Hexanitrohexaazaisowurtzitane (CL-20) is an emerging explosive that may replace the currently used explosives such as RDX and HMX, but little is known about its fate in soil. The present study was conducted to determine degradation products of CL-20 in two sandy soils under abiotic and biotic anaerobic conditions. Biotic degradation was prevalent in the slightly acidic VT soil, which contained a greater organic C content, while the slightly alkaline SAC soil favored hydrolysis. CL-20 degradation was accompanied by the formation of formate, glyoxal, nitrite, ammonium, and nitrous oxide. Biotic degradation of CL-20 occurred through the formation of its denitrohydrogenated derivative (m/z 393 Da) while hydrolysis occurred through the formation of a ring cleavage product (m/z 156 Da) that was tentatively identified as CH2N-C(N-NO2)-CHN-CHO or its isomer N(NO2)CH-CHN-CO-CHNH. Due to their chemical specificity, these two intermediates may be considered as markers of in situ attenuation of CL-20 in soil. Two key intermediates of CL-20 degradation are potential markers of its natural attenuation in soil.

Zerovalent iron (Fe0, ZVI) has drawn great interest as an inexpensive and effective material to promote the degradation of environmental contaminants. A focus of ZVI research is to increase degradation kinetics and overcome passivation for long-term remediation. Halide ions promote corrosion, which can increase and sustain ZVI reactivity. Adding chloride or bromide salts with Fe0 (1% w/v) greatly enhanced TNT, RDX, and HMX degradation rates in aqueous solution. Adding Cl or Br salts after 24 h also restored ZVI reactivity, resulting in complete degradation within 8 h. These observations may be attributed to removal of the passivating oxide layer and pitting corrosion of the iron. While the relative increase in degradation rate by Cl- and Br- was similar, TNT degraded faster than RDX and HMX. HMX was most difficult to remove using ZVI alone but ZVI remained effective after five HMX reseeding cycles when Br- was present in solution. The addition of halide ions promotes the degradation of high explosives by zerovalent iron.

It is difficult to achieve simultaneous and efficient removal of heterocyclic drugs (HCDs) and total nitrogen (TN) in conventional denitrification biofilter (DNBF). Inspired by the effective degradation of refractory organic matter by cobalt-based advanced oxidation process and the need for in-situ upgrading of DNBF, peracetic acid (PAA)/cobalt-loaded ceramsite-based DNBF system was constructed for the first time to treat biochemical tailwater containing HCDs. Results showed that PAA/Co-DNBF had relatively high removal rates for the four HCDs with the order of CBZ > TMP > SDZ > SMX, and the optimal DNBF was H2 with 150 μg L⁻¹of PAA. Overall, TN and HCDs removal increased by 178%–455% and 2.50%–40.99% respectively. When the influent concentration of NO₃⁻-N, COD and each HCDs of 20 mg/L, 60 mg/L and 20 μg/L, below 15 mg/L of effluent TN and the highest average removal rate of SMX (67.77%) could be achieved, under HRT of 4 h in H2. More even distribution of microbial species and low acute toxicity of effluent were also achieved. More even distribution of microbial species and low acute toxicity of effluent were also achieved. In addition, high extracellular polymeric substance (EPS) content and Gordonia after the addition of PAA contributed to the degradation of HCDs. This study supplied a potentially effective strategy for the treatment of biochemical tailwater containing HCDs and provided new insight into the advance of denitrification technology.

Rising global demand for energy promotes extensive mining of natural resources, such as oil sands extractions in Alberta, Canada. These extractive activities release hazardous chemicals into the environment, such as polycyclic aromatic compounds (PACs), which include the parent polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and sulfur-containing heterocyclic dibenzothiophenes (DBTs). In areas adjacent to industrial installations, Indigenous communities may be exposed to these PACs through the consumption of traditional foods. Our objective was to evaluate and compare the concentrations of total PACs (∑PAC), expressed as the sum of the 16 U.S. EPA priority PAHs (∑PAH), 49 alkylated PAHs (∑alkyl-PAH), and 7 DBTs (∑DBT) in plant and animal foods collected in 2015 by the Bigstone Cree Nation in Alberta, Canada. We analyzed 42 plant tissues, 40 animal muscles, 5 ribs, and 4 pooled liver samples. Concentrations of ∑PAC were higher in the lichen, old man’s beard (Usnea spp.) (808 ± 116 ng g⁻¹ w.w.), than in vascular plants, and were also higher in smoked moose (Alces alces) rib (461 ± 120 ng g⁻¹ w.w.) than in all other non-smoked animal samples. Alkylated-PAHs accounted for between 63% and 95% of ∑PAC, while the concentrations of ∑PAH represented 4%–36% of ∑PAC. Contributions of ∑DBT to ∑PAC were generally lowest, ranging from <1% to 14%. While the concentrations of benzo(a)pyrene (B[a]P) and ∑PAH4 (∑benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and B[a]P) in all samples were below guideline levels for human consumption as determined by the European Commission, guideline levels for the more prevalent alkylated PAHs are not available. Given the predominance of alkylated PAHs in all food samples and the potentially elevated toxicity relative to parent PAHs of this class of PACs, it is critical to consider a broader range of PACs other than just parent PAHs in research conducted close to oil sands mining activities.

Groundwater serves as a main drinking water source for rural residents in China. However, little is known regarding the pollution of organic micropollutants in groundwater that may pose health risks. In this study, more than 1300 organic micropollutants were screened in the groundwater samples collected from 13 drinking water wells distributed across five rural regions of Liaodong Peninsula in China. A total of 80 organic micropollutants including 12 polycyclic aromatic hydrocarbons, 11 alkanes, 9 pesticides, 7 substituted phenols, 7 perfluoroalkyl acids, 6 heterocyclic compounds, 5 alcohols, 5 phthalic acid esters, 5 pharmaceutical and personal care products, 3 ketones, 2 polychlorinated biphenyls (PCBs), 2 alkylbenzenes and 2 chlorinated benzenes were detected, with their total concentration of 32–1.5 × 104 ng/L. Noncarcinogenic and carcinogenic risks of a part of pollutants were assessed. Exposure through skin absorption and oral ingestion was considered in the assessment. Generally the risks are within the acceptable limits, except for that the carcinogenic risk at two sites in Jinzhou is higher than 10−6. To the best of our knowledge, this is the first report on health risks of groundwater micropollutants in China.

This study aimed at investigating the photochemical behavior of sulfa drugs containing five and six-membered heterocyclic substituents (sulfamethoxazole (SMX) and sulfadiazine (SDZ), respectively), in an aqueous medium. Despite their importance, studies devoted to the use of photochemical models to predict the environmental phototransformation of pollutants in surface waters, by combining laboratory results and natural aquatic systems parameters, are still scarce in the scientific literature. In this work, the second-order reaction rate constants of SDZ and SMX with hydroxyl radicals (●OH), singlet oxygen (¹O₂), and triplet excited states of chromophoric dissolved organic matter (³CDOM*) were experimentally determined at pH 7, using the competition kinetics approach. The results show that ●OH and ³CDOM* are the key species involved in sulfonamide degradation, with anionic SMX, most prevalent at pH 6–9, being degraded much slower than the anionic form of SDZ. Moreover, SDZ and SMX photodegradation in natural water samples (spring-fed natural pond, public supply reservoir, and sea water) was significantly enhanced relative to depletion in pure water. Finally, from mathematical simulations of the sunlight-driven sulfonamide degradation, half-life times were predicted for these drugs varying from less than 2 to about 90 days, depending on the water depth, concentration of key species (DOC, HCO₃⁻, NO₂⁻, CO₃²⁻) in natural aqueous systems, as well as on the particular heterocyclic substituent.

The green synthesis of metal nanoparticles is growing dramatically; however, the toxicity of these biosynthesized particles against living organisms is not fully explored. Therefore, this study was designed to synthesize and characterize TiO₂-NPs, encapsulation and characterization thyme essential oil (ETEO), and determination of the bioactive constituents of ETEO using GC-MS and evaluate their protective role against TiO₂-NPs-induced oxidative damage and genotoxicity in rats. Six groups of rats were treated orally for 30 days including the control group, TiO₂-NPs (300 mg/kg b.w)-treated group, ETEO at low (50 mg/kg b.w) or high dose (100 mg/kg b.w)-treated groups, and TiO₂-NPs plus ETEO at the two doses-treated groups. Blood and tissues were collected for different assays. The GC-MS results indicated the presence of 21 compounds belonging to phenols, terpene derivatives, and heterocyclic compounds. The synthesized TiO₂-NPs were 45 nm tetragonal particles with a zeta potential of −27.34 mV; however, ETEO were 119 nm round particles with a zeta potential of −28.33 mV. TiO₂-NPs administration disturbs the liver and kidney markers, lipid profile, cytokines, oxidative stress parameters, the apoptotic and antioxidant hepatic mRNA expression, and induced histological alterations in the liver and kidney tissues. ETEO could improve all these parameters in a dose-dependent manner. It could be concluded that ETEO is a promising candidate for the protection against TiO₂-NPs and can be applied safely in food applications.

Sulfadiazine (SDZ) was effectively removed by the heterogeneous catalytic sulfate radical (SO₄•⁻) oxidation using a novel composite material of mesoporous carbon (MC) loaded nano zero-valent iron (nZVI). Possessing larger specific area (433.3 m² g⁻¹) and high mesopores volume (2.537 cm³ g⁻¹), the composite material (nZVI/MC) was used as the activator to activate persulfate for the degradation of SDZ. The results of degradation experiments indicated that the removal efficiency of SDZ in nZVI/MC+ persulfate (PS) process reached the highest, due to good dispersing property of MC for nZVI. The removal of SDZ was further enhanced by the increase of nZVI loading as well as the nZVI/MC composite content. Quenching experiments showed that SO₄•⁻ acted a crucial role in the degradation process of SDZ. Both the FT-IR and XPS analyses showed that the FeO contents decreased after degradation reaction, which indicated the occurrence of active oxidation reaction between SO₄•⁻ and Fe²⁺ from the breakage of the Fe–O bond. The LC-MS analysis indicated that the cleavages of C–N bond in the heterocyclic ring and N–S bond were the major degradation pathway of SDZ, attributing to the attack of SO₄•⁻ and •OH. These results demonstrated that the novel nZVI/MC composite with excellent stability could be used for the effective degradation of SDZ through activating PS to produce SO₄•⁻. Graphical Abstract

A composite Mn-Cu-Ce tri-metal oxide supported on γ-Al₂O₃ (Mn-Cu-Ce/Al₂O₃) catalyst was prepared by an impregnation-calcination method and investigated in the catalytic ozonation treatment of real coal chemical wastewater (CCW). The catalyst was characterized by XRD, SEM, TEM, XRF, BET, and XPS techniques. The results showed that Mn, Cu, and Ce metal oxides were evenly distributed on the Al₂O₃ surface and the catalyst maintained a large surface area and a high pore volume compared with the pristine Al₂O₃. The synergy between Mn, Cu, and Ce oxides greatly enriched the catalytic active sites and enhanced the ozonation performance. The catalytic ozonation process with Mn-Cu-Ce/Al₂O₃ increased the removal rate of total organic carbon (TOC) by 31.6% compared with ozonation alone. The ketones, aromatic compounds, phenols, and nitrogen-containing heterocyclic compounds in CCW have been effectively degraded and mineralized by Mn-Cu-Ce/Al₂O₃ catalytic ozonation process, and its biodegradability has also been significantly improved. The experimental results of ∙OH scavengers revealed that the mechanism of Mn-Cu-Ce/Al₂O₃ catalytic ozonation was to promote the generation of ∙OH radicals. The catalytic activity of Mn-Cu-Ce/Al₂O₃ was only a slight decrease in six consecutive catalytic ozonation treatments, showing good stability. Therefore, Mn-Cu-Ce/Al₂O₃ can be used as a candidate catalyst for the advanced treatment of refractory organic wastewaters upon catalytic ozonation.

Geothermal waters exploited in the southeastern region of Hungary are alkali-hydrogen-carbonate type, and beside the high amount of dissolved salt, they contain a variety of aromatic, heteroaromatic, and polyaromatic hydrocarbons. The majority of these geothermal waters used for heating are directed into surface waters following a temporary storage in reservoir lakes. The aim of this study was to gain information about the temporal and spatial changes of the water quality as well as the bacterial community composition of an alkaline and saline oxbow lake operated as reservoir of used geothermal water. On the basis of the water physical and chemical measurements as well as the denaturing gradient gel electrophoresis (DGGE) patterns of the bacterial communities, temporal changes were more pronounced than spatial differences. During the storage periods, the inflow, reservoir water, and sediment samples were characterized with different bacterial community structures in both studied years. The 16S ribosomal RNA (rRNA) gene sequences of the bacterial strains and molecular clones confirmed the differences among the studied habitats. Thermophilic bacteria were most abundant in the geothermal inflow, whereas the water of the reservoir was dominated by cyanobacteria and various anoxygenic phototrophic prokaryotes. In addition, members of several facultative anaerobic denitrifying, obligate anaerobic sulfate-reducing and syntrophic bacterial species capable of decomposition of different organic compounds including phenols were revealed from the water and sediment of the reservoir. Most of these alkaliphilic and/or halophilic species may participate in the local nitrogen and sulfur cycles and contribute to the bloom of phototrophs manifesting in a characteristic pink-reddish discoloration of the water of the reservoir.