Gold mining in the 1800s has led to the contamination of wetlands with introduced mercury (Hg) and geogenic arsenic (As). In situ risk management tools to reduce mobility and toxicity of Hg and As are needed to support natural restoration of impacted ecosystems. Here, we explored whether a nanoscale zero-valent iron (nZVI) slurry injected into two different contaminated wetland sediments can reduce Hg and As mobility to the overlaying water and toxicity to two aquatic invertebrates, burrowing mayflies (Hexagenia spp.) and Chinese mystery snails (Cipangopaludina chinensis). Total water Hg and As concentrations overlying both contaminated sediments were reduced by at least 75% and 88% respectively when treated with nZVI slurry. In the first sediment, juvenile snail survival increased from 75% in the untreated sediment to 100% in all nZVI treatments. The 2% nZVI treatment level was the only one with surviving mayflies (33%) and growth of juvenile snails. No snails or mayflies survived in the second sediment, regardless of nZVI treatment level. However, snails survived longer in this sediment with 4% and 8% nZVI. To improve reactivity of nZVI without increasing nZVI dose, future studies should investigate matrix-supported nZVI for reducing mobility and toxicity of As and Hg in wetland sediments.

An indoor simulation experiment was conducted to explore the effects of cuticular wax content and specific leaf area (SLA) on accumulation and distribution of PAHs in different tissues of wheat leaf. Three levels (0, 1.25, 6.0 mg L⁻¹) of mixed solution of five PAHs (Σ₅PAHs) including phenanthrene (PHE), anthracene (ANT), pyrene (PYR), benz[a]anthracene (BaA), and benzo[a]pyrene (BaP) were sprayed on leaves of seven varieties of winter wheat for every other day during 20 consecutive days. Shoot and root biomass of wheat under 6.0 mg L⁻¹ Σ₅PAHs exposure were 5.87 and 0.33 g, which were significantly (p < 0.05) lower than those (7.14 and 0.65 g) without spraying Σ₅PAHs solution, respectively. Elevated Σ₅PAHs concentration in spraying solution significantly (p < 0.0001) decreased cuticular wax content (59.1 and 65.1 vs. 67.8 mg g⁻¹) in leaves of wheat but exerted slight effects on SLA. Regardless of spraying Σ₅PAHs or not, SLA in leaves of Jiaomai (269–276 cm² g⁻¹) and Zhengmai (265–285 cm² g⁻¹) and cuticular wax content (104–118 mg g⁻¹) in leaves of Zhengmai were significantly higher than other varieties of wheat, respectively. Σ₅PAHs concentration in cuticular waxes ranged from 24,616 to 106,353 μg kg⁻¹, which was 2~3 orders and 1~2 orders of magnitude higher than that in mesophylls (46.0–535 μg kg⁻¹) and leaves (785–5366 μg kg⁻¹). There was a significant (r = 0.46, p < 0.05, n = 28) positive correlation between SLA and Σ₅PAHs concentration in wheat leaves when spraying 1.25 mg L⁻¹ of Σ₅PAHs. The present study indicated that cuticular wax content was significantly (p < 0.01) positive correlated with Σ₅PAHs concentration in the leaves and the translocation factor (TFw₋ₘ) of PHE, ANT, PYR, and Σ₅PAHs from cuticular wax to mesophyll. Based on principal component analysis (PCA), cuticular wax content was the main limiting factor for folia uptake of PAHs in winter wheat. The present study suggested that cuticular wax could play significant roles in foliar uptake of PAHs of wheat via affecting their accumulation in cuticular wax and translocation to mesophyll.

In-depth study of the key sectors and supply chain paths driving coal consumption in China is valuable for effectively formulating coal reduction and replacement policies to achieve sustainable development. This study conducted a structural path analysis, based on the latest publicly available input–output tables and energy use data provided by the World Input–Output Database, to trace China’s coal consumption transmission throughout its entire supply chain. The results indicate that investment, exports, and household consumption are important factors in coal consumption. “Electricity, Gas and Water Supply” is a critical sector for, largely indirect, coal consumption. The path of “Electricity, Gas and Water Supply→ intermediate sectors→ Construction→ Investment” accounts for the bulk of coal consumption in China. The node path analysis shows that the 2-node transmission paths, starting from Construction and ending with “Other Non-Metallic Mineral” and “Basic Metals and Fabricated Metal” are important sources of coal consumption induced by investment demand. The 1-node path of “Basic Metals and Fabricated Metal” is an important path for coal consumption induced by export demand. The 1-node path of “Electricity, Gas and Water Supply” is an important path for coal consumption caused by household consumption demand. In order to effectively implement coal reduction and replacement policies, China should control coal consumption in these key sectors and channels and optimize intermediate input and energy use structures.

Sediment is an endogenous pollution source, which often leads water systems to eutrophication due to the release of nutrients, especially phosphorus (P). Calcium nitrate (CN) was dosed to the water systems under different modes to control P release from the sediments in this study. A 63-day static laboratory test was conducted to explore the effects of intermittent dosing and one-time dosing modes of CN on P locking in the sediment and the concentrations of nitrogen (N) and P in waters. Results showed that 89% total phosphorus (TP) in the overlying water and 91% TP in the interstitial water of sediment were reduced in the intermittent dosing reactor, which were 4% and 13% higher than those in the one-time dosing reactor, respectively. Thus, the concentration of TP in the overlying water of the dosing reactors was both below 0.1 mg/L during the whole experiment. Meanwhile, the mean values of oxidation–reduction potential (ORP) in the sediment increased to − 110.7 ± 42.02 mV when CN was added intermittently, which were significantly higher than those of the one-time dosing reactor (− 158.3 ± 44.61 mV) and control reactor (− 320.7 ± 0.05 mV). Compared with one-time dosing mode, the intermittent dosing not only reduced the maximum concentrations of NO₂⁻-N from 9.21 to 1.79 mg/L and NO₃⁻-N from 92.42 to 27.58 mg/L but also shorten their retention time in the overlying water, which might depress the toxic threats to aquatic animals in water environments. Therefore, the intermittent dosing of CN could not only improve the P locking effect but also minimize the risks to aquatic animals in water environments under the premise of reasonable dosage selected. In a word, this research provided an effective operation mode for locking P with CN in the heavily polluted water bodies, which is also advantageous to avoid toxic threats to aquatic animals in water environment.

Treated wastewater reuse is one of the most important ways to confront the water shortage, especially in arid and semiarid regions facing a water crisis such as Iran. This study aims to develop a wastewater quality index (WWQI) to evaluate the effluent quality of the North Wastewater Treatment Plant (WWTP) of Isfahan for agriculture. Three indices, namely overall, acceptability, and health wastewater quality indices (OWWQI, AWWQI, and HWWQI), are developed, using 23 quality parameters of the WWTP effluent. Four different aggregation functions, i.e., weighted arithmetic mean function, weighted geometric function, and two weighted mix functions, are tested. The results revealed that all aggregation functions are free from eclipsing and ambiguity. The weighted arithmetic mean function (WWQI₍A₎) gave the highest values of OWWQI, AWWQI, and HWWQI, whereas the lowest values were related to the weighted geometric function (WWQI₍G₎). The sensitivity analysis showed that the OWWQI₍G₎ and OWWQI₍Mᵢₓ₁₎ were more sensitive to the group quality rating values. In all aggregation functions, the OWWQI was more sensitive to groups 5 and 6, while group 1 in the OWWQI showed the least sensitivity. It is concluded that the OWWQI₍G₎ and OWWQI₍Mᵢₓ₁₎ were the most representative aggregation functions for the estimation of the OWWQI.

The production of fertilizer magnesium ammonium phosphate (MAP, Mg.NH₄PO₄.6H₂O), commonly known as struvite, has been investigated in this study by mixing waste effluents of different sources. Effluents form pigment preparation industry rich in ammonium carbonate and poly phosphoric acid have been used as source of nitrogen (N) and phosphorus (P), respectively, whereas sea bittern has been used as a source of Mg. The stoichiometric mole ratio of the Mg²⁺ to NH₄⁺ to PO₄³⁻ in the mixed reaction liquid was maintained as 1:0.5:1 and 1:1:1, and the pH value of the reaction liquid was adjusted to 8.5 using sodium hydroxide. Struvite formation has been confirmed by using FTIR and P-XRD techniques. Thermal stability and morphology of the product were characterized employing thermo-gravimetric analysis (TGA) and field emission scanning electron microscopy (FE-SEM). The method reported is easy to implement and cost-effective. The adoption of the method will not only help in waste management but also in controlling environment hazards of P and N discharge in water bodies with economic benefits. The method is particularly useful for solar works which are in vicinity of industries releasing P- and N-containing effluents. After precipitation of struvite, the left out liquor can be further recycled into the salt works for enhanced recovery of common salt.

Bamboo forests are one of the most important forest resources in subtropical China. A pure, single-layer bamboo forest is considered an optimal habitat for intercropping medicinal herbs. Soil microorganisms have an important role in various ecological processes and respond quickly to environmental changes. However, changes in soil nutrients and microbial communities associated with agroforestry cultivation methods remain poorly documented. In the present study, a pure moso bamboo (Phyllostachys edulis) forest (Con) and three adjacent moso bamboo–based agroforestry (BAF) systems (moso bamboo–Paris polyphylla (BP), moso bamboo–Tetrastigma hemsleyanum (BT) and moso bamboo–Bletilla striata (BB)) were selected; and their soil chemical properties and bacterial communities were studied and compared to evaluate the effects of agroforestry on soil bacterial communities and the relationship between soil properties and bacterial communities in BAF systems. Results showed that compared with soils under the Con, soils under the BAF systems had more (p < 0.05) soil organic carbon (SOC) and available nitrogen (AN) but lower (p < 0.05) pH and available potassium (AK). In addition, compared with the Con system, the BB and BT systems had significantly greater (p < 0.05) available phosphorus (AP). Compared with that in the Con system, the Shannon index in the BAF systems was significantly greater (p < 0.05), but the Chao1 index not different. On the basis of relative abundance values, compared with the Con soils, the BAF soils had a significantly greater abundance of (p < 0.05) Bacteroidetes and Planctomyces but a significantly lower abundance of (p < 0.05) Verrucomicrobia, Gemmatimonadetes and Candidatus Xiphinematobacter. Moreover, compared with the Con system, the BB and BT systems had a greater (p < 0.05) abundance of Actinobacteria, Rhodoplanes, Candidatus Solibacter and Candidatus Koribacter. Redundancy analysis (RDA) revealed that soil pH, SOC and AP were significantly correlated with bacterial community composition. Results of this study suggest that intercropping medicinal herbs can result in soil acidification and potassium (K) depletion; thus, countermeasures such as applications of K fertilizer and alkaline soil amendments are necessary for BAF systems.

The genotoxicity and cytotoxicity of lanthanum (La(III)) were studied in fish micronucleus analysis in erythrocytes of the rare minnow (Gobiocypris rarus). Fish were exposed to 0.04, 08, 0.16, 0.32, and 0.80 mg L–¹ of La concentration for 21 days. Several important morphological alterations of the nucleus were noted, such as the ratio of micronucleated erythrocyte, and total ratio of erythrocytes with nuclear anomalies, blebs, notches, and so on. The total ratio of nuclear anomalies was significantly higher (P < 0.05) in G. rarus exposed to La(III) (except for 0.04 mg L–¹) compared with the control. Hypsometric analysis indicated significant dose-dependent changes in erythrocyte and nucleus dimensions (P < 0.05). Various abnormal morphological forms of erythrocytes were also observed. These results showed that La(III) was cytotoxic to erythrocytes of the rare minnow.

The present study aimed to analyze the chemical composition of five species of the genus Piper (P. aduncum L.; P. crassinervium Kunth.; P. malacophyllum Prels.; P. gaudichaudianum Kunth.; P. marginatum L.), and assess their toxicity to the adults of Drosophila suzukii (Diptera: Drosophilidae) and the pupal parasitoid Trichopria anastrephae Lima (Hymenoptera: Diapriidae). The major compounds were monoterpene hydrocarbons (5.3–60.9%); oxygenated monoterpenes (13.3%); sesquiterpenes hydrocarbons (8.3–45.3%), oxygenated sesquiterpenes (5.2–58.8%); and arylpropanoids (15.2–29.6%). In bioassays of ingestion and topical application, essential oils (EOs) from P. aduncum, P. gaudichaudianum, and P. marginatum killed approximately 100% of adults of D. suzukii, similarly to the insecticide based on spinetoram (75 mg L⁻¹) (96.2% of mortality). Besides, the dry residues from P. aduncum, P. gaudichaudianum, and P. marginatum provided a repellent effect on oviposition (≅ 7 eggs/fruits) and negative effects on egg viability (≅ 2 larvae/fruits) of D. suzukii on artificial fruits. Based on the estimate of the lethal concentration required to kill 90% of exposed flies, EOs from P. aduncum, P. crassinervium, P. gaudichaudianum, P. malacophyllum, and P. marginatum provided low toxicity to the parasitoid T. anastrephae in a bioassay of ingestion and topical application (mortality < 20%), similarly to the water treatment (≅ 5% of mortality). EOs of Piper species tested in this work showed to be promising plant insecticides for the management of D. suzukii.

Biochar is widely used as a soil amendment, either alone or in association with fertilizer. However, the effects of biochar particle size on the soil microbial community are largely unclear. Biochar was divided into two groups according to diameter sizes: < 1 mm and 2.5–5 mm (labeled as CB1 and CB5, respectively). A pot experiment was established in which maize (Zea maize L.) was treated with CB1, CB5, and/or external nitrogen (N, NH₄NO₃). At the end of the seedling period (45 days), analyses of soil microbial community structure and other soil and crop properties were conducted. The biochar (regardless of N addition) enhanced microbial biomass and activity. CB1 had a stronger capacity than CB5 to modify soil microbial community structure by promoting soil microbial groups (e.g., fungi, Gram-negative bacteria), which is likely due to CB1 undergoing a series of more intense processes (e.g., nutrient release, mineralization) than CB5. However, this difference was diminished or disappeared when N was added, mainly due to the masking effect of soil acidification that was induced by N fertilization. Collectively, fine biochar has a stronger effect on soil microbial community than coarse biochar. Particle size only affects soil microbial community structure when biochar is applied alone; it has no effect when biochar is applied in association with chemical N fertilizer, at least during the seedling period. The relationship between particle size and soil microbial community needs to be considered when using biochar for soil amendment.