某地加油站土壤地下水现状调查与分析

通过对某地10个加油站所在场地土壤及地下水现场采样、实验室检测,分析加油站对土壤与地下水污染原因,结合国家政策法规以及加油站土壤地下水调查现状,针对加油站污染状况提出加强加油站土壤及地下水污染隐患排查力度、强化加油站土壤地下水方面日常管理、污染加油站风险管控及修复工作、加快推进防渗池及双层罐等设施改造工作等建议。     

In situ construction of Z-scheme FeS2/Fe2O3 photocatalyst via structural transformation of pyrite for photocatalytic degradation of carbamazepine and the synergistic reduction of Cr(VI)

Pyrite is the most abundant sulfide semiconductor mineral with excellent optical properties. However, few reports have investigated its photocatalytic activity because of the low photogenerated carrier separation efficiency. In this work, a Z-scheme FeS₂/Fe₂O₃ composite photocatalyst was fabricated in situ via structural transformation of pyrite through heat treatment. A remarkably enhanced photocatalytic performance was observed over the FeS₂/Fe₂O₃ composite photocatalyst. Compared with the pristine pyrite, the degradation efficiency of carbamazepine (CBZ) reached 65% at the added hexavalent chromium (Cr(Ⅵ)) concentration of 20 mg/L and the Cr(Ⅵ) was nearly completely reduced in the mixed system using FeS₂/Fe₂O₃ within 30 min under simulated solar light irradiation. The enhanced photocatalytic activity can be attributed to the efficient separation and transfer of photogenerated carriers in the FeS₂/Fe₂O₃ composite photocatalyst. This facilitated the generation of ?OH, hole (h⁺) and ?O₂^? species, which participated in the photocatalytic reaction with CBZ. Based on the measurement of the active species and electric properties, a Z-scheme electron transfer pathway was proposed for the FeS₂/Fe₂O₃ composite photocatalyst. This work broadens the application potential of pyrite in environmental remediation.     

Nano Fe2O3 embedded in montmorillonite with citric acid enhanced photocatalytic activity of nanoparticles towards diethyl phthalate

Nano-Fe₂O₃ embedded in montmorillonite particles (Fe-Mt) were prepared to degrade diethyl phthalate (DEP) with citric acid (CA) under xenon light irradiation. Compared to pristine montmorillonite (Na-Mt), the embedding process increased 14.5-fold of iron content and 1.8-fold of specific surface area. The synthesized Fe-Mt have more oxygen vacancies than Fe₂O₃ nanoparticles (nFe₂O₃), which could induce more reactive oxygen species (ROSs) generation in the presence of CA under xenon lamp irradiation. Fe-Mt with CA enhanced photo-assisted degradation of DEP 2.5 times as compared to nFe₂O₃ with CA. Quenching experiments, electron paramagnetic resonance (EPR) spectroscopy and identification of products confirmed that surface-bound ?OH was the main radical to degrade DEP. Common anions (i.e., NO₃^?, CO₃^2?, Cl^?) and humic acid could compete ?OH with DEP and cause slower degradation of DEP. The removal efficiency of DEP was more than 56% with Fe-Mt after three recycles, and the dissolved Fe concentration from Fe-Mt was below 75 μmol/L, indicating Fe-Mt had a good stability as a catalyst. Fe-Mt together with CA appeared to be a promising strategy to remove organic pollutants in surface water, or topsoil under solar irradiation.     

Long-range atmospheric transport and alpine condensation of short-chain chlorinated paraffins on the southeastern Tibetan Plateau

Pristine alpine regions are ideal regions for investigating the long-range atmospheric transport and cold trapping effects of short chain chlorinated paraffins (SCCPs). The concentrations and alpine condensation of SCCPs were investigated in lichen samples collected from the southeastern Tibetan Plateau. The concentrations of SCCPs ranged from 3098 to 6999 ng/g lipid weight (lw) and appeared to have an increasing trend with altitude. For congeners, C₁₀ dominated among all the congener groups. The different environmental behavior for different congener groups was closely related to their octanol-air partition coefficient (K_oa). C₁₀ congeners showed an increasing trend with altitude, whereas C₁₃ congeners were negatively correlated with altitude. Volumetric bioconcentration factors (BCF) of SCCPs reached 8.71 in lichens, which were higher than other semivolatile organic compounds (SVOCs) such as organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and hexabromocyclododecane (HBCD). These results suggested that SCCPs were prone to accumulate in the lichen from the air and provided evidence for the role of lichens as a suitable atmospheric indicator in the Tibetan Plateau.     

Volatile organic compounds concentration profiles and control strategy in container manufacturing industry: Case studies in China

Volatile organic compounds (VOCs), important precursors of ozone (O₃) and fine particulate matter (PM_2.5), are the key to curb the momentum of O₃ growth and further reducing PM_2.5 in China. Container manufacturing industry is one of the major VOC emitters, and more than 96% containers of the world are produced in China, with the annual usage of coatings of over 200,000 tons in recent years. This is the first research on the emission characteristics of VOCs in Chinese container manufacturing industry, including concentration and ozone formation potential (OFP) of each species. The result shows that the largest amounts of VOCs are emitted during the pretreatment process, followed by the paint mixing process and primer painting process, and finally other sprays process. The average VOC concentrations in the workshops, the exhausts before treatment and the exhausts after treatment are ranging from 82.67–797.46 , 170–1,812.65 , 66.20–349.63 mg/m³, respectively. Benzenes, alcohols and ethers are main species, which contribute more than 90% OFP together. Based on the emission characteristics of VOCs and the technical feasibility, it is recommended to set the emission limit in standard of benzene to 1.0 mg/m³, toluene to 10 mg/m³, xylene to 20 mg/m³, benzenes to 40 mg/m³, alcohols and ethers to 50 mg/m³, and VOCs to 100 mg/m³. The study reports the industry emission characteristics and discusses the standard limits, which is a powerful support to promote VOCs emission reduction, and to promote the coordinated control of PM_2.5 and O₃ pollution.     

Influence of drying and calcination temperatures for Ce-Cu-Al trimetallic composite catalyst on simultaneous removal H2S and PH3: Experimental and DFT studies

This work explored the influences of the drying and calcination temperatures on a Ce-Cu-Al trimetallic composite catalyst for the simultaneous removal of H₂S and PH₃. The effects of both temperatures on the structural features and activity were examined. The density functional theory method was used to calculate adsorption energies and further analyze their adsorption behavior on different slabs. Experiments revealed suitable drying and calcination temperatures to be 60 and 500°C, respectively. The capacity reached 323.8 and 288.1 mg/g. Adjusting drying temperature to 60°C is more inclined to form larger and structured grains of CuO. Rising calcinating temperature to 500°C could increase the grain size and redox capacity of CuO to promote performance. Higher temperatures would destroy the surface structure and lead to a crystal phase transformation, which was that the CuO and Al₂O₃ were gradually recombined into CuAl₂O₄ with a spinel structure. The exposed crystal planes of surficial CuO and CuAl₂O₄ were determined according to characterization results. Calculation results showed that, compared with CuO (111), H₂S and PH₃ have weaker adsorption strength on CuAl₂O₄ (100) which is not conducive to their adsorption and removal.     

Assessment of health benefit of PM2.5 reduction during COVID-19 lockdown in China and separating contributions from anthropogenic emissions and meteorology

The national lockdown policies have drastically disrupted socioeconomic activities during the COVID-19 pandemic in China, which provides a unique opportunity to investigate the air quality response to such anthropogenic disruptions. And it is meaningful to evaluate the potential health impacts of air quality changes during the lockdown, especially for PM_2.5 with adverse health effects. In this study, by using PM_2.5 observations from 1388 monitoring stations nationwide in China, we examine the PM_2.5 variations between the COVID-19 lockdown (February and March in 2020) and the same period in 2015–2019, and find that the national average of PM_2.5 decreases by 18 μg/m³, and mean PM_2.5 for most sites (about 75%) decrease by 30%–60%. The anthropogenic and meteorological contributions to these PM_2.5 variations are also determined by using a stepwise multiple linear regression (MLR) model combined with the Kolmogorov–Zurbenko filter. Our results show that the change of anthropogenic emissions is a leading contributor to those widespread PM_2.5 reductions, and meteorological conditions have the negative influence on PM_2.5 reductions for some regions, such as Beijing–Tianjin–Hebei (BTH). Additionally, the avoided premature death due to PM_2.5 reduction is estimated as a predicted number based on a log-linear concentration-response function. The total avoided premature death is 9952 in China, with dominant contribution (94%) from anthropogenic emission changes. For BTH, Yangtze River Delta, Pearl River Delta and Hubei regions, the reductions of PM_2.5 are 24.1, 24.3, 13.5 and 29.5 μg/m³, with the avoided premature deaths of 1066, 1963, 454 and 583, respectively.     

Remediation of preservative ethylparaben in water using natural sphalerite: Kinetics and mechanisms

As a typical class of emerging organic contaminants(EOCs), the environmental transformation and abatement of preservative parabens have raised certain environmental concerns. However, the remediation of parabens-contaminated water using natural matrixes(such as, naturally abundant minerals) is not reported extensively in literature. In this study, the transformation kinetics and the mechanism of ethylparaben using natural sphalerite(NS) were investigated. The results show that around 63% of ethy...     

锰矿区周边农田土壤重金属污染特征、来源解析及风险评价

为了解锰矿周边农田土壤重金属污染和生态风险情况,采集某矿区周边174份农田土壤样品,分析了土壤中8种重金属(Cu、 Zn、 Pb、 Cr、 Ni、 Mn、 As和Hg)的含量,采用主成分分析(PCA)和正定矩阵因子分解模型(PMF)分析土壤重金属的来源,通过单因子污染指数法、地累积指数法、潜在生态风险指数法和人体健康风险评价模型评价土壤重金属生态环境风险.结果表明,研究区农田土壤Cu、 Zn、 Cr、 Ni、 Mn和Hg含量的均值均高于贵州省土壤背景值,100%样本Zn和38.86%样本Cu均超过农用地土壤污染风险筛选值.源解析显示农田土壤重金属的主要来源为矿业开采排放源,其次为农业活动和交通运输混合源、自然源和农业活动源.风险评价结果表明,土壤中Ni、 Cr、 Pb和As属于清洁水平,Hg和Cu属于轻度污染水平,Zn属于偏中度污染水平,Mn属于偏重污染水平.Cu、 Zn、 Pb、 Cr、 Ni、 Mn和As存在轻微潜在生态风险,Hg存在强潜在生态风险.研究区整体存在强潜在生态风险,8种重金属存在致癌风险和0～5岁儿童非致癌风险,主要贡献因子分别是Cr和Mn.     

Analysis of Cell Concentration,Volume Concentration,and Colony Size of Microcystis Via Laser Particle Analyzer

The analysis of the cell concentration, volume concentration, and colony size of Microcystis is widely used to provide early warnings of the occurrence of blooms and to facilitate the development of predictive tools to mitigate their impact. This study developed a new approach for the analysis of the cell concentration, volume concentration, and colony size of Microcystis by applying a laser particle analyzer. Four types of Microcystis samples (55 samples in total) were analyzed by a laser particle analyzer and a microscope. By the application of the laser particle analyzer (1) when n = 1.40 and k = 0.1 (n is the intrinsic refractive index, whereas k is absorption of light by the particle), the results of the laser particle analyzer showed good agreement with the microscopic results for the obscuration indicator, volume concentration, and size distribution of Microcystis; (2) the Microcystis cell concentration can be calculated based on its linear relationship with obscuration; and (3) the volume concentration and size distribution of Microcystis particles (including single cells and colonies) can be obtained. The analytical processes involved in this new approach are simpler and faster compared to that by microscopic counting method. From the results, it was identified that the relationship between cell concentration and volume concentration depended on the colony size of Microcystis because the intercellular space was high when the colony size was high. Calculation of cell concentration and volume concentration may occur when the colony size information is sufficient.