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941.
介绍了1μmol/mol氮气中5种氯代烯气体标准样品的研制方法。这5种氯代烯包括氯乙烯、1,1-二氯乙烯、顺1,2-二氯乙烯、三氯乙烯、四氯乙烯,其中氯乙烯常温下为气态,其他4种为液态,并且沸点低,将这几种氯代烯制备成气体标准样品存在制备精度低、气液转换不完全等困难。经研究,采用2步称量法制备5种氯代烯气体标准样品,重复制备的相对标准偏差小于1.6%。建立了5种氯代烯标准气体瓶内均匀性的实验方法,并通过考察样品量值伴随样品压力的变化来评价样品的均匀性。结果显示,5种氯代烯标准气体是均匀的,最低使用压力为1 MPa。依照ISO 15000.3来考察样品的时间稳定性,样品有效期为12个月。相对扩展不确定度为3%(置信度为95%)。 相似文献
942.
京津冀典型城市采暖季颗粒物浓度与元素分布特征 总被引:5,自引:4,他引:1
选择京津冀地区3个典型城市和从南至北的4个国家大气背景站作为研究对象,收集采暖季空气颗粒物PM2.5、PM10样品,微波消解-ICP-MS法分析了样品中的68种元素。结果表明,北京、天津、石家庄PM2.5和PM10日均质量浓度均高于国家二级标准限值和背景点,一元线性回归分析结果表明,PM10与PM2.5质量浓度呈线性相关,Na、Mg、Al、S、K、Ca、Fe质量浓度为0.1~10μg/m3,Si、P、Ti、Mn、Ni、Cu、Zn、Ba、Pb质量浓度为10~100 ng/m3,其他元素质量浓度为0.01~10 ng/m3或未检出。在元素构成上,S、Na、Al、K、Fe、Mg、Ca、P、Si等是主要元素,元素含量均大于1%。其他微量元素每种元素含量为0.1%~1%。14种重点防控重金属在PM2.5中的吸附显著高于PM10,主要来源于燃煤、燃油、工业排放、机动车尾气等。 相似文献
943.
通过研究各仪器性能指标以及测定实际水质样品,对3种便携式分光光度计快速测定水中砷的方法进行了优化和比对研究。结果表明,ZZW-Ⅱ测试仪快速测定水中砷的方法检出限(0.2 mg/L)高于JH 916检测仪和PORS-15 V光谱仪的方法检出限(0.008和0.009 mg/L),在突发性环境污染事故应急监测中,JH 916检测仪和PORS-15 V光谱仪具有相对较高的灵敏度。ZZW-Ⅱ测试仪和JH 916检测仪快速测定水中砷的方法精密度相近,其测定结果相对标准偏差均未超过5.7%(n=6),PORS-15 V光谱仪快速测定水中砷的方法精密度稍差,其相对标准偏差最大值为17%。测定实际样品时,加标回收率分别为110%~126%(ZZW-Ⅱ测试仪),63%~108%(PORS-15 V光谱仪),78%~101%(JH 916检测仪)。3种便携式分光光度计与实验室分析方法相比,测定结果精密度均存在显著性差异,测定结果相对偏差亦较大,相对偏差最大值分别为-19.0%(ZZW-Ⅱ测试仪),17.0%(PORS-15 V光谱仪),-15.0%(JH 916检测仪)。 相似文献
944.
An enzyme-limited immunosorbent assay (ELISA) was used to monitor spatial and temporal variation of microcystins (MCs) in Lake Taihu. MC concentrations were higher in summer and autumn than in other seasons. Maximal MC concentration was 15.6 mug L(-1). Compared to central Lake Taihu and Wuli Bay, Meiliang Bay had higher MC concentrations due to high biomass of Microcystis. 相似文献
945.
ICP-MS法同时测定地表水中18种金属元素 总被引:4,自引:1,他引:3
以115In-103Rh为双内标校正系统,采用电感耦合等离子体质谱法同时测定地表水中铜、锌、硒、砷、汞、镉、铅、铁、锰、钼、钴、铍、锑、镍、钡、钒、钛、铊等18种金属元素,优化了测量同位素、内标元素等试验条件。18种金属元素在0μg/L~100μg/L范围内线性良好,检出限为0.006μg/L~0.123μg/L,标准样品的测定值均在保证值范围内,平行测定的RSD为1.7%~4.2%,实际水样加标回收率为89.0%~100%。 相似文献
946.
947.
Both the net primary productivity (NPP) and the normalized difference vegetation index (NDVI) are commonly used as indicators
to characterize vegetation vigor, and NDVI has been used as a surrogate estimator of NPP in some cases. To evaluate the reliability
of such surrogation, here we examined the quantitative difference between NPP and NDVI in their outcomes of vegetation vigor
assessment at a landscape scale. Using Landsat ETM+ data and a process model, the Boreal Ecosystem Productivity Simulator,
NPP distribution was mapped at a resolution of 90 m, and total NDVI during the growing season was calculated in Heihe River
Basin, Northwest China in 2002. The results from a comparison between the NPP and NDVI classification maps show that there
existed a substantial difference in terms of both area and spatial distribution between the assessment outcomes of these two
indicators, despite that they are strongly correlated. The degree of difference can be influenced by assessment schemes, as
well as the type of vegetation and ecozone. Overall, NDVI is not a good surrogate of NPP as the indicators of vegetation vigor
assessment in the study area. Nonetheless, NDVI could serve as a fairish surrogate indicator under the condition that the
target region has low vegetation cover and the assessment has relatively coarse classification schemes (i.e., the class number
is small). It is suggested that the use of NPP and NDVI should be carefully selected in landscape assessment. Their differences
need to be further evaluated across geographic areas and biomes. 相似文献
948.
Impact of socioeconomic development on ecosystem services and its conservation strategies: a case study of Shandong Province,China 总被引:1,自引:0,他引:1
Ecosystems and their components provide a lot of benefits for the welfare of human beings. Coupled with increasing socioeconomic
development, most of the rapidly developing and transitional countries and regions have been experiencing dramatic land use
changes. This has resulted in a large amount of forestland, grassland, and wetland being occupied as residential and industrial
land or reclaimed for arable land, which in turn results in a sharp deterioration of ecosystem services around the world.
Shandong Province, an economically powerful province of China, was chosen as a case study in order to capture the impact of
socioeconomic development on ecosystem services. By way of the study, land uses and their changes were categorized between
1980 and 2006, and the ecosystem services capital and changes of 111 counties of Shandong Province in different phases were
evaluated, as well as the total ecosystem services capital, followed by the zoning of ecosystem services function region of
Shandong Province. We found that the counties in mountainous areas and wetlands, where generally the prefectural-level cities
are located with a rapid socioeconomic development, experienced a successive deterioration of ecosystem services especially
during the 2000s. Finally, three conservation strategies for managing and improving ecosystem services were proposed and discussed
with the aim of achieving coordinate and sustainable development of the socioeconomy, environment, and ecosystems not only
in Shandong Province but also in other provinces of China, as well as in other developing and transitional countries and regions. 相似文献
949.
950.
成都府南河叶绿素a和氮、磷的分布特征与富营养化研究 总被引:3,自引:2,他引:1
通过对成都市府南河上中下游共21个断面叶绿素a和总溶解态氮(TDN)、总溶解态磷(TDP)含量的测定,绘制时空分布图,并应用SPSS 13.0统计软件分析了3个指标之间的相关性,初步评价了府南河的富营养化状况。结果表明,府南河叶绿素a含量不高,磷污染较为严重;相关性分析显示叶绿素a和TDP含量呈显著正相关关系,氮是河水富营养化的主要限制因子;按照叶绿素a的含量判定府南河基本属于贫营养化型,但按照氮、磷含量评价已达到富营养化水平。这对评价城市河流的富营养化状态及生态环境整治和恢复有着积极意义。 相似文献