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181.
根据2008年3~11月逐月对青木关北段地下河水质的监测,以及2010年6~11月逐月对青木关南段地下河水质的监测,利用15N同位素技术并结合水化学指标,分析地下河的水化学特征以及硝酸盐来源的时空变化特征。结果表明:在北段和南段地下河出口硝酸盐平均浓度分别为2035 mg/L和5077 mg/L,入口分别为320 mg/L和0842 mg/L,两段的硝酸盐平均浓度在出口处均比入口处高6倍多。此外,通过分析青木关整个地下河流域的SymboldA@15N空间分布情况,可以得出:南段地下河水中NO-3 δ15N值较高,且变化显著,最高值37825‰出现在9月21日丁家龙洞取样点,其硝酸盐来源可能是粪便和污水;而北段地下河水中NO-3 δ15N值都比较低,变化幅度较小,均未超过10‰,说明北段地下河水中硝酸盐的主要来源是土壤有机氮或农业氮肥 相似文献
182.
采用浸渍法制备了Pd/SBA-15催化剂,并考察了PVP辅助分散对Pd/SBA-15催化剂催化甲苯燃烧性能的影响,利用XRD、Raman、N2吸附-脱附、HRTEM和XPS对催化剂结构及Pd物种的存在状态等进行了研究。结果表明,适量PVP辅助分散剂的加入,促进了Pd物种的分散并形成了稳定的活性物种,Pd物种主要以高度分散的PdO纳米粒子存在。通过PVP辅助分散作用,Pd/SBA-15催化剂表现出极好的甲苯催化燃烧活性。当空速为19 500 mL·(g?h)-1,反应温度为200 °С时,即有97%的甲苯可被催化氧化为CO2和H2O,明显优于传统浸渍法制备的Pd/SBA-15催化剂催化性能。 相似文献
183.
Nitrogen Subsidies from Hillslope Alder Stands to Streamside Wetlands and Headwater Streams,Kenai Peninsula,Alaska
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Michael K. Callahan Dennis F. Whigham Mark C. Rains Kai C. Rains Ryan S. King Coowe M. Walker Jasmine R. Maurer Steven J. Baird 《Journal of the American Water Resources Association》2017,53(2):478-492
We examined nitrogen transport and wetland primary production along hydrologic flow paths that link nitrogen‐fixing alder (Alnus spp.) stands to downslope wetlands and streams in the Kenai Lowlands, Alaska. We expected that nitrate concentrations in surface water and groundwater would be higher on flow paths below alder. We further expected that nitrate concentrations would be higher in surface water and groundwater at the base of short flow paths with alder and that streamside wetlands at the base of alder‐near flow paths would be less nitrogen limited than wetlands at the base of long flow paths with alder. Our results showed that groundwater nitrate‐N concentrations were significantly higher at alder‐near sites than at no‐alder sites, but did not differ significantly between alder‐far sites and no‐alder sites or between alder‐far sites and alder‐near sites. A survey of 15N stable isotope signatures in soils and foliage in alder‐near and no‐alder flow paths indicated the alder‐derived nitrogen evident in soils below alder is quickly integrated downslope. Additionally, there was a significant difference in the relative increase in plant biomass after nitrogen fertilization, with the greatest increase occurring in the no‐alder sites. This study demonstrates that streamside wetlands and streams are connected to the surrounding landscapes through hydrologic flow paths, and flow paths with alder stands are potential “hot spots” for nitrogen subsidies at the hillslope scale. 相似文献
184.
以介孔硅基分子筛SBA-15为载体,采用溶胶-凝胶法在SBA-15分子筛表面包覆TiO_2。制备了不同TiO_2含量的链状二维六方形介孔复合材料。采用电子显微镜扫描仪、X射线衍射仪、傅立叶红外光谱、紫外-固体漫反射等技术对复合材料进行表征。SEM结果表明样品具有良好的包覆效果,UV-Vis光谱结果表明样品具有较好的光吸收能力。XRD结果表明复合材料表面包覆的TiO_2为锐钛矿和金红石的混合晶型,随载体用量的增加TiO_2的粒径逐渐减小。以光催化降解亚甲基蓝为目标,研究复合材料在煅烧温度、载体用量、底物溶液初始浓度等影响因素下的光催化效果。考察复合材料的再生光催化活性。研究表明:介孔TiO_2复合材料相比于市售P-25有较高的光催化活性。复合材料可进行回收利用,并且其介孔结构牢固不易崩塌。 相似文献
185.
C_8-SBA-15新型介孔涂层SPME-HPLC联用测定水样中的芘 总被引:1,自引:0,他引:1
以辛基键合SBA-15为固相微萃取(SPME)的吸附涂层,考察了吸附和解吸时间、萃取温度、搅拌速率对SPME效率的影响。该方法的线性范围为3.0—320μg/L,检出限为0.5μg/L,依据此方法测定了环境水样中芘,具有灵敏度高和精密度好的特点。 相似文献
186.
We report an anencephalic fetus with acrania, cervicodorsal rachischisis, and a 46,X,del(X)(p22·1) karyotype. Necropsy revealed a left diaphragmatic hernia, ipsilateral lung hypoplasia, and intestinal malrotation. The fetus also had horseshoe kidneys and adrenal gland hypoplasia with absence of the fetal zone. 相似文献
187.
Jonathan P. Park John B. Moeschler Eileen Rawnsley Susan Z. Berg Doris H. Wurster-Hill 《黑龙江环境通报》1989,9(7):501-504
Prenatal diagnosis of trisomy 20 mosaicism in this case was based on cytogenetic analysis of cultured amniotic fluid cells (23/52 cells were trisomy 20 representing cells from each of four primary cultures). The pregnancy continued to term and the mosaicism was confirmed in the phenotypically normal male neonate by analysis of cultured foreskin fibroblasts (7/49 cells + 20) and placental cells 20/20 cells + 20) whereas the peripheral lymphocytes were cytogenetically normal (20/20 cells were 46,XY). This represents the first confirmation of trisomy 20 mosaicism in a phenotypically normal full-term neonate. 相似文献
188.
Chromosomal aberrations and DNA damage in human populations exposed to the processing of electronics waste 总被引:1,自引:0,他引:1
Qiang Liu Jia Cao Ke Qiu Li Xu Hong Miao Guang Li Fei Yue Fan Yong Cheng Zhao 《Environmental science and pollution research international》2009,16(3):329-338
Background, aim, and scope It has been known that the pollutants of electronic wastes (E-wastes) can lead to severe pollution to the environment. It
has been reported that about 50% to 80% of E-wastes from developed countries are exported to Asia and Africa. It has become
a major global environmental problem to deal with ‘E-wastes’. E-waste recycling has remained primitive in Jinghai, China.
This not only produces enormous environmental pollution but also can bring about toxic or genotoxic effects on the human body,
threatening the health of both current residents and future generations living in the local environment. The concentration
of lead in the blood of children in the E-waste polluted area in China is higher than that of the control area. But little
is known about the cytogenetic effect to human beings caused by the pollution of E-wastes. In the present study, experiments
have been performed to investigate the genetics of permanent residents of three villages with numerous E-waste disposal sites
and to analyze the harmful effects of exposure to E-wastes.
Materials and methods In total, 171 villagers (exposed group) were randomly selected from permanent residents of three villages located in Jinghai
County of Tianjin, China, where there has been massive disposal of E-wastes. Thirty villagers were selected from the neighboring
towns without E-waste disposal sites to serve as controls. Chromosomal aberrations and cytokinesis blocking micronucleus were
performed to detect the cytogenetic effect, dic + r (dicentric and ring chromosome), monomer, fragments (acentric fragments,
minute chromosomes, and acentric rings), translocation, satellite, quadriradial, total aberrations, and micronuclear rate
were scored for each subject. DNA damage was detected using comet assay; the DNA percentage in the comet tail (TDNA%), tail
moment (TM), and Olive tail moment (OTM) were recorded to describe DNA damage to lymphocytes.
Results The total chromosome aberration rates (5.50%) and micronuclear rates (16.99%) of the exposure group were significantly higher
than in the control group (P = 0.000). The percentage of DNA in the comet tail, tail moment, and Olive tail moment detected by comet assay showed that
there was a significant difference in DNA damage in the exposure group (P = 0.000). The chromosome aberration, micronucleus rate, and DNA damage observed in women were significantly higher than those
in men. Chromosome aberration and micronuclear rates of both smokers and non-smokers in the exposure group are obviously higher
than that in the control group (P = 0.000).
Discussion The use of outdated (and unsafe) ways to deal with E-wastes can lead to exposure to a variety of substances harmful to human
health. The components of pollution may enter the human body through the air, drinking water, and food chain to damage human
genetic material, resulting in genomic instability. The rates of chromosomal aberration, micronucleus formation, and the degree
of DNA damage in women in the group exposed to electronic waste were significantly higher than in men. The reason for this
may be concerned with the traditional lifestyle of the local residents or the difference of sensitivity to the exposure to
E-wastes or any others. Further investigations are needed to provide evidence to demonstrate this.
Conclusions Here, we report the obviously cytogenetic toxicity to the exposure population by the E-waste pollution for the first time.
E-waste pollution may be a potential agent of genetic mutation, and may induce cytogenetic damage within the general population
exposed to the pollution. These findings need to be considered, and steps should be taken to protect the current population
and future generations from the effects of pollution with E-wastes.
Recommendations and perspectives The above results remind us that the impact of E-waste recycling on environmental quality of Jinghai should be evaluated soon.
Moreover, it is urgent for the government to prohibit E-waste import and its processing by outdated ways. The future studies
such as pollutant details of drinking water, air, and soil in the area as well as epidemiological investigations on the harmful
effect to children must be performed eagerly. All the data available do provide a compelling case for immediate action in
both countries to address workplace health and safety and waste management.
Qiang Liu and Jia Cao contributed equally to this study and share the first authorship. 相似文献
189.
The emergence of Corporate Social Responsibility (CSR) in the extractive industries represents a bid to legitimize the sector after decades of environmental disasters and the trampling of indigenous rights. But whilst the rise in CSR has meant safer technologies and better stakeholder engagement, there is little evidence of any real socio-economic development at the grassroots. This paper examines the uneasy relationship existing between the strategic ‘business model’ of CSR and the brand of development it delivers. Using evidence from two multinational extractive industries in Papua New Guinea, we show how weaknesses in CSR practice come from greater emphasis on meeting global ‘performance standards’ than on the specificities of the social contexts in which strategies are implemented. These weaknesses, we argue, lead to ill-conceived and inappropriate development programmes that generate inequality, fragmentation, and social and economic insecurity. We conclude that greater engagement with affected communities will facilitate the development of more mutually beneficial and appropriate CSR strategies. 相似文献
190.
合成了以N-甲基咪唑为配体,Cu为活性中心的络合金属多相催化剂Cu(Ⅰ)-NHC-SBA-15.通过1H-NMR、13C-NMR、有机元素分析和FTIR对各步合成反应产物结构经行了鉴定;用SEM、N2吸附脱附等方法对催化剂进行了表征;用ICP测定了催化剂Cu含量.对催化剂催化2,4-二甲氧基溴苯还原脱溴活性进行了测试.在反应时间为24 h,通过正交实验和单因素实验,考察了催化剂用量、反应温度、还原剂用量等因素对脱溴率的影响,并确定了最佳反应条件:催化剂用量为0.05 g、水合肼用量为2 mL、反应温度为80℃,脱溴效果较好,脱溴率达到98.5%.对催化剂重复使用进行了初步研究.对催化反应动力学进行了初步研究,结果表明,该多相催化反应是由表面反应速度控制,并符合一级动力学反应.对反应机理进行了初步探讨. 相似文献