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51.
Michael H. Ramsey Paul D. Taylor Katy A. Boon 《中国地球化学学报》2006,25(B08):209-210
All geochemical measurements require the taking of field samples, but the uncertainty that this process causes is often ignored when assessing the reliability of the interpretation, of the geochemistry or the health implications. Recently devised methods for the estimation, optimisation and reduction of this uncertainty have been evaluated by their application to the investigation of contaminated land. Uncertainty of measurement caused by primary sampling has been estimated for a range of six different contaminated land site investigations, using an increasingly recognized procedure. These site investigations were selected to reflect a wide range of different sizes, contaminants (organic and metals), previous land uses (e.g. tin mining, railway sidings and gas works), intended future use (housing to nature reserves) and routinely applied sampling methods. The results showed that the uncertainty on measurements was substantial, ranging from 25% to 186% of the concentration values at the different sites. Sampling was identified as the dominant source of the uncertainty (〉70% of measurement uncertainty) in most cases. The fitness-for-purpose of the measurements was judged using the optimized contaminated land investigation (OCLI) method. This identifies the optimal level of uncertainty that reduces to overall financial loss caused by the measurement procedures and the misclassification of the contamination, caused by the uncertainty. Generally the uncertainty of the actual measurements made in these different site investigations was found to be sub-optimal, and too large by a factor of approximately two. The uncertainty is usually limited by the sampling, but this can be reduced by increasing the sample mass by a factor of 4 (predicted by sampling theory). It is concluded that knowing the value of the uncertainty enables the interpretation to be made more reliable, and that sampling is the main factor limiting most investigations. This new approach quantifies this problem for the first time, and allows sampling procedures to be critically evaluated, and modified, to improve the reliability of the geochemical assessment. 相似文献
52.
Christina A. Kellogg 《中国地球化学学报》2006,25(B08):218-219
Desert winds aerosolize several billion tons of soil-derived dust each year, including concentrated seasonal pulses from Africa and Asia. Huge dust events create an atmospheric bridge over continents and oceans, and eject a large pulse of soil-associated microorganisms into the atmosphere. These dust events might therefore have a role in expanding the biogeographical range of some microorganisms by facilitating rare long-distance dispersal events. The goal of this study is to characterize the microbes associated with African dust events and determine if they pose a risk to humans or downwind ecosystems. Air samples were collected by vacuum filtration in a source region (Mali, West Africa) during dust events and plated on R2A media to culture microorganisms. These organisms were compared to those in similar samples collected in the Caribbean during Saharan/Sahelian dust events. A high-volume liquid impinger is currently being tested in Barbados, collecting aerosol samples during African dust events. Over 100 bacteria and fungi (19 genera of bacteria and three genera of fungi) have been characterized from source region dust events. 相似文献
53.
54.
Toxic and radioactive elements in soils and vegetation of natural and technogenic geosystems of Pribaikalye (Lake Baikal region) 总被引:1,自引:0,他引:1
《中国地球化学学报》2006,25(B08):245-245
55.
Shaoqi ZHOU Weidong LU 《中国地球化学学报》2006,25(B08):252-253
Mixture of municipal sewage sludge and organic garbage, which was alternatively treated by aerobic and anaerobic composting technologies for 60 days. The characteristics of the compost are as follows: the total nitrogen (TN), total phosphors (TP) and total potassium (TK) are 1.40%, 0.101% and 1908.32 mg/kg on dry weight basis, the contents of Cu, Ni, Cd, Cr, Pb and Zn are 131.23, 21.49, 1.31, 35.49, 72.50 and 616.76 mg/kg on dry weight basis. A basin-scale experiment was carded out by planting watercress with kailyard soil fertilizing with the compost, the results showed that the municipal sewage sludge and organic garbage compost could promote the production of watercress to different degrees, the crop biomass increased from 74.46% to 312.00% with the amount of compost fertilizing on the kaliyard soil while the amount of compost fertilizing on the kaliyard soil below 150 g per 3.75 kg kaliyard soil and decreased from 312.00% to 102.29% while the amount of compost fertilizing on it over 150 g per 3.75 kg kaliyard soil, so the optimal addition of compost in the watercress and soil was 150 g compost per 3.75 kg kailyard soil. Furthermore, 相似文献
56.
从地上、地下有机物质生产对湿地碳输入的贡献,湿地土壤碳库以及土地利用变化对湿地土壤碳库和碳排放的影响,甲烷排放和可溶性有机碳输出以及影响因子,湿地生态系统碳循环动态模型4个方面对湿地生态系统碳循环国内外研究进展和研究成果进行综述、分析,提出了我国亚热带区域天然湿地碳循环研究的主要热点和方向:⑴沿海湿地碳库估算及土地利用转化对土壤碳库和温室气体排放的影响;⑵酸沉降对于我国东南沿海低纬度地区湿地甲烷排放的影响;⑶沿海湿地生态系统碳循环动态模型的应用与开发;⑷湿地系统可溶性有机碳的输出机理探讨. 相似文献
57.
采用密闭室红外气体分析仪法(IRGA法)观测了中亚热带红壤侵蚀裸地植被恢复后不同季节土壤呼吸速率的日动态变化,并比较了IRGA法与碱吸收法(AA法)测定的土壤呼吸速率.结果表明:侵蚀裸地植被恢复后土壤呼吸速率日动态呈单峰曲线,与土壤温度的昼夜变化基本一致,最高值一般出现在午后13∶00~17∶00,最低值出现在凌晨3∶00~7∶00;植被恢复显著提高了土壤日呼吸速率,但明显降低了土壤呼吸速率日变化幅度;马尾松林对土壤呼吸速率日变化幅度降低程度高于板栗园和百喜草地,且对夏季的降低程度影响最大.而IRGA法和AA法测定的土壤呼吸速率具有显著的幂函数关系,AA法测定的土壤呼吸速率为IRGA法的27.5%~218%,平均为76.2%.当土壤呼吸速率较低时,AA法比IRGA法高估了土壤呼吸速率;反之,AA法则低估了土壤呼吸速率. 相似文献
58.
大气CO2浓度升高对土壤中不同粒级碳的影响 总被引:4,自引:0,他引:4
不同粒级土壤中的碳有着不同的周转规律,在高CO2浓度条件下,它们含量的变化将在一定程度上反映土壤碳是累积还是减少,对明确土壤碳的变化趋势有重要意义.采用田间培养试验初步模拟研究在高CO2浓度条件下土壤不同粒级碳的分布.结果表明,加入秸秆培养1年,由于CO2浓度升高的原因导致在低氮(LN)、常规氮(NN)和高氮(HN)水平下土壤中碳分别增加0.01、1.10、1.22g/kg,表现为粒级〈53μm土壤颗粒中碳分别增加1.53、2.19、2.70g/kg.粒级〈53μmm土壤颗粒碳量的增加,主要是由于其重量分配百分数显著增加36.2%,碳浓度增加5.4%;粒级〉250μm和250~53μm土壤颗粒部分虽然其碳浓度分别增加20.8%和17.3%(P〈0.05),怛由于重量分配百分数分别显著降低22.8%和36.1%,结果碳量降低.试验表明高CO2浓度导致不同粒级土壤的分配及碳浓度的变化;高氮施肥水平下有增加土壤碳量特别是小粒级土壤碳量的趋势. 相似文献
59.
60.
环境样品中痕量元素的化学形态分析Ⅱ.砷汞镉锡铅硒铬的形态分析 总被引:2,自引:6,他引:2
环境中元素的生物有效性和毒性依赖于其存在的化学形态。文章依据文献的有关报道介绍砷、汞、镉、锡、铅、硒和铬在环境中的分布、毒性及它们在环境样品如水、土壤、沉积物和生物体中的形态分析方法,包括分析物的保存、提取、分离和检测。引用文献120篇。 相似文献