基于137Cs的苏南丘陵区的土壤侵蚀和土壤养分研究

土壤侵蚀是中国最严重的环境问题之一,给生态和人类发展带来极大的影响。137Cs在土壤中的再分配和侵蚀小区土壤的运移之间紧密相关,用它做示踪剂可推算出土壤侵蚀的速率和空间分布,以及研究土壤侵蚀的空间变化和土壤迁移的空间分配。采用137Cs示踪技术对铜山地区的土壤侵蚀进行了研究,并进一步探讨了土壤侵蚀对土壤养分造成的影响。研究区137Cs的背景值为1 732.48 Bq/m2,随着土壤深度的增大,137Cs质量浓度呈对数下降的趋势。该研究区137Cs含量的范围是787.62~2 380.96 Bq/m2,土壤沉积和土壤侵蚀同时发生在研究区内,林地中137Cs含量最高,其次是竹林和茶园。TN、TP和SOC在不同用地类型中的分布也有差异。SOC与137Cs呈极显著的线性正相关,而137Cs与TN、TP之间相关性不显著。侵蚀运动对于土壤表层的影响最为显著,与背景区相比,侵蚀区和沉积区土壤表层（0~5 cm）的137Cs和SOC都有明显的损失,分别达到了31％、17％和45％、29％。研究结果表明：①林地抵抗土壤侵蚀的能力相较于茶园和竹林更强;②土壤侵蚀过程中土壤再分配对SOC、TN和TP的分布都会产生不同程度的影响,其中对于SOC的影响最强烈;③土壤侵蚀对于土壤表层的影响最为显著,土壤上层通常是养分最为集中的地方,因此土壤侵蚀造成的土壤养分的流失以及富集养分的径流污染下游河流,引起很多农业环境问题都值得被关注。     

水稻对~(137)Cs的叶面吸收

水稻不同生育期污染主茎单个叶片结果表明,１３７Ｃｓ向植株未污染部位的转移与污染叶的叶位有关,植株中的１３７Ｃｓ主要分布在茎叶中。受污染的水稻各部位１３７Ｃｓ积累量与污染量呈线性正相关,植株各未污染部位１３７Ｃｓ比活度大小顺序为叶＞茎＞根＞穗。     

经济林营建后基于~(137)Cs示踪法的土壤侵蚀特征研究

土壤侵蚀问题一直是备受关注的热点问题,为了深入探究土壤侵蚀与土壤理化性质的相关性,利用~(137)Cs核示踪技术,在赣榆区针阔混交林以及由针阔混交林改造而成的山楂林、苹果林和板栗林四种林分进行采样分析,对该地区的土壤侵蚀特征进行定量评价。结果表明:①针阔混交林土壤~(137)Cs含量为546. 92Bq/m~2,经济林营造降低了土壤~(137)Cs含量。针阔混交林土壤年均流失厚度为0.79 mm,苹果林、山楂林和板栗林的土壤年平均流失厚度分别是针阔混交林的2.92倍、2.33倍和1.10倍。②研究区的土壤~(137)Cs与土壤全氮和土壤有机碳呈极显著正相关(P0.01),与土壤碳氮比呈显著正相关(P0.05),与其他土壤理化性质无显著相关关系。土壤~(137)Cs与粒径0.25 mm、0.25～0.5 mm及0.5～1 mm团聚体有机碳含量呈极显著正相关(P0.01),与粒径1 mm团聚体有机碳含量呈显著正相关(P0.05)。经济林营造使得土地利用方式改变在影响土壤侵蚀量的同时,也在影响不同土地利用方式的土壤部分养分指标和团聚体有机碳。     

利用137Cs示踪技术对土壤侵蚀的研究

统计了1985年-2009年3月利用137Cs示踪技术研究土壤侵蚀的国内现有电子资料,并对当前的研究文献做了归纳分析,从背景值、模型、土壤侵蚀的空间变异规律及影响因子等方面阐述了137Cs的研究现状,基于此,对其研究前景进行了展望。     

137Cs和210Pbex示踪江西红壤区耕作土壤侵蚀速率的研究

[目的]准确估算江西红壤区土壤侵蚀模数,为该区土壤侵蚀状况评估和水土流失防治提供数据支持。[方法]选择江西省鹰潭市余江县中国科学院红壤试验基地的一个小流域作为研究区,运用137Cs与210Pbex示踪技术计算耕作土壤侵速率。[结果]江西红壤区137Cs与210Pbex的背景值分别为1 746.64和44 383.83 Bq/m2,耕地平均侵蚀速率为4 857.66 t/(km2.年)。[结论]不同耕地土壤137Cs与210Pbex含量存在差异,但整体趋势一致,即水稻田萝卜地花生地红薯地芝麻地;在耕作土中农作物不同,侵蚀速率也不同,大小顺序是芝麻地红薯地花生地萝卜地水稻田;红薯地和芝麻地为极强烈侵蚀,萝卜地、花生地、水稻田为强烈侵蚀。     

Strontium-90 and cesium-137 in North American milk

The strontium-90 and cesium-137 concentrations in powdered milk in North America vary roughly with the specific activity of rain. The Sr(90)/Cs(137). ratios in over 800 powdered milk samples taken from 60 stations in North America from 1957-60 have a standard deviation of only 44 percent.     

Ratio of Cesium-137 and Strontium-90 Radioactivity in Soil

The similarity in genesis and the more pertinent physical characteristics of fission-produced Cs(137) and Sr(90) suggests the use of the first as a convenient monitor for the other prior to uptake in the biosphere. Results are presented which indicate the feasibility of this approach in the case of soils.     

Content of 137Cs and 90Sr in the forages of various ecological zones of Western Siberia

The results of the monitoring of ¹³⁷Cs and ⁹⁰Sr accumulation in the different types of vegetable forages of Western Siberia were presented. The average values of the radionuclides accumulation were revealed. The correlation between the levels of the radionuclides in various forages was found. The variability parts (r _w ) in the accumulation of ¹³⁷Cs and ⁹⁰Sr caused by an influence of both the type of forage in various oblasts and environment factors in forages were determined.     

Regularities of cesium-137 elimination from sheep with the addition of the sorbent Bifezh to the ration

The parameters for eliminating ¹³⁷Cs from sheep organs and tissues with the addition of the Ferrocin-containing preparation Bifezh, making it possible to determine the time of reduction of the radionuclide content to the radiation safety standards of meat production, are established.     

北太平洋公海中心渔场海域放射性核素137Cs的生态环境监测与风险评估

为合理开发北太平洋公海渔业资源并了解日本福岛核泄漏对公海渔业的影响,利用2011—2013年连续3年在北太平洋公海中心渔场采集的海洋生物样品,经济品种以巴特柔鱼(Ommastrephes bartramii)为主,采用γ谱仪进行检测放射性核素137Cs,开展核素在渔场中海洋生物体内的分布富集分析及其风险评估。研究结果显示:2011—2012年采集海洋生物品种较多,所有样本都检测出了超出本底值的137Cs核素比活度。2011年所测核素137Cs比活度范围为0.05~6.21 Bq·kg-1,2012年比活度范围为0.02~0.46Bq·kg-1;而2013年采集的样品较少仅有2类,比活度范围为0~0.37 Bq·kg-1。将各个营养级生物的137Cs核素质量活度进行均值化,3年期间大型鱼类的平均值为0.49 Bq·kg-1,巴特柔鱼的平均值为0.18 Bq·kg-1,小型鱼类平均值为0.10 Bq·kg-1,随营养级上升核素质量活度整体呈倒金字塔分布。研究表明,中心渔场调查期间所测核素质量活度水平均未超过中国食品中放射性核素质量活度的限制浓度与通用水平的标准限。目前对放射性元素137Cs的风险评估显示核素含量处于相对安全限度范围内,但需保持可续性的生态监测。     

GAMMA-EMITTING RADIONUCLIDES IN NEWBORNS, INFANTS, AND CHILDREN

During the period April 1962 to April 1963, 28 newborn infants, 7 stillborns, and 21 children from 4 to 15 years of age were examined for emission of gamma activity in a low-background, high-sensitivity, total-body counting facility. The 21 children contained traces of combined Zr(95) and Nb(95), Ru(103), (106), and Cs(137) in addition to the normal K(40). The greatest concentration of Cs(137) observed was 80 picocuries per kilogram of body weight, or about 4 percent of the natural K(40) radioactivity. Four of the seven stillborns, each counted for 10 hours, shoWed K(40) and traces of Zr(95), Nb(95), and Ru(103), (106). The ratios of Zr(95) to Nb(95) were lower in the stillborns than in their placentas which suggested placental discrimination against Zr(95). The ratios of Cs(137) to K(40) were lower in infants than in children or adults. Thyroid glands obtained atautopsy from 24 infants during April to September 1962 contained no detectable radioiodine ( less than 30 pc).     

Assessment of factors influencing changes in <Superscript>137</Superscript>Cs contamination density of agricultural lands

A comparative analysis of predictive estimates of the ¹³⁷Cs contamination level of agricultural lands with real measurement data is given for the example of southern districts of the Kaluga oblast that suffered from the accident at the Chernobyl nuclear power plant. Predictive calculations based on consideration of only radionuclide decay are sufficiently reliable; however, for greater accuracy it is necessary to take into consideration the amount of agrotechnical protective measures being carried out.     

三株O_(78)、O_(137)混合血清型鸡大肠埃希菌iss基因的序列分析

采用1日龄雏鸡对3株O78、O137混合血清型鸡大肠埃希菌的致病性进行了测定,并扩增了iss基因。结果表明,3株O78、O137混合血清型鸡大肠埃希菌均对1日龄雏鸡具有较强的毒力。iss基因在3株O78、O137混合血清型鸡大肠埃希菌中的序列与已知的禽大肠埃希菌iss基因序列的同源性为100%,与人源大肠埃希菌iss基因序列的同源性为90.9%,显示了此基因的保守性。     

一种新的锶超积累植物——串叶草

[目的]筛选适合污染区生长的超积累植物。[方法]采用野外采样法,以国内某核设施退役厂放射性污染区域为研究对象,测定了该区优势植物(共9科17种)和土壤中的~(137)Cs、~(90)Sr放射性含量,并进行了筛选与田间修复试验。[结果]污染区土壤~(137)Cs和~(90)Sr放射性含量的最大值分别为5.06×10~6和3.29×10~4Bq/kg,均超过国际规定活度限值;菊科串叶草对~(137)Cs的富集和转移系数均小于1.00,而对~(90)Sr的富集和转移系数分别是3.25和2.95,均大于1.00;串叶草具备~(90)Sr超积累植物特征且能修复土壤中5.9%的~(90)Sr,可推荐串叶草对~(90)Sr的污染土壤进行修复处理。[结论]首次发现并证实菊科串叶草是一种~(90)Sr超积累植物,为开展污染区域修复治理工作提供参考。     

CESIUM-137 IN ALASKAN ESKIMOS

During the summer of 1962, levels of radioactivity in over 700 people at four villages above the Arctic Circle in Alaska were measured with a transportable whole-body counter. The averages for body burden of cesium-137 were much higher than the average for people in the rest of the United States. The people of the interior village of Anaktuvuk Pass had the highest average burden of cesium-137, which was 421 nanocuries; the maximum burden was 790 nanocuries.     

Barium isotopes in chondritic meteorites: implications for planetary reservoir models

High-precision barium isotope measurements yielded differences of up to 25 parts per million in the 137Ba/136Ba ratio and 60 parts per million in the 138Ba/136Ba ratio between chondrites and Earth. These differences probably arose from incomplete mixing of nucleosynthetic material in the solar nebula. Chondritic meteorites have a slight excess of supernova-derived material as compared to Earth, demonstrating that the solar nebula was not perfectly homogenized upon formation.     

冬性面包小麦品系88-137种子蛋白抗虫性的研究

通过生物测定,观察面包小麦花培品系88-137及对照品系76-2抗虫情况,结果表明:(1)88-137麦粒对花斑皮蠹确有致死及抑制其生长发育的作用,并且主要是蛋白质起抑虫作用.(2)88-137粗提蛋白质对棉蚜、棉铃虫、二化螟的生长发育也有一定抑制作用,其中用25;硫酸铵沉淀的粗提蛋白质抑制棉铃虫、棉蚜作用最明显.(3)76-2、88-137饲喂黄粉虫的平均体重均较麦麸的高,说明这两个品系对黄粉虫没有毒性.     

黑色素细胞中过量表达miR-137对TYRP-1和TYRP-2的影响

【目的】证明miR-137通过调控MITF而间接影响小鼠黑色素细胞TYRP-1和TYRP-2的表达,从而影响黑色素的生成。【方法】通过细胞转染技术在细胞水平过量表达miR-137,对黑色素细胞中黑色素含量进行了测定,经RT-PCR以及western blot检测转染后细胞TYRP-1和TYRP-2在mRNA和蛋白水平的变化。【结果】黑色素含量明显减少,在mRNA水平,TYRP1显著降低至0.4倍,TYRP-2显著降低至0.6倍。在蛋白水平,TYRP-1显著降低至0.61倍,TYRP-2显著降低至0.73倍。【结论】过量表达miR-137会通过调控MITF而使黑色素细胞TYRP-1和TYRP-2的表达量降低,从而揭示了miR-137通过调节TYRP-1和TYRP-2的表达间接调控了黑色素的生成。     

蚕豆幼苗光合特性及抗氧化酶对Cs~+胁迫的响应

为研究蚕豆的光合特性及抗氧化酶在铯(Cs~+)胁迫下的响应特征,用浓度为0～200 mg/L Cs~+溶液浇灌盆栽蚕豆,模拟~(137)Cs随雨水沉降造成的土壤放射性污染,测定不同浓度Cs~+溶液浇灌下蚕豆幼苗的光合特性及抗氧化酶活性等的变化。结果显示,蚕豆叶片叶绿素含量随Cs~+浓度的增加呈现先增加后下降的趋势,低浓度Cs~+(25 mg/L)处理净光合速率(Pn)有所增加,高浓度(200 mg/L)处理Pn略有下降;蒸腾速率(E)、气孔导度(Gs)、胞间CO_2浓度(Ci)在一定程度上显著增加;蚕豆叶片的原初光能转化效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)、光化学淬灭系数(qP)、电子传递速率(ETR)等无显著性变化,非光化学淬灭系数(qNP)在50 mg/L和200 mg/L处理下显著升高,非光化学耗散增强;过氧化物酶(peroxidase,POD)和抗坏血酸(ascorbate peroxidase,APX)活性显著降低,POD和APX对Cs~+胁迫的响应要强于超氧化物歧化酶(superoxide dismutase,SOD);相关性分析表明,蚕豆的Pn和POD、APX活性与其体内Cs~+富集量呈一定的负相关关系。结果表明蚕豆对Cs~+胁迫的耐受性强,有较强的Cs~+富集能力,且主要蓄积在根中,安全性增强,在土壤铯污染修复中具有较大的应用潜力。     

Seasonal cycling of cesium-137 in a reservoir

Studies of a reservoir in the southeastern United States show that cesium-137, introduced into the system from a leak in a nuclear fuel element, cycles between the water and sediment on a seasonal basis. The cycling, which coincides with the annual periods of thermal stratification in this monomictic lake, has been occurring for over 10 years.