浅埋衬砌隧道-邻近建筑地震动力相互作用IBEM模拟

采用高精度间接边界元方法(IBEM)考察地震波入射下隧道-邻近建筑物二维地震动力相互作用的规律。结果表明:建筑物与邻近隧道存在着明显的相互作用,整体动力反应规律取决于隧道,建筑物之间的空间位置关系、隧道埋深、入射波的频率和角度等因素。隧道位于建筑物正下方时,刚性衬砌隧道(相对围岩)对上部结构主要表现为隔震效应;隧道位于建筑物两侧时,隧道对建筑顶部位移有明显放大效应,最大可放大约40%。同时隧道应力也明显增大,最大可放大约43%。因此实际中需根据隧道-建筑物的空间位置关系,适当调整衬砌隧道与沿线建筑物的抗震设防水平。     

Decontamination of Cr(VI) facilitated formation of persistent free radicals on rice husk derived biochar

PFRs were produced on biochar during Cr(VI) decontamination. PFRs formation on biochar was owing to the oxidization of phenolic-OH by Cr(VI). Appearance of excessive oxidant led to the consumption of PFRs on biochar. Biochar charred at high temperature possessed great performance to Cr(VI) removal. This study investigated the facilitation of Cr(VI) decontamination to the formation of persistent free radicals (PFRs) on rice husk derived biochar. It was found that Cr(VI) remediation by biochar facilitated the production of PFRs, which increased with the concentration of treated Cr(VI). However, excessive Cr(VI) would induce their decay. Biochar with high pyrolysis temperature possessed great performance to Cr(VI) removal, which was mainly originated from its reduction by biochar from Inductively Coupled Plasma Optical Emission Spectroscopy and X-ray Photoelectron Spectroscopy. And the corresponding generation of PFRs on biochar was primarily ascribed to the oxidization of phenolic hydroxyl groups by Cr(VI) from Fourier Transform Infrared Spectroscopy analysis, which was further verified by the H₂O₂ treatment experiments. The findings of this study will help to illustrate the transformation of reactive functional groups on biochar and provide a new insight into the role of biochar in environmental remediation.     

Using mRNA to investigate the effect of low-pressure ultraviolet disinfection on the viability of E. coli

UV can induce damages on mRNA consistently among different genes. SOS response was more active after UV treatment. Programmed cell death was not found to be more active after UV treatment. The efficacy of ultraviolet (UV) disinfection has been analyzed and validated by numerous studies using culture-based methods, yet the discovery of the viable but nonculturable state necessitates the investigation of UV disinfection based on viability parameters. Paired regulators of the SOS response system, recA-lexA, and the programmed cell death system, mazEF, in Escherichia coli were chosen as the target genes, and the effect of UV irradiation on the mRNAs of the four genes was studied. This research showed that, after UV irradiation, the responses of the mRNAs were highly consistent, with reduction percentages of approximately 60% at 20 mJ/cm², 70% at 40 mJ/cm², and 90% at 80 mJ/cm², and these reductions were believed to be the result of direct UV damage to nucleic acids. After 24 h of dark incubation, recA and lexA were both upregulated but to a lesser extent for repressor lexA; and mazE and mazF were both downregulated. This result implies that UV irradiation induces the dark repair system more actively, and the cells will proceed to death at a rate similar to that associated with natural decay.     

Do trace metal(loid)s in road soils pose health risks to tourists? A case of a highly-visited national park in China

Nowadays, more people tend to spend their recreational time in large national parks, and trace metal(loid)s in soils have attracted long-term attention due to their possible harm to human health. To investigate the pollution levels, potential sources and health risks of trace metal(loid)s in road soils, a total of eight trace metal(loid)s (including As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) from 47 soil samples along roads were studied in the Huangshan National Park in Southeast China. The results showed that the concentrations of As, Cd, Pb, Zn and Hg appeared different degrees of pollution compared with their corresponding background values. According to the pollution indices, Hg and Cd were recognized as significant pollutants presenting moderate to high ecological risk. Combining principal component analysis and positive matrix factorization model, the results showed that traffic, industrial, agricultural and natural sources were the potential origins of trace metal(loid)s in this area, with contribution rates of 39.93%, 25.92%, 10.53% and 23.62%, respectively. Non-carcinogenic risks were all negligible, while the carcinogenic risk of As was higher than the limit (1 $\times$ 10⁻⁶). Moreover, children were more susceptible to trace metal(loid)s by ingestion which appeared to be a more important exposure pathway than dermal contact and inhalation. The contribution rates of different sources to non-carcinogenic risks and carcinogenic risks were similar among children and adults, while traffic and industrial sources have a significant impact on health risks. This study will give more insights to control the environmental risks of trace metal(loid)s in national parks.     

Contamination characteristics of trace metals in dust from different levels of roads of a heavily air-polluted city in north China

Concentrations of eight trace metals (TMs) in road dust (RD) (particles?<?25 μm) from urban areas of Xinxiang, China, were determined by inductively coupled plasma mass spectrometry. The geometric mean concentrations of Zn, Mn, Pb, As, Cu, Cr, Ni and Cd were 489, 350, 114, 101, 60.0, 39.7, 31.6, and 5.1 mg kg^?1, respectively. When compared with TM levels in background soil, the samples generally display elevated TM concentrations, except for Cr and Mn, and for Cd the enrichment value was 69.6. Spatial variations indicated TMs in RD from park path would have similar sources with main roads, collector streets and bypasses. Average daily exposure doses of the studied TMs were about three orders of magnitude higher for hand-to-mouth ingestion than dermal contact, and the exposure doses for children were 9.33 times higher than that for adults. The decreasing trend of calculated hazard indexes (HI) for the eight elements was As?>?Pb?>?Cr?>?Mn?>?Cd?>?Zn?>?Ni?>?Cu for both children and adults.     

Selective removal of common cyanotoxins: a review

Environmental Science and Pollution Research - The development of cyanobacterial blooms can have adverse effects on water bodies and may produce cyanotoxins. Several physical and chemical methods...     

Effects of intercropping with floricultural accumulator plants on cadmium accumulation in grapevine

Environmental Science and Pollution Research - Grapevine (Vitis vinifera L.) intercropping with floricultural cadmium (Cd) accumulator plants (Helianthus annuus L., Cosmos sulphureus Cav., Cosmos...     

Simultaneous adsorption and immobilization of As and Cd by birnessite-loaded biochar in water and soil

Environmental Science and Pollution Research - A novel biochar was prepared by loading birnessite to improve its capability to simultaneously adsorb As(III), As(V), and Cd(II) in water and soil....     

Electrocatalytic oxidation of ciprofloxacin by Co-Ce-Zr/γ-Al2O3 three-dimensional particle electrode

Environmental Science and Pollution Research - In this work, Co-Ce-Zr/γ-Al2O33 particle electrodes were prepared for the efficient degradation of ciprofloxacin (CIP). Co-Ce-Zr/γ-Al2O3...     

Viable contribution of Tibetan sacred mountains in southwestern China to forest conservation

The Tibetan sacred mountains (TSMs) cover a large area and may represent a landscape‐scale conservation opportunity. We compared the conservation value of forests in these mountains with the conservation value of government‐established nature reserves and unmanaged open‐access areas in Danba County, southwestern China. We used Landsat satellite images to map forest cover and to estimate forest loss in 1974–1989, 1989–1999, and 1999–2013. The TSMs (n = 41) and nature reserves (n = 4) accounted for 21.6% and 29.7% of the county's land area, respectively. Remaining land was open‐access areas (i.e., areas without any restrictions on resource use) (56.2%) and farmlands (2.2%). Within the elevation range suitable for forests, forest cover did not differ significantly between nature reserves (58.8%) and open‐access areas (58.4%), but was significantly higher in TSMs (65.5%) after controlling for environmental factors such as aspect, slope, and elevation. The TSMs of great cultural importance had higher forest cover, but patrols by monastery staff were not necessarily associated with increased forest cover. The annual deforestation rate in nonsacred areas almost tripled in 1989–1999 (111.4 ha/year) relative to 1974–1989 (40.4 ha/year), whereas the rate in TSMs decreased in the later period (19.7 ha/year vs. 17.2 ha/year). The reduced forest loss in TSMs in 1989–1999 was possibly due to the renaissance of TSM worship and strengthened management by the local Buddhist community since late 1980s. The annual deforestation rate in Danba decreased dramatically to 4.4 ha/year in 1999–2013, which coincided with the implementation of a national ban on logging in 1998. As the only form of protected area across the Tibetan region during much of its history, TSMs have positively contributed to conserving forest at a landscape scale. Conservation of TSM forests largely relied on the strength of local religious institutions. Integrating community‐based conservation of TSMs within the government conservation network would benefit the conservation of the Tibetan region.