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1.
Phosphates in fertilizers contain cadmium. When vegetables usually devoid of cadmium were grown in soil heavily fertilized with 20 percent superphosphate, they absorbed it. Vegetables normally containing cadmium absorbed larger quantities in the presence of superphosphate and little or none in its absence. The superphosphate showed 7.25 parts of cadmium per million. Five grains usually containing cadmium were grown in unfertilized soil poor in this element; four did not absorb it. Phosphate fertilizers may be a source of the cadmium in some vegetable foods. 相似文献
2.
In oceanic, coastal, and estuarine environments, an average of 25 to 41 percent of the dissolved inorganic nitrogen (NH(4) (+) and NO(3) (-)) taken up by phytoplankton is released as dissolved organic nitrogen (DON). Release rates for DON in oceanic systems range from 4 to 26 nanogram-atoms of nitrogen per liter per hour. Failure to account for the production of DON during nitrogen-15 uptake experiments results in an underestimate of gross nitrogen uptake rates and thus an underestimate of new and regenerated production. In these studies, traditional nitrogen-15 techniques were found to underestimate new and regenerated production by up to 74 and 50 percent, respectively. Total DON turnover times, estimated from DON release resulting from both NH(4) (+) and NO(3) (-) uptake, were 10 +/- 1, 18 +/- 14, and 4 days for oceanic, coastal, and estuarine sites, respectively. 相似文献
3.
DDE residues and eggshell changes in Alaskan falcons and hawks 总被引：1，自引：0，他引：1
T J Cade J L Lincer C M White D G Roseneau L G Swartz 《Science (New York, N.Y.)》1971,172(986):955-957
Eggshell thickness after exposure to DDT was reduced by 21.7 percent in Alaskan tundra peregrines, by 16.8 percent in taiga peregrines, by 7.5 percent in Aleutian peregrines, by 3.3 percent in rough-legged hawks, and not at all in gyrfalcons. Tundra peregrine eggs contain an average of 889 parts of DDE per million (lipid basis); taiga peregrine eggs contain 673 parts per million; Aleutian peregrine eggs contain 167 parts per million; rough-legged hawk eggs contain 22.5 parts per million; and gyrfalcon eggs contain 3.88 parts per million. These changes in eggshell thickness and the pesticide residues reflect different degrees of exposure to contamination. There is a highly significant negative correlation between shell thickness and DDE content in peregrine eggs. Tundra and taiga peregrines have fledged progressively fewer young each year since 1966. 相似文献
4.
Ammonia volatilized from aboveground parts of winter wheat was collected with an enclosuregrowth chamber and measured from jointing to maturing stage. The results showed that ammonia releasedfrom unfertilized plants grown in high and low fertility soils remained at low rates of 2.3 and 0.9 μg NH3 40plant-1 h-1 respectively at late filling stage. However, fertilized plants rapidly increased the rates to 43.4 and52.2 μg NH3 40 plant-1 h-1 in the high and low fertility soils, respectively, at the same period. The released a-mount was different in different parts of plants. At filling stage, lower senescing stems and leaves volatilizedmore ammonia than upper parts, i.e. , ears and flag leaves that grew normally, with an average of 1.4 and0.7 μg NH3 20 plant-1 h-1 respectively, strongly suggesting that it was the senile organs that released largeamounts of ammonia. At the grain filling stage, shortage of water supply (drought stress) reduced ammoniavolatilization. The average rate of ammonia released under water stress was 0.9 μg NH3 40 plant-1 h-1 , but 1.2μg NH3 40 plant-1 h-1 with moderate water supply. Application of N together with P fertilizer resulted in ahigher ammonia volatilization than N fertilization alone at the maturing stage. The average rate released was135.3 μg NH3 40 plant-1 h-1 when 0.4 g N and 0.13 g P had been added to per kg soil, while 33.7 μg when0.4 g N added alone. Ammonia volatilization from plants was closely related with plant biomass and N up-take; P fertilization increased plant biomass and N uptake and therefore increased its release. 相似文献
5.
The two-filter method described by Thomas and LeClare was used to investigate the effects of trace concentrations of nitric oxide and nitrogen dioxide in dry nitrogen on the diffusion coefficient of radium A (polonium-218). Charged radium A was neutralized in 10 parts per million (ppm) nitrogen dioxide in dry nitrogen, in 8.3 ppm nitric oxide in dry 92 percent nitrogen and 8 percent oxygen, and in nitrogen with 20 and 80 percent relative humidity. No neutralization was seen in dry nitrogen, dry oxygen, dry air, or 10 ppm nitric oxide in dry nitrogen. The diffusion coefficient of the neutral radium A species was found to be 0.079 square centimeters per second, regardless of the relative humidity of the nitrogen gas atmosphere. Lower values were observed for charged species. 相似文献
6.
Apollo 16 breccia 66095 contains a remarkably high amount of lead (15 parts per million), 85 percent of which is not supported by uranium and thorium in the rock. An acid leach experiment coupled with separate analyses of the whole rock and mineral fractions for uranium, thorium, and lead indicate that the excess lead has a lunar source and was apparently introduced about 4.0 x 10(9) years ago. The data also suggest that a major lunar crustal differentiation occurred about 4.47 x 10(9) years ago. 相似文献
7.
Radiation doses from airborne effluents of model coal-fired and nuclear power plants (1000 megawatts electric) are compared. Assuming a 1 percent ash release to the atmosphere (Environmental Protection Agency regulation) and 1 part per million of uranium and 2 parts per million of thorium in the coal (approximately the U.S. average), population doses from the coal plant are typically higher than those from pressurized-water or boiling-water reactors that meet government regulations. Higher radionuclide contents and ash releases are common and would result in increased doses from the coal plant. The study does not assess the impact of non-radiological pollutants or the total radiological impacts of a coal versus a nuclear economy. 相似文献
8.
Ethyl mercury p-toluene sulfonanilide (active ingredient of Ceresan M) at a dietary concentration of 30 parts per million (12.5 parts of mercury per million) was lethal to adult ring-necked pheasants. Egg production and survival of third-week embryos were sharply reduced when breeders were maintained on feed containing 10 parts of this compound per million (4.2 parts of mercury per million). 相似文献
9.
魔芋防病高产栽培关键技术研究 总被引：3，自引：0，他引：3
笔者连续 3年在湖北省咸丰县进行了魔芋健身栽培试验 ,分别对魔芋的种芋消毒、最佳播期、遮荫覆盖、施钾量等进行了研究。结果表明 :外调种芋用 10 0 0万单位农用链霉素 10 0 0倍液 + 2 0 %龙克菌 5 0 0倍液混合消毒 3次 ,效果最好 ;海拔 80 0～12 0 0m山区魔芋的适播期为 5月上旬 ,不仅出苗率可达 99.0 6% ,还可以缩短魔芋出苗前在土壤中的时间 ,减少病原菌侵染机会 ,发病率也最低 ;在海拔 80 0～ 12 0 0m地区种植魔芋 ,遮荫越好 ,发病越轻 ,同时土表覆盖可以降低发病率 7%左右 ;魔芋属喜钾作物 ,在底肥中施 5 0 %硫酸钾 45 0kg/hm2 ,增产效果最好 ,可增产 5 1.2 9%。 相似文献
10.
When Corchorus pascuorum (Tiliaceae), native to Australia, was grown in the arid region of West Pakistan, it flowered abundantly but produced no fruit. It was induced to form fruit by treatment with 25 percent sucrose solution containing indolebutyric acid (300 parts per million). When plants were raised from the induced fruits, they fruited without any further treatment and retained the ability to produce fruits in two subsequent generations, whereas those raised from the original seeds produced no fruit. 相似文献
11.
Lead contamination around secondary smelters: estimation of dispersal and accumulation by humans 总被引：4，自引：0，他引：4
T M Roberts T C Hutchinson J Paciga A Chattopadhyay R E Jervis J VanLoon D K Parkinson 《Science (New York, N.Y.)》1974,186(4169):1120-1123
A high rate of lead fallout around two secondary lead smelters originated mainly from episodal large-particulate emissions from low-level fugitive sources rather than from stack fumes. The lead content of dustfall, and consequently of soil, vegetation, and outdoor dust, decreased exponentially with distance from the two smelters. Between 13 and 30 percent of the children living in the contaminated areas had absorbed excessive amounts of lead (more than 40 micrograms per 100 milliliters of blood and more than 100 micrograms per gram of hair) as compared with less than 1 percent in a control group. A relationship between blood and hair was established which indicated that the absorption was fairly constant for most children examined. It seemned that the ingestion of contaminated dirt and dusts rather than "paint pica" was the major route of lead intake. Metabolic changes were found in most of 21 children selected from those with excessive lead absorption; 10 to 15 percent of this group showed subtle neurological dysfunctions and minor psychomotor abnormalities. 相似文献
12.
Concentrations of 2,3-dihydro-5-carboxanilido-6-methyl-1,4-oxathiin lower than 8 parts per million prevented mycelial growth of a number of Basidiomycetes. By contrast, mycelial growth of various other fungi-Phycomycetes, Ascomycetes, and Deuteromycetes-was 50 percent inhibited only by concentrations of 32 ppm or higher. Two exceptions to this pattern of selective fungitoxicity were found:an isolate of Rhizoctonia solani was not as sensitive as other Basidiomycetes, and the deuteromycete Verticillium alboatrum was inhibited by lower concentrations than affected other fungi in this group. Spore germination of two Basidiomycetes, Uromyces phaseoli and Ustilago nuda, was inhibited 95 percent or more at 10 ppm. 相似文献
13.
The effects of atmospheric carbon dioxide on corn, soybeans, loblolly pine, and sweetgum were studied in the field during a growing season. The plants were exposed to a range of concentrations of carbon dioxide day and night in open-topped, flow-through chambers. At a mean daytime carbon dioxide concentration of 910 parts per million, increases in total biomass ranged from 157 to 186 percent of the control values. Seed yield and wood volume increased and there were changes in plant anatomy and form. Net photosynthesis increased with increasing carbon dioxide concentration in soybeans and sweetgum, but was unaffected in corn. Water use efficiency also increased in corn, soybeans, and sweetgum. 相似文献
14.
The lunar samples were analyzed for total organic carbon content by pyrolysis at 850 degrees C and subsequent detection of the resulting volatilized organic compounds in a hydrogen flame ionization detector. The organic content ranged from 10 to 126 parts per million, depending primarily upon the handling in the sample processing. No correlation of organic content with rock type has been shown. The small quantities of organic matter are primarily contamination, and the indigenous organic content is estimated to be less than 10 parts per million. 相似文献
15.
Clouds of impurity atoms near line defects are believed to affect the plastic deformation of alloys. Three-dimensional atom probe techniques were used to image these so-called Cottrell atmospheres directly. Ordered iron-aluminum alloys (40 atomic percent aluminum) doped with boron (400 atomic parts per million) were investigated on an atomic scale along the <001> direction. A boron enrichment was observed in the vicinity of an <001> edge dislocation. The enriched region appeared as a three-dimensional pipe 5 nanometers in diameter, tangent to the dislocation line. The dislocation was found to be boron-enriched by a factor of 50 (2 atomic percent) relative to the bulk. The local boron enrichment is accompanied by a strong aluminum depletion of 20 atomic percent. 相似文献
16.
A Penicillium urticae Bainer, isolated from subsurface-tilled plots showing reduced wheat growth, produced a phytotoxic substance. The melting point and infrared and ultraviolet spectra of the crystalline material showed this substance to be patulin. Wheat shoot growth inhibition of 50 percent required 20, 20, and 75 parts per million of patulin in solution, sand, and soil culture, respectively. 相似文献
17.
Misidentification of two peaks from the Pioneer Venus sounder probe gas chromatograph (SPGC), also formerly known as the LGC, gave rise to quantitative errors in the abundances of oxygen, argon, and carbon monoxide. The argon abundance is estimated at 67 parts per million and that of carbon monoxide at 20 parts per million. At this time, no estimates for the oxygen abundance can be made. 相似文献
18.
Lunar rock 66095 contains a hydrated iron oxide and has an unusual amount of water for a lunar rock (140 to 750 parts per million), 90 percent of which is released below 690 degrees C. The deltaof water released at these low temperatures varies from -75 to -140 per mil relative to standard mean ocean water (SMOW). The small amount of water released between 690 degrees and 1300 degrees C has a delta of about -175 +/-25 per mil SMOW. These delta values are not unusual for terrestrial water. The delta(18)O of water extracted from 110 degrees to 400 degrees C has a value of +5+/- I per mil SMOW, similar to the value for lunar silicates from rock 66095 and different from the value of -4 to -22 per mil found for samples of terrestrial rust including samples of rusted meteoritic iron. The amount of carbon varies from 11 to 59 parts per million with a delta(13)C from -20 to -30 per mil relative to Pee Dee belemnite. Only very small amounts of reduced species (such as hydrogen, carbon monoxide, and methane) were found, in contrast to the analyses of other lunar rocks. Although it is possible that most of the water in the iron oxide (goethite) may be terrestrial in origin or may have exchanged with terrestrial water during sample return and handling, evidence presented herein suggests that this did not happen and that some lunar water may have a deltaD that is indistinguishable from that of terrestrial water. 相似文献
19.
大连市公园绿地植物配置模式研究 总被引：1，自引：0，他引：1
为进一步了解和改善大连市公园绿地植物配置模式,采用典型样地取样法,对大连市5个公园样地的植物配置模式进行了研究,并在设置的30个样方内进行了植物组成、生长型、群落密度、乔灌比和覆盖度等的调查。结果表明:(1)配置模式所占比例分别为乔灌草型70%,乔灌型10%和乔草型20%,主要采用乔灌草型;(2)乔木覆盖度是62.94%,灌木覆盖度是6.95%,草本覆盖度是66.51%。总体覆盖度较高,中层结构简单;(3)乔木层的平均密度为每300m214株,灌木层的平均密度为每300m217株,灌木层密度略大于乔木层;(4)应用最多的乔木有水杉和银杏等7种;应用的主要灌木有冬青和小叶黄杨等8种;应用的地被植物有花叶玉簪和矮牵牛等12种;草坪草都是早熟禾。 相似文献
20.
The reactions of nitrogen dioxide with cyclohexene have been studied as a model for the reactions that occur between nitrogen dioxide in smoggy air and unsaturated fatty acids in pulmonary lipids. As predicted from earlier studies at high nitrogen dioxide concentrations, this gas reacts with cyclohexene predominantly by addition to the double bond at nitrogen dioxide concentrations of 1 percent (10,000 parts per million) to 40 percent in nitrogen; in the presence of air or oxygen, this reaction initiates the autoxidation of the alkene. However, at concentrations below 100 parts per million in nitrogen, nitrogen dioxide reacts with cyclohexene almost exclusively by abstraction of allylic hydrogen; this unexpected reaction also initiates the autoxidation of the alkene in the presence of oxygen or air, but it leads to the production of nitrous acid rather than of a product containing a nitro group attached to a carbon atom. The nitrous acid can react with amines to produce nitrosamines. Moreover, the nitrite ion produced by the hydrogen abstraction mechanism would be expected to diffuse throughout the body, unlike nitrated lipids that would be confined to the pulmonary cavity. These findings have been confirmed with methyl oleate, linoleate, and linolenate; some of the kinetic features of the nitrogen dioxide-initiated autoxidation of these unsaturated fatty acids have been studied. 相似文献