Acetochlor is a widely used chloroacetanilide herbicide and has posed environmental risks in soil and water due to its toxicity and high leaching capacity. Earthworm represents the dominant invertebrate in soil and can promote the decomposition of organic pollutants. The effect of earthworm on acetochlor degradation in soil was studied by soil column experiment with or without acetochlor and earthworm in sterile and natural soils. The degradation capacities of drilosphere components to acetochlor were investigated by microcosm experiments. Bacterial and fungal acetochlor degraders stimulated by earthworm were identified by high-throughput sequencing. The degradation kinetics of acetochlor suggested that both indigenous microorganisms and earthworm played important roles in acetochlor degradation. Acetochlor degradation was quicker in soil with earthworms than without earthworms, with the degradation rates increased by 62.3 ± 15.2% and 9.7 ± 1.7% in sterile and natural treatments respectively. The result was related to the neutralized pH, higher enzyme activities and enhanced soil microbial community diversity and richness in the presence of earthworms. Earthworm cast was the degradation hotpot in drilosphere and exhibited better anaerobic degradation capacity in microcosm experiments. The acetochlor degradation rate of cast in anaerobic environment was 12.0 ± 0.1% quicker than that in aerobic environment. Residual acetochlor in soil conferred a long-term impairment on fungal community, and this inhibition could be repaired by earthworm. Earthworm stimulated indigenous degraders like Sphingomonas and Microascales and carried suspected intestinal degraders like Mortierella and Escherichia_coli to degradation process. Cometabolism between nutrition cycle species and degraders in casts also contributed to its faster degradation rates. The study also presented some possible anaerobic degradation species like Rhodococcus, Pseudomonas_fulva and Methylobacillus.

Graphene oxide (GO) may strongly interact with toxic metal ions and mineral particles upon release into the soil environment. We evaluated the mutual effects between GO and Ni (Ni(II)) with regard to their adsorption and co-adsorption on two minerals (goethite and hematite) in aqueous phase. Results indicated that GO and Ni could mutually facilitate the adsorption of each other on both goethite and hematite over a wide pH range. Addition of Ni promoted GO co-adsorption mainly due to the increased positive charge of minerals and cation–π interactions, while the presence of GO enhanced Ni co-adsorption predominantly due to neutralization of positive charge and strong interaction with oxygen-containing functional groups on adsorbed GO. Increasing adsorption of GO and Ni on minerals as they coexist may thus reduce their mobility in soil. Extended X-ray absorption fine structure (EXAFS) spectroscopy data revealed that GO altered the microstructure of Ni on minerals, i.e., Ni formed edge-sharing surface species (at RNᵢ₋Fₑ∼3.2 Å) without GO, while a GO-bridging ternary surface complexes (at RNᵢ₋C∼2.49 Å and RNᵢ₋Fₑ∼4.23 Å) was formed with GO. These findings improved the understanding of potential fate and toxicity of GO as well as the partitioning processes of Ni ions in aquatic and soil environments.

Strong acid rain was recently observed over Northeastern China, particularly in summer in Liaoning Province where alkaline dust largely neutralized acids in the past. This seems to be related to the regional transboundary pollution and poses new challenges in acid rain control scheme in China. In order to delve into the regional transport impact, and quantify its potential contributions to such an “eruption” of acid rain over Liaoning, this paper employs an online source tagging model in coupling with the Nested Air Quality Prediction Modeling System (NAQPMS). Validation of predictions shows the model capability in reproducing key meteorological and chemical features. Acid concentration over Liaoning is more pronounced in August (average of 0.087 mg/m³) with strong pollutant import from regional sources against significant depletion of basic species. Seasonal mean contributions from regional sources are assessed at both lower and upper boundary layers to elucidate the main pathways of the impact of regional sources on acid concentration over Liaoning. At the upper layer (1.2 km), regional sources contribute to acid concentration over Liaoning by 67%, mainly from Shandong (16%), Hebei (13%), Tianjin (11%) and Korean Peninsula (9%). Identified main city-receptors in Liaoning are Dandong, Dalian, Chaohu, Yingkou, Liaoyang, Jinfu, Shengyang, Panjin, Tieling, Benxi, Anshan and Fushun. At lower layer (120 m) where Liaoning local contribution is dominant (58%), regional sources account for 39% in acid concentration. However, inter-municipal acid exchanges are prominent at this layer and many cities in Liaoning are revealed as important sources of local acid production. Seasonal acid contribution average within 1.2 km-120 m attains 55%, suggesting dominance of vertical pollutant transport from regional sources towards lower boundary layer in Liaoning. As direct environmental implication, this study provides policy makers with a perspective of regulating the regional transboundary environmental impact assessment in China with application to acid rain control.

Sediments nearby harbors are dredged regularly, and the sediments require the stringent treatment to meet the regulations on reuse and mitigate the environmental burdens from toxic pollutants. In this study, FeCl₃ was chosen as an extraction agent to treat marine sediment co-contaminated with Cu, Zn, and total petroleum hydrocarbons (TPH). In chemical extraction process, the extraction efficiency of Cu and Zn by FeCl₃ was compared with the conventional one using inorganic acids (H₂SO₄ and HCl). Despite the satisfactory level for extraction of Cu (78.8%) and Zn (73.3%) by HCl (0.5 M) through proton-enhanced dissolution, one critical demerit, particularly acidified sediment, led to the unwanted loss of Al, Fe, and Mg by dissolution. Moreover, the vast amount of HCl required the huge amounts of neutralizing agents for the post-treatment of the sediment sample via the washing process. Despite a low concentration, extraction of Cu (70.1%) and Zn (69.4%) was done by using FeCl₃ (0.05 M) through proton-enhanced dissolution, ferric-organic matter complexation, and oxidative dissolution of sulfide minerals. Ferric iron (Fe³⁺) was reduced to ferrous iron (Fe²⁺) with sulfide (S²⁻) oxidation during FeCl₃ extraction. In consecutive chemical oxidations using hydrogen peroxide (H₂O₂) and persulfate (S₂O₈²⁻), the resultant ferrous iron was used to activate the oxidants to effectively degrade TPH. S₂O₈²⁻ using FeCl₃ solution (molar ratio of ferrous to S₂O₈²⁻ is 19.8–198.3) removed 42.6% of TPH, which was higher than that by H₂O₂ (molar ratio of ferrous to H₂O₂ is 1.2–6.1). All experimental findings suggest that ferric is effectively accommodated to an acid washing step for co-contaminated marine sediments, which leads to enhanced extraction, cost-effectiveness, and less environmental burden.

This study aimed to assess the chemical composition of the rainwater in three areas of different environmental impact gradients in Southern Brazil using the receptor model EPA Positive Matrix Factorization (EPA PMF 5.0). The samples were collected in a bulk sampler, from October 2012 to August 2014, in three sampling sites along with the Sinos River Basin: Caraá, Taquara, and Campo Bom. The major ions NH₄⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, F⁻, Cl⁻, NO₃⁻, SO₄²⁻, and pH were analyzed, as well as identify the main emission sources. The most abundant cations and anions were Ca²⁺, Na⁺, Cl⁻, and SO₄²⁻, respectively. The mean pH value in the Sinos River Basin during the study period was 6.07 ± 0.49 (5.13–7.05), which suggests inputs of alkaline species into the atmosphere. The most important neutralizing agents of sulfuric and nitric acids in the Sinos River Basin are Ca²⁺ (NF = 1.36) and NH₄⁺ (NF = 0.57). The source apportionment provided by the EPA PMF 5.0 resulted in four factors, which demonstrate the influence of anthropogenic and natural sources, in the form of (a) industry/combustion of fossil fuels (F⁻ and SO₄²⁻), (b) marine contribution (Na⁺ and Cl⁻), (c) crustal contribution (K⁺, Ca²⁺, and NO₃⁻), and (d) agriculture/livestock (NH₄⁺). Therefore, this study allows a more appropriate understanding of factors that contribute to rainwater chemical composition and also to possible changes in air quality.

Mojave yucca (Yucca schidigera) is widely grown in the deserts. This herb is commercially used because it is rich in saponins and phenolic compounds with antioxidant effect. Y. schidigera or its derivatives are included as nontoxic food supplements, in cosmetics, and in the pharmaceutical industry. Saponins originated from Y. schidigera have anti-inflammatory, antioxidant, immunostimulatory, growth promoter, hypocholesterolemic, and hypoglycemic effects. To date, the key role of Y. schidigera or its products in animal nutrition is to reduce the ammonia content in the atmosphere and fecal odor in poultry excreta. Mitigating ammonia by using this plant could be achieved by the modification of gut microbiota, enhancement in digestion, and absorption of nutrients, leading to a better growth and production performance of animals and poultry. Various methods were applied to mitigate the emission of odor from the litter by different strategies including biofilters, litter treatments, air scrubbers, neutralizing agents, windbreak walls, etc., but these techniques are expensive. This article provides a new insight to scientists and poultry breeders to use Y. schidigera plant or its products as inexpensive and safe sources of a feed supplement to overcome the ammonia and fecal odor problems, as well as reduce environmental pollution in poultry houses.

Neutralization is the necessary operation to ensure the Fenton effluent pH. In situ coagulation can be induced during neutralization. In this study, three types of alkaline neutralizers (Ca(OH)₂, NaOH, and Ca(OH)₂ + NaOH) were added into the Fenton oxidized PSE to control the effluent pH of 6 to 9. The coagulation behavior, floc structure, and properties were investigated. The results indicated that the coagulation with the adding of three neutralizers can remove 9.68 to 24.02% of the TOC. Ca(OH)₂ exhibited the highest TOC removal efficiency at the dosage of 0.4 g/L. Charge neutralization ability was in the following order: Ca(OH)₂ > Ca(OH)₂ + NaOH > NaOH. Ca(OH)₂ and Ca(OH)₂ + NaOH showed the increase of floc growth rate with the increase of agent dosage, especially for Ca(OH)₂ + NaOH. Moreover, Df of NaOH flocs was higher than that of Ca(OH)₂ and Ca(OH)₂ + NaOH, indicating the floc formed by NaOH was more compact than that of Ca(OH)₂. The main coagulation process of three neutralizers was different, and it was also affected by the agent dosage (or pH). When the dosage was 0.35 g/L (pH 6–7.5), the complexation, adsorption, and bridging were the predominant processes while charge neutralization gradually became the main coagulation process for Ca(OH)₂ and Ca(OH)₂ + NaOH with the increase of dosage (pH 7.5–9).

This study aims to investigate the spatiotemporal variation, chemical composition, and source apportionment of marine fine particles (PM₂.₅) as well as their regional transport toward the Matsu Islands located near the coastline of northwestern Taiwan Strait. Four offshore island sites located at the Matsu Islands were selected to conduct both regular and intensive sampling of marine PM₂.₅. Water-soluble ionic species, metallic elements, and carbonaceous contents were then analyzed to characterize the chemical characteristics of marine PM₂.₅. In order to identify the potential sources and their contributions to marine PM₂.₅, chemical mass balance (CMB) receptor model was employed along with the backward trajectory simulation to resolve the source apportionment of marine PM₂.₅ and to explore their transport routes in different seasons. The results showed that high PM₂.₅ concentrations were commonly observed during the northeastern monsoon periods. Additionally, marine PM₂.₅ concentration decreased from the west to the east with the highest PM₂.₅ at the Nankang Island and the lowest PM₂.₅ at the Donyin Island in all seasons, indicating an obvious concentration gradient of PM₂.₅ transported from the continental areas to the offshore islands. In terms of chemical characteristics of PM₂.₅, the most abundant water-soluble ions of PM₂.₅ were secondary inorganic aerosols (SO₄²⁻, NO₃⁻, and NH₄⁺) which accounted for 55–81% of water-soluble ions and 29–52% of marine PM₂.₅. The neutralization ratios of PM₂.₅ were always less than unity, indicating that NH₄⁺ cannot solely neutralize nss-SO₄²⁺ and NO₃⁻ in marine PM₂.₅ at the Matsu Islands. Although crustal elements (Al, Ca, Fe, K, and Mg) dominated the metallic content of marine PM₂.₅, trace anthropogenic metals (Cd, As, Ni, and Cr) increased significantly during the northeastern monsoon periods, particularly in winter. Organic carbons (OCs) were always higher than elemental carbons (ECs), and the mass ratios of OC and EC were generally higher than 2.2 in all seasons, implying that PM₂.₅ was likely to be aged particles. During the poor air quality periods, major air mass transport routes were the northern transport and the anti-cyclonic circulation routes. Source apportionment results indicated that fugitive soil dusts and secondary aerosols were the major sources of marine PM₂.₅ at the Matsu Islands, while, in winter, biomass burning contributed up to 15% of marine PM₂.₅. This study revealed that cross-boundary transport accounted for 66~84% of PM₂.₅ at the Matsu Islands, suggesting that marine PM₂.₅ at the Matsu Islands has been highly influenced by anthropogenic emissions from neighboring Fuzhou City as well as long-range transport from Northeast Asia.

Eutrophication in lakes and rivers caused by the nitrogen (N) and phosphorus (P) is urgent since the accumulation of N and P can possibly cause the algal blooms and devastation to the water ecological system. The removal of N and P in the landscape water would be an efficient way to reduce the enrichment of nutrition before they reach the large water system. The N and P removal efficiency of PFS as well as the synergistic effect of natural rocks (four types of purple parent rock (J₃p, J₂s, T₁f, and J₃s)) as promoter was examined under laboratory conditions. The results indicated that TN and TP removal efficiency of the composite coagulant was significantly better than that of PFS or purple parent rock alone and J₃p + PFS (combination of PFS and J₃p purple parent rock) showed the best TN and TP removal efficiency. TN and TP removal efficiency of 53.53 and 86.48%, respectively, were achieved with coagulant dosage of 6 g L⁻¹ J₃p and 30 mg L⁻¹ PFS, water temperature of 30 °C, and wastewater initial pH of 9. In addition, Fourier transformed infrared (FTIR) spectrophotometer, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis (EDX), and the water quality index analysis revealed that the treatment of TN and TP by using J₃p + PFS was taking advantage of the flocculation function of PFS and the adsorption function of PFS and J₃p. In which, the flocculation mechanism was mainly charge neutralization; adsorption mechanism was mainly physical and chemical adsorption.

In this study, cow dung was identified as a neutralizing agent for red mud (RM). Present research estimated a significant reduction in pH value of red mud (10 g) from 10.28 to 8.15 and reduction in alkalinity of ~148 mg/L from ~488 mg/L by adding 80 g of cow dung in 40 days of anaerobic condition. XRD results exhibit a high intensity of quartz and found new compound, the calcium carbide. The acid neutralizing capacity (ANC) of NRM reduces to ~0.87 from ~1.506 mol H⁺/kg. Based on the resultant research, present study proposes cow dung as an efficient neutralizing agent for reducing the pH and alkalinity in the red mud.