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Lead analysis of sediment cores from seven Connecticut lakes 总被引：2，自引：0，他引：2
Lead analyses were performed on sediment cores from seven Connecticut lakes by dilute acid leaching. The absolute concentrations of lead varied from core to core, but the lead profiles were similar in all of the cores, and each depicted a point where the concentration of lead sharply increased above background levels. The background lead concentrations observed in the bottom portions of the cores ranged from 12-54 g Pb/g sediment with a mean of 30 g Pb/g, and increased to a mean maximum of 310 g Pb/g. In six of the lakes significant increases above background levels were not noted until between 1924 and 1952, suggesting that, at least for Connecticut lakes, the point in a lake sediment core where the concentration of lead began to increase was after ca. 1924, and on average about 1930. Lead concentrations declined in the surface sediments of only three of the lakes, mostly since the 1980's, and presumably in response to the phasing out of leaded gasoline. However, significant declines in lead concentrations were not observed in the remaining cores, possibly due to increased motor vehicle use within the airshed of the lakes and/or changes in the export of lead to the lakes from their watersheds. 相似文献
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《The Professional geographer》2013,65(3):331-341
This study analyzes the extent and pattern of lead contamination along roadways in Trujillo, Venezuela, using traffic counts and soil samples collected in the field. The normalized mean lead level for frontyard samples along major traffic arteries was 200 μgg -1 versus 0 μgg-1 for backyard samples. Furthermore 55%of the frontyard lead levels were hazardous, versus 7% of the backyard samples. This suggests a strong relationship between traffic and soil lead content. However, a relationship between lead level spatial patterns and traffic volume patterns was not established, suggesting that factors beyond traffic volume, such as slope and erosion, play a significant role in contamination patterns. 相似文献
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This study analyzes the extent and pattern of lead contamination along roadways in Trujillo, Venezuela, using traffic counts and soil samples collected in the field. The normalized mean lead level for frontyard samples along major traffic arteries was 200 μgg -1 versus 0 μgg-1 for backyard samples. Furthermore 55%of the frontyard lead levels were hazardous, versus 7% of the backyard samples. This suggests a strong relationship between traffic and soil lead content. However, a relationship between lead level spatial patterns and traffic volume patterns was not established, suggesting that factors beyond traffic volume, such as slope and erosion, play a significant role in contamination patterns. 相似文献
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重金属铅和镉对溪荪生理特性的影响 总被引：2，自引：0，他引：2
采用水培法,研究重金属铅和镉及其复合胁迫对溪荪(Iris sanguine)生理特性的影响。结果表明,在500mg/L铅和500mg/L铅+25 mg/L镉复合胁迫下,溪荪的叶绿素a、叶绿素b和类胡萝卜素含量增加,其中,叶绿素a含量增加显著(p<0.05);在25 mg/L镉胁迫下,溪荪的叶绿素a、叶绿素b和类胡萝卜素含量均减少,其中叶绿素a含量减少显著(p<0.05);25 mg/L镉胁迫增大了溪荪地上部分细胞膜的透性,比对照升高了27%,并使丙二醛含量增加到对照的1.19倍;在500mg/L铅胁迫下,丙二醛含量有所上升,但与对照相比差异不显著,说明在该实验浓度下,溪荪对铅的耐性比对镉的耐性强;在500mg/L铅+25 mg/L镉复合胁迫下,无论溪荪地上部分(叶片)还是地下部分(根茎和根)的丙二醛含量都明显增加,说明复合胁迫给溪荪细胞膜带来很大的伤害;铅和镉胁迫对溪荪过氧化物酶(POD)和超氧化物歧化酶(SOD)活性的影响相似,所有污染处理都对溪荪的地下部分酶活性起明显的促进作用,而对溪荪地上部分的酶活性有明显抑制作用。过氧化物酶和超氧化物歧化酶活性在溪荪耐铅和镉胁迫中起到了非常重要的作用。 相似文献
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北京市不同土地利用方式下土壤铅的积累 总被引：65，自引：3，他引：62
通过对北京市菜地、稻田、果园、绿化地、麦地以及自然土壤等土地利用类型600个土壤的监测分析,探讨了不同土地利用方式对土壤铅积累的影响。研究结果表明,全部土壤样品中铅浓度的几何平均值为26.6 mg/kg,显著高于北京市土壤背景值 (24.6 mg/kg),呈现出明显的积累趋势。不同土地利用方式对土壤铅积累有明显影响,其中绿化地土壤的平均铅浓度最高,依次为果园、菜地、稻田、自然土壤,麦地平均铅浓度最低,绿化地土壤的铅浓度要显著高于除果园外的其他土地利用类型。果园土壤的铅浓度同样与其他大多数土地利用类型的土壤有较显著的差别。以基线值为标准,除自然土壤外,其他5种土地利用类型下均有不同程度的样品超标：果园超标率最高 (21.4%),其他分别为绿化地18.2%,菜地11.1%,稻田8.3%,麦地5.2%;样品总体的超标率为7.2%。从行政区域来看,城区土壤的铅浓度高于近郊区,近郊区要明显高于远郊区土壤,超标样点主要分布在昌平、朝阳、大兴、丰台、海淀、石景山区等城区或近郊区,因而土壤铅浓度有从城市中心区向外逐渐降低的趋势。在本研究中,大气沉降、垃圾填埋以及农药施用等人类活动可能是影响不同土地利用类型下土壤铅积累浓度的重要原因。 相似文献
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北京城市公园土壤铅含量及其污染评价 总被引：54，自引：5，他引：49
通过对北京市市区 30个典型公园的土壤取样调查 ,测定了表层土壤中铅的含量 ,并以欧盟“土壤环境质量建议标准”对污染状况进行了评价。结果表明 ,北京市区已有部分公园存在铅污染问题 ,其表土的铅含量平均值为 66 2mg/kg ,变幅为 2 5～ 2 0 7mg/kg,污染指数为0 5～4 1。用增长曲线拟合的结果表明 ,土壤铅含量随着公园建园时间的延长呈不断增加的趋势 ,尤其是近几十年来土壤铅含量的增加较快。历史悠久且距离市中心较近的公园土壤铅含量明显偏高 ;对于大多数开放历史较短且相对偏僻的公园而言 ,表土一般都未见明显的铅污染。 相似文献
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N.A. Onishchuk T.V. Khodzher E.P. Chebykin E.V. Chipanina 《Geography and Natural Resources》2009,30(4):345-349
Presented are the results from investigating the lead isotopic composition in atmospheric precipitation in the Baikal region and Primorski Krai. It is established that at three stations of the Baikal region, differing in their physical-geographical location and in the degree of anthropogenic influence, the isotopic ratios are similar to those for lead ores of Kazakhstan, the main supplier of lead to Russia. Atmospheric precipitation in Primorski Krai is intermittently influenced by the trans-boundary transport of atmospheric impurities from industrial areas of China. 相似文献
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Estimates of the number of undiscovered deposits on a statewide basis offer a different perspective on the nation's undiscovered resources of gold, silver, copper, lead, and zinc. Mean estimates of the number of undiscovered deposits statewide were extracted from the estimates of undiscovered deposits nationwide. More than 50 undiscovered deposits are estimated to occur in Alaska, Arizona, Nevada, and Wisconsin. Estimating the number of undiscovered deposits statewide serves as a measure of a state's total remaining mineral resources in known conventional deposit types. 相似文献
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Jason C. Senkbeil David A. Scott Pilar Guinazu-Walker Meganne S. Rockman 《The Professional geographer》2013,65(4):610-620
The 27 April 2011 EF4 Tuscaloosa tornado directly impacted more than 50,000 residents, causing forty-five fatalities within the city and sixty-five in total. It was a rare urban tornado with varying impacts on the three major ethnic and racial groups within the city. A hybrid survey and interview of open-ended and closed questions was conducted with 211 Tuscaloosa area residents in a two-week period after the tornado. Results indicate significant differences in risk perception, preparedness, and shelter lead time among the three ethnic and racial groups. Furthermore, results were still significant for perception after controlling for the effects of age, education, and experience. 相似文献
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从矿区土壤分离得到的罗尔斯通菌(Ralstonia Bcul-1)对重金属离子具有广谱抗性,可在重金属铅含量为87.35 mg·kg-1的酸性土壤生长(pH 5.62).低浓度Pb2+可诱导部分重金属抗性基因表达,但高浓度Pb2+(>15 mg·L-1)则抑制这些基因的表达.在Pb2+胁迫下,一些蛋白质的表达同样受到诱... 相似文献
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通过水培方法,研究了铅(Pn)和锌(Zn)及其复合胁迫对花菖蒲(Iris ensata)幼苗生长与生理指标的影响.将花菖蒲栽植于300 mL培养瓶中,以1/2 Hoagland营养液培养7d,在0.5 mmol/L Pb+l mmol/L Pb处理下,花菖蒲幼苗地上部干重与对照组相比差异显著;其他处理与对照处理相比差异不显著;在所有Pb和Zn及其复合胁迫处理下,花菖蒲地下部干重与对照处理相比没有显著差异.除了在1 mmol/L Zn处理下,花菖蒲光合色素含量与对照处理相比没有显著差异之外,其他处理的光合色素含量都比对照处理有所减少.高浓度Pb和Pb+Zn的复合胁迫对花菖蒲幼苗地上部的过氧化物酶活性诱导能力很强,在0.5 mmol/LPb+1 mmol/LZn复合胁迫下,花菖蒲幼苗地上部的过氧化物酶活性最高,比对照处理高81.8％;而其超氧物歧化酶活性在高浓度Pb和Zn处理下受到一定抑制;在0.5 mmol/LZn胁迫下,花菖蒲地上部超氧物歧化酶活性最高,是对照处理的1.1倍.除单因子Zn处理外,花菖蒲植株地上部丙二醛的含量与对照处理相比都显著上升.研究结果说明,过氧化物酶在花菖蒲抗单因子Pb和Zn及其复合胁迫中起到了非常重要的作用,花菖蒲对Pb和Zn具有较强的耐受性,可以用于修复Pb和Zn及其复合污染的环境. 相似文献
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中国北方沙尘源区铅同位素分布特征及其示踪意义的初步研究 总被引：4，自引：1，他引：3
对中国北方沙尘源区风成沙Pb同位素的分布特征以及示踪意义进行了初步研究。结果表明,中国北方沙尘源区风成沙Pb同位素的空间分布具有明显的区域差异,毛乌素沙地具有最低的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb值,塔克拉玛干沙漠具有最大的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb值,其他地区介于两者之间。通过对比研究,Pb同位素在中国北方黄土、格陵兰冰芯粉尘和北太平洋深海沉积物源区示踪方面具有较好的有效性。 相似文献
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采用液体培养法,研究了铅(Pb)和镉(Cd)及其复合胁迫对黄菖蒲(Iris pseudacorus)幼苗生长及生理的响应。将黄菖蒲幼苗培养于250mL培养瓶中,以1/2Hoagland营养液预培养7d后,然后进行500mg/LPb、25mg/LCd和500mg/LPb+25mg/LCd复合胁迫处理,28d后测定幼苗的各项生长及生理指标。结果表明,在500mg/LPb和25mg/LCd+500mg/LPb胁迫下,黄菖蒲幼苗地上部和地下部干重与对照相比都显著下降,所有处理的地下部干重与对照处理相比都显著下降;在所有处理下,幼苗的叶绿素a含量都下降;在500mg/LPb和25mg/LCd+500mg/LPb处理下,幼苗的叶绿素b和胡萝卜素含量下降都不显著;在500mg/LPb和25mg/LCd+500mg/LPb处理下,幼苗根和叶中的丙二醛(MDA)含量、脯氨酸(Pro)含量和过氧化物酶(POD)活性都增加,但是在25mg/LCd处理下,幼苗根和叶中的POD活性和叶中的MDA含量都显著减少。Pb和Cd可以有效诱导黄菖蒲幼苗Pro的合成,能提高黄菖蒲幼苗的抗性。 相似文献
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Estimates of the number of undiscovered deposits offer a unique perspective on the nation's undiscovered mineral resources. As part of the 1998 assessment of undiscovered deposits of gold, silver, copper, lead, and zinc, estimates of the number of deposits were made for 305 of the 447 permissive tracts delineated in 19 assessment regions of the country. By aggregating number of undiscovered deposits by deposit type and by assessment region, a picture of the nation's undiscovered resources has emerged. For the nation as a whole, the mean estimate for the number of undiscovered deposits is 950. There is a 90% chance there are at least 747 undiscovered deposits and a 10% chance there are as many as 1,160 undiscovered deposits. For Alaska, the mean estimate for the number of undiscovered deposits is 281. There is a 90% chance there are at least 168 undiscovered deposits and a 10% chance there are as many as 402 undiscovered deposits. Assuming that the majority of deposits used to create the grade and tonnage models that formed the basis for estimating the number of undiscovered deposits are significant deposits, there remain about as many undiscovered deposits as have already been discovered. Consideration of the number of undiscovered deposits as part of national assessments carried out on a recurring basis serves as a leading indicator of the nation's total mineral resources. 相似文献
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选择长白山地区2种不同类型的泥炭沼泽,进行了典型剖面的大气铅沉降研究。植物残体和泥炭性质表明老白山泥炭地已经发育到贫营养阶段,而大桥泥炭地还处于富营养状态。两地泥炭记录的总铅含量和沉降速率与中国其他地区在同一个数量级上。老白山泥炭记录的大气铅在总铅中占主导地位,大气铅与富集因子呈明显的正相关（r=0.874,n=16,p<0.01）,且在16世纪中叶、18世纪初和20世纪出现峰值。大桥泥炭记录的铅可能存在再迁移和再沉降现象,但是相对较弱,因此,它也可以被用来重建当时的大气沉降。 相似文献