Passive sampling of PAHs in indoor air in Nepal

PAHs were sampled in ten homes in the Makwanpur region, Nepal. SPMDs and moss bags (Sphagnum girgensohnii) were used as passive samplers. Soot particles on the SPMD surfaces were also analyzed for PAHs. The overall PAH concentrations in SPMDs were significantly higher than those in moss bags. Total PAH mean concentrations of ten houses were 535μg/g lipid for SPMDs and 7.2 μg/g moss (dw) for moss bags. Ratios of phenanthrene/anthracene in indoor SPMDs and particulate matter varied from 2.9 to 3.5 and ratios of fluoranthene/pyrene varied from 1.1 to 1.4. The values for moss bags were respectively 1.7–3.6 and 0.8–2.4. These ratios indicate that the PAHs are from combustion origin. The PAH concentrations in ambient air were estimated as B(a)P TEQs and they were 17–64 times higher than acceptable limit for Finnish community air. Based on PAH levels in the gas phase (SPMD) we may expect PAHs to have an impact on respiratory disease prevalence in Nepalese villages. Both of the sampling methods were feasible in the difficult conditions under which the study was performed.     

Effects of Coffee Management on Deforestation Rates and Forest Integrity

Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest‐agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973–2010) across elevations in 2 forest‐agriculture mosaic landscapes (1100 km² around Bonga and 3000 km² in Goma‐Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee‐growing elevations compared with at higher elevations (?10/20% vs. ?40/50% comparing relative rates at 1800 m asl and 2300–2500 m asl, respectively). Within the coffee‐growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest‐specialist species. Even if the presence of coffee slows down the conversion of forest to annual‐crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value. Efectos de la Administración Cafetalera sobre las Tasas de Deforestación y la Integridad de los Bosques     

Response of bacterial communities to short-term pyrene exposure in red soil

Pyrene, a representative polycyclic aromatic hydrocarbon (PAH) compound produced mainly from incomplete combustion of fossil fuels, is hazardous to ecosystem health. However, long-term exposure studies did not detect any significant effects of pyrene on soil microorganism. In this study, short-term microcosm experiments were conducted to identify the immediate effect of pyrene on soil bacterial communities. A freshly-collected pristine red soil was spiked with pyrene at 0, 10, 100, 200, and 500 mg·kg^-1 and incubated for one day and seven days. The bacterial communities in the incubated soils were analyzed using 16S rRNA sequencing and terminal restriction fragment length polymorphism (T-RFLP) methods. The results revealed high bacterial diversity in both unspiked and pyrene-spiked soils. Only at the highest pyrene-spiking rate of 500 mg·kg^-1, two minor bacteria groups of the identified 14 most abundant bacteria groups were completely suppressed. Short-term exposure to pyrene resulted in dominance of Proteobacteria in soil, followed by Acidobacteria, Firmutes, and Bacteroidetes. Our findings showed that bacterial community structure did respond to the presence of pyrene but recovered rapidly from the perturbation. The intensity of impact and the rate of recovery showed some pyrene dosage-dependent trends. Our results revealed that different levels of pyrene may affect the bacterial community structure by suppressing or selecting certain groups of bacteria. It was also found that the bacterial community was most susceptible to pyrene within one day of the chemical addition.     

Influence of inoculating earthworms on removal of pyrene in soils growing Festuca arundinacea

ABSTRACT

The aim of this study was to examine the potential of inoculating earthworms (Pheretima sp.) in order to enhance phytoremediation of polycyclic aromatic hydrocarbons (PAH) present in soils with the use of tall fescue (Festuca arundinacea). In particular, experiments with or without inoculating earthworms for removal of pyrene was investigated. Results showed that planting of F. arundinacea enhanced the removal of pyrene at initial content over 70 days approximately 54%–80% but only 12%–24% occurred in non-planted soils. After inoculating earthworms, the dissipation rates of pyrene in planted soils were increased up to 61%–86%, which was 6%–12% higher than those in corresponding soils without inoculating earthworms. Among all possible pathways, the contribution of plant--microbial interactions on removal of pyrene was predominant, either with (46%) or without inoculating earthworms (52%), is the primary mechanism of contaminant removal. Data suggest inoculating earthworms may be a feasible way for reinforcing removal of PAH in contaminated sites.     

枯草芽孢杆菌对铜绿微囊藻抑制效果的研究

为探讨枯草芽孢杆菌(Bacillus subtilis)对铜绿微囊藻(Microcystis aeruginosa)的抑制效果,在实验室条件下,研究了枯草芽孢杆菌不同生长时期(延迟期、对数期、稳定期和衰亡期)无菌滤液对铜绿微囊藻生长的影响、枯草芽孢杆菌抑制铜绿微囊藻生长的作用方式以及无菌滤液影响下铜绿微囊藻丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性和光合色素含量的变化.结果显示:枯草芽孢杆菌对数期、稳定期和衰亡期滤液抑藻效果明显好于延迟期,作用第8d,对铜绿微囊藻的去除率分别达到81.19%、91.41%、91.82%;4个处理组铜绿微囊藻的叶绿素a含量均显著低于对照组.添加稳定期滤液后,铜绿微囊藻MDA含量显著升高,SOD活性先升高后降低;在对光合色素的影响中,类胡萝卜素受到的影响不如叶绿素a显著.结果表明,枯草芽孢杆菌对铜绿微囊藻的抑制效果是通过分泌胞外物质实现的,且分泌物具有很强的热稳定性.推测该胞外分泌物能够破坏光合色素,影响光合作用,抑制藻细胞的生长;同时抑制SOD活性,使细胞膜脂过氧化程度不断加深,进而破坏藻细胞的完整性,表现出对藻很强的抑制效果.     

芘在土壤不同粒径组分中的形态分布

以芘为PAHs代表物,采用土壤粒径分级和PAHs连续提取方法,研究了老化4周污染黄棕壤中芘在不同粒径组分中的形态分布.结果表明,供试土壤中芘主要以有机溶剂提取态和可脱附态存在,结合态残留量所占比例甚小;细砂粒、粉粒、粗黏粒和细黏粒中芘残留占原土总残留的比例分别为6.00%、4.66%、34.68%和40.88%.各粒径组分中各形态芘含量大小顺序为有机溶剂提取态>可脱附态>结合态,有机溶剂提取态和可脱附态是各粒径组分中芘残留的主要存在形态(占比98.82%以上),芘结合态残留量占比<1.18%.土壤中黏粒(包括细黏粒和粗黏粒)是芘可脱附态、有机溶剂提取态、结合态和可提取态残留储存的主要粒径组分.     

Combination of the direct electro-Fenton process and bioremediation for the treatment of pyrene-contaminated soil in a slurry reactor

A combined treatment technology (DEF-BIO) using the direct electro-Fenton (DEF) process and bioremediation (BIO) was established in this study. The performance of the DEF-BIO process on the remediation of a pyrene (PYR)-contaminated soil was evaluated in a slurry reactor. The appropriate order of application was to conduct the DEF process followed by BIO, evaluated through analysis of the degradation characteristics of each process individually. In addition, the application time of the DEF process affected the efficiency of the combined process. The optimum time to apply the DEF process was determined through an analysis of the induced changes in PYR intermediates, pH, soil organic matter (SOM) and bacteria. The optimum application time of the DEF process was 6 h. All the induced changes were beneficial for the BIO phase. The removal of PYR was 91.02% for DEF–BIO after 72 h, and the efficiency was almost 50% increased, compared with the individual DEF and BIO treatments. Therefore, the combined process of DEF–BIO process may be an efficient and promising method for the remediation.     

火电厂烟塔合一和烟囱排放大气环境影响比较——以宝鸡第二发电厂为例

以宝鸡第二发电厂间接空冷机组为例,分别采用德国AUSTAL2000大气预测模式与美国AERMOD大气预测模式,对烟塔合一和烟囱两种排放方式的大气环境影响进行分析预测,并分析了地形因素对预测结果的影响。通过对比分析得知,烟塔合一排放的地面浓度分布较分散,而烟囱排放造成的地面浓度分布较集中。考虑地形影响时采用AUSTAL2000计算的烟塔合一地面浓度比AERMOD计算的烟囱小,不考虑地形时则反之。     

条件价值法评估生命价值的应用探讨

分别对条件价值法评估生命价值的经济学理论基础和研究进展进行阐述;分析条件价值法应用于生命价值评估可能会产生的偏差有假想偏差、策略偏差和信息偏差,并探讨支付意愿与受偿意愿、诱导技术、风险变化率对其结果有效性的影响。根据文献分析结果,结合前期应用条件价值法评估生命价值实证研究的成果,就如何提高条件价值法评估生命价值结果的可靠性和有效性给出实证研究设计方案,通过总体设计框架、工作环境风险认知调查、工作风险支付意愿的设计、社会经济信息变量的设置、调查准备与预调查、样本容量及抽样设计、数据统计分析等多个方面的优化设计可以保障评估生命价值的有效性和可靠性。     

气相色谱-质谱法测定环境空气中恶臭硫化物成分

摘要：采用苏玛罐采样、冷阱顶浓缩处理样品、气相色谱质谱联用法测定环境空气中的甲硫醇、乙硫醇、甲硫醚、乙硫醚、甲乙硫醚、二甲二硫、二硫化碳等7种恶臭硫化物。结果表明,该方法的线性较好,7种硫化物的检出限为8．0×10-4～1．4×10-3mg／m3,混合标准气体平行测定时RSD范围在3．32％～6．17％,加标回收率为100％～117％。该方法对于环境空气恶臭硫化物的测定准确可靠,能够用于常规环境空气中恶臭硫化物的分析检测。