Arsenic (As) is a toxic metalloid and its widespread contamination in agricultural soils along with soil salinization has become a serious concern for human health and food security. In the present study, the effect of cotton shell biochar (CSBC) in decreasing As-induced phytotoxicity and human health risks in quinoa (Chenopodium quinoa Willd.) grown on As-spiked saline and non-saline soils was evaluated. Quinoa plants were grown on As contaminated (0, 15 and 30 mg kg⁻¹) saline and non-saline soils amended with 0, 1 and 2% CSBC. Results showed that plant growth, grain yield, stomatal conductance and chlorophyll contents of quinoa showed more decline on As contaminated saline soil than non-saline soil. The application of 2% CSBC particularly enhanced plant growth, leaf relative water contents, stomatal conductance, pigment contents and limited the uptake of As and Na as compared to soil without CSBC. Salinity in combination with As trigged the production of H₂O₂ and caused lipid peroxidation of cell membranes. Biochar ameliorated the oxidative stress by increasing the activities of antioxidant enzymes (SOD, POD, CAT). Carcinogenic and non-carcinogenic human health risks were greatly decreased in the presence of biochar. Application of 2% CSBC showed promising results in reducing human health risks and As toxicity in quinoa grown on As contaminated non-saline and saline soils. Further research is needed to evaluate the role of biochar in minimizing As accumulation in other crops on normal as well as salt affected soils under field conditions.

The present study investigated the beneficial role of selenium-nanoparticles (Se-NPs) in mitigating the adverse effects of soil-salinity on growth and yield of strawberry (Fragaria × ananassa Duch.) plants by maneuvering physiological and biochemical mechanisms. The foliar spray of Se-NPs (10 and 20 mg L⁻¹) improved the growth and yield parameters of strawberry plants grown on non-saline and different saline soils (0, 25, 50 and 75 mM NaCl), which was attributed to their ability to protect photosynthetic pigments. Se-NPs-treated strawberry plants exhibited higher levels of key osmolytes, including total soluble carbohydrates and free proline, compared with untreated plants under saline conditions. Foliar application of Se-NPs improved salinity tolerance in strawberry by reducing stress-induced lipid peroxidation and H₂O₂ content through enhancing activities of antioxidant enzymes like superoxide dismutase and peroxidase. Additionally, Se-NPs-treated strawberry plants showed accumulation of indole-3-acetic acid and abscisic acid, the vital stress signaling molecules, which are involved in regulating different morphological, physiological and molecular responses of plants to salinity. Moreover, the enhanced levels of organic acids (e.g., malic, citric and succinic acids) and sugars (e.g., glucose, fructose and sucrose) in the fruits of Se-NPs-treated strawberry plants under saline conditions indicated the positive impacts of Se-NPs on the improvement of fruit quality and nutritional values. Our results collectively demonstrate the definite roles of Se-NPs in management of soil salinity-induced adverse effects on not only strawberry plants but also other crops.

Silver (Ag) is released from a range of products and accumulates in agricultural soils as silver sulfide (Ag₂S) through the application of Ag-containing biosolids as a soil amendment. Although Ag₂S is comparatively stable, its solubility increases with salinity, potentially altering its impacts on microbial communities due to the anti-microbial properties of Ag. In this study, we investigated the impacts of Ag on the microbially mediated N cycle in saline soils by examining the relationship between the (bio)availability of Ag₂S and microbial functioning following the application of Ag₂S-containing sludge. Synchrotron-based X-ray absorption spectroscopy (XAS) revealed that the Ag₂S was stable within the soil, although extractable Ag concentrations increased up to 18-fold in soils with higher salinity. However, the extractable Ag accounted for <0.05% of the total Ag in all soils and had no impact on plant biomass or soil bacterial biomass. Interestingly, at high soil salinity, Ag₂S significantly increased cumulative N₂O emissions from 80.9 to 229.2 mg kg⁻¹ dry soil (by 180%) compared to the corresponding control sludge treatment, which was ascribed to the increased abundance of nitrification and denitrification-related genes (amoA, nxrB, narG, napA, nirS, and nosZ) and increased relative abundance of denitrifiers (Rhodanobacter, Salinimicrobium, and Zunongwangia). Together, our findings show that the application of Ag₂S-containing sludge to a saline soil can disrupt the N cycle and increase N₂O emissions from agroecosystems.

Microbial remediation is a potential remediation method for petroleum-contaminated soil. In order to explore the petroleum degradation mechanism by microorganisms, the oilfield soil was remedied by Acinetobacter baumannii combined with Talaromyces sp. The degradation mechanism was studied by analyzing soil microbial community and functional genes through metagenomics during the degradation process. The result showed the degradation rate of petroleum was 65.6% after 28 days. The concentration of petroleum decreased from 1220 mg/kg to 420 mg/kg. In the co-culture group, Acinetobacter baumannii became the dominant species, the annotated genes of it at the species level accounted for 7.34% while that of Talaromyces sp. accounted for only 0.34%. Meanwhile, the annotated genes of Bacillus, Halomonas, and Nitriliruptor at the genus level were up-regulated by 1.83%, 0.90%, and 0.71%, respectively. In addition, large functional genes were significantly up-regulated, including the peroxisome, P450 enzyme (CYP53, CYP116, CYP102, CYP645), and biofilm formulation, promoting the oxidation and hydroxylation, and catalyzing the epoxidation of aromatic and aliphatic hydrocarbons. Meanwhile, the degrading genes of alkanes and aromatic hydrocarbons were expressed promotionally, and degradation pathways were deduced. In conclusion, the inoculation of Acinetobacter baumannii combined with Talaromyces sp. accelerated the degradation of petroleum in oilfield soil and improved the growth of indigenous petroleum-degrading bacteria. Many functional genes related to petroleum degradation were promoted significantly. These results proved the co-culture of bacteria-fungi consortium contributes to the bioremediation of petroleum-contaminated soil.

This study aimed to investigate the difference of osmoregulation between two edible amaranth cultivars, Liuye (high Cd accumulator) and Quanhong (low Cd accumulator), under salinity stress and determine the effects of such difference on Cd accumulation. A pot experiment was conducted to expose the plants to sewage-irrigated garden soil (mean 2.28 mg kg⁻¹ Cd) pretreated at three salinity levels. Under salinity stress, the concentrations of Cd in the two cultivars were significantly elevated compared with those in the controls, and the Cd concentration in Liuye was statistically higher than that in Quanhong (p < 0.05). Salinity-induced osmoregulation triggered different biogeochemical processes involved in Cd mobilization in the rhizosphere soil, Cd absorption, and translocation by the two cultivars. Rhizosphere acidification induced by an imbalance of cation over anion uptake was more serious in Liuye than in Quanhong, which obviously increased soil Cd bioavailability. Salinity-induced injuries in the cell wall pectin and membrane structure were worse in Liuye than in Quanhong, increasing the risk of Cd entering the protoplasts. The chelation of more cytoplasmic Cd²⁺ with Cl⁻ ions in the roots of Liuye promoted Cd translocation into the shoots. Furthermore, the less organic solutes in the root sap of Liuye than in that of Quanhong also favored Cd translocation into the shoots. Hence, osmoregulation processes can be regarded as important factors in reducing Cd accumulation in crop cultivars grown on saline soils.

Ability of Achromobacter xylosoxidans, a chrysene degrading marine halotolerant bacterium to degrade polycyclic aromatic hydrocarbons (PAHs) using a cost effective laboratory microcosm approach, was investigated. Effect of variables as chrysene, glucose as a co-substrate, Triton X-100 as a non-ionic surfactant and β-cyclodextrin as a PAHs solubilizer was examined on degradation of low molecular weight (LMW) and high molecular weight (HMW) PAHs. A total of eleven PAHs detected from polluted saline soil were found to be degraded. Glucose, in combination with Triton X-100 and β-cyclodextrin resulted in 2.8 and 1.4-fold increase in degradation of LMW PAHs and 7.59 and 2.23-fold increase in degradation of HMW PAHs, respectively. Enhanced biodegradation of total PAHs (TPAHs) by amendments with Triton X-100 and β-cyclodextrin using Achromobacter xylosoxidans can prove to be promising approach for in situ bioremediation of marine sites contaminated with PAHs.

The study proposes a novel and sustainable method to appropriately utilize wastes from granite as well as glass industries in brick manufacturing. An ecofriendly and low-cost manufacturing process of ash-based bricks pertaining to the Indian standard codal provisions that can be adopted on the commercial scale is deliberated. The research also recommends the method for predicting the strength of the ash-based bricks using machine learning algorithms like random forests and decision trees. For positive synergy in the performance, both the granite tailings and glass waste must be used together. Using the granite tailings and glass waste together led to a significant reduction of 75% in the fly ash requirement without compromising the brick’s performance. The addition of the granite tailings and glass waste in the mix could increase the strength of the brick by 90.5% and 37.7%, respectively. Beyond 30% dosage of granite, tailings are not recommended as they may lead to the poor gradation of particles and weak bonding in the microstructure. The glass waste in the mixture should not be more than 15% as it causes the dilution of pozzolanic reactions thereby forming fewer hydrated compounds. Brick’s durability is known after exposing the specimens for 1 year to sewers and biogenic corrosion environment, marine environment, and saline soil environment, respectively. The inclusion of the industrial wastes significantly reduced the specimen damage in the extreme environmental conditions along with the least absorption rates. The dosage of ash, granite tailings, and glass waste has to be maintained around 15%, 30%, and 15%, respectively for attaining the optimum performance. Out of the generated machine learning algorithms, only random forests could be able to predict the values accurately with R² values at 0.90 and with comparatively lesser errors.

Salt-affected soils have poor structure and physicochemical properties, which affect soil nitrogen cycling process closely related to the environment, such as denitrification and ammonia volatilization. Biochar and polyacrylamide (PAM) have been widely used as soil amendments to improve soil physicochemical properties. However, how they affect denitrification and ammonia volatilization in saline soils is unclear. In this study, the denitrification and ammonia volatilization rates were measured in a saline soil field ameliorated with three biochar application rates (0%, 2%, and 5%, w/w) and three PAM application rates (0‰, 0.4‰, and 1‰, w/w) over 3 years. The results showed that denitrification rates decreased by 23.63–39.60% with biochar application, whereas ammonia volatilization rates increased by 9.82–25.58%. The denitrification and ammonia volatilization rates decreased by 9.87–29.08% and 11.39–19.42%, respectively, following PAM addition. However, there was no significant synergistic effect of biochar and PAM amendments on the denitrification and ammonia volatilization rates. The addition of biochar mainly reduced the denitrification rate by regulating the dissolved oxygen and electrical conductivity of overlying water and absorbing soil nitrate nitrogen. Meanwhile, biochar application increased pH and stimulated the transfer of NH₄⁺–N from soil to overlying water, thus increasing NH₃ volatilization rates. Hence, there was a tradeoff between denitrification and NH₃ volatilization in the saline soils induced by biochar application. PAM reduced the denitrification rate by increasing the infiltration inorganic nitrogen and slowing the conversion of ammonium to nitrate. Moreover, PAM reduced the concentration of NH₄⁺–N in the overlying water through absorbing soil ammonium and inhibiting urea hydrolysis, thereby decreasing NH₃ volatilization rate.

The soil saltiness in the Brazilian semiarid environment is a common problem caused by incorrect agricultural practices, allied to the local weather and soil condition. The use of phosphogypsum (PG) to recover these soils still is a concern since this material has in its composition natural radionuclides. An experiment was conducted to study the use of phosphogypsum to reduce the salinity and evaluate the bioavailability of radionuclides on the Brazilian semiarid region soils. The radionuclide content of phosphogypsum samples were previously analyzed by gamma spectrometry. Three differents doses of phosphogypsum were mixed with samples of surface soil in the greenhouse, and after a reaction time and irrigation, controlled soil samples + phosphogypsum underwent simple extractions based on the sequential extraction method by Tessier et al. Ra isotopes and ²¹⁰Pb in the extracted fractions were analyzed by counting alpha and beta. The higher concentration of Ra isotopes and ²¹⁰Pb were associated to residual fraction, followed by exchangeable fraction due to the low levels of carbonates, organic matter, and manganese and iron oxides. The use of phosphogypsum studied did not contribute to increase the ²²⁶Ra activity on the analyzed soils. ²²⁶Ra levels in phosphogypsum were lower than those recommended by the USEPA to allow the use of phosphogypsum in agricultural soils, but can contribute to the accumulation of ²²⁸Ra and ²¹⁰Pb. The phosphogypsum Imbituba promoted a satisfactory reduction of electrical conductivity in the soils, which indicates the possibility of recovery of these soils.

Trace element concentrations on a dry ash basis in saline-irrigated biomass feedstock from the San Joaquin Valley are investigated using multi-element spectroscopic techniques. The results show high concentrations of both Na and K compared to local baseline soil. The content of Na is higher than observed for nonsaline-irrigated biomass reflecting the salinity of the drainage water. The alkali earth elements as well as other alkali trace elements are, however, not markedly affected by the salinity of the irrigation water. The transition elements Cu and Zn are enriched only in the herbaceous feedstock compared to nonsaline biomass. Sulfur, chlorine, and phosphorus are markedly enriched in the saline feedstock. The ash content of toxic elements invariably exceeds the concentrations in the baseline soil for Cu, As, Se, Cd, Sb, and Pb. Compared to nonsaline biomass ashes, Cu is relatively enriched in the herbaceous feedstock ashes, As only in eucalyptus wood, and Cd, Sb, and Pb in woody feedstock. Selenium is relatively enriched in all saline feedstock. Only the concentrations of Cd in woody saline-irrigated feedstock may potentially exceed environmental guideline concentrations and may, thus, warrant caution for using saline biomass for soil amendment.