Cadmium (Cd) toxicity is a widespread problem in crops grown on contaminated soils, and little information is available on the role of inorganic amendments in Cd immobilization, uptake, and tolerance in crops especially under filed conditions. The effect of three amendments, monoammonium phosphate (MAP), gypsum, and elemental sulfur (S), on Cd immobilization in soil and uptake in wheat and rice plants, under rotation, were investigated under field conditions receiving raw city effluent since >20 years and contaminated with Cd. Three levels of each treatment, 0.2, 0.4, and 0.8 % by weight, were applied at the start of the experiment, and wheat was sown in the field. After wheat harvesting, rice was sown in the same field without application of amendments. Both crops were harvested at physiological maturity, and data regarding grain yield, straw biomass, Cd concentrations, and uptake in grain and straw, and bioavailable Cd in soil and soil pH were recorded. Both MAP and gypsum application increased grain yield and biomass of wheat and rice, while S application did not increase the yield of both crops. MAP and gypsum amendments decreased gain and straw Cd concentrations and uptake in both crops, while S application increased Cd concentrations in these parts which were correlated with soil bioavailable Cd. We conclude that MAP and gypsum amendments could be used to decrease Cd uptake by plants receiving raw city effluents, and gypsum might be a better amendment for in situ immobilization of Cd due to its low cost and frequent availability.

Oxidative degradation of aqueous organic contaminants 2,4-dichlorophenol (2,4-DCP) using ethylenediaminetetraacetic acid (EDTA)-enhanced bimetallic Cu–Fe system in the presence of dissolved oxygen was investigated. The proposed process was applied for the pH range of 3~7 with the degradation efficiency of 2,4-DCP and EDTA varying within 10 %, and achieved at 100 % degradation of 40 mg L⁻¹2,4-DCP in 1 h, at the initial pH of 3, 25 g L⁻¹of bimetallic Fe–Cu powder (WCᵤ/WFₑ = 0.01289) and initial EDTA of 0.57 mM. However, the removal efficiency of 2,4-DCP in control tests were 7.52 % (Cu–Fe/O₂system) and 84.32 % (EDTA-enhanced Fe/O₂process), respectively, after 3 h, reaction. The proposed main mechanism, involves the in situ generation of H₂O₂by the electron transfer from Fe⁰to O₂which was enhanced by ethylenediaminetetraacetic acid (EDTA), and the in situ generation of ·OH via advanced oxidation reaction. Accordingly, 2,4-DCP was attacked by ·OH to achieve complete dechlorination and low molecular weight organic acids, even mineralized. Systematic studies on the effects of initial EDTA and 2,4-DCP concentration, Cu–Fe dosing, Cu content, and pH revealed that these effects need to be optimized to avoid the excessive consumption of ·OH and new EDTA and heavy metal Cu pollution.

In this study, anthracene was employed as a probe to explore the potential catalytic effect of clay minerals in soil environment. Clay minerals saturated with various exchangeable cations were tested. The rate of anthracene transformation follows the order: Fe–smectite >> Cu–smectite > Al–smectite ≈ Ca–smectite ≈ Mg–smectite ≈ Na–smectite. This suggests that transition-metal ions such as Fe(III) play an important role in anthracene transformation. Among Fe(III)-saturated clays, Fe(III)–smectite exhibits the highest catalytic activity followed by Fe(III)–illite, Fe(III)–pyrophyllite, and Fe(III)–kaolinite, which is in agreement with the interlayer Fe(III) content. Moreover, effects by two common environmental factors, pH and relative humidity (RH), were evaluated. With an increase in pH or RH, the rate of anthracene transformation decreases rapidly at first and then is leveled off. GC-MS analysis identifies that the final product of anthracene transformation is 9,10-anthraquinone, a more bioavailable molecule compared to anthracene. The transformation process mainly involves cation-π bonding, electron transfer leading to cation radical, and further oxidation by chemisorbed O₂. The present work provides valuable insights into the abiotic transformation and the fate of PAHs in the soil environment and the development of contaminated land remediation technologies.

Bromacil (5-bromo-3-sec-butyl-6-methyluracil) is a substituted uracil herbicide used worldwide. It is not readily biodegradable and has the potential to contaminate different types of water bodies with possible impact on diverse non-target species. In this work, degradation of bromacil in aqueous Au/TiO₂suspension under simulated sunlight allowed fourteen degradation products to be identified. The photodegradation of bromacil followed (pseudo) first order kinetics in the presence of 0.2 g L⁻¹of Au/TiO₂with a half-life of 25.66 ± 1.60 min and a rate constant of 0.0271 ± 0.0023 min⁻¹. Transformation routes of the photo-catalytic degradation of bromacil were then proposed. Complementary toxicity assessment of the treated bromacil solution revealed a marked decrease in toxicity, thereby confirming that by-products formed would be less harmful from an environmental point of view. Photo-catalytic degradation of bromacil thus appears to hold promise as a cost-effective treatment technology to diminish the presence of this herbicide in aquatic systems.

Nuclear power reactors are operating in 31 countries around the world. Along with reactor operations, activities like mining, fuel fabrication, fuel reprocessing and military operations are the major contributors to the nuclear waste. The presence of a large number of fission products along with multiple oxidation state long-lived radionuclides such as neptunium (²³⁷Np), plutonium (²³⁹Pu), americium (²⁴¹/²⁴³Am) and curium (²⁴⁵Cm) make the waste streams a potential radiological threat to the environment. Commonly high concentrations of cesium (¹³⁷Cs) and strontium (⁹⁰Sr) are found in a nuclear waste. These radionuclides are capable enough to produce potential health threat due to their long half-lives and effortless translocation into the human body. Besides the radionuclides, heavy metal contamination is also a serious issue. Heavy metals occur naturally in the earth crust and in low concentration, are also essential for the metabolism of living beings. Bioaccumulation of these heavy metals causes hazardous effects. These pollutants enter the human body directly via contaminated drinking water or through the food chain. This issue has drawn the attention of scientists throughout the world to device eco-friendly treatments to remediate the soil and water resources. Various physical and chemical treatments are being applied to clean the waste, but these techniques are quite expensive, complicated and comprise various side effects. One of the promising techniques, which has been pursued vigorously to overcome these demerits, is phytoremediation. The process is very effective, eco-friendly, easy and affordable. This technique utilizes the plants and its associated microbes to decontaminate the low and moderately contaminated sites efficiently. Many plant species are successfully used for remediation of contaminated soil and water systems. Remediation of these systems turns into a serious problem due to various anthropogenic activities that have significantly raised the amount of heavy metals and radionuclides in it. Also, these activities are continuously increasing the area of the contaminated sites. In this context, an attempt has been made to review different modes of the phytoremediation and various terrestrial and aquatic plants which are being used to remediate the heavy metals and radionuclide-contaminated soil and aquatic systems. Natural and synthetic enhancers, those hasten the process of metal adsorption/absorption by plants, are also discussed. The article includes 216 references.

The exogenous organic pollutant linear alkylbenzene sulfonate (LAS) pollution and Microcystis bloom are two common phenomena in eutrophic lakes, but the effects of LAS alone on Microcystis remain unclear. In the present study, we investigated the effects of LAS on the growth, photochemical efficiency, and microcystin production of Microcystis aeruginosa in the laboratory. Results showed that low LAS (≤10 mg/L) concentrations improved the growth of M. aeruginosa (12 days of exposure). High LAS (20 mg/L) concentrations inhibited the growth of M. aeruginosa on the first 8 days of exposure; afterward, growth progressed. After 12 days of exposure, the concentrations of chlorophyll a in algal cells were not significantly affected by any of LAS concentrations (0.05 to 20 mg/L) in the present study; by contrast, carotenoid and protein concentrations were significantly inhibited when LAS concentrations reached as high as 20 mg/L. After 6 and 12 days of exposure, low LAS (≤10 mg/L) concentrations enhanced the maximal photochemical efficiency (Fv/Fm) and the maximal electron transport rate (ETRmax) of M. aeruginosa. Furthermore, LAS increased the microcystin production of M. aeruginosa. Extracellular and intracellular microcystin contents were significantly increased after M. aeruginosa was exposed to high LAS concentrations. Our results indicated that LAS in eutrophic lakes may increase the risk of Microcystis bloom and microcystin production.

Autotrophic biofilms are complex and fundamental biological compartments of many aquatic ecosystems. Since microbial species differ in their sensitivity to stressors, biofilms have long been proposed for assessing the quality of aquatic ecosystems. Among the many stressors impacting aquatic ecosystems, eutrophication and metal pollution are certainly the most common. Despite that these stressors often occur together, their effects on biofilms have been far much studied separately than interactively. In this study, we evaluated the interactive effects of silver (Ag), a reemerging contaminant, and phosphorus (P), a nutrient often associated with freshwater eutrophication, on the structure and functioning of two types of autotrophic biofilms, one dominated by diatoms and another one dominated by cyanobacteria. We hypothesized that P would alleviate the toxic effects of Ag, either directly, through the contribution of P in metal detoxification processes, or indirectly, through P-mediated shifts in biofilm community compositions and associated divergences in metal tolerance. Results showed that Ag impacted biofilm community structure and functioning but only at unrealistic concentrations (50 μg/L). P availability led to significant shifts in biofilm community composition, these changes being more pronounced in diatom- than those in cyanobacteria-dominated biofilm. In addition, P tended to reduce the impact of Ag but only for the cyanobacteria-dominated biofilm. More generally, our results highlight the preponderant role of the initial community structure and nutrient level on biofilm response to metallic pollutants.

Soil pollution in Egypt became far more serious than before due to either the heavy usage of different toxic pesticides or aerosol deposition of industrial pollutants. The present mentioned ground beetle, Blaps polycresta Tschinkel 1975 (Coleoptera: Tenebrionidae), showed ecological, morphological, and histological alterations in adult insects as biomonitors. Two cultivated sites (reference and polluted) were chosen for sampling the insects. The results indicated a significant increase in soil cadmium concentration of the polluted site leading to sex-specific difference in cadmium accumulation in gonads and alimentary canal of insects that being higher in males than females. The cadmium pollution leads significantly to a decrease in population density, a reduction in body weight, an increase in mortality rate, and an increase in sex ratio of the insects. The results also revealed a striking decrease in body length of the polluted insects with a marked increase in the percentage of deformed gonads and alimentary canal of both sexes. Some histopathological alterations were also recorded in testis, ovary, and midgut of the polluted insects. Our results confirmed that beetles are a good bioindicator for soil pollution, and the different studied parameters could be easily employed as sensitive monitors for cadmium soil pollution.

Increasing land utilization through diverse forms of human activities, such as agriculture, forestry, urban growth, and industrial development, has led to negative impacts on the water quality of rivers. To find out how catchment attributes, such as land use, hydrologic soil groups, and lithology, can affect water quality variables (Ca²⁺, Mg²⁺, Na⁺, Cl⁻, HCO₃⁻, pH, TDS, EC, SAR), a spatio-statistical approach was applied to 23 catchments in southern basins of the Caspian Sea. All input data layers (digital maps of land use, soil, and lithology) were prepared using geographic information system (GIS) and spatial analysis. Relationships between water quality variables and catchment attributes were then examined by Spearman rank correlation tests and multiple linear regression. Stepwise approach-based multiple linear regressions were developed to examine the relationship between catchment attributes and water quality variables. The areas (%) of marl, tuff, or diorite, as well as those of good-quality rangeland and bare land had negative effects on all water quality variables, while those of basalt, forest land cover were found to contribute to improved river water quality. Moreover, lithological variables showed the greatest most potential for predicting the mean concentration values of water quality variables, and noting that measure of EC and TDS have inversely associated with area (%) of urban land use.

Literature on recovery of nitrogen and phosphorous from wastewater in the form of value-added struvite fertilizer has been critically reviewed towards the evolution of a sustainable management strategy. Presence of nitrogen and phosphorus is widespread in both domestic as well as industrial wastewater streams such as swine wastewater, landfill leachate, urine waste, dairy manure, coke wastewater, and beverage wastewater. Where these nitrogen and phosphorus compounds cause eutrophication of water bodies and considered as harmful discharges to the environment, they can be turned useful through simple chemical conversion into struvite (MgNH₄PO₄·6H₂O). In extensive studies on wastewater treatment, aspects of recovery of valuable materials remain dispersed. In the present article, almost all relevant aspects of sources of raw materials, chemistry and technology of struvite production, and its detailed characterization have been captured in a systematic and classified way so as to help in planning and designing an integrated scheme of struvite production through conversion of nitrogen and phosphorus components of waste streams. The study will help in formulating a new waste management strategy in this context by shifting focus from removal to recovery of nutrients from waste streams.