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Industrial processes and municipal wastes largely contribute to the fluctuations in iron (Fe) content in soils. Fe, when present in unfavorable amount, causes harmful effects on human, flora, and fauna. The present study is an attempt to evaluate the composition of Fe in surface soils from paper mill and municipal landfill sites and assess their potential ecological and human health risks. Geochemical fractionation was conducted to explore the chemical bonding of Fe across different fractions, i.e., water-soluble (F1) to residual (F6). Different contamination factors and pollution indices were evaluated to comprehend Fe contamination extent across the study area. Results indicated the preference for less mobile forms in the paper mill and landfill, with 26.66% and 43.46% of Fe associated with the Fe–Mn oxide bound fraction (F4), and 57.22% and 24.78% in the residual fraction (F6). Maximum mobility factor (MF) of 30.65% was observed in the paper mill, and 80.37% in the landfill. The enrichment factor (EF) varied within the range of 20 < EF < 40, signifying a high level of enrichment in the soil. The individual contamination factor (ICF) ranged from 0 to >6, highlighting low to high contamination. Adults were found to be more vulnerable towards Fe associated health risks compared to children. The Hazard Quotient (HQ) index showed the highest risk potential pathways as dermal contact > ingestion > inhalation. The study offers insights into potential Fe contamination risks in comparable environments, underscoring the crucial role of thorough soil assessments in shaping land use and waste management policies. [Display omitted] • Geochemical fractionation unveils less bioavailable Fe in contaminated soil. • EF, ICF, and I geo indicate high Fe contamination. • Adults are more susceptible to potential health risks from surplus Fe exposure. • HQ analysis pinpoints dermal contact as the primary pathway for Fe exposure risks. [ABSTRACT FROM AUTHOR]

Earthworms are known to bio-degrade various types of organic materials added or already present in soil. Two soils were collected from different land use patterns viz. an agricultural land (AL) and an undisturbed land (UL) of a mountain ecosystem of State of Himachal Pradesh in India for the present investigation. A laboratory microcosm study was carried out to elucidate effects of various agricultural-soil amendments, viz. wood ash (WA), rice husk (RH), cow dung (CW) and their mixture (MA) applied @25 t ha −1 , on selective biological and chemical properties of earthworm ( Eisenia fetida ) casts and growth in the collected soils. Subsequently, earthworms were reared in soils from both AL & UL, treated with the amendments; and the resultant earthworm cast (E w C) properties were found to be largely determined by the nature of amendments rather than land use types. Soils treated with MA produced casts displayed higher nutrient content, microbial biomass C with higher activities of dehydrogenase and urease. Earthworm growth and cast formation were greater in the soil from UL over soil from AL for all treatments except WA, implying better acclimatization and earthworm activity in the former. Further, casts produced under UL had higher nutrient mobilization and enzyme activity in comparison to AL. Results suggested that agricultural intervention in an undisturbed land might weaken its ability to support growth, development in conjunction with the activities of earthworms and associated enzymes. [ABSTRACT FROM AUTHOR]

Soil quality management through effective utilization of agricultural residue is the cynosure of intense global research. Therefore, we have explored the pyrolytic conversion of a locally available agricultural residue, the areca nut husk (AH), into biochar (BC) as a sustainable option towards residue management. The AH was carbonized at 250–400 °C, and residence times of 30–90 min. Subsequent detailed analysis revealed areca nut husk biochar (AHBC) formed at 250 °C with 60 min residence time, had the highest soil organic matter yield index (SOMYI), the lowest H/C and O/C ratio, and an average particle size of 1191.6 nm. Further characterization exposed the highly porous structure of prepared AHBC with oxygenated functional groups attached to its surface. The application of AHBC in conjunction with vetiver (Chrysopogon zizanioides L.) was used as a novel agrotechnological approach to assess soil quality improvement. Various doses of AHBC (5 t ha−1, 10 t ha−1, and 15 t ha−1) were applied in the experimental soils, and the principal component analysis (PCA) revealed that the 15 t ha−1 dose was optimum for the growth of the vetiver. AHBC amendment in soil resulted in increase of plant height and relative water content. This could be attributed to the increase in organic carbon, cation exchange capacity, and nutrients in the soil. Application of AHBC along with vetiver could be a simple, yet effective option, for sustainable agricultural residue and soil management. [Display omitted] • Areca nut husk is a potential agricultural residue for biochar preparation. • Areca nut husk biochar (AHBC) prepared at 250 °C is suitable for soil applications. • The application of AHBC improved the physico-chemical properties of soil. • AHBC enriched soil nutrients and favored soil enzymatic activities. • 15 t ha−1 AHBC application proved to the best for soil quality and vetiver growth. [ABSTRACT FROM AUTHOR]

Abstract: Methane (CH4) production and emission from three rice-growing soils (Luisiana, Maahas and Pila) of Luzon Island in the Philippines were estimated by incubation and pot culture studies, respectively, to understand their interrelationship. Topsoil (0–20cm depth) and subsoil (30–50cm depth) were used for the study along with their blend (1:1) for generating a gradient in soil properties, which allowed evaluating the importance of organic carbon content in regulating CH4 production in both layers of soil. For all the three soil samples, total CH4 production showed a decreasing trend in the order Topsoil>1Topsoil:1Subsoil>Subsoil. Inoculation by non-sterilized soil suspension in sterilized soils triggered higher CH4 production. It was observed that with the addition of external organic substrates like rice straw, even subsoil produced appreciable amount of CH4. Methane emission was also studied from the same soils cultivated with a rice seedling (IR-72) grown in pots. Temporal pattern of CH4 emission deviated from temporal pattern of its production, i.e. emission patterns either showed a certain time lag (Luisiana and Pila soil) or no significant correlation to the CH4 production (Maahas soil). Methane production and emission rates recorded in this study yielded significant relationship. [Copyright &y& Elsevier]

A holistic appraisal of three non-edible biofuel plants, with in depth analysis of their environmental impact, socioeconomic potential, and contribution to rural and circular bio-economy is the main focus of this review. Bioenergy is designated as a smart option to mitigate energy-based demands of an escalating human population, the resultant environmental pollution, and challenges of climate change. To the best of our knowledge, this is the first concerted and comparative assessment of Jatropha curcas, Pongamia pinnata and Mesua ferrea as biofuel resources, with concurrent evaluation of the environmental and socioeconomic perspectives. Ease of availability, non-edibility, higher biomass, and resilience to climatic variations, render them potential biofuel capital for a cleaner and greener future. Their environmental perspectives are critically assessed in this review based on the roles in phytoremediation, bioadsorption, carbon sequestration, and soil conditioning. The detailed analysis of biogas, biopesticide, cosmetic products, and biofuel yield, reinforce the economic potential of the three plants under review. The socioeconomic implications, practical challenges, and limitations of crops for biofuel, especially in the predominantly rural, low income, agrarian milieu, are comprehensively discussed. Therefore, in the concluding section, the review offers new directions for policies and frameworks toward sustainable and circular bio-economy in biofuel sector. [Display omitted] • First comparative study of three biofuel plants J. curcas, P. pinnata and M. ferrea. • Environmental and socio-economic aspects of biofuel plants were discussed. • Multipurpose usage of these plants was explored. • Discussed challenges and limitations associated with the farming of these plants. • Deliberated on sustainable and circular bio-economy in biofuel sector. [ABSTRACT FROM AUTHOR]

The main aim of this work is to assess the extent of soil contamination, potential ecological and health risks associated with the disposal of municipal solid waste (MSW) near a Ramsar site in Assam, India. Soil samples were collected and analysed for three heavy metals (HMs), namely, chromium (Cr), manganese (Mn) and zinc (Zn). The sources of HMs and their pollution levels were evaluated using different indices. The results demonstrated that Cr contamination was high near the metal scrap segregations unit within the dumping site, otherwise, the ecological risks associated with Zn and Mn were found to be low. The speciation of Cr and Zn were associated with the Fe–Mn oxide bound (F4) fraction, accounting 44.23% and 30.68%, respectively, whereas Mn (52.55%) was associated with the exchangeable fraction (F2). The fate and origin of HMs were assessed using mobility and enrichment factors and 16 out of the 20 sampling sites fell under the category of heavily polluted category for Cr, while others which were nearby the metal segregation units fell under the strongly to extremely polluted category. In few sites, significant enrichment was observed for Zn and minimal to moderate enrichment for Mn, respectively. Health risk assessment results indicated that Cr posed higher threat to human health through ingestion. Image 1 • Soil contamination, ecological and health risks were evaluated for a dumping site. • 80% of the sampling sites fell under the category of heavily polluted category for Cr. • Presence of Cr resulted in high soil contamination and low ecological risks. • Cr posed health hazards to children and adults. • Children were found to be more prone to heavy metal contamination. [ABSTRACT FROM AUTHOR]

Soil amendment with biochar is evaluated globally as a means to improve soil fertility, restoration of the ecological functions for anthropogenically polluted soils and also is a potential candidate to mitigate climate change. Application of biochar, a carbon-rich material developed from the combustion of biomass under no or limited oxygen supply has been found to ameliorate some of the negative effects of soil. Biochar modifications can lead to an increase in the water holding capacity as well as pH modification may also be used as a soil amendment. There are various other physical, chemical, and biological properties of biochar that can impact soils. However, the effects of biochar on soil biota have received much less attention than its effects on soil chemical properties. This review highlights essentially the various methods of preparation of biochar from waste biomasses and its usage as a potential soil amendment agent with a special emphasis on the effect of biochar on soil microbiology. A well-accepted mechanism of the effect of biochar on soil microbe environment still needs more focus. Therefore, the current review will further help in understanding the feasibility, safety, and effectiveness of biochar utilization for improving the fertility of the soil. This paper presents a detailed review of the biochar utilization as soil amendment describing the various methods of biochar preparation, its modification, usage for soil improvement, etc. A constructive review of the impact of biochar on soil microbiology has also been presented in the paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyrolysis process parameters influence the physicochemical properties of biochar. • Application of various designs of experiments in biochar production is explained. • Advanced soft computing techniques in biochar process modeling are examined. • Techniques like RSM, ANN, and other ML methods to optimize pyrolysis are deliberated. • Advantages and drawbacks of modeling and optimization techniques are explained. Enhancement of crop yield, conservation and quality upgradation of soil, and efficient water management are the main objectives of sustainable agriculture and mitigating climate change's impact on agriculture. In recent days, biochar, obtained via thermochemical alteration of biomass is becoming a powerful agent for soil and water quality improvement, carbon sequestration, greenhouse gas emission reduction, and heavy metal adsorption. The present study predominantly focuses on various process parameters related to biochar preparation through pyrolysis, their impact on biochar production as well as physicochemical characteristics, and the optimization of such process parameters. Different designs of the experiment (DOE) and optimization techniques including traditional and non-traditional optimizations are discussed in the current review, along with their applicability and shortcomings. Since the biochar preparation process is tedious and energy-consuming, the present review will help to understand the importance of optimization in preparing biochar, thereby leading to a better way to prepare biochar. [ABSTRACT FROM AUTHOR]

This study aimed to assess the influence of municipal solid waste (MSW) disposal on soil microbial communities. Soil samples from 20 different locations of an MSW dumping site contaminated with toxic heavy metals (HMs) and a native forest (as control) were collected for phospholipid fatty acid (PLFA) profiling to predict microbial community responses towards unsegregated disposal of MSW. PLFA biomarkers specific to arbuscular mycorrhizal fungi (AMF), Gram-negative and Gram-positive bacteria, fungi, eukaryotes, actinomycetes, anaerobes, and microbial stress markers-fungi: bacteria (F/B) ratio, Gram-positive/Gram-negative (GP/GN) ratio, Gram-negative stress (GNStr) ratio and predator/prey ratio along with AMF spore density and the total HM content (Cu, Cr, Cd, Mn, Zn, and Ni) were assessed. The results showed that all of the PLFA microbial biomarkers and the F/B ratio were positively correlated, while HMs and microbial stress markers were negatively correlated. The significant correlation of AMF biomass with all microbial groups, the F/B ratio, and T. PLFA confirmed its significance as a key predictor of microbial biomass. With AMF and T. PLFA, Cd and Cr had a weak or negative connection. Among the toxic HMs, Zn and Cd had the greatest impact on microbial populations. Vegetation did not have any significant effect on soil microbial communities. This research will aid in the development of bioinoculants for the bioremediation of MSW-polluted sites and will improve our understanding of the soil microbial community's ability to resist, recover, and adapt to toxic waste contamination. • Prolonged municipal waste dumping influenced soil microbial communities. • Toxic heavy metals influenced soil microbial communities. • Microbial populations were greatly influenced by Zn and Cd. • AMF biomass was positively correlated with all key microbial groups and total PLFA. • Total heavy metals were negatively correlated with microbial biomarkers. [ABSTRACT FROM AUTHOR]

A letter to the editor about the challenges posed by climate change to disaster management is presented.

Unscientific municipal solid waste (MSW) dumping provokes heavy metal (HM) associated ecological and human health hazards through heightened bioavailability and bioaccumulation. In this study, we focused on three important HMs Cadmium (Cd), Copper (Cu) and Nickel (Ni) and their geochemical fractions, to enable clutter free data management, analysis and interpretation. Stratified random soil sampling was carried out from twenty different locations around a Ramsar site (Deepor Beel) in Guwahati, India. The spatial concentration profiles of Cd, Cu and Ni were determined by data elicited from geochemical fractionation and the Geographic Information System (GIS). Ecological and health risks indices were used to evaluate the severity of soil pollution and assess the level of health risks. All the three HMs thus evaluated, conformed to the potential bioavailable category. Cd (54.59%) was associated mostly with the carbonate bound fraction (F3), while 25.53% of Cu and 40.60% Ni were associated with the exchangeable fraction (F2). Significant contamination levels and higher ecological risks posed by these metals were in the order Cd > Ni > Cu. Children were found to be more vulnerable towards Cd associated health risks whereas, Ni posed threats to both adults and children. Cu posed no risk to human health. Geochemical fractionation and different indices played a critical role in the integrated assessment of soil pollution, ecological and health risk assessment, and provided an empirical basis for the sustainable future planning and comprehensive adaptive management practices for MSW. [Display omitted] • MSW dumping site has resulted in considerable environmental and health risk. • Geochemical fractions of HMs were examined using sequential extraction procedure. • 55% of Cd is associated with the carbonate bound fraction. • I geo , PLI and PERI indicated significant pollution load due to Cd. • Higher human health risks are associated with Cd and Ni. [ABSTRACT FROM AUTHOR]

The Yamuna is one of the most polluted rivers in India and the land adjacent to river flowing through Delhi city is widely irrigated with its water for growing various food crops. Present study was undertaken to assess the heavy metal load in Yamuna water and surrounding soils of the river bank and its impact on soil enzyme activities. Long term impact of irrigation by Yamuna water on the activities of various soil enzymes namely dehydrogenase (DHA), urease (UA), fluroscein diacetate (FDA), aryl sulphatase (ASA), nitrate reductase (NRA), microbial biomass carbon (MBC) and potentially mineralizable nitrogen (PMN) were assessed. The sensitivity of soil enzymes to heavy metals were observed as DHA>UA>ASA>NRS. Total organic carbon, easily oxidisable soil organic carbon, available phosphorus and available potassium in different sites varied significantly. Total heavy metal contents in soils showed a decreasing order: Fe>Mn>Zn>Cr>Ni>Cu>Pb>Co>As>Cd and the DTPA extractable heavy metal contents followed the order: Mn>Cu>Pb>Zn >Fe>Ni>Cd>Cr>Co>As. Potential ecological risk factors (Er) were under low risk and comprehensive potential ecological risk indices (Ri) were found to be under low, moderate and high risk categories. Copper (Cu) is the main pollutant contributing considerable load to Ri. From (Ri) principal component analysis and cluster analysis, it is evident that the Okhla site (S8) is most contaminated. The water from Yamuna river needs to be cautiously used for growing various food crops on land adjacent to the river as its long-term usage might cross the permissible limits of heavy metals in the soil. Image 1 • This study estimates the heavy metal load in Yamuna river water and surrounding soils, and soil enzyme activities. • Irrigation with Yamuna water significantly accumulated heavy metals in soil and soil enzyme activities. • Total organic C, easily oxidisable soil organic carbon masked the effect of heavy metal on soil enzymes activities. • Dehydrogenase, and urease were most sensitive, while nitrate reductase was least sensitive to heavy metalin soil. [ABSTRACT FROM AUTHOR]

The cardinal focus of this study is to optimize the best reaction conditions for maximizing laccase activity from spent mushroom waste (SMW) of Pleurotus florida. Optimization process parameters were studied by the modeling techniques, artificial neural networking (ANN) embedded in particle swarm optimization (PSO), and response surface model (RSM). The best topology of ANN-PSO architecture was obtained on 4-10-1. The R2, IOA, MSE, and MAE values of the ANN model were obtained as 0.98785, 0.9939, 0.0023, and 0.0251 while, that of the RSM model were obtained as 0.74290, 0.9210, 0.0244, and 0.1110 respectively. The higher values of R2, IOA, and lower values of MSE and MAE of the ANN-PSO model depict that ANN-PSO outperformed compared to RSM and also verified the effectiveness of the ANN-PSO model. The ANN-PSO model performance demonstrates the robustness of the technique in optimizing laccase activity in SMW of P. florida. The optimization results revealed that pH 4.5, time 3 h, solid: solution ratio 1:5, and ABTS concentration of 1 mM was optimal for achieving maximum laccase activity at temperature 30 °C. The enzymatic activity of crude laccase enzyme was obtained as 1.185 U ml−1 without loss of enzyme activity. Additionally, crude laccase enzyme was 1.74 fold partially purified, and 83.54% of the enzyme was yielded. Out of all the independent process variables, ABTS and pH had an influence on laccase activity. Therefore, we anticipate that the findings of this investigation will reduce the ambiguity in maximizing laccase activity and ease the screening process. This study also highlights the comparative cost evaluation of crude laccase enzyme extracted from P. florida and commercial enzymes. There is a great potential for the utilization of the laccase enzyme extracted from SMW and using it for the degradation of recalcitrant micropollutants. Thus, SMW promises a cost-effective and sustainable approach leading towards circular economy. • This study dealt with extraction of laccase enzyme from SMW of P.florida. • Optimized various parameters for maximum laccase activity in lesser time. • ANN-PSO and RSM are both modeling techniques. • R 2 value obtained for ANN-PSO validates the experimental value. • Insights into the cost economics of extraction procedure through crude laccase enzyme and commercial enzyme. [ABSTRACT FROM AUTHOR]

The primary source of soil pollution is a complex mixture of numerous inorganic and organic compounds (including chlorinated compounds, nutrients, and heavy metals, etc.). The presence of all of these compounds makes remediation and cleanup difficult. In this study, the phytoremediation ability of Jatropha curcas and Pongamia pinnata was tested to remove nickel (Ni) and Zinc (Zn) from paper mill and municipal landfill contaminated soils, to understand the uptake potential and to estimate the accumulation pattern of Ni and Zn in the vegetative parts of the plant. The experiments were carried out in pots (3 kg capacity) and the different combinations of soil were made by mixing the contaminated soil with a reference soil (forest soil) as T 0 , T 25 , T 50 , T 75 and T 100. The plant biomass, chlorophyll content, proline, nitrate reductase activity and metal removal efficiency (%)were determined after 120 DAS (i.e., the days after sowing). The results of the study showed that with increasing metal stress, there is a reduction in the above-ground biomass content in both the plant species with a slightly less impact on the root biomass. Over a period of 4 months, J. curcas and P. pinnata removed 82–86% and 93-90% Ni, respectively. The removal of Zn was significantly less as compared to Ni as most of the Zn remained in the belowground part (roots) and in the soil. Besides, the phytostabilization capacities of the plants were calculated on the basis of their tolerance index (TI), bioaccumulation factor (BAF) and translocation factor (TF). The low BAF and TF values with increasing heavy metals (HMs) content indicates its higher phytostabilization capacity in the root and rhizospheric region as compared to phytoaccumulation. [Display omitted] • J. curcas and P. pinnata removes 82 - 86 % and 93- 90 % Ni respectively. • High biomass and bioaccumulation factor (BAF) > 1: Suitable for metal phytoextraction. • Low biomass and BAF < 1: Suitable for metal phytostabilization. • Low translocation factor (< 1) indicated the phytostabilization capacity of the plants. [ABSTRACT FROM AUTHOR]

Due to the complicated structure of lignocellulosic plant cell wall, their utilization for biogas production via anaerobic digestion has not been widely adopted. Alternative to this is to use aquatic plant materials as feedstock for biogas production. In this context, duckweed, an aquatic plant may prove to be a promising new energy source for bioenergy as well efficient CO 2 sequestration. This study entails a detailed characterization of duckweed to evaluate their potential as an alternate feedstock to cattle dung for biogas production. The duckweed was characterized for volatile matter, moisture content, ash content and carbon, hydrogen, and nitrogen (CHN) content. Property analysis of duckweed was also done by Fourier transform spectroscopy and thermogravimetric analysis. The volatile matter of duckweed was found to be 84.24± 0.2% with a lignin content of 12.2%, which is very encouraging for biogas production. Co-digestion of duckweed (DW) with cattle dung (CD) in varying ratios (DW:CD = 90:10, 75:25, and 50:50 respectively) in batch type anaerobic digesters was performed at 37 °C temperature for 55 days. The cumulative biogas production for CD (100%), DW/CD (90:10), (75:25) and (50:50) was found to be 11,620, 305, 11,695, and 12,070 mL, respectively, which indicated that duckweed can be a potential lignocellulosic feedstock when co-digested with cattle dung at an optimum ratio of 1:1. Methane content of the biogas from co-digested feedstock is comparable to the biogas from cattle dung alone. [ABSTRACT FROM AUTHOR]

Cleanup (CU) demineralizer of TAPS 1 and 2, containing mixed bed resins, is used to maintain reactor water chemistry. Once the bed is saturated, spent resin needs to be transferred to resin fixation facility for fixation and subsequent disposal in near-surface disposal facility. This is done by transporting the spent resin in a shielded resin transportation cask (SRTC) from radwaste building. The SRTC was manufactured with shielding thickness, based on methodology proposed by Rautela et al., "Shielding adequacy of proposed cask for transporting TAPS 1 and 2 CU spent resins." Extensive radiation monitoring was carried out during the entire transfer and transportation process. Observed radiation levels on cask surface were within the accepted and calculated radiation levels. This paper describes verification methodology proposed by Rautela et al. and health physics operating experience during first CU spent resin transfer process at TAPS 1 and 2. [ABSTRACT FROM AUTHOR]

We studied the effects of tillage and straw management on soil aggregation and soil carbon sequestration in a 30-year split-plot experiment on clay soil in southern Finland. The experimental plots were under conventional or reduced tillage with straw retained, removed or burnt. Wet sieving was done to study organic carbon and soil composition divided in four fractions: 1) large macroaggregates, 2) small macroaggregates, 3) microaggregates and 4) silt and clay. To further estimate the stability of carbon in the soil, coarse particulate organic matter, microaggregates and silt and clay were isolated from the macroaggregates. Total carbon stock in the topsoil (equivalent to 200 kg m − 2 ) was slightly lower under reduced tillage (5.0 kg m − 2 ) than under conventional tillage (5.2 kg m − 2 ). Reduced tillage changed the soil composition by increasing the percentage of macroaggregates and decreasing the percentage of microaggregates. There was no evidence of differences in the composition of the macroaggregates or carbon content in the macroaggregate-occluded fractions. However, due to the higher total amount of macroaggregates in the soil, more carbon was bound to the macroaggregate-occluded microaggregates in reduced tillage. Compared with plowed soil, the density of deep burrowing earthworms ( Lumbricus terrestris ) was considerably higher under reduced tillage and positively associated with the percentage of large macroaggregates. The total amount of microbial biomass carbon did not differ between the treatments. Straw management did not have discernible effects either on soil aggregation or soil carbon stock. We conclude that although reduced tillage can improve clay soil structure, generally the chances to increase topsoil carbon sequestration by reduced tillage or straw management practices appear limited in cereal monoculture systems of the boreal region. This may be related to the already high C content of soils, the precipitation level favoring decomposition and aggregate turnover in the winter with topsoil frost. [ABSTRACT FROM AUTHOR]

Phosphate solubilizing bacteria (PSB) that can withstand high cadmium (Cd) stress is a desired combination for bioremediation. This study evaluated the Cd bioremediation potential of four PSB strains isolated from the contaminated soils of a municipal solid waste (MSW) discarding site (Guwahati, India). PSB strains were cultured in Pikovskaya (PVK) media, which led to higher acid phosphatase (ACP) activity and the release of organic acid. Optical density (OD) measurements were performed to determine the growth pattern of PSB; furthermore, Cd uptake by PSB was evaluated using infrared spectroscopy (IR) and X-Ray Diffraction (XRD) analyses. The 16S rRNA taxonomic analysis revealed that all the four promising PSB strains belonged to either Bacillus sp. or Enterobacter sp. One strain (SM_SS8) demonstrated higher tolerance towards Cd (up to 100 mg L−1). Flow cytometry analysis revealed 70.92%, 46.93% and 20.4% viability of SM_SS8 in 10, 50 and 100 mg L−1, respectively in PVK media containing Cd. This study has therefore substantiated the bioremediation of Cd from polluted soil by the PSB isolates. Thus, experimental results revealed a potential combo benefit, phosphate solubilization along with Cd remediation. [Display omitted] • Isolated four phosphate solubilizing bacteria (PSB) from MSW dumping site's soil. • One of the isolated PSB strains (SM_SS8) demonstrated significant Cd tolerance. • Flow cytometry analysis revealed that SM_SS8 strain can resist 100 mg L−1 Cd stress. • Intracellular accumulation of Cd in PSB was confirmed by FTIR and XRD analyses. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) accumulation in the soils poses risks towards the environment and health. Glomalin related soil protein (GRSP) produced by arbuscular mycorrhizal fungi (AMF) has metal-sorption and soil aggregation properties and is critical in the survival of plants and AMF. For the first time, this study attempted to examine the GRSP mediated bio-stabilization of HMs in soils contaminated with municipal solid wastes (MSW). The content and interrelationship of GRSP and HMs, along with soil physicochemical properties were studied in 20 different soil samples from the dumping site. Higher amount of GRSP indicated potential bio-stabilization of HMs at some sites. GRSP exhibited weak positive correlation with essential (Zn, Cu) and toxic HMs (Cd, Ni). Cr and Mn were possibly sequestered in AMF structures and thus found to be negatively correlated with GRSP. The positive correlation observed between GRSP and soil nutrients like N, P and soil organic carbon (SOC) indicating potential of AMF-GRSP in sustaining soil health. Results revealed that AMF residing at contaminated sites produced higher amount of GRSP potentially to bio-stabilize the HMs, and reduce their bioavailability and also facilitate SOC sequestration. [Display omitted] • GRSP distribution in soil is regulated by types of vegetation and waste. • GRSP assists in remediation of heavy metals (Cd, Ni, Cr, Zn, Cu and Mn). • GRSP showed potentials in enriching soil carbon and soil nutrients. • GRSP can serve as a bioindicator of native arbuscular mycorrhizal fungi biomass. [ABSTRACT FROM AUTHOR]

Assessing the relationship between soil enzyme activities (SEAs) and heavy metals (HMs) without any amendment has rarely been conducted in soils contaminated with municipal solid wastes (MSW). Five soil enzymes [dehydrogenase (DHA), alkaline phosphatase (ALP), acid phosphatase (ACP), urease (UR), and nitrate reductase (NR)] have been assessed for HMs bioremediation using Zea mays L. grown in unamended soils that were contaminated with different types of MSW. Pot experiment was conducted for two seasons with soils collected from seven different locations within the MSW site. Experimental soil samples included a control (CA), contaminated by brick kiln wastes (SA1), kitchen and household wastes (SA2), medical wastes (SA3), mixed wastes (SA4), glass wastes (SA5), and metal scrap wastes (SA6). Rhizospheric soils were collected after the harvest of each season to investigate the impact of HMs on SEAs and physicochemical properties of soil. The results revealed an increase in DHA, ALP, and NR activities by 89.30%, 58.03% and 21.98% in SA1. Likewise, enhanced activities for UR (28.26%) and ACP (19.6%) were observed in SA3 and SA5 respectively. Insignificant increase in the macronutrients and organic carbon (OC) were also noted. The increased microbial count and the relatively higher amount of organic matter (OM) in the rhizosphere indicated the role of OM in HMs immobilization. Principal component analysis (PCA) indicated that DHA and NR are the important soil enzymes, underscored by their active involvement in the C and N turnover in the soil. Likewise, correlation analysis showed that DHA and NR activities were positively correlated with copper (Cu) (0.90, p < 0.01; 0.88, p < 0.01), suggesting its participation as a cofactor in enzymatic activities. In contrast, DHA was negatively correlated with cadmium (Cd) (−0.48, p < 0 0.05). Finally, these results indicated that in the absence of exogenous nutrient amendment, the SEAs were governed by OC, available nitrogen (Avl. N), Cu and Cd respectively. The study also highlighted the need for extensive research on SEAs for its utilization as a bioindicator in various soil bioremediation and quality management practices. [Display omitted] • Present study examined SEAs and its dynamics in MSW contaminated soil. • Over time increase in SEAs observed even without any nutrient input. • Organic matter promoted nutrient recycling under HM stress. • DHA and NR activities significantly correlated with Cu. • SEAs could be used as a bio-indicator for integrated soil management practices. [ABSTRACT FROM AUTHOR]

This study reports the environmental fate and ecological hazard of the three heavy metals (HMs), viz. copper (Cu), manganese (Mn) and zinc (Zn) in soil influenced by municipal solid waste (MSW) dumping. The experimental site is situated in the vicinity of Deepor Beel, a Ramsar site located in Guwahati, India. This study assessed (i) the distribution pattern of Cu, Mn and Zn in six geochemical fractionations; (ii) the mobility, bioavailability and toxicity of Cu, Mn and Zn based on eight contamination and ecological indices, and (iii) the impact of Cu, Mn and Zn on soil quality. Altogether, 18 soil samples were collected and analysed from the study site using stratified random sampling. Pollution indices and multivariate statistics were applied on the data to identify the level and source of analysed HMs. Sequential extraction has revealed that the binding strength of Cu, Mn and Zn had a uniform trend. Mobility and potential bioavailability of studied HMs were in the order Mn > Cu > Zn. Analysed HMs were dominantly associated with non-bioavailable fractions. The observed low values of various contamination factors indicated the lesser contamination load posed by these metals. Conversely, their high enrichment factor and geo-accumulation index values indicated the sources of these metals were anthropogenic. Overall, the pollution and ecological indices registered lower contamination. Yet, it would be prudent to adopt efficient MSW management strategies for eliminating any future risk emanating out of this dumping site and posing threat to nearby Deepor Beel and its associated flora and fauna. Image 1 • Environmental risks associated with three heavy metals (Cu, Mn and Zn) in the soils were determined. • Municipal solid wastes (MSW) containing heavy metals (HM) pose ecological risk. • Major sources of these HMs were anthropogenic in nature. • Scientific waste management is needed to protect Deepor Beel, a Ramsar site. [ABSTRACT FROM AUTHOR]

There is dearth of studies on climate change based vulnerabilities of the urban people. It has been a matter of widespread debate whether nature of livelihood has any role to play in regulating the vulnerabilities of an individual. To find an answer, in a first ever attempt, this study tested three different approaches viz. Livelihood Vulnerability Index (LVI), LVI IPCC (Intergovernmental Panel on Climate Change) models and Climate Vulnerability Index (CVI) to estimate climate change vulnerability of urban communities from various livelihoods in Guwahati city, Assam, India. Guwahati is considered to be the gateway to the seven North Eastern states of India and therefore strategically very important for this region. A structured survey was conducted involving 200 stakeholders from various livelihood sectors viz. construction workers, perishable item sellers, farmers, taxi/auto driver/rickshaw puller/coolie, tea stall/fast food seller, gas cylinder deliverymen, street vendors/salespersons, traffic police/police, doctors and boatmen. Data was systematically aggregated and examined using the above-mentioned composite indices. The differential vulnerabilities were compared and results suggested that the farmers were the most vulnerable community by virtue of their high sensitivity towards health, economic losses, exacerbated by their poor adaptive capacity toward unpredictable climatic variations. Doctors were the least vulnerable owing to their higher levels of awareness and adaptive capacity. These results reiterated the importance of awareness and access to resources in regulating vulnerability. The vulnerability scores also revealed that LVI and Model II (M II) of LVI IPCC approaches were the two most suitable indices and could be used for comparative vulnerability analysis. These pragmatic approaches can be used to assess the community vulnerabilities and could stimulate robust Climate Smart Urban Planning (CSUP). Image 104472 • Three different vulnerability index models were tested for Guwahati city, India. • Nature of livelihood regulated the vulnerabilities of urban communities. • Education, awareness and income found to be critical for coping capacity. • Farmers found to be the most vulnerable, while doctors were the least. • Outcome of this study calls for designing Climate Smart Urban Planning (CSUP). [ABSTRACT FROM AUTHOR]