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991.
Jun-juan Shao Cheng-bin Liu Qing-hua Zhang Jian-jie Fu Rui-qiang Yang Jian-bo Shi Yong Cai Gui-bin Jiang 《Environmental geochemistry and health》2017,39(3):475-482
The accumulation and species of mercury (Hg) in mosses and lichens collected from high-altitude Tibetan Plateau were studied. The altitudes of the sampling sites spanned from 1983 to 5147 m, and a total of 130 mosses and 52 lichens were analyzed. The total mercury (THg) contents in mosses and lichens were in the ranges of 13.1–273.0 and 20.2–345.9 ng/g, respectively. The average ratios of methylmercury (MeHg) in THg in mosses and lichens were 2.4 % (0.3–11.1 %) and 2.7 % (0.4–9.6 %), respectively, which were higher than those values reported in other regions. The contents of THg in both mosses and lichens were not correlated with the THg in soils (p > 0.05). The lipid contents displayed a significantly positive correlation with concentrations of MeHg in mosses (r = 0.461, p < 0.01, n = 90), but not in lichens. The correlations between Hg contents in mosses and the altitudes, latitudes and longitudes of sampling sites indicated the mountain trapping and spatial deposition of Hg in the Tibetan Plateau. 相似文献
992.
Seasonal variations effects on desert steppe soil culturable bacteria in northwestern China and physicochemical parameters were investigated. Soil temperature ranged from 5.37 to 23.73 °C. Moisture content varied from 3.22% to 7.62%. The pH was between 7.98 and 8.72. Soil nutrients were altered in different seasons. Total potassium (K) remained the same, but available K levels ranged from 101.29 to 227.55 mg/kg. The culturable bacterial counts in January, April, July and October were 0.13 × 107, 4.09 × 107, 5.33 × 107 and 1.8 × 107 colony forming units (cfu)/g, respectively. Bacterial populations were most abundant in surface layers and declined with increase of soil depth. Seventy-two bacterial strains were isolated and classified according to 27 genera of 5 phyla groups: Firmicutes, Actinobacteria, Alphaproteobacteria, Gammaproteobacteria and Bacteroidates. The bacterial diversities varied according to seasons. In spring, only Firmicutes and Actinobacteria were isolated. In summer, Firmicutes, Actinobacteria and Bacteroidetes were detected with Firmicutes the dominant species. In autumn and winter, Firmicutes, Actinobacteria, α-Proteobacteria and γ-Proteobacteria predominated. Our results indicated that climatic variations, vegetation coverage and soil physicochemical parameters are critical factors for maintaining culturable bacterial populations and diversity in the desert steppe. Soil moisture content and temperature exerted marked influence on bacterial quantities and diversities. 相似文献
993.
剩余活性污泥和厨余垃圾续批式混合中温消化试验研究 总被引:1,自引:0,他引:1
将加碱水解和未水解剩余活性污泥与厨余垃圾混合后进行序批式中温厌氧消化,对生化产甲烷势(BMP)进行了测定.剩余活性污泥的水解通过添加NaOH进行,合理的NaOH投量为40 mmol/L,在25 ℃和35 ℃下经过6 h的水解后SCOD水解率分别提高27.4%和31.1%.厨余垃圾、25℃和35℃下水解污泥的最终甲烷产量分别为607、284、312 mL/g(VS),两种水解污泥比未水解污泥分别高出43%、57.6%,水解污泥和厨余垃圾混合消化的可降解能力要优于未水解污泥和厨余垃圾的混合进料. 相似文献
994.
995.
选取北京市环境电磁辐射自动监测站点2年多的数据,利用SPSS统计软件,对各站点数据进行了主要电磁辐射源、长期数据趋势、各站点时间代表性分析;并结合网格法监测数据,对自动站点空间代表性进行分析。结果表明,5个环境电磁辐射自动站周围主要电磁辐射源均为移动通信基站;其总体电磁辐射水平为0.69~0.97 V/m,低于北京市1 V/m的电磁辐射环境本底水平,且单站点连续12个月的监测数据可以描述该点位电磁辐射平均水平和变化趋势;经分析,连续5年全市网格法电磁辐射射频电场的监测数据总体具有较好的一致性,但单站点的电磁辐射水平不能代表所在行政区的电磁辐射总体水平。提出了电磁辐射自动监测网络建设建议。 相似文献
996.
997.
塞曼石墨炉原子吸收法测定废水中低含量锡 总被引:2,自引:0,他引:2
试验了集恒温平台石墨炉 (STPF)于一体的纵向塞曼效应背景校正 ,最大功率升温 ,钯作为基体改进剂和峰面积积分 (A -s)测定废水中低含量锡的新方法。测定结果表明 ,锡含量在 0 μg/L~ 10 0 μg/L范围内呈良好的线性关系 ,检测限 (3σ) 3 5× 10 -11g ,特征量为 9 1× 10 -11g ,相对标准差小于 6 % ,回收率在 91%~ 10 7%之间 相似文献
998.
999.
Seasonal variation, source, and regional representativeness of the background aerosol from two remote sites in western China 总被引:1,自引:0,他引:1
Wenjun Qu Dan Wang Yaqiang Wang Lifang Sheng Gang Fu 《Environmental monitoring and assessment》2010,167(1-4):265-288
Using observations from two remote sites during July 2004 to March 2005, we show that at Akdala (AKD, 47° 06′ N, 87° 58′ E, 562 m asl) in northern Xinjiang Province, there were high wintertime loadings of organic carbon (OC), elemental carbon (EC), and water-soluble (WS) ${\rm SO}_{4}^{2-}$ , ${\rm NO}_{3}^{2-}$ , and ${\rm NH}_{4}^{+}$ , which is similar to the general pattern in most areas of China and East Asia. However, at Zhuzhang (ZUZ, 28° 00′ N, 99° 43′ E, 3,583 m asl) in northwestern Yunnan Province, the aerosol concentrations and compositions showed little seasonal variation except for a decreasing trend of OC from August to autumn–winter. Additionally, the OC variations dominated the seasonal variation of PM10 (particles ≤10 μm diameter) level. Chemical characteristics combined with transport information suggested sea salt origin of ionic Na?+?, Mg2?+?, and Cl??? at ZUZ. At AKD, ionic Ca2?+?, Mg2?+?, Na?+?, and Cl??? primarily originated from salinized soil. Furthermore, the WS Ca2?+? contributions (5.4–6%) to the PM10 mass during autumn, winter, and early spring reflected a constant dust component. The results of this study indicated that both sites were regionally representative. However, the representative regions and scales of these background sites may vary seasonally as the regional atmospheric transport patterns change. Seasonal variations in the background aerosol levels from these two areas need to be considered when evaluating the regional climate effects of the aerosols. 相似文献
1000.
Effects of temperature parameters on thermal-optical analysis of organic and elemental carbon in aerosol 总被引:1,自引:0,他引:1
Thermal-optical analysis (TOA) is a popular method to determine aerosol elemental carbon (EC) and organic carbon (OC) collected on quartz fiber filter. However, temperature protocol adopted in TOA has great effects on OC and EC results. The purpose of this study is to investigate and quantify the effects of maximum temperature (T(max)) and residence time (RT) for each step in helium stage on ECOC measurements. Fourteen typical source samples and 20 ambient samples were collected and six temperature programs were designed for this study. It was found that EC value decreases regularly as T(max ) ascends, i.e., EC results from T(max) of 650 degrees C, 750 degrees C and 850 degrees C are 0.89 +/- 0.06, 0.76 +/- 0.10, 0.62 +/- 0.13 times EC value from T( max) of 550 degrees C, respectively, and the magnitude of EC drop (EC(d), percent) is significantly correlated with OC abundance in total carbon (R(OC/TC)), expressed as EC(d) = 66.8R(OC/TC)-14.4 (r = 0.87); pyrolized OC(POC) values are also sensitive to T(max), but there are various trends for samples with different OC constituents. On average of the samples studied here, prolonged RT reduces EC values by only 3%, almost negligible compared to the effect of T(max), and reduces POC by 9%, much less than that by previous report. 相似文献