共查询到20条相似文献，搜索用时 250 毫秒
1.
T S Baskett 《Pesticides monitoring journal》1975,9(2):67-78
Samples of breast muscle from 327 ducks collected from October 1970 to March 1971 in the conterminous United States were analyzed for total mercury by flameless atomic absorption spectrometry. Mercury levels for the entire collection ranged from less than 0.01 to 3.91 ppm wet weight with a median of 0.10 ppm. Twenty-five ducks had levels equalling or exceeding the 0.5 ppm guideline for fish and shellfish established by the Food and Drug Administration, U.S. Department of Health, Education, and Welfare. Dabbling ducks, which are shallow-water feeders and mostly vegetarian in fall, winter, and spring, usually had lower levels than diving and sea ducks. Levels were generally higher in ducks collected in areas where environmental mercury levels were known to be greater than in ducks from nonsuspect areas. Despite the mobility of the ducks, levels seemed more closely linked to local environmental contamination than to various factors associated with large geographic areas. 相似文献
2.
A 1971-72 study of the Nevada Carson River drainage system by the Geological Survey, U.S. Department of Interior, revealed substantial amounts of mercury from pre-1900 gold and silver milling operations of the Comstock Lode. A monitoring survey was initiated to determine the extent of mercury uptake from corresponding surface water and sediments for seven aquatic species collected from five sampling stations along the watercourse. Total mercury content in fish ranged from 0.02 to 2.72 ppm; highest concentrations occurred in piscivorous white bass (0.50-2.72 ppm) sampled from Lahontan Reservoir. Residue levels appeared to be related to fish size, as demonstrated by highly significant correlations between wet weight and mercury content of five of the six species. Concentrations also appeared to be directly influenced by the species' position on the aquatic food chain. These results indicate that mercury levels in some fish from the Carson River drainage system may exceed the 0.50 ppm maximum concentration considered by the Food and Drug Administration, U.S. Department of Health, Education, and Welfare, to be safe for human consumption. 相似文献
3.
基于RS与GIS的阜新地区土地荒漠化时空演变规律研究 总被引：10，自引：5，他引：5
土地荒漠化是气候、环境及人类活动多因素综合影响的结果,它的发展与逆转,不仅表现在空间结构、规模和环境上的变化。而且也直接影响社会经济的发展。本文以RS和GIS作为信息获取与分析工具,通过对1978年、1989年和1999年研究区土地荒漠化遥感影象解译分析,对阜新地区21年来土地荒漠化的时空演变规律进行了系统的研究,结果表明,荒漠化的空间演变经历了“强化－逆转－强化”的过程,风蚀荒漠化程度考察,则表现为“重度荒漠化逆转,轻度荒漠化扩展”的演变格局,不同荒漠化分布形式呈现条带状片状分布,且有向西扩展的趋势。水蚀荒漠化到1989年以来,已基本得到控制,特别是中北部地区10个乡镇逆转效果最为明显。盐渍荒漠化在1978年基础上向四周扩散,主要集中在东部和西南部,呈不连续片状分布。 相似文献
4.
Mercury, arsenic, and cadmium in fish, water, and sediment of American Falls Reservoir, Idaho, 1974.
Mercury and cadmium were found in fish, water, and sediment of American Falls Reservoir (AFR), Idaho. Mercury and cadmium levels in some fish exceeded human health standards set by the Food and Drug Administration, U.S. Department of Health, Education and Welfare, and the World Health Organization. Analyses performed on the flesh of rainbow trout showed mercury residues of up to 1.20 mg/kg, which were higher than residues previously reported in trout collected in 1970 and 1971 from AFR. Cadmium residue levels were as high as 0.80 mg/kg. Although arsenic was found in reservoir sediment at levels of 1.36-2.40 mg/kg, it was not detected in fish. 相似文献
5.
Concentrations of DDT, TDE, DDE, and sigma DDT were determined in homogenized whole fish samples of 129 northern pike (Esox lucius). These fish were netted between June 1974 and June 1975 in the first 10 km of the Richelieu River flowing in Canadian territory. Two years after the banning of DDT, sigma DDT levels ranged from 0.2 ppm fresh body weight in two-year-old specimens to 1.5 ppm in a six-year-old pike. Residues increased greatly with age, and significant seasonal variations in the sigma DDT levels were found in five- and six-year-old pike. 相似文献
6.
Levels of p,p'-DDT, p,p'-TDE, p,p'-DDE, dieldrin, polychlorinated biphenyls (PCBs), and HCB were determined in certain tissues of 31 harp seals (P hagophilus groenlandicus) taken from the Gulf of St. Lawrence during 1971 and 1973. The seals ranged in age from less than two weeks to 18 years. Mean concentrations of PCBs and sigma DDT in the various tissues were about the same sigma DDT levels were 1.64--9.88 ppm in adult seal blubber and 1.08--3.73 ppm in seal pup blubber. Organochlorine levels in harp seal samples taken in 1973 were similar to those reported by other workers for samples collected in the Gulf of St. Lawrence during 1967-71. 相似文献
7.
Freshwater mullet harvested commercially during various seasons of 1975-76 from the upper Great Lakes were analyzed for organochlorine pesticides, PCBs, and mercury. Species analyzed were Catostomus commersoni, C. catostomus, and Moxostoma erythruran. Whole ground fish, mechanically deboned flesh, head, middle, and tail steaks, and various muscles were analyzed for pesticides and PCBs; only edible flesh was analyzed for mercury. Dieldrin ranged from none detected to 0.23 ppm in deboned and whole ground samples, the DDT range was a trace to 0.30 ppm, and PCBs ranged from 0.06 ppm to 0.79 ppm. Levels were also higher in head sections and in high fat-containing medial muscle and belly flap. Mercury levels ranged from 0.03 ppm to 0.28 ppm in the flesh of mullet from Lake Michigan. 相似文献
8.
运用大气质点轨迹分析平台HYSPLIT 4.8对2007-2011年广西兴安地区早期灯下稻纵卷叶螟Cnaphalocrocis medinalis Guenée主要迁入峰进行了轨迹模拟,并运用气象图形处理软件GrADS对迁飞高峰期进行气象背景分析。结果显示,广西兴安地区稻纵卷叶螟于5月初开始零星迁入,迁入高峰期集中在5月下旬至6月下旬,最大迁入峰集中在6月中下旬。诱虫量及迁入峰次年度间存在差异。广西兴安地区稻纵卷叶螟5月迁入虫源主要来自海南中部、西南部,老挝和泰国北部,广西南部、广东西南部也能提供部分虫源。6月迁入虫源主要集中在广西南部、广东西南部、海南中部、老挝中部稻区,越南中部稻区也能提供部分虫源。稻纵卷叶螟迁入峰期925 hPa等压面上气流方向均为较强的西南或偏南气流。降雨和气流的垂直扰动导致稻纵卷叶螟大规模迁入降落。 相似文献
9.
Mercury concentrations were determined in muscle and liver of 41 species of fish and a limited number of plankton, sediment, and invertebrate samples collected from North Atlantic offshore waters in 1971. The average mercury concentration in fish muscle was 0.154 ppm with a standard deviation of 0.124. Invertebrate samples had mercury concentrations which were generally less than 0.1 ppm. In a single lobster sample, however, 0.31 ppm mercury was found in the tail muscle and there was 0.60 ppm in the liver. Mercury levels in all 9 plankton and 10 sediment samples taken were less than 0.05 ppm. 相似文献
10.
Muscle, liver, brain, and abdominal body fat samples of goats, buffalo, and chickens, all common meat sources in India, were analyzed by gas-liquid chromatography (GLC) for residues of DDT and benzene hexachloride (BHC). A few samples of goat and buffalo bone marrow were also included. Relatively high residue levels were found in body fat and bone marrow compared with other tissues. DDT and BHC residue levels were highest in chicken body fat, averaging 4.157 ppm sigma DDT and 3.879 ppm BHC. DDT content was much higher in goat and buffalo bone marrow than in the corresponding body fat. DDT levels in brain samples were highest (0.138 ppm) in buffalo. p,p'-TDE levels were higher than p,p'-DDE levels in buffalo; overall DDT levels were lowest in goats. BHC residues were generally low in buffalo; alpha-BHC accounted for most BHC residues in brain tissues. Greater accumulations of DDT and BHC were found in leg muscles than in breast muscles of chickens. 相似文献
11.
为了解入侵杂草狼毒Stellera chamaejasme在当前(1970—2000年)和未来气候情景下的扩散动态,采用最近邻体距离法选取样本数据,采用相关性分析和主成分分析选择环境变量,应用最大熵方法建立生态位模型用来预测当前(1970—2000年)和未来(2050年和2070年)气候变化下狼毒的潜在分布区,并应用Matlab软件计算气候变化下狼毒地理分布重心、平均海拔和等级分布区范围的动态变化。结果表明,当前(1970—2000年)气候条件下狼毒种群的潜在分布区从西南到东北呈带状分布,适生区等级随纬度的增加逐渐降低;未来气候变化下狼毒的潜在分布区将向西南方向和高海拔地区扩散,平均海拔将增高638 m,高适生区面积增长尤为迅速,2050年的相对增长率达51%;高寒草地将成为未来狼毒扩散的主要区域,因此应进一步加强对该区狼毒的防控。 相似文献
12.
Eighteen species of fish from Lake Saint Clair and 19 species from Lake Erie were analyzed for organochlorine pesticides and polychlorinated biphenyls (PCBs) between 1968 and 1976. Mean residues of sigma DDT peaked at 1.19 ppm in longnose gar (Lepisosteus osseus) caught in Lake Saint Clair in 1970-71, but had declined in all species by 1975-76. Dieldrin levels in fish tissues increased over the same period. White bass (Morone chrysops), caught in 1975 in Lake Erie, had the highest mean residue of dieldrin at 0.17 ppm. PCB residues increased in some species and decreased in others. PCB residues exceeding the tolerance level of Health and Welfare Canada were found in the following: from Lake Saint Clair, smallmouth bass (Micropterus dolomieui) in 1975 and channel catfish (Ictalurus punctatus) in 1971; from Lake Erie, coho salmon (Oncorhynchus kisutch) in 1970, smallmouth bass, alewife (Alosa pseudoharengus), freshwater drum (Aplodinotus grunniens), and gizzard shad (Dorosoma cepedianum) in 1971, and white bass in 1971 and 1976. 相似文献
13.
利用阿勒泰地区7个气象站1981-2010年6-8月降水量以及计算得到的蒸发量和K指数,用经验正交函数分解（EOF）和旋转经验正交函数分解（REOF）方法,分析了近30 a阿勒泰地区夏季干旱特征,用最大熵谱和谐波分析方法对阿勒泰3个分区K干旱指数的主要周期进行了分析。结果显示：用K干旱指数为指标,阿勒泰地区中西部干旱发生频率高于偏东地区;全地区可分为3个区域,Ⅰ西南谷地平原,Ⅱ东部丘陵地区,Ⅲ北部山区;各分区夏季干旱总体呈下降趋势。阿勒泰干旱的空间分布除受大尺度天气系统影响外,还受地理位置、地形地势等多种因子影响。各区干旱存在准10 a的长周期和3～5 a短周期振荡,且相对稳定,但其显著周期及其年代变化差异较大。 相似文献
14.
PCB residues in fish from 41 stations throughout New York State were monitored in 1975. Nearly all fish contained PCB's in detectable amounts although the levels of contamination and specific Aroclor varied. The Hudson River contained the highest known PCB concentrations within the United States; levels often exceeded 100 ppm. Other waters and fish which were significantly contaminated include Lake Ontario salmonids and Cayuga Lake lake trout. Onondaga Lake, previously closed to fishing because of mercury contamination, also appears to have abnormally high levels of PCB's approaching in some instances the action level of the Food and Drug Administration, U.S. Department of Health, Education, and Welfare. Samples from marine waters generally have contaminant levels substantially below 5.0 ppm. 相似文献
15.
R Frank M Holdrinet H E Braun D P Dodge G E Sprangler 《Pesticides monitoring journal》1978,12(2):60-68
Five species of fish from Lake Superior and 12 species from Lake Huron were analyzed for organochlorine pesticides and polychlorinated biphenyls (PCBs) between 1968 and 1975. Mean residues of sigma DDT peaked at 1.72 ppm and 7.60 ppm in lake trout (Salvelinus namaycush) from Lakes Superior and Huron, respectively. By 1975, the mean level of sigma DDT had decreased in lake trout and was highest in bloaters (Coregonus hoi) from both lakes: 1.06 ppm and 1.87 ppm, respectively. Dieldrin levels in fish from Lake Superior changed little over the same period. However, in 1969-70, dieldrin levels in fish from Lake Huron exceeded the 0.3 ppm tolerance level set by Health and Welfare Canada or the Food and Drug Administration, U.S. Department of Health, Education, and Welfare in 5 percent of lake whitefish (Coregonus clupeaformis) and 10 percent of bloaters. By 1975, 50 percent of bloaters caught in Georgian Bay and North Channel had dieldrin levels above 0.3 ppm. PCB residues declined in lake trout and lake whitefish caught in Lake Superior between 1971 and 1975, but increased slightly in bloaters and white sucker (Catostomus commersoni). Mean PCB residues in bloaters caught in Lake Huron in 1969-71 and 1975-76, and splake (Salvelinus fontinalis and S. namaycush) and cisco (Coregonus artedii) caught in 1975 exceeded the 2 ppm tolerance level. 相似文献
16.
More than a half million pounds of DDT were applied to control mosquitoes in salt marsh estuaries of Cape May County, New Jersey, from 1946 to 1966. The use of DDT was discontinued in the County after 1966. In 1967, mean concentrations of DDT and metabolites ranged from 0.63 to 9.05 ppm in aquatic fauna, but by 1973 mean residue levels had decreased 84 to 99 percent among nine species. DDE was still present at reduced levels in nearly all samples in 1973, but other DDT isomers had mostly disappeared. Dieldrin was detected only in clapper rails, and residue levels decreased during the period. Mean concentrations of PCB's increased in the clapper rail, remained the same in the fiddler crab and mud snail, and decreased in the sheepshead minnow, mummichog, striped killifish, and salt marsh snail. Small amounts of mirex, toxaphene, cis-chlordane (and/or trans-nonachlor), oxychlordane, and HCB were detected in a few specimens. 相似文献
17.
为明确草地贪夜蛾Spodoptera frugiperda的捕食性天敌——叉角厉蝽Eocanthecona furcellata在全球的潜在地理分布,基于叉角厉蝽在全球已有的历史分布记录,结合环境数据,采用MaxEnt生态位模型结合GIS技术对其在全球范围的适生区进行分析。结果显示,最暖季降水和最冷季平均温度是影响叉角厉蝽分布的主要环境因素。预测的叉角厉蝽在各个洲均可能发生,适生区集中分布在亚洲东部、东南亚大部、印度半岛东部、非洲南部东西沿海岸地区、南美洲中部地区及澳洲北部沿海岸地区。表明叉角厉蝽适生性较强,可以充分利用其捕食性释放到田间用于生物防治。 相似文献
18.
小火蚁是中国大陆新发现的重要外来入侵害虫, 目前对该虫的传入来源和在我国的适生区范围尚不明确?为明确我国小火蚁适生区范围, 有效防控该虫在我国的扩散和蔓延, 本研究通过该虫全球已有的分布数据, 采用最大熵模型对其适生区进行了预测?研究表明, 最大熵模型预测小火蚁适生区精度较高?预测结果显示, 我国小火蚁的潜在适生区主要分布于南方, 其中, 高适生区分布在台湾?海南?云南南部边境?广西西南局部?福建西南部?广东南部及其沿海地区?预测结果与该物种现有地理范围的生态条件一致?年降水量对小火蚁的适生性影响最大, 理论年降水量为2 040 mm时小火蚁分布的概率最高?随着全球气候变暖, 未来我国小火蚁的适生区有向北扩大的趋势, 但主要适生区还是以南方为主? 相似文献
19.
20.
The 50% survival ofBemisia tabaci Genn. females was reduced to 5.9 days by exposure to bean seedlings treated with 1000 ppm buprofezinvs 8.9 days in the control. At lower concentrations ranging from 50 to 500 ppm, survival was extended to 11.8–14.2 days. Mean
fecundity was significantly reduced on plants treated with 1000 ppm as compared with the control, whereas at 50 to 500 ppm
the oviposition period was extended with a considerable increase in mean fecundity, irrespective of concentrations. Overall
mean percent hatch dropped gradually from 25.8 to 12.9 with increase of concentration from 50 to 1000 ppm, as against 96.9%
in the control. The survival of hatched nymphs was greatly affected at all buprofezin concentrations. No immature stages survived
at 50, 100, 250 and 500 ppm; nymphal survival was 13.8, 7.0, 1.9 and 1.2%, respectively, as against 81.6% in the control. 相似文献