Soil thawing can affect the turnover of soil carbon (C) and nitrogen (N) and their release into the atmosphere. However, little has been known about the release of C and N during the thawing of alpine soils in the Qinghai-Tibet Plateau. This study investigated the effects of soil thawing on the release of CO₂, CH₄, and N₂O from alpine peatland soils and alpine meadow soils through an indoor experiment and determined the changes in the dissolved organic C (DOC), dissolved organic N (DON), NO₃ ⁻-N, NH₄ ⁺-N, and NO₂ ⁻-N concentrations in the soils after soil thawing. The freeze–thaw treatments were performed by incubating the soil columns at mild (−5 °C) and severe (−15 °C) for 14 days, and then at 5 °C for 18 days. The control columns were incubated at 5 °C. During thawing, the cumulative CO₂ emissions from the severely frozen alpine peatland soils and alpine meadow soils were 36 and 85 % higher than those from the control soils, and the cumulative N₂O emissions were 3.9 and 5.8 times higher than those from the control soils. However, the thawing after mild freezing produced no significant effects. The two freezing temperatures significantly increased the release of CH₄ from the alpine peatland soils, but the thawing of the severely frozen soils reduced the CH₄ uptake of the alpine meadow soils by 27 %. After the severely frozen alpine peatland soils thawed, the concentrations of DOC, DON, NO₃ ⁻-N, NH₄ ⁺-N, and NO₂ ⁻-N increased significantly, but NO₂ ⁻-N showed no significant changes for the alpine meadow soils. After thawing with mild freezing, DOC in the alpine peatland soils and NH₄ ⁺-N, NO₂ ⁻-N, and DOC in the alpine meadow soils showed no significant changes. This study indicates that the potential for release of C and N from alpine soils during thawing periods strongly depends on the freezing temperature and soil types.

A simple, cost-effective, and efficient pretreatment method, namely, vortex- and shaker-assisted liquid–liquid microextraction (VSA-LLME) coupled with gas chromatography and mass spectrometry (GC-MS), is developed for determining 16 trace-level polycyclic aromatic hydrocarbons (PAHs) in offshore produced water. The parameters affecting the VSA-LLME performance including solvent volume, ion strength, shaking time, and centrifuge speed were optimized. Under the optimized condition, the enrichment factors range between 68 and 78. The method linearities (R ²) for all 16 PAHs were above 0.99 at concentration range between 10 and 200 ng/L. The recoveries of the method were 74–85 %, and the limits of detection were as low as 2 to 5 ng/L. The relative standard deviations (RSD%) were 6~11 %. The developed method was also validated in industrial wastewater sample and showed good capability in determination of 16 PAHs in offshore produced water. The developed method offers advantages including simplicity of operation, low cast, and high sensitivity.

Poly(vinyl alcohol)/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM) nanofiber membranes (NFm) were synthesized by a combination of UV radiation and an electrospinning technique. The PVA/MA/ATM NFm were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Brunauer–Emmert–Teller (BET) analysis, scanning electron microscopy (SEM), and energy dispersion spectrometry (EDS). These membranes were used for adsorption–desorption of platinum (Pt(IV)) and palladium (Pd(II)) from a fire assay (FA) leaching waste solution, and the effect of process parameters such as pH of solution, contact time, NFm dosage, temperature, and adsorption isotherms and kinetics studies on the recovery of Pt(IV) and Pd(II) from the waste solution were investigated. The adsorption equilibrium data fit better using the Langmuir model than the Freundlich model. Maximum adsorption capacities, Q ₘₐₓ, at 45 °C were found to be 69.93 and 112.36 mg/g for Pt(IV) and Pd(II), respectively. The activation energies (E ₐ) of Pt(IV) and Pd(II) were 27.90 and 20.29 kJ/mol, respectively. The best desorption reagent was a 1.0 M HCl–1.0 M thiourea (TU) solution for both Pd(II) and Pt(IV). Reusability studies showed that the adsorption capacity can remain up to 90 % after five times of usage. This study provides a promising NFm with an effective adsorption property for Pt(IV) and Pd(II) ions.

Mesostructured CuMnCeO ₓ catalysts were prepared and tested in chlorobenzene destruction. Mn and Cu phases enter CeO₂matrix with a fluorite-like structure to form Cu–Mn–O–Ce solid solution. Both synthesis protocol and metal-doping content affect the metal state, reducibility, and oxygen distribution of composites. The c₀.₁₅c₀.₁₅c₀.₇sample exhibits the highest activity with 90 % of chlorobenzene oxidized at around 250 °C. Enhanced oxygen concentration and mobility, and abundant oxygen vacancy promote the desorption of adsorbed Cl, which guarantees the superior stability of CuMnCeO ₓ . Incorporation of CuO and MnO ₓ effectively inhibits the formation of organic byproducts, such as phenolates, maleates, and o-benzoquinone, especially at elevated temperatures.

Previous studies with bioindicator organisms have used somatic length distributions, i.e., population structure, to understand the effects of management, environment, or a potential contaminant on populations. We describe a statistical approach to separate somatic length classes of Folsomia candida juveniles as an endpoint for the assessment of changes in population structure. Reproduction-survival bioassays were carried out with five different biochars applied at increasing concentrations. Multi-Gaussian models parameterized juvenile size class cohorts, and the biomass of each size class cohort was estimated. Population structure was modified by both material type as well as concentration. Both biomass and population structure were sensitive to effects not reflected in juvenile number, the classic endpoint. Treatments with more size classes and larger individuals were taken to represent favorable conditions, and less size classes and smaller individuals indicated less favorable conditions. This extension of the standardized test provided additional information about the demography of the population.

Glyphosate applied in association with atrazine provides the best cost/benefit for weed control for genetically modified corn. Therefore, the aim of this work was to evaluate the effects of applying glyphosate in mixture with atrazine on soil microbial population and on herbicides fate in a representative Oxisol from Brazil. The treatments consisted in applying the recommended field rate of glyphosate in association with 0, 1, and 2 times the recommended field rate of atrazine (and vice versa), plus the control (without herbicides application). The presence of atrazine temporarily (21 days) decreased soil microbial biomass (SMB) and increased soil carbon mineralization (SCₘᵢₙ, up to 13 times) and microbial metabolic quotient (qCO₂) due to the stresses caused by its toxicity. When the mixture was applied independent of the rates, SMB was recovered and the amounts of extractable and non-extractable¹⁴C-residues were the same for both herbicides at 63 days. These results suggest that glyphosate may mitigate atrazine’s temporary impact on soil microbes by supplying them nutrients during their adaptation.

The aim of this study was to compare the pollution levels of risk elements in flooded and non-flooded alluvial soils as a function of inundation frequency and river distance, depth of soil horizon, and pollution origin. Totally, 43 soil profiles of flooded and non-flooded soils were sampled in two layers (topsoil and subsoil). The total contents of As, Cd, Co, Cr, Cu, Mo, Ni, Pb, V, and Zn were measured and grouped according to the assumed geogenic or anthropogenic origin. Flooded soils were classified according to inundation stage/river distance. Concerning the depth gradient, it can be concluded that the content of anthropogenic risk elements decreased with the depth, while geogenic risk elements revealed no trend. The distance from the river had no influence on the distribution of anthropogenic risk elements in soil. On the contrary, geogenic risk elements showed increasing concentrations with increasing distance. These results indicate that frequency of floods has no influence on the risk elements distribution in soil. The process of sedimentation seems to be the main factor influencing the level of pollution, it differs between groups of anthropogenic and geogenic risk elements. The result of this countrywide study shows higher levels of soil contamination in flooded areas even without significant point sources of pollution, than in non-flooded areas in standard agricultural conditions.

To obtain a good catalytic effect of removing refractory organics from water by Fenton process, granular activated carbon (GAC) supported nano-zero valent iron (nZVI) composite (nZVI/GAC) was prepared by adsorption–reduction method, and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). The catalytic degradation activity of the composite was evaluated to remove nitrobenzene (NB) pollutant via a heterogeneous Fenton-like system, and the initial pH value, nZVI/GAC dosage, and H₂O₂concentration influencing on NB removal were also investigated at room temperature. Experimental results showed that nZVI particle was uniformly dispersed over GAC matrix, and average particle size was 40–100 nm without agglomeration. The nZVI/GAC composite was very efficient in removing NB with average percentage of more than 85 %. However, the removal rate of Fenton-like reaction was highly affected by pH value, H₂O₂concentration, and nZVI/GAC dosage. The optimal reaction conditions were pH 4.0, 40 mg/L NB, 5.0 mmol/L H₂O₂, and 0.4 g/L nZVI/GAC in this study. Stability and repeatability tests as well as mechanism analysis illustrated that GAC improved catalytic action via enhancing nZVI dispersion and accelerating Fe(III)/Fe(II) cycle attributing to internal iron–carbon microelectrolysis in nZVI/GAC composite. Iron utilization efficiency, which played an important role in NB degradation by Fenton-like greatly increased resulting in dissolved iron <0.6 mg/L. This phenomenon strongly implied that the nZVI/GAC Fenton-like process was not only a practical combination of adsorption and Fenton oxidation but also some synergetic effects existing in such an nZVI/GAC composite.

The feasibility of batch and continuous (60, 80, and 100 mL/min) mode photocatalysis systems in real-time livestock wastewater treatment was investigated. The photocatalytic experiments were conducted with two types of photocatalysts namely slurry titanium-dioxide (UV-TiO₂) and granular activated carbon supported TiO₂(GAC-TiO₂). The performance of the systems was compared using economic analysis based on cost and time required to attain maximum efficiency. The photocatalytic reactors operated with GAC-TiO₂was highly effective under both batch (total volatile solids (TVS) removal of 100 % within 6 min and a total operational cost of 0.68 USD per kg of TVS removal) and continuous (at 60 mL/min) (TVS removal of 63 % at a hydraulic retention time (HRT) of 240 min and a total operational cost of 62.16 USD per kg of TVS removal) mode experiments. The economic analyses indicated that cost reduction was a function of optimum time taken for maximum removal efficiency. Subsequently, the experiments were repeated with ultraviolet light (UV) alone, UV-GAC, and GAC alone to quantify effects of adsorption and photolysis. The results confirmed that the effect of GAC in the treatment/degradation of livestock wastewater by adsorption was negligible. However, the presence of GAC in UV systems propelled the rate of biochemical oxygen demand (BOD) and TVS removals. The entire observations reveal that the degradation was mainly by two reaction mechanisms: firstly, adsorption on the GAC surface and secondly by photocatalytic degradation on the GAC-TiO₂surface. Therefore, GAC-TiO₂photocatalysis could be cost-effectively applied for high-rate treatment of industrial wastewaters.

The contents of As, Cu, Cd, Pb, Mn, along with the Pb isotopic ratios ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁶Pb were studied in both soils and tree rings of the marula tree (Sclerocarya birrea) in the vicinity of the Tsumeb deposit (Namibia). Amounts of all the studied metals and As are higher in the immediate vicinity of the Tsumeb Cu-Pb smelter in the soil. The tree rings also have their maximum content of all the studied substances in the vicinity of the smelter (with the exception of Pb). At a more distant site, the maximum concentration of Pb in the soils was 29.8 mg/kg, while the content in the soil in the vicinity of the smelter was as much as 8,174 mg/kg. In the vicinity of the smelter, the maximum Pb content in the tree rings reaches a value of 5.7 mg/kg, compared to a more distant site, where the contents are as high as 9.2 mg/kg. The lower Pb content in the trees on contaminated soil indicates that the composition of the xylem determines the above-ground uptake, rather than the root uptake. Similarly, the above-ground uptake is documented by the isotopic composition of Pb at the distant location, where the tree rings have different contents of Pb isotopes compared to in the soil. The As, Cd, Cu, Pb, and Zn contents are highest in the tree rings from the 1950s (and older), along with those from the 1990s, while the Mn contents were highest in those from the 1960s and 1990s. The contaminant peaks in the 1950s and 1960s could be associated with the roasting of sulfidic ores, while the peak values in the 1990s could have been caused by the start of Cu slag reprocessing in the late 1980s, and culmination of works at the smelter prior to the closing of the mine. The tree rings of the marula tree were found to be a suitable archive for above-ground pollution close to Cu and Pb smelters.