The net global warming potential (NGWP) and net greenhouse gas intensity (NGHGI) of double-rice cropping systems are not well documented. We measured the NGWP and NGHGI including soil organic carbon (SOC) change and indirect emissions (IE) from double-crop rice fields with fertilizing systems in Southern China. These experiments with three different nitrogen (N) application rates since 2012 are as follows: 165 kgN ha⁻¹ for early rice and 225 kgN ha⁻¹ for late rice (N1), which was the local N application rates as the control; 135 kgN ha⁻¹ for early rice and 180 kgN ha⁻¹ for late rice (N2, 20 % reduction); and 105 kgN ha⁻¹ for early rice and 135 kgN ha⁻¹ for late rice (N3, 40 % reduction). Results showed that yields increased with the increase of N application rate, but without significant difference between N1 and N2 plots. Annual SOC sequestration rate under N1 was estimated to be 1.15 MgC ha⁻¹ year⁻¹, which was higher than those under other fertilizing systems. Higher N application tended to increase CH₄ emissions during the flooded rice season and significantly increased N₂O emissions from drained soils during the nonrice season, ranking as N1 > N2 > N3 with significant difference (P < 0.05). Two-year average IE has a huge contribution to GHG emissions mainly coming from the higher N inputs in the double-rice cropping system. Reducing N fertilizer usage can effectively decrease the NGWP and NGHGI in the double-rice cropping system, with the lowest NGHGI obtained in the N2 plot (0.99 kg CO₂-eq kg⁻¹ yield year⁻¹). The results suggested that agricultural economic viability and GHG mitigation can be simultaneously achieved by properly reducing N fertilizer application in double-rice cropping systems.

Generation of secondary sludge is a major concern of textile dye removal by coagulation process. Combinatorial coagulation-biodegradation treatment system has been found efficient in degradation of coagulated textile dye sludge. Moringa oleifera seed powder (700 mg L⁻¹) was able to coagulate textile dyestuff from real textile wastewater with 98 % color removal. Novel consortium-BBA was found to decolorize coagulated dye sludge. Parameters that significantly affect coagulation process were optimized using response surface methodology. The bench-scale stirred tank reactor (50-L capacity) designed with optimized parameters for coagulation process could efficiently remove 98, 89, 78, and 67 % of American Dye Manufacturer’s Institute (ADMI) in four repetitive cycles, respectively. Solid-state fermentation composting reactor designed to treat coagulated dye sludge showed 96 % removal of dye within 10 days. Coagulation of dyes from textile wastewater and degradation of coagulated dye sludge were confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. Cell morphology assay, comet assay, and phytotoxicity confirmed the formation of less toxic products after coagulation and degradation mechanism.

A new method for bisphenol A (BPA) degradation in aqueous solution was developed. The characteristics of BPA degradation in a heterogeneous ultraviolet (UV)/Fenton reaction catalyzed by FeCo₂O₄/TiO₂/graphite oxide (GO) were studied. The properties of the synthesized catalysts were characterized using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry. FeCo₂O₄ and TiO₂ were grown as spherical shape, rough surface, and relatively uniform on the surface of GO (FeCo₂O₄/TiO₂/GO). Batch tests were conducted to evaluate the effects of the initial pH, FeCo₂O₄/TiO₂/GO dosage, and H₂O₂ concentration on BPA degradation. In a system with 0.5 g L⁻¹ of FeCo₂O₄/TiO₂/GO and 10 mmol L⁻¹ of H₂O₂, approximately 90 % of BPA (20 mg L⁻¹) was degraded within 240 min of UV irradiation at pH 6.0. The reused FeCo₂O₄/TiO₂/GO catalyst retained its activity after three cycles, which indicates that it is stable and reusable. The heterogeneous UV/Fenton reaction catalyzed by FeCo₂O₄/TiO₂/GO is a promising advanced oxidation technology for treating wastewater that contains BPA.

This work was designed to investigate the removal efficiency as well as the ratios of toluene and xylene transported from air to root zone via the stem and by direct diffusion from the air into the medium. Indoor plants (Schefflera actinophylla and Ficus benghalensis) were placed in a sealed test chamber. Shoot or root zone were sealed with a Teflon bag, and gaseous toluene and xylene were exposed. Removal efficiency of toluene and total xylene (m, p, o) was 13.3 and 7.0 μg·m⁻³·m⁻² leaf area over a 24-h period in S. actinophylla, and was 13.0 and 7.3 μg·m⁻³·m⁻² leaf area in F. benghalensis. Gaseous toluene and xylene in a chamber were absorbed through leaf and transported via the stem, and finally reached to root zone, and also transported by direct diffusion from the air into the medium. Toluene and xylene transported via the stem was decreased with time after exposure. Xylene transported via the stem was higher than that by direct diffusion from the air into the medium over a 24-h period. The ratios of toluene transported via the stem versus direct diffusion from the air into the medium were 46.3 and 53.7 % in S. actinophylla, and 46.9 and 53.1 % in F. benghalensis, for an average of 47 and 53 % for both species. The ratios of m,p-xylene transported over 3 to 9 h via the stem versus direct diffusion from the air into the medium was 58.5 and 41.5 % in S. actinophylla, and 60.7 and 39.3 % in F. benghalensis, for an average of 60 and 40 % for both species, whereas the ratios of o-xylene transported via the stem versus direct diffusion from the air into the medium were 61 and 39 %. Both S. actinophylla and F. benghalensis removed toluene and xylene from the air. The ratios of toluene and xylene transported from air to root zone via the stem were 47 and 60 %, respectively. This result suggests that root zone is a significant contributor to gaseous toluene and xylene removal, and transported via the stem plays an important role in this process.

Cytological effects of Endosri-ES (endosulfan), Nuvan-NU (dichlorvos), and Kvistin-KS (carbendazim) were evaluated on mitotic and meiotic cells of Allium cepa. Test concentrations were chosen by calculating EC₅₀ values of formulated ES, NU, and KS, which turned to be 60, 200, and 500 ppm (parts per million), respectively. Cytological studies were undertaken on root meristem cells of A. cepa using EC₅₀, 1/2 × EC₅₀, and 2 × EC₅₀ of these pesticides for 24 and 48 h. Similarly, a meiotic study was conducted by applying the pesticides at the aforesaid concentrations from seedling to bud stage. A set of onion bulbs exposed to tap water was run parallel for negative control and maleic hydrazide (112.09 ppm) as positive control. During the study period, mitotic index (MI) decreased at all the pesticide concentrations compared to the negative control. Among various chromosomal aberrations, chromatin bridges, breaks, stickiness, laggard, vagrant chromosomes, fragments, C-mitosis, multipolarity, ring chromosome as well as micronuclei were observed in mitotic preparations. In contrast, meiotic aberrations revealed comparatively less frequency of chromosomal aberrations and the most frequent were lagging chromosome, stray bivalents, secondary association, chromatin bridge, disturbed anaphase, and stickiness. Comparative analysis of the pesticides showed that NU was highly toxic to plant cells than KS, while as ES showed intermediate effects between the two. Further, our study revealed that all the three pesticides produce genotoxic effects which can cause health risks to the human populations. Graphical Abstract ᅟ

The effect of sewage sludge on the mobility and the bioavailability of trace metals in plant-soil systems have aroused wide interested and been widely explored. Based on a wheat-cultivating experiment, the effect of municipal sludge compost (MSC) on the mobility and bioavailability of Cd in a soil-wheat system was studied. With the application of MSC, soil organic matter (SOM), total nitrogen (TN), and total phosphorus (TP) in the soil increased significantly, while concentrations of trace metals (Cu, Zn, Ni, Pb, Cd) were below the China’s minimum thresholds. The application of MSC could improve wheat growth. The application of MSC at the rate of 0.5 % had no significant effect on the chemical fraction distribution of Cd in soil. In two soil treatments, Cd mainly existed in the labile chemical fractions (exchangeable chemical fraction (EXCF) and carbonate chemical fraction (CABF)). However, the application of MSC could reduce accumulation of Cd by wheat. Cd contents in each part of the MSC-applied wheat were significantly less than that of non-MSC-applied wheat. In the tested soils, the extractable concentrations decreased in the order: EDTA > MgCl₂ ≈ NH₄OAc > DTPA. There were no significant differences between soil treatments in the amounts of extractable Cd when the extraction was done under neutral conditions, although significant differences were observed when the extraction was done under alkaline conditions. In this study, the DTPA extraction procedure provided a good indication of Cd bioavailability. Our results suggest that, in the short term at least, amending soils with MSC may benefit crop dry matter production while not increasing the risk of human exposure to Cd through consumption of wheat grown on MSC-amended soils.

The aim of this study was to evaluate the level of lead (Pb) in the livers and kidneys of free-living animals from Poland, with regard to the differences in tissue Pb content between the species. The research material consisted of liver and kidney samples collected from roe deer (Capreolus capreolus), red deer (Cervus elaphus), and wild boar (Sus scrofa) that had been hunted in 16 voivodeships of Poland. The concentration of lead had been measured using inductively coupled plasma optical emission spectrometry (ICP-OES) method. The results show that differences in lead concentration in the organs depended on the geographic location. In roe deer and red deer, the highest mean lead concentrations in the livers and kidneys, observed in the central region of Poland, were twice as high as the lowest concentration of Pb in these animals from the northeastern region of the country. In wild boar, the highest mean concentration of Pb was noted in the livers of animals from the central region of Poland and in the kidneys of animals from the northwestern region, while the lowest lead concentrations in both organs were typical for wild boar from the southeast part of the country. Our results show that areas located in the center and in the north of Poland carry most of the burden of lead bioaccumulation.

Chlor-alkali plants using mercury (Hg) cell technology are acute point sources of Hg pollution in the aquatic environment. While there have been recent efforts to reduce the use of Hg cells, some of the emitted Hg can be transformed to neurotoxic methylmercury (MeHg). Here, we aimed (i) to study the dispersion of Hg in four reservoirs located downstream of a chlor-alkali plant along the Olt River (Romania) and (ii) to track the activity of bacterial functional genes involved in Hg methylation. Total Hg (THg) concentrations in water and sediments decreased successively from the initial reservoir to downstream reservoirs. Suspended fine size particles and seston appeared to be responsible for the transport of THg into downstream reservoirs, while macrophytes reflected the local bioavailability of Hg. The concentration and proportion of MeHg were correlated with THg, but were not correlated with bacterial activity in sediments, while the abundance of hgcA transcript correlated with organic matter and Cl⁻ concentration, indicating the importance of Hg bioavailability in sediments for Hg methylation. Our data clearly highlights the importance of considering Hg contamination as a legacy pollutant since there is a high risk of continued Hg accumulation in food webs long after Hg-cell phase out.

This study investigated polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins/furans (PBDD/Fs), and dechlorane plus (DP) in air around three concentrated vehicle parking areas (underground, indoor, and outdoor) in a metropolitan of South China. The parking areas showed higher concentrations of PBDEs, PBDD/Fs, and DP than their adjacent urban area or distinct congener/isomer profiles, which indicate their local emission sources. The highest PBDE and DP concentrations were found in the outdoor parking lot, which might be related to the heating effect of direct sunlight exposure. Multi-linear regression analysis results suggest that deca-BDEs without noticeable transformation contributed most to airborne PBDEs in all studied areas, followed by penta-BDEs. The statistically lower anti-DP fractions in the urban area than that of commercial product signified its degradation/transformation during transportation. Neither PBDEs nor vehicle exhaust contributed much to airborne PBDD/Fs in the parking areas. There were 68.1–100 % of PBDEs, PBDD/Fs, and DP associated with particles. Logarithms of gas-particle distribution coefficients (K ₚs) of PBDEs were significantly linear-correlated with those of their sub-cooled vapor pressures (p Ls) and octanol-air partition coefficients (K OAs) in all studied areas. The daily inhalation doses of PBDEs, DP, and PBDD/Fs were individually estimated as 89.7–10,741, 2.05–39.4, and 0.12–4.17 pg kg⁻¹ day⁻¹ for employees in the parking areas via Monte Carlo simulation.

Diffusive gradients in thin films (DGT)-induced flux in sediments (DIFS) (DGT-DIFS) model for phosphorus (P) has been investigated to provide a numerical simulation of a dynamic system of the DGT–pore water–sediment in Dianchi Lake (China). Kinetic parameter—T C (33–56,060 s), distribution coefficient—K d (134.7–1536 cm³g⁻¹), and resupply parameter—R (0.189–0.743) are derived by DGT measurement, the sediment/pore water test, and the DIFS model. The changes of dissolved concentration in DGT diffusive layer and pore water and sorbed concentration in sediment, as well as the ratio of C DGT and the initial concentration in pore water (R) and mass accumulated by DGT resin (M) at the DGT–pore water–sediment interface (distance) of nine sampling sites during DGT deployment time (t) are derived through the DIFS simulation. Based on parameter and curves derived by the DIFS model, the P release-transfer character and mechanism in sediment microzone were revealed. Moreover, the DGT-DIFS parameters (R, T C , K ₋₁ , C DGT), sediment P pool, sediment properties (Al and Ca), and soluble reactive P (SRP) in overlying water can be used to assess “P eutrophication level” at different sampling sites with different types of “external P loading.” The DGT-DIFS model is a reliable tool to reveal the dynamic P release in sediment microzone and assess “internal P loading” in the plateau lake Dianchi.