Salmonella is a common zoonotic pathogen. Few studies have explored the effects of biochar on the survival of Salmonella in soil. Biochar made by pig manure at different temperatures were applied to four typical vegetable soils to investigate the survival dynamics of Salmonella. The results showed that the survival of Salmonella in latosol, red soil, and black soil was significantly promoted after biochar addition, but not in brown soil. The pyrolysis temperature of biochar had great effects on the survival of Salmonella. The survival time of Salmonella in the soil with biochar at 300°C was longer than that at 500 °C and 700 °C. The longest survival time of Salmonella was observed in Latosol with 300 °C biochar (111.36 days). Correlation analysis showed that soil pH, organic matter, and total nitrogen content were significantly positively correlated with the survival time of Salmonella in vegetable soils without biochar. However, the content of total potassium was the main controlling factor affecting the survival dynamics of Salmonella in soils with biochar.

Bioleaching is suggested as a methodology with benefits in ex situ/in situ bioremediation for reducing metal contamination in dredged sediments. The process of bioleaching assisted by microorganisms in a stirred tank is widely used, among other biohydrometallurgical techniques, for the efficient extraction of metals of interest if the recovery costs of valuable metals allow it. Measurement of the mass transfer capacity of oxygen in an aerobic bioreactor is of vital importance; this factor determines the productivity of the system, since it promotes microbial growth and hence enables a bioconversion process at the mineral surface takes place. The main objective of the present research was to determine the volumetric oxygen transfer coefficient (kLₐ) during the manganese bioleaching process in a stirred tank reactor using silicone oil as a vector to improve the transfer of gaseous substrates. Experiments were carried out in triplicate with a 2² factorial design analyzing temperature (30 and 40 °C) and stirring speed (300 and 500 rpm). The effect of viscosity on the system was also determined by modifying the concentrations of mining waste (30, 40, and 50%), ferrous sulfate (FeSO₄ · 7H₂O) (2, 4, 8, and 14%), and silicone oil (0, 5, and 10%) at 0 and 24 h of mixing. The results showed an increase in the value of kLₐwith respect to time, from kLₐ₍₀ ₕ, ₃₀ °C, ₅₀₀ ᵣₚₘ₎ = 8.75 s⁻¹ to kLₐ₍₂₄ ₕ, ₄₀ °C, ₅₀₀ ᵣₚₘ₎ = 18.18 s⁻¹; ANOVA statistical analysis was performed with the Fisher and Tukey tests and showed that there were statistically significant differences.

Several studies were carried out and drought coexistence technologies were developed to deal with the problem of drought in semiarid regions, such as the construction of underground dams, which became a tool for rural development, mainly for family agriculture. However, there are still scarce informations regarding technical studies on the water security level of underground dams, especially about trace metal contamination due to the use and agricultural occupation of the soils downstream of the dams. In this work, the level of contamination of trace metals in waters of underground dams, during two hydrological years, was evaluated around of the sub-basin of the Cobras river, in the Rio Grande do Norte state, Brazil. The analysis of the results indicated that the water samples stored in the Alexandre and Ginaldo underground dams are within the permitted drinking patterns and did not suffer, on the other hand, any alteration in their quality that requires treatment for human consumption, fitting into Class 1. Most of the samples from the waters of the Boa Vista and Ademar dams are above the maximum allowable value for iron (Fe), lead (Pb), chromium (Cr), and nickel (Ni), requiring a differentiated treatment for human consumption, and can be classified as Class 2. The probable contamination of the waters stored in the underground dams may be of geological origin, since the largest accumulation of trace metals occurred in the lower area of the river course greater drained area, leading to believe that the metals come from the rock weathering that make up the geological framework of the region.

The aim of the study was to evaluate the influence of the application of increasing proportions (0%, 10%, 25%, 50%, 75%, and 100%) of an admixture of PCB-contaminated Hudson River sediment collected from the Upper Hudson River, near Waterford, Saratoga county (New York, USA) on soil properties, phytotoxicity, and biometric and physiological responses of cucumber (Cucumis sativus L. cv ‘Wisconsin SMR 58’) and zucchini (Cucurbita pepo L. cv ‘Black Beauty’) grown as potential phyto- and rhizoremediators. The experiment was performed for 4 weeks in a growth chamber under controlled conditions. Amendment of Hudson River sediment to soil led to a gradual increase in PCB content of the substratum from 13.7 μg/kg (with 10% sediment) to 255 μg/kg (with 100% sediment). Sediment amendment showed no phytotoxic effects during the initial stages, even Lepidium sativum root growth was stimulated; however, this positive response diminished following a 4-week growth period, with the greatest inhibition observed in unplanted soil and zucchini-planted soil. The stimulatory effect remained high for cucumber treatments. The sediment admixture also increased cucurbit fresh biomass as compared to control samples, especially at lower doses of sediment admixture, even though PCB content of the soil amended with sediment increased. Cucurbits’ leaf surface area, in turn, demonstrated an increase for zucchini, however only for 50% and 75% sediment admixture, while cucumber showed no changes when lower doses were applied and decrease for 75% and 100% sediment admixture. Chlorophyll a + b decreased significantly in sediment-amended soils, with greater inhibition observed for cucumber than zucchini. Our results suggest that admixture of riverine sediment from relatively less-contaminated locations may be used as soil amendments under controlled conditions; however, further detailed investigation on the fate of pollutants is required, especially in terms of the bioaccumulation and biomagnification properties of PCBs, before contaminated sediment can be applied in an open environment.

The modified Fe₃O₄ nanoparticles were used as a support for the immobilization of horseradish peroxidase (HRP). The immobilized enzyme (HRP@Fe₃O₄) was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectrometer (FTIR), and vibration sample magnetometer (VSM). According to the results, the optimum concentration of glutaraldehyde (GA) and agitation time were 300 μL and 7 h. HRP was well loaded on the surface of the Fe₃O₄. There was no change in the crystal structure of HRP@Fe₃O₄ compared with Fe₃O₄. The removals of bisphenol A (BPA) and 17α-ethinylestradiol (EE2) using HRP@Fe₃O₄ had been investigated. The degradation efficiencies of BPA and EE2 catalyzed by HRP@Fe₃O₄ were higher than that of soluble HRP. In addition, HRP@Fe₃O₄ can be reused through magnetic separation. After the fifth repeated use, the removal efficiencies of BPA and EE2 were up to 56% and 48%, respectively. Batch studies of catalyzed oxidation and coagulation on the degradation of BPA and EE2 in the presence of humic acid (HA) were also investigated. The order of the removal efficiencies was HRP+PACl (polyaluminum chloride)+SDS (lauryl sodium sulfate)>HRP+PACl>HRP>HRP+PAM (Polyacrylamide)>HRP+PAM+SDS. The coagulation effect of HRP@Fe₃O₄ and PACl was better than that of HRP@Fe₃O₄ and PAM. The removals of BPA and EE2 were 90.3% and 64.5% by use HRP@Fe₃O₄ and PACl as coagulant, while the removals were 78.7% and 57.6% by use HRP@Fe₃O₄ and PAM as coagulant. SDS had a positive effect on PACl, while a negative effect on PAM. Moreover, the products generated by enzymatic oxidation reaction can be effectively removed after coagulation.

In this study, the occurrence, spatial distribution, sources, and ecological risks of perfluoroalkyl substances (PFASs) in the surface waters of the Lingang hybrid constructed wetland were systematically investigated. Twenty-three PFASs were analyzed from 7 representative sampling zones. The obtained results indicated that PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFBS, PFOS, and HFPO-DA were frequently detected; and PFBA, PFOA, and PFOS were the dominant PFASs with the relative abundances in ranges of 26.91 to 52.26%, 11.79 to 28.79%, and 0 to 31.98%, respectively. The total concentrations of 8 PFASs (Σ₈PFASs) ranged from 25.9 to 56.6 ng/L, and the highest concentration was observed in subsurface flow wetland. Moreover, HFPO-DA with high toxicity was detected in wetlands for the first time. Based on the principal component analysis-multiple linear regression (PCA-MLR) analysis, three sources and their contributions were fluoropolymer processing aids (67.6%), fluororesin coatings and metal plating (17.9%), and food packaging materials and atmospheric precipitation (14.5%), respectively. According to the risk quotients (RQs), the ecological risk of 8 PFASs was low to the aquatic organisms.

In this study, a composite aerogel (WP-MMT) composed of wastepaper (WP) and montmorillonite (MMT) was prepared by ambient pressure drying technology to adsorb Cd²⁺. The study of compression performance indicated that the composite aerogel had ideal mechanical strength when the mass ratio of WP to MMT was 1:1. The specific surface areas of the aerogels modified by hydrogen peroxide (WP-MMT-H₂O₂) and sodium hydroxide (WP-MMT-NaOH) were increased greatly. The sorption isotherms and kinetics of Cd²⁺ sorption on WP-MMT-H₂O₂ and WP-MMT-NaOH were investigated. The Cd²⁺ sorption data could be well described by a simple Langmuir model, and the pseudo-second-order kinetic model best fitted the kinetic data. The maximum sorption capacity obtained from the Langmuir model was 232.50 mg/g for WP-MMT-NaOH. The adsorption mechanism of WP-MMT was chemical adsorption of a single-molecule layer. In general, it was proved that the composite aerogel with high adsorption capacity of Cd²⁺ could be synthesized from modified WP and MMT by ambient pressure drying. The composite aerogel fabricated by wastepaper and montmorillonite showed bright application prospect in the aqueous heavy metal pollution control.

A lower expansive heavy metal adsorbent, high crosslinked sodium carboxyl methylstarch-g-poly (acrylic acid-co-acrylamide) resin (HCAA), has been prepared by enhancing the crosslinking degree of the traditional water-absorbing polymer under the graft copolymerization reaction. Further heavy metal adsorption experiments, morphology analysis, and structure characteristic observations indicate that HCAA resin has an excellent heavy metal adsorption properties for Cr³⁺, Cu²⁺, Ni²⁺, and Zn²⁺ of 80.08, 158.07, 155.71, and 137.15 mg/g, respectively. The nanoholes in network structures of HCAA resin expanding in solution provide an effective diffusion and exchange channels for heavy metal ions and Na⁺. The adsorption process of HCAA containing –COONa is attributed to ion exchange process, and its essence is to form the coordination bond with heavy metals. The adsorption capacity differences of –COO⁻ have been explained by using the coordination chemistry theory. In addition, the adsorption selectivity of an expansive adsorbent containing –COONa are heavy metals > H₂O >> Na⁺. Our research puts forward an insight that increasing the crosslinker content on the basis of the traditional super absorbent resin can obtain a lower expansive adsorbent to heavy metal pollutants.

Paddy soil contamination by cadmium (Cd) and arsenic (As) is a great concern. Field experiments were conducted to study the effects of steel slag (SS, 2.0 and 4.0 t ha⁻¹) on the solubility of Cd and As in soil and their accumulation by rice plants grown in a historically co-contaminated paddy field with Cd and As. The results showed that SS amendment (4.0 t ha⁻¹) significantly decreased soluble concentrations of Cd in pore-water but increased that of As, related to markedly elevated soil pH and soluble silicon, phosphorus of pore-water in rice rhizosphere at both heading and mature stages. The amendments also evidently decreased Cd but enhanced As in iron plaque on root surfaces, while the formation of iron plaque was not significantly increased. Further, SS amendment (4.0 t ha⁻¹) markedly reduced Cd concentrations in rice tissues (roots, straw, and brown rice) by 48–78% at both stages, though increased As by 13–38%. Cadmium translocation from roots to aerial parts decreased significantly after the amendments, but not for As. Besides, SS application increased the biomass of roots, straw and grains, and root antioxidant enzyme activities. Collectively, steel slag decreased Cd accumulation in rice tissues and in iron plaque but increased those of As, likely due to steel slag decreasing soluble Cd and enhancing soluble As in pore-water, related to soil pH and soluble nutrients (Si, P), and restraining Cd translocation within rice. Our results indicate that steel slag represents a favorable potential for Cd-contaminated paddy soils, though it seems undesirable for Cd and As co-contamination.

Oil spills can result in significant damage to marine estuaries, rivers, lakes, wetlands, and shorelines. Electrospun nanofibers containing biosurfactant (ENFs) can be used to clean oil spills up and protect the environmental biology. Present work aimed to study the side-effects of prepared nanofibers on animal models. Screening of the prepared ECNFs on animals showed that three of them (PVA-5, PEO-1, and PEO-5) are safe to hepatic tissues and liver functions. Furthermore, oxidative stress did not change after using these nanofibers. The PVA-1 nanofibers, however, were found to cause major pathological changes in the liver tissue. In addition, PVA-1 nanofibers were proved to alter the total white blood count and the neutrophil percentages significantly in comparison to the control. In conclusion, PVA-5, PEO-1, and PEO-5 are safe to hepatic tissues and liver functions.