall, it was concluded that PLB application might be effective in reducing the toxic effects of Cr in spinach and enhancing plant growth. [ABSTRACT FROM AUTHOR]

Soil toxic metal pollution is one of the most prominent environmental problems in the rapid industrialization of societies because of the considerable harm caused to human existence and the surrounding environments. Soil samples from 80 sampling sites around the coal-mining region of northwestern China were collected, and the geo-accumulation index (Igeo), pollution index (PI), and potential ecological risk index (PRI) were calculated, with the objective of assessing the soil toxic metal pollution level. The results showed that the average concentrations of Cr, Hg, and As exceeded the regional background values and the national soil environmental quality standards of China, while those of Zn, Cu, and Pb were below both soil-quality standards. The Igeo of toxic metals was ranked as Hg > As > Cr > Pb > Cu > Zn. The Igeo of Zn, Cu, and Pb indicated low pollution; the soils were moderately polluted by Hg and slightly moderately polluted by As, while other elements presented low pollution levels. The PI values of both As and Hg were higher than 3, indicating heavy pollution of these two metals. Zn and Cu originated from parent material, while Cr, As, and Hg originated from human activities such as coal burning, chemical industry, and traffic. Pb was influenced by both natural factors and human activities. The results of ecological risk assessment in the region showed that Zn, Cu, Cr, and Pb in all sample sites presented a low ecological risk, while Hg presented a high ecological risk. Therefore, Hg is the most hazardous toxic metals in the region. The spatial distribution trends revealed that the high-risk regions were found to be the industrial region of the study area. The research results provide a scientific basis and technical support for monitoring and early warning of soil pollution in arid regions. [ABSTRACT FROM AUTHOR]

Biochar, a solid product produced from biomass pyrolysis under low oxygen conditions, has gained wide acknowledgment in its usage as a means for carbon sequestration as well as improving the soil chemical and physical properties of the soil. Although the effects of biochar application on chemical characteristics and fertility of soils have been intensively investigated, there is little information on its role in improving soil physical characteristics. Therefore, this review aimed to (i) summarize the impact of biochar application on soil physical properties, (ii) discuss the factors and mechanisms influencing biochar performance on soil physical properties, and (iii) identify future research priorities. This review concluded that the improved impact of biochar application on soil physical characteristics is dependent upon feedstock and pyrolyetic conditions of biochars, application rate of biochar, biochar particle size, and soil type and texture. Pyrolysis temperature is the main factor controlling biochar properties such as porosity and surface area, which reflect their effects on soil physical characteristics. For the same feedstock, the temperature will control the properties of resulting biochars. But, the biochar properties greatly depend on the properties of feedstock. For example, manure-derived biochars contain a large amount of ash, but biochars from cellulose-lignin biomass mainly consist of the carbon fraction. Despite the profound effect of biochar in improving the physical properties of soil, the economic impact of its implementation in large-scale farming has not been established. Therefore, there is need for its economic evaluation. [ABSTRACT FROM AUTHOR]

Biochar has been considered a safe soil additive to enhance soil fertility and agronomic traits of different crops. This study was conducted to explore the impacts of sugarcane waste straw biochar on soil characteristics and some agronomic traits of okra. The experiment was carried out with four treatments, i.e., control, sugarcane waste straw biochar (10 ton ha−1), farmyard manure (FYM, 10 ton ha−1), and chemical fertilizers (NPK; 120:100:80 kg ha−1) having three replications of each treatment. Soil samples were tested for texture, bulk density, particle density, pH, electrical conductivity (EC), organic matter content, nitrate nitrogen (NO3-N), and extractable-P. The sugarcane waste straw biochar was characterized for plant major nutrient elements. The impact of various treatments was observed on soils and agronomic traits of okra like plant height, fruit size, fruit length, and yield of okra. Results revealed that sugarcane waste straw biochar expressed higher EC value and noticeable amounts of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and magnesium (Mg). The sugarcane waste straw biochar, in comparison with FYM and NPK, significantly improved the NO3-N, extractable-P, OM and EC of the calcareous soil, and reduced the soil bulk density. Furthermore, plant growth and yield parameters were significantly improved under biochar application over the control, FYM and NPK. Overall, sugarcane waste straw biochar proved to be a good alternative to conventional organic and inorganic fertilizers under calcareous soil conditions. [ABSTRACT FROM AUTHOR]

Biochar prepared from organic waste through pyrolysis, thermal combustion in an inert environment, generates a stable form of carbon. The review of established literature reveals that conversion of organic matter into biochar and its addition to soil also reduces the negative effects of carbon aerosols on human health and greenhouse gas effects on environment through carbon sequestration. Physicochemical properties of biochar such as nutrient sorption capacity, pH, pore structure, particle size, surface area, and mineral content play a vital role in determining the soil structure and function. Biochar addition to soil exerts measurable changes in physicochemical soil properties such as bulk density, water-holding capacity, pH and cation exchange capacity, microbial community structure, and their interrelated functions in soil. However, addition of biochar to specific soil improves the soil fertility, and consequently improves the crop yield. It is concluded that optimized pyrolysis of organic waste for biochar production and its use for soils need diversified investigation in diverse environmental conditions. [ABSTRACT FROM AUTHOR]

Biochar is considered a promising amendment for the reduction of metal concentration in plants; however, the effects of biochar in terms of dose and feedstock on metal uptake by plants remain widely unclear. In the current study, three individual biochars were prepared at 450 °C from different feedstocks (wheat straw, sukh chain (Pongamia pinnata), and cotton sticks). The main aim was to evaluate their ability to remediate cadmium (Cd)-spiked soil in terms of growth response and Cd uptake by wheat (Triticum aestivum) tissues. Biochars were separately applied at 0, 1, and 2% (w/w) in Cd-spiked soil and wheat was grown until maturity in pots and then morphological and physiological parameters and Cd concentrations in grains, roots, and shoots were determined. The post-harvest soil was analyzed for extractable Cd concentrations. Plants grown in Cd-spiked soil treated with biochars had higher seed germination, lengths of roots, shoots, and spikes, grains per spike and leaf relative water contents, chlorophyll contents, and dry weight of roots, shoots, and grains as compared to the untreated control. Biochar treatments significantly decreased the Cd concentrations in shoots, roots, and grains as well as total Cd uptake by grains. Soil extractable Cd concentrations were significantly decreased with biochar treatments. The application of 2.0% wheat straw biochar was the most efficient treatment in increasing grain yield and decreasing Cd in grains as well as soil extractable Cd than the other two biochars and doses applied. [ABSTRACT FROM AUTHOR]

Soil contamination with cadmium has become major concern all over the world because of its adverse impacts on ecosystem health and agricultural land. Soil amendment with biochar may have varied effects on physical and chemical properties of soil. The objective of the study was to explore the impact of sugarcane filter-cake biochar on physiological performance and growth of lettuce in an aged soil. Four different doses (0, 1.5%, 3%, and 5%) of biochar were used in the soil and conditioned for 1 month. After this, lettuce seedlings were grown in the soil. The results showed that the biochar treatment improved the fresh and dry biomass of leaves and roots as well as plant height while diminished the bioavailability of cadmium from the soil. As compared to control, biochar significantly enhanced the chlorophyll content in lettuce leaves. Due to the biochar amendment, the oxidative stress decreased in lettuce shoots over the control. As compared to control, concentration of cadmium in lettuce significantly decreased after the application of biochar. It was concluded that biochar could mitigate the toxicity of cadmium in lettuce by altering the biochemical and physiological processes in cadmium contaminated soil. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is the family member of toxic heavy metals, and its accumulation in food crops has become a global environmental constraint. Biochar potentially minimizes the metal contents in plants, but limited work has been reported on its residual effect on subsequent crops. The residual effect of various biochar levels (0, 1.5, 3.0, and 5.0% w/w) on Cd accumulation in rice has been investigated in this study. Biochar treatments enhanced the rice growth, photosynthesis, and antioxidant enzymes, whereas diminished the Cd contents and oxidative stress in rice. Cadmium concentration in shoots decreased by 24.4, 36.6, and 57.5% in 1.5, 3.0, and 5.0% biochar treatments over the control. Biochar supply enhanced the soil pH and electrical conductivity, whereas diminished the soil bioavailable Cd. Overall, the results depicted a significant residual impact of rice straw biochar on rice growth attributes and Cd uptake. However, studies are still needed to explore the long-term sustainability of biochars prepared from different feedstocks on bioavailability of toxic metals in soils and uptake by food crops under field conditions. [ABSTRACT FROM AUTHOR]

Decreased phosphorus (P) losses and improved environmental quality are crucial to consider while recycling farm wastes and adding various soil amendments. This study investigated the impact of coal and wood ash on the extractability of P from soils (sandy loam and loamy sand) amended with organic and inorganic phosphorus fertilizers. These soils were further amended coal and wood ash, and analyses were carried out to quantify the water-, Olsen-, and Mehlich 1-extractable P. Ratio of the ashes applied to soils were 5% to sandy loam soil while 10% to loamy sand soil. Water-extractable P was observed to be mainly dependent on the ash type as well as the extraction method. Ash amendment reduced the solubilization of P across soils up to 9% and 23% and 7% to 17% upon 5% and 10% ash amendment in loamy sand and sandy loam soils, respectively. However, the water-extractable P was found to be low in wood ash-amended soil as compared to coal ash. Interestingly, this extractability was greater in soils treated with inorganic P. Phosphorus extraction from soil followed the trend as Mehlich 1 > Olsen > water. P leachability was found to be mainly dependent on ash amendment but values were high for the soil treated with inorganic P. The study inferred that using ash materials such as coal ash and wood ash can be a practical measure for moderating P losses from soils important for economic and environmental perspectives. [ABSTRACT FROM AUTHOR]