Chiral mesoporous silica (SiO₂) with helical structure was synthesized by using anionic surfactants as template. Pre-prepared graphene oxide (GO) was then loaded onto SiO₂ to synthesize composite carrier chial-meso-SiO₂@GO for the immobilization of laccase. The enzyme activity, thermostability, acid stability, and repeatability of the immobilized enzyme were significantly improved after immobilization. The chial-meso-SiO₂@GO-immobilized laccase was then used for the degradation of MXC in aqueous phase. The degradation conditions, including temperature, time, pH, MXC concentration, and the dose of immobilized enzyme for cellulosic hydrolysis, were optimized. The optimum conditions for degradation of methoxychlor were selected as pH 4.5, MXC concentration 30 mg/L, immobilized enzyme dose 0.1 g, the maximum MXC removal of over 85% and the maximum degradation rate of 50.75% were achieved after degradation time of six h at temperature of 45 °C. In addition, the immobilized cellulase was added into the immobilized laccase system to form chial-meso-SiO₂@GO-immobilized compound enzyme with the maximum MXC degradation rate of 59.58%, higher than that of 50.75% by immobilized laccase. An assessment was made for the effect of chial-meso-SiO₂@GO-immobilized compound enzyme on the degradation of MXC in soil phase. For three contaminated soils with MXC concentration of 25 mg/kg, 50 mg/kg, and 100 mg/kg, the MXC removals were 93.0%, 85.8%, and 65.1%, respectively. According to the GC-MS analyses, it was inferred that chial-meso-SiO₂@GO-immobilized compound enzyme had a different degradation route with that of chial-meso-SiO₂@GO-immobilized laccase. The hydrolysis by immobilized cellulase might attack at a weak location of the MXC molecule with its free radical OH and ultimately removed three chlorine atoms from MXC molecule, leading to generating small molecular amount of degradation product.

Aging effects play a crucial role in determining applications of green-synthesised iron-based nanoparticles in wastewater treatment from laboratory scale to practical applications. In this study, iron-based nanoparticles (Ec-Fe-NPs) were synthesised using the extract of Eichhornia crassipes and ferric chloride. Scanning electron microscopy (SEM) revealed that the fresh Ec-Fe-NPs were spherical and had a narrow particle size range (50 to 80 nm). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) demonstrated that the Ec-Fe-NPs were mainly amorphous in nature and consisted of Fe⁰, FeO, Fe₂O₃ and Fe₃O₄. As they aged, the particle size of the liquid Ec-Fe-NPs gradually increased and then tended to stabilise. Ec-Fe-NPs that were aged for 28 days were only 19% less efficient than fresh material at removing Cr(VI). Extracts aged up to 28 days were also tested, and their antioxidant capacity was found to be 15.4% lower than that of the fresh extracts. Furthermore, the removal efficiency of Cr(VI) using iron-based nanoparticles synthesised with the aged extracts was 67.2%. Finally, the active components of the extracts, which were responsible for the reactivity and stability of the iron-based nanoparticles, were identified by liquid chromatography–mass spectrometry. Overall, green-synthesised iron-based nanoparticles show promise for Cr(VI) removal from wastewater in practical applications.

A total of 53 feeds from 23 brands for four types of animals, i.e., fish, chicken, duck, and pig, as well as six types of raw materials, were bought from Guangxi, Hubei, Anhui, and Guangdong provinces in China and analyzed for polybrominated diphenyl ethers (PBDEs). The raw materials including super fish meal, ordinary fish meal, poultry ore, soybean, stone powder, and rapeseed were selected because they were added to all the animal feeds manufactured. The occurrence of PBDEs was ubiquitous in the feeds and raw materials, with BDE-209 as the most abundant congener. The average concentration of ∑₈PBDE was 1.1 and 0.44 ng g⁻¹ dry weight in feeds (range 0.25–5.7) and raw materials (range 0.27–0.84), respectively. No statistically significant differences in ∑₈PBDE concentrations were observed among the four groups of animal feeds. Feeds from Yangzhiyuan Brand (n = 11) contained statistically (p < 0.01) lower ∑₈PBDE concentrations than all other brands except for Baoshun Brand. Chicken was selected as a representative animal to assess health risk for human exposure to PBDEs via the consumption of chicken raised by the feeds under investigation. Hazard quotients based on per-capita consumption of chicken were all below 1, indicating low potential risk to humans consuming chicken raised with the feeds. Graphical abstract

To investigate and assess heavy metal contamination on the farmland soils of a typical mining city, the concentrations of Cu, Cd, Zn, Pb, As, and Cr were analyzed from four mining areas (Tongguan District (TGD), Shunan Town (SAT), Tianmen Town (TMT), and Zhongmin Town (ZMT)) and two control areas (Xilian Township (XLT), Donglian Township (DLT)) in Tongling City, China. The total metal concentrations in the soils were in the following order: Cd ˂ As ≤ Pb ˂ Cu ˂ Cr ≤ Zn. Total metal concentrations in the soils of mining areas were significantly higher than those of the control areas (P < 0.05). According to the Chinese Environmental Quality Standard for Soils (GB 15618-1995) and geo-accumulation index (Igₑₒ), Cd and As pollution in the farmland soils of the mining areas was the most severe, followed by Cu. The Igₑₒ values of soil heavy metals of TGD and SAT were the most highest, followed by those of TMT and ZMT. The health risk quotient (HQ) of heavy metals in the soils showed as follows: HQAₛ ˃ HQPb ˃ HQCᵣ ˃ HQCd ˃ HQCᵤ ˃ HQZₙ, and the total average daily exposed dose (non-carcinogenic risk) of As was the highest except that of Cd. The contribution rate of carcinogenic risk index (CR) to total carcinogenic risk index (TCR) of As and Cd in the topsoil for adults was 99.91% and 0.09% respectively, and the value for children was 99.87% and 0.13%. The CR and TCR of As in the farmland of mining areas were greater than 10⁻⁴, which showed the carcinogenic risk is an intolerable range for both adults and children. According to the results of the present study, it can help the local people know the pollution of heavy metals in farmland and adopt the best suitable agriculture practices.

The comparative anticoccidial effects of herbal products with a standard synthetic anticoccidial drug on the production performance, intestinal histology, and some blood biochemical parameters in broilers exposed to experimental coccidiosis was investigated. One-day-old broiler chicks (n = 336) were randomly distributed into six groups. One group served as a control, the second was treated with the coccidial infection, the third was treated with synthetic anticoccidial drug (Elancoban), the fourth group was treated with an herbal product (Cozante), the fifth group of birds was treated with Norponin, and the sixth group was treated with Emanox. The results indicated that BWG, BW, FCR, and PEF decreased significantly (P < 0.05) in the positive control. Body weight gain, BW, and PEF were significantly (P < 0.01) high in Elancoban-treated birds. On day 25, lesion score was significantly (P < 0.01) low in duodenum, jejunum, and ceca in Elancoban-treated birds control. On day 30, lesion score was significantly (P < 0.05) low in Emanox-treated birds as compared with the positive control. Albumin concentration was significantly (P < 0.01) low in Emanox while glucose concentration was significantly (P < 0.01) high in all the treated groups compared with the positive control birds. The total antioxidant capacity was significantly (P < 0.05) high in Emanox on day 15 and 30 as compared with the positive control. The results showed that birds exposed to the natural anticoccidial products showed improved villi and total antioxidant capacity. We concluded that herbal products performed better than the positive control group.

Sulfur dioxide emissions have been regulated at a global scale; sulfur (S) deposition no longer contributes to soil acidification instead of an alleviation effect in temperate regions; however, it remains unclear whether S deposition still contributes to soil acidification in the tropics. The Pearl River Delta (PRD), South China, has been suffering serious soil acidification, but the contribution of S deposition was ignored because of the regulation of S emission since 2001. Here, we chose the evergreen broadleaf forests, which are the typical forest type at the regional scale in PRD to examine the contribution of S deposition and its characteristics in this acidification, based on an established urban–rural gradient in the range of 260 km. A substantial acidification was evidenced by the significant decline of soil pH from rural to urban sites, with mean pH values decreased by more than 0.60 U through the whole 40-cm depths. However, there was no significant difference in soil pH from 0–10 cm, 10–20 cm, and to 20–40 cm at each site (P > 0.05). Acid-neutralizing capacity (ANC) showed a similar trend to soil pH, with a significant decline along the urbanization gradient and no significant effect of soil depths. Soil sulfate (SO₄²⁻), as the most abundant species in ANC, contributed greatly to soil acidification for the whole 40-cm depth, as shown by the significant positive relationships between it with soil pH and base cations. Soils also exhibited the depletion of base cations with low base saturation (< 20%) and the release of Al and Fe. Our research demonstrated that the severe soil acidification in the PRD region has extended to the subsoil level (40-cm depth), and S deposition is still an important driver to this acidification. Therefore, both recovering the acidified soils and controlling the acidifying pollutants, especially S, are particularly difficult in southern China.

Solanum nigrum L. is a hyperaccumulator and shows very high phytoremediation potential for Cd-contaminated soil. Fertilizer addition to soil is an effective pathway to improve Cd hyperaccumulation. This article compared the strengthening roles of commonly used four nitrogen fertilizers with three organic fertilizers on S. nigrum hyperaccumulating Cd at the same total nitrogen level. The results showed that Cd concentrations in roots and shoots of S. nigrum were not affected by the addition of inorganic nitrogen like NH₄HCO₃, NH₄Cl, (NH₄)₂SO₄, and CH₄N₂O compared with the control without nitrogen addition. However, Cd concentrations in S. nigrum roots and shoots were significantly decreased (p < 0.05) when the organic nitrogen was added in the form of chicken manure, pig manure, and commercial organic fertilizer (by 15.6% and 15.1%, 30.1% and 23.6%, 20.3% and 16.8%, respectively). On the other hand, of all nitrogen treatments, the addition of (NH₄)₂SO₄ and CH₄N₂O to the soil enormously increased S. nigrum biomass, i.e., S. nigrum shoot biomass increased 2.0- and 2.1-fold compared with the control. Correspondingly, Cd loads in S. nigrum shoots were also the highest in former two treatments and amounted to 79.91 μg pot⁻¹ and 80.17 μg pot⁻¹, respectively. Compared with the control, the addition of three organic fertilizers significantly increased (p < 0.05) pH and decreased (p < 0.05) available Cd concentrations in the soil, which could be the main reasons for their negative effects on S. nigrum accumulating Cd. (NH₄)₂SO₄ and CH₄N₂O significantly increased S. nigrum biomasses and exerted no effects on the available soil Cd concentration, which made them more better fertilizers in practice. In general, the same fertilizer may show different effects on different hyperaccumulators. The selection of fertilizer should be decided in accordance with the specific conditions in the phytoremediation practice of contaminated soil.

Performance of raw and two Fe-loaded biochars, produced either by evaporation (E-product, 26.9% Fe) or precipitation (P-product, 12.6% Fe), was evaluated in batch and column testing for As(V) and Sb(III) removal from contaminated neutral drainage (CND). Batch testing results showed that sorption capacity of the E-product tripled for As(V) and quintupled for Sb(III), whereas for the P-product, it doubled for both contaminants, relative to the raw biochar. Moreover, As(V) removal by the E-product reached 90% in less than 8 h, for initial concentrations up to 50 mg/L. In column testing, the E-product efficiently treated the influent [pH 6; 1 mg/L As(V)] for more than 286 days. The pH of the final effluent was within the legally allowed limits (6–9.5) while less than 0.3 mg/L Fe leached out. Based on these findings, Fe-loaded biochar by evaporation (E-product) seems promising for As(V) treatment in CND.

Path analysis has been largely used in marketing research but has recently been applied in an environmental management context. This study evaluated the potential of path analysis in identifying the influence of moisture content on odor from decomposing food waste. Food waste with varying moisture content was monitored for odor concentration, microbial population density, oxygen uptake rate, volatile fatty acids, ammonia, and hydrogen sulfide. These various parameters were later analyzed using SmartPLS 3.0 software to produce the path analysis model using simultaneous equation modeling. Results indicate that odor concentration of food waste was not directly affected by moisture content (not significant, t-statistical 1.46 < 1.96), rather; moisture content influenced the microbial population density and biodegradability of the food residue which influenced the formation of hydrogen sulfide (significant, t-statistical 3.79 > 1.96) and subsequently odor. In order to manage food waste–related odors, it is recommended that the waste be kept at a moisture content lower than 40%. This is especially critical if prolonged storage is unavoidable.

This paper uses the 1990–2010 natural disaster and carbon emission data of G20 countries to examine the impact of natural disasters and climate change on the natural capital component of inclusive wealth. Our study shows that climate change and GDP have no positive impacts on the growth of natural capital. By contrast, trade openness and natural disaster frequency contribute to the accumulation of natural capital in G20 countries. There is an inverted U-shaped relationship between the growth of natural capital and the magnitude of natural disaster. Natural capital growth is not affected very much by small disasters. By contrast, large disasters tend to make the growth of natural capital fall sharply.