The aim of the study was to determine the effect of soil contamination with diesel oil (0, 5, 10 and 15 mL/kg d.m. of soil) on the macroelement content (nitrogen, phosphorus, potassium, sodium, magnesium and calcium) in the above-ground parts of oats (Avena sativa L.). A remediation effect of sludge as a substance which reduces the negative impact of this petroleum product on its element content in oats was also evaluated. Sewage sludge was applied in doses 0, 4, 8 and 12 g/kg of soil. The macroelement content in the above-ground parts of oats depended on the soil contamination with diesel oil and on the addition of sewage sludge to the soil. Soil contamination with diesel oil caused significant changes in the content of all macroelements in the above-ground biomass of oats. Increasing doses of the petroleum product in the series without sewage sludge decreased the content of all macroelements, except phosphorus and calcium. The highest effect was observed for the content of sodium in oats. The addition of sewage sludge to the soil alleviated the negative impact of diesel oil on the chemical composition of the plants. The application of sewage sludge to soil resulted in an increase in average content of nitrogen, sodium and magnesium (as opposed to phosphorus and partly calcium) in the above-ground parts of oats, compared to the series without sewage sludge.

Anthropogenic activities have caused extensive arsenic (As) contamination in soils. The role of biochar in the remediation of As-contaminated soils has been attracting attention lately. In this study, effects of straw biochar, iron oxide, and iron oxide–modified biochar on soil microbial community composition and soil chemical properties were tested in an As-contaminated soil. After 9 months of incubation, soil chemical properties and microbial communities were analyzed. Our results showed that biochar addition significantly increased soil pH value, soil organic carbon (SOC) concentration, and the ratio of soil carbon to nitrogen (soil C:N ratio) but decreased soil dissolved organic C. Adding iron oxide also increased soil pH value, while iron oxide–modified biochar decreased it. Interestingly, compared with the control, all treatments significantly decreased soil total microbial biomass and biomasses of soil bacteria, fungi, Actinomyces, and protozoa. In addition, significantly positive correlations were found between soil pH and soil total microbial biomass as well as bacterial, Actinomyces, and arbuscular mycorrhizal fungal biomass. There were negative relationships between SOC, soil C:N ratio, and all soil microbial biomass indicators in all treatments. These results indicated that biochar and iron oxide–modified biochar affected soil microbial community composition by altering the soil C:N ratio, but iron oxide affected it via adjusting soil pH. Furthermore, the iron oxide–modified biochar effects on soil microbial community and soil chemical properties are not the same as the additive effects of biochar and iron oxide alone, and its effect on soil microbial community is regulated by the soil C:N ratio. These findings will help guide the development of remediation practices for As-contaminated soil using biochar.

A combined process comprised of electro-Fenton and bioslurry (EF–bioslurry) was developed at lab scale for remediating a real coking plant soil with an initial polycyclic aromatic hydrocarbons (PAHs) content of 3605 mg/kg. Sodium citrate was used as a complexant to keep the iron in solution at near-neutral pH conditions for increasing the reaction rate. The appropriate order of application was to perform EF process followed by bioslurry, which was evaluated through analysis of degradation characteristics of individual processes. The optimum EF duration was assessed through an analysis of the induced changes in PAHs degradation and bacterial counts. The optimum application time of EF process was determined to be 24 h. The removal of PAHs was 95.2% for EF–bioslurry after 40 days, and the efficiency was increased by almost 150%, compared with the individual bioslurry treatment. The EF reaction caused significant cell death and high inhibition to polyphenol oxidase (PPO) activity of soil. The bacterial activity and counts in the slurry recovered rapidly after EF oxidation through the addition of raw soil (2%, w/w). Therefore, the combined process of EF–bioslurry process may be an efficient and promising approach for the remediation of highly organic-contaminated soil.

The scholars of environmental economics have attempted the investigation of the impact of foreign direct investment-growth nexus, but they have missed the essential role played by technological innovation and financial development regarding the environmental costs. The notable economic growth and the consequent speedy process of urbanization in BRICS countries have brought about colossal escalation of energy needs leading to environmental degradation. The present study endeavors to explore the effect of foreign direct investment, technological innovation, and financial development on carbon emissions in BRICS member countries, with data from 1990 to 2017. The results verify a strong cross-sectional dependence within the panel countries. The Augmented Mean Group (AMG) estimator shows that foreign direct investment, technological innovation, and financial development in the BRICS countries possess a negative and statistically significant long-run association with CO₂ emissions, while economic growth, trade openness, urbanization, and energy use are found to contribute statistically significant and positive with carbon emissions. The current study chose to employ the Dumitrescu and Hurlin panel causality test for examining the direction of causality. Findings reveal a bidirectional long-run causality running among financial development, economic growth, trade openness, urbanization, energy use, and CO₂ emissions; on the contrary, unidirectional causality is found between foreign direct investment and carbon emissions. Consequently, for the BRICS member countries, the development of industries, financial institutions, and development of technological innovation are required to attract quality foreign direct investment. Moreover, urbanization contributes enormously to environmental degradation and necessitates urgent policy responses in these countries.

Effects of turbulent energy dissipation rate (increased from 1.28 × 10⁻⁶ to 1.67 × 10⁻⁵ m² s⁻³) on Scenedesmus obliquus biomass and lipid accumulation at different aeration rates (0.3, 0.6, 0.9, 1.2, and 1.5 L min⁻¹) were investigated. The turbulent energy dissipation rate was calculated by CFD model simulation. When the turbulent energy dissipation rate increased to 7.30 × 10⁻⁶ m² s⁻³, the biomass and lipid productivity increased gradually, and finally reached their maximum values of 1.11 × 10⁷ cells mL⁻¹ and 16.0 mg L⁻¹ day⁻¹, respectively. When it exceeded 7.30 × 10⁻⁶ m² s⁻³, the biomass and lipid productivity showed a decreasing trend. Therefore, the most favorable turbulent energy dissipation rate for S. obliquus growth and lipid accumulation was 7.30 × 10⁻⁶ m² s⁻³.

In a context of scarcity of good quality water, reuse is a mandatory practice to increase water availability, thus allowing the exploitation of more cropland. Although several studies have evaluated the hydric potential of domestic gray water to promote the economic and environmental sustainability of agriculture, the focus of this study was to evaluate the application of this effluent on an ornamental plant, the sunflower. The experiment was conducted in a protected environment using a completely randomized block design with split plots and four replicates. Irrigation solutions containing different mixtures of treated gray water effluent (TGW) and drinking water (DW) (100% DW, 25% TGW + 75% DW, 50% TGW + 50% DW, 75% TGW + 25% DW, and 100% TGW) were arranged in the plots, while the ornamental sunflower cultivars (Bonito de Outono Sortido and Sol Vermelho) were arranged in the split plots. Irrigation with treated gray water did not affect the growth of the plants and the quality of the flowers until the dilution of 55% in drinking water. The cultivar Sol Vermelho showed better plant growth and flower quality when fertigated with dilutions of treated gray water. The principle of mixing fresh with gray water, applied to the production of ornamental sunflowers, allows obtaining flowers of good quality while saving drinking water and decreasing the deposition of effluents in the environment.

One of the main herbicides used in the agricultural environments is 2,4-dichlorophenoxyacetic acid (2,4-D). It is a synthetic plant hormone auxin employed in many crops including rice, wheat, sorghum, sugar cane, and corn to control wide leaf weeds. The indiscriminate use of pesticides can produce numerous damages to the environment. Therefore, this review has the objective to provide an overview on the main characteristics of the herbicides based on 2,4-D, mostly on the role of microorganisms in its degradation and its main degradation metabolite, 2,4- dichlorophenol (2,4-DCP). The remediation processes carried out by microorganisms are advantageous to avoid the pollution of the environment as well as to safeguard the population health.

Leachate generation is one of the problems present in the landfills and dumps, needing monitoring and quantification for the environmental conservation. The objective of this paper is to evaluate temporal data of leachate contamination in a municipal solid waste (MSW) landfill, located in the midwest of São Paulo state, Brazil. The physical-chemical parameters and chemical compounds of the local groundwater were evaluated during 13 years (2002 to 2015). The methodology included data processing and temporal behavior analysis by Mann-Kendall test. Physical-chemical parameters demonstrated a change from acid to basic medium and decrease of BOD, COD, and TOC concentrations. Chemical compounds demonstrated high concentrations close to the administration building of the landfill, despite the decrease of certain compounds (Al, Fe, Hg, K, Na, Pb, SO₄²⁻, total PO₄³⁻, Zn) over time in the entire landfill area. The results demonstrate that the landfill is in natural attenuation process, and the structures of the surrounding landscape and the location of the MSW disposal are fundamental to understand the presence and rate of each chemical compound.

Long-term monitoring is essential to assess the patterns and distribution of the residues of organochlorine pesticides (OCPs) in biota. Bird eggs have several advantages than other environmental matrixes, which have been used extensively to portray the accumulation and distribution of OCPs. The present study investigated the organochlorine pesticide (OCP) residues in eggs of 22 species of terrestrial birds collected from Tamil Nadu, India. Eggs found abandoned were collected during nest monitoring between 2001 and 2008 and analyzed for the presence of organochlorine pesticide residues. The results showed that the mean concentrations of total hexachlorohexane (∑HCHs), total dichlorodiphenyltrichloroethane (∑DDTs), heptachlor epoxide, and dieldrin ranged from non-detectable (nd) to 2800 ng/g, nd to1000 ng/g, nd to 700 ng/g, and nd to 240 ng/g on a wet mass (wm) basis, respectively. The variation in magnitude of contamination among the species and feeding guilds were not significantly different (p > 0.05). Among the OCPs analyzed, the residues of β-HCH and p,p′-DDE were found to be the abundant in concentration. Similarly, among various bird species studied, the highest concentrations of ∑OCPs (> 5000 ng/g wm) were recorded in the eggs of gray junglefowl, scaly-breasted munia, and red-whiskered bulbul. This may be due to their widespread occurrence of their habitat at proximity to the agricultural fields, where organochlorines were in use until recently. Among the various contaminants analyzed, concentrations of p,p′-DDE and heptachlor epoxide exceeded the threshold levels of toxicity for wild birds in > 5% of the egg samples. Hence, this study indicates the need for continued monitoring and further systematic ecotoxicological investigation of these compounds not only in eggs but also in other environmental media.

Fluoride is highly present in the environment, especially in water and its derivatives. Excessive fluoride contribution to diet poses a health risk. Tea leaves accumulate fluoride and the consumption of tea (Camellia sinensis) could pose a risk to human by the excessive fluoride intake. Ninety tea samples were analyzed by potentiometry using a selective fluoride ion electrode. Mixed tea samples (2.82 ± 1.11 mg/L) and black tea samples (2.28 ± 0.79 mg/L) recorded the highest fluoride levels. The contribution of drinking water is important for increasing fluoride levels in teas. The daily consumption of two cups (250 mL per cup) of mixed and black teas prepared with La Laguna tap water does pose a health risk for children (4–8 years old) because of the high contribution percentages (74.4% and 63.6%, respectively) of the Tolerable Upper Intake Level set in 2.5 mg/day by the EFSA (European Food Safety Authority). A minor consumption in children (4–8 years old) and adults during pregnancy is advisable.