High-performance two-dimensional montmorillonite supported-poly (acrylamide-co-acrylic acid) hydrogel for dye removal was investigated. Montmorillonite cooperated with acrylamide and acrylic acid via polymerization, hydrogen-bond, amidation and electrostatic interactions to form the three-dimensional reticular-structured hydrogel with the free entrance for macromolecules. Adsorption tests revealed that the efficient removal (97%) for methylene blue at high concentration (200 mg/L) could be achieved via a small dose of hydrogel (0.5 g/L) within a short time (20 min). The excellent adsorption performance was profited from the electronegative surface and fully exposed reaction sites of two-dimensional montmorillonite, which could save the treatment cost and promote the removal effect compared with the conventional adsorbents. The adsorption process of methylene blue onto hydrogel could be fitted by both the pseudo-first-order and pseudo-second-order kinetics models, and the adsorption isotherm corresponded to the Sips model. The mechanism analysis based on Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy measurements illustrated that the reaction between carboxyl groups and methylene blue molecules as well as the cation-exchange enabled the hydrogel performing extraordinary adsorption efficiency.

Soils have the ability to modify contaminant bioavailability and toxicity. Prediction the modifying effect of soil on arsenic phytoaccumulation and phytoavailability using either soil property data or soil chemical extraction data in risk assessment of contaminated soil is highly desirable. In this study, plant bioassays important to ecological receptors, were conducted with 20 soils with a wide range in chemical and physical soil properties to determine the relationships between As measured by soil chemical extraction (soil pore water, Bray-1, sodium phosphate solution, hydroxylamine hydrochloride, and acid ammonium oxalate) or soil physico/chemical properties on arsenic phytotoxicity and phytoaccumulation. Soil pore water As and Bray-1 extracted As were significantly (P < 0.01) correlated with lettuce tissue As and those extractants and sodium phosphate were correlated with ryegrass tissue As. Hydroxylamine and acid ammonium oxalate extractions did not correlate with plant bioassay endpoints. Simple regression results showed that lettuce tissue relative dry matter growth (RDMG) was inversely related to tissue As concentration (r² = 0.85, P < 0.01), with no significant relationship for ryegrass. Soil clay exhibited strong adsorption for As and significantly reduce tissue As for lettuce and ryegrass. In addition to clay content, reactive aluminum oxide (AlOx), reactive Fe oxide (FeOx) and eCEC was inversely related to ryegrass tissue As. Multiple regression equation was strongly predictive (r² = 0.83) for ryegrass tissue As (log transformed) using soil AlOx, organic matter, pH, and eCEC as variables. Soil properties can greatly reduce contaminant phytoavailability, plant exposure and risk, which should be considered when assessing contaminant exposure and site-specific risk in As-contaminated soils.

The levels of eight organophosphate esters (OPEs) were analyzed in air and soil samples collected at Ny-Ålesund and London Island, Svalbard during the Chinese Scientific Research Expedition to the Arctic during 2014–2015. The concentrations of total OPEs (∑OPEs) ranged from 357 pg/m³ to 852 pg/m³ in the air and from 1.33 ng/g to 17.5 ng/g dry weight (dw) in the soils. Non-Cl OPEs accounted for 56 ± 13% and 62 ± 16% of ∑OPEs for the air and soil, respectively. Tris(2-chloroethyl) phosphate (TCEP) was the dominant compound in the air, with an average concentration of 180 ± 122 pg/m³. Triphenyl phosphate, tri(1-chloro-2-propyl) phosphate, and TCEP were the most abundant OPEs in the soils, with mean values of 1.77, 2.13, and 1.02 ng/g dw, respectively. Compared with the levels of polybrominated diphenyl ethers found in Arctic regions in previous studies, OPEs showed significantly higher concentrations, thereby indicating the large production and wide usage of OPEs globally. In addition, the fugacity fraction results indicated that net deposition from air to soil was dominated in the area. Overall, the occurrence and distribution of OPEs in the air and soils in the Arctic region indicated that OPEs can undergo long-range atmospheric transport and accumulate in remote regions.

We investigated the profiles and levels of perfluoroalkyl carboxylic acids in edible clams from five fishing sites in Japan (Hokkaido, Himakajima-Aichi, Atsumi-Aichi, Kyoto, and Kumamoto) and one site in Vancouver, Canada in 2017. The mean concentrations of perfluoroalkyl carboxylic acids with 6–15 carbon atoms (C6–C15) in edible clams from Japanese coastal waters ranged from 197 to 1757 pg/g wet weight, but were only 48 pg/g wet weight in clams from the site in Canada. Total perfluoroalkyl carboxylic acid concentrations in clams collected in Japanese waters were 4–40 times higher than concentrations in clams from Canada. Perfluorooctanoic acid (C8) contributed 53% of total perfluoroalkyl carboxylic acid concentrations in the clams from Japanese waters, which may be contaminated from terrestrial sources though river effluents, but was not detected in the clam samples from Canada. Principal component analysis separated shorter- and longer-chain perfluoroalkyl carboxylic acids, suggesting differing emission sources or environmental fate. Consumption of clams may be an exposure pathway of perfluorooctanoic acid in the Japanese population.

Particulate air pollution is a continuing challenge in China, and its adverse effects on chronic obstructive pulmonary disease (COPD) have been widely reported. However, epidemiological evidence on the associations between size-fractionated particle number concentrations (PNCs) and COPD mortality is limited. In this study, we utilized a time-series approach to investigate the associations between PNCs of particles at 0.25–10 μm in diameter and COPD mortality in Shanghai, China. Quasi-Poisson regression generalized additive models were applied to evaluate these associations, with adjustment of time trend, day of week, holidays, temperature and relative humidity. Stratification analyses were performed by season and gender. There were a total of 3238 deaths due to COPD during the study period. We found that daily COPD deaths were significantly associated with PNCs of particles <0.5 μm, and the magnitude of associations increased with decreasing particle size. An interquartile range (IQR) increase in PNC₀.₂₅—₀.₂₈, PNC₀.₂₈—₀.₃, PNC₀.₃—₀.₃₅, PNC₀.₃₅—₀.₄, PNC₀.₄—₀.₄₅ and PNC₀.₄₅—₋₀.₅ was associated with increments of 7.51% (95%CI: 2.45%, 12.81%), 7.22% (95%CI: 2.16%, 12.53%), 6.95% (95%CI: 1.81%, 12.35%), 6.26% (95%CI: 1.25%, 11.52%), 5.24% (95%CI: 0.56%, 10.13%) and 4.15% (95%CI: 0.14%, 8.32%), respectively. The associations remained robustness after controlling for the mass concentrations of gaseous air pollutants. In stratification analyses, significant associations between PNCs and COPD mortality were observed in the cold seasons, and in males. Our results suggested that particles <0.5 μm in diameter might be most responsible for the adverse effects of particulate air pollution on COPD mortality, and COPD patients are more susceptible to PM air pollution in the cold seasons, especially for males.

Phthalates are widely used as additives to consumer products. Many diseases have been shown to be related to the uptake of phthalates. To achieve equilibrium constant phthalate generation for mass transfer and exposure experiments, the present study developed a porous media based method using Teflon generators connected to the media with stainless steel connectors. Carbon sponges with the porosities of 20 ppi (pores per inch), 30 ppi, 40 ppi and honeycomb ceramics of 14 ppi were used as porous media fillers to evaluate the effect of temperature-controlled states, materials, and pore sizes on the generating performance of phthalates. The results showed that 30 ppi carbon sponge fillers at 25.0 ± 0.4 °C performed satisfactorily. DMP, DiBP and DEHP were used as examined phthalates and were generated at 12,800 ± 740 μg/m³, 330 ± 13 μg/m³ and 2.37 ± 0.15 μg/m³, respectively. The times to reach stable concentrations were 4.5 h, 18.5 h and 89.5 h, respectively. The reproducibility of DiBP and DEHP delivery deviated by less than 2.4%. Long-term generating experiments should be performed in the future. The porous media based method could stably deliver gaseous PAEs and tends to be widely used in the research of the adsorption of PAEs on surfaces (airborne particles, settled dust and indoor surfaces) and exposure experiments.

In recent years, reports of plastic debris in the gastrointestinal (GI) tract of fish have been well documented in the scientific literature. This, in turn, increased concerns regarding human health exposure to microplastics through the consumption of contaminated fish. Most of the available research regarding microplastic toxicity has focused on marine organisms through direct feeding or waterborne exposures at the individual level. However, little is known about the trophic transfer of microplastics through the aquatic food chain. Freshwater zooplankton Daphnia magna (hereafter Daphnia), and the fathead minnow Pimephales promelas (FHM), are well-known model species used in standard toxicological studies and ecological risk assessments that provide a simple model for trophic transfer. The aim of this study was to assess the tissue translocation, trophic transfer, and depuration of two concentrations (20 and 2000-part ml⁻¹) of 6 μm polystyrene (PS) microplastics particles between Daphnia and FHM. Bioconcentration factors (BCF) and bioaccumulation factors (BAF) were determined. Fluorescent microscopy was used to determine the number of particles in the water media and within the organs of both species. Throughout the five days of exposure, PS particles were only found within the GI tract of both species. The BCF for Daphnia was 0.034 ± 0.005 for the low concentration and 0.026 ± 0.006 for the high concentration. The BAF for FHM was 0.094 ± 0.037 for the low concentration and 0.205 ± 0.051 for the high concentration. Between 72 and 96 h after exposure all microplastic particles were depurated from both species. The presence of food had a significant effect on the depuration of microplastic particles from Daphnia but not for FHM. Based on the low BCF and BAF values for both species, rapid depuration rates, and null translocation of microplastic particles to organs and tissues from the GI tract, there is a low probability that microplastics will bioconcentrate and bioaccumulate under environmental conditions.

Spirotetramat, a member of tetronic and tetramic acid derivatives, is a unique insecticide and acaricide. Although the effect on zebrafish embryos lipid biosynthesis of spirotetramat has been characterized, the energy metabolism and toxic effect mechanism warrant further investigation. To investigate the toxic mechanism of spirotetramat on energy metabolism, zebrafish embryos were exposed to 100, 500 and 1000 µg/L of spirotetramat for 4 days. Untargeted metabolomics showed the synthesis and degradation of ketone pathway metabolites (R)-3-Hydroxybutyric acid and Acetoacetate significantly decreased, as well as increasing the abundance of Anti-Acetyl Coenzyme A Carboxylase protein (ACC1). Down-regulation of the genes related to ß-oxidation and the tricarboxylic acid cycle in the embryos show decreased energy metabolism. Carnitine palmitoyltransferase 1 (CPT- I) significantly decreased while citrate synthase (CS) significantly increased. Additionally, mitochondrial lesions in embryos were found using electron microscopy. Our study provides novel and robust perspectives, which show that spirotetramat treatment in embryos leads to metabolic disturbances that adversely affect cellular energy homeostasis.

The soybean processing wastewater (SPW) supplementation to facilitate the simultaneously treatment (SPW and mesosulfuron-methyl) of wastewater and production of biological substances by Rhodopseudomonas sphaeroides (R. sphaeroides) was discussed. Compared with the control group, with the addition of SPW, mesosulfuron-methyl was removed, and the yields of single-cell proteins, carotenoids, and bacteriochlorophyll were increased. In the 3 mg/L dose group, the mesosulfuron-methyl removal rate reached 97% after 5 days. Molecular analysis revealed that mesosulfuron-methyl exhibited induction effects on expression of the cpm gene and regulation effects on the synthesis of cytochrome P450 monooxygenases (P450) by activating HKs gene in TCS signal transduction pathway. For R. sphaeroides, this induction process required 1 day. The synthesis of P450 occurred 1 day after inoculation. Prior to expressing cpm gene and synthesizing P450, R. sphaeroides need a period of time to adapt to external mesosulfuron-methyl stimulation. However, the R. sphaeroides growth could not be maintained for more than 1 day due to the lack of organic matter in the raw wastewater. The SPW supplementation provided a sufficient carbon source in four groups with added SPW. After 5 days, R. sphaeroides became the dominant microflora in the wastewater. This new method could complete the treatment of mixed wastewater, the increased of biological substances output and the reuse of wastewater and R. sphaeroides cells as resources at the same time.

Acceleration of urbanization and industrialization has resulted in the drastic rise of waste generation with majority of them being biowaste. This constitutes a global challenge since conventional waste management methods (i.e., landfills) present environmental issues including greenhouse gases emissions, leachate formation and toxins release. A sustainable and effective approach to treat biowaste is through composting. Various aspects of composting such as compost quality, composting systems and compost pelletization are summarized in this paper. Common application of compost as fertilizer or soil amendment is presented with focus on the low adoption level of organic waste compost in reality. Rarely known, compost which is easily combustible can be utilized to generate electricity. With the analysis on critical approaches, this review aims to provide a comprehensive study on energy content of compost pellets, which has never been reviewed before. Environmental impacts and future prospects are also highlighted to provide further insights on application of this technology to close the loop of circular bioeconomy.