Thunderstorms: an important mechanism in the transport of air pollutants   总被引：3，自引：0，他引：3  

Dickerson RR  Huffman GJ  Luke WT  Nunnermacker LJ  Pickering KE  Leslie AC  Lindsey CG  Slinn WG  Kelly TJ  Daum PH  Delany AC  Greenberg JP  Zimmerman PR  Boatman JF  Ray JD  Stedman DH 《Science (New York, N.Y.)》1987,235(4787):460-465

Acid deposition and photochemical smog are urban air pollution problems, and they remain localized as long as the sulfur, nitrogen, and hydrocarbon pollutants are confined to the lower troposphere (below about 1-kilometer altitude) where they are short-lived. If, however, the contaminants are rapidly transported to the upper troposphere, then their atmospheric residence times grow and their range of influence expands dramatically. Although this vertical transport ameliorates some of the effects of acid rain by diluting atmospheric acids, it exacerbates global tropospheric ozone production by redistributing the necessary nitrogen catalysts. Results of recent computer simulations suggest that thunderstorms are one means of rapid vertical transport. To test this hypothesis, several research aircraft near a midwestern thunderstrom measured carbon monoxide, hydrocarbons, ozone, and reactive nitrogen compounds. Their concentrations were much greater in the outflow region of the storm, up to 11 kilometers in altitude, than in surrounding air. Trace gas measurements can thus be used to track the motion of air in and around a cloud. Thunderstorms may transform local air pollution problems into regional or global atmospheric chemistry problems.  相似文献   

Rapid late Pleistocene incision of Atlantic passive-margin river gorges     

Reusser LJ  Bierman PR  Pavich MJ  Zen EA  Larsen J  Finkel R 《Science (New York, N.Y.)》2004,305(5683):499-502

The direct and secondary effects of rapidly changing climate caused large rivers draining the Atlantic passive margin to incise quickly into bedrock beginning about 35,000 years ago. Measured in samples from bedrock fluvial terraces, 10-beryllium shows that both the Susquehanna and Potomac Rivers incised 10- to 20-meter-deep gorges along steep, convex lower reaches during the last glacial cycle. This short-lived pulse of unusually rapid down-cutting ended by 13,000 to 14,000 years ago. The timing and rate of downcutting are similar on the glaciated Susquehanna and unglaciated Potomac Rivers, indicating that regional changes, not simply glacial meltwater, initiated incision.  相似文献   

Retrospective. Jürg Tschopp (1951-2011)     

O'Neill LA 《Science (New York, N.Y.)》2011,332(6030):679

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The mass disruption of Oort cloud comets     

Levison HF  Morbidelli A  Dones L  Jedicke R  Wiegert PA  Bottke WF 《Science (New York, N.Y.)》2002,296(5576):2212-2215

We have calculated the number of dormant, nearly isotropic Oort cloud comets in the solar system by (i) combining orbital distribution models with statistical models of dormant comet discoveries by well-defined surveys and (ii) comparing the model results to observations of a population of dormant comets. Dynamical models that assume that comets are not destroyed predict that we should have discovered approximately 100 times more dormant nearly isotropic comets than are actually seen. Thus, as comets evolve inward from the Oort cloud, the majority of them must physically disrupt.  相似文献   

Immunology. After the toll rush     

O'Neill LA 《Science (New York, N.Y.)》2004,303(5663):1481-1482

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Carbon and trace element fluxes in the pore water of an urban soil following greenwaste compost, woody and biochar amendments, inoculated with the earthworm Lumbricus terrestris     

Luke Beesley  Nicholas Dickinson 《Soil biology & biochemistry》2011,43(1):188-196

The benefits of adding composted organic materials to soils to enhance carbon storage could be countered by the mobilisation of some harmful pollutants commonly found in frequently degraded urban soils. Therefore non-composted materials could be a safer option. In the present study, carbon and trace element fluxes in soil pore water were studied in response to the surface mulch addition and the incorporation into an urban soil of greenwaste compost versus two non-composted amendments; a woody oversize material and biochar following inoculation with the vertical burrowing earthworm Lumbricus terrestris. The aim was to establish (i) to what extent the non-composted amendments impacted on mobility of soluble trace elements in the soil, compared to the composted amendment, and (ii) if/how this was regulated by earthworm activity.Both composted and non-composted amendments enhanced dissolved organic carbon (DOC) in soil pore water to ∼100-300 mg l⁻¹ in the upper depth of the soil profile above which they were applied as a mulch and similarly within the mesocosms in which they were mixed. Dissolved organic carbon, dissolved nitrogen (DTN) and trace metals, especially Cu and Pb, where enhanced to the greatest extent by greenwaste compost, because of strong co-mobilisation of metals by DOC. Biochar enhanced As and Cu mobility in the field profile and, additionally Pb in the mesocosms, with no effect on Cd. The woody, oversize amendment neither greatly increased DOC nor As, Cu, Pb or Zn mobility although, unlike the other amendments, earthworms increased DOC and Cd mobility when soils were amended with this material.This study concludes that non-composted amendments had a lower impact on DOC and thus trace element co-mobility than the composted greenwaste in this urban soil, whilst the general influence of earthworms was to reduce DOC and hence associated trace element mobility. In wider environmental terms the addition of non-composted materials to some urban soils, versus composted greenwaste could reduce the risk of mobilising potentially harmful elements, whilst usefully improving soil quality.  相似文献   

Levels and incidences of pesticide residues in various foods and animal feeds analyzed by the Luke multiresidue methodology for fiscal years 1982-1986     

M A Luke  H T Masumoto  T Cairns  H K Hundley 《Journal of the Association of Official Analytical Chemists》1988,71(2):415-433

During a 5 year period from 1982 to 1986, the FDA Los Angeles District Laboratory analyzed 19,851 samples of domestic and imported food and feed commodities for pesticide residues. A single, rapid, multiresidue method was used. The resultant data have been compiled showing the commodities sampled and the identity and range of levels of pesticide residues detected, including an indication of those residue findings that did not comply with U.S. federal tolerance levels. The residue data presented should not be viewed as being representative of the U.S. food supply; rather, the results are indicative of a surveillance- and compliance-oriented sampling of various food shipments collected by the Los Angeles District.  相似文献   

A Dairy Industry Information Cooperative Service System Based on a Production Process Ontology     

XU Yong  NIU Fang-qu  Luke Bergmann  WANG Zhi-qiang  WANG Jian 《中国农业科学(英文版)》2012,11(5):839-848

Agricultural information cooperative services (AICS) are now becoming an important aspect of agriculture informatization.This study offers an ontological conception of the agricultural production proce...  相似文献   

A systematic survey of loss-of-function variants in human protein-coding genes     

MacArthur DG  Balasubramanian S  Frankish A  Huang N  Morris J  Walter K  Jostins L  Habegger L  Pickrell JK  Montgomery SB  Albers CA  Zhang ZD  Conrad DF  Lunter G  Zheng H  Ayub Q  DePristo MA  Banks E  Hu M  Handsaker RE  Rosenfeld JA  Fromer M  Jin M  Mu XJ  Khurana E  Ye K  Kay M  Saunders GI  Suner MM  Hunt T  Barnes IH  Amid C  Carvalho-Silva DR  Bignell AH  Snow C  Yngvadottir B  Bumpstead S  Cooper DN  Xue Y  Romero IG; Genomes Project Consortium  Wang J  Li Y  Gibbs RA  McCarroll SA  Dermitzakis ET  Pritchard JK  Barrett JC 《Science (New York, N.Y.)》2012,335(6070):823-828

Genome-sequencing studies indicate that all humans carry many genetic variants predicted to cause loss of function (LoF) of protein-coding genes, suggesting unexpected redundancy in the human genome. Here we apply stringent filters to 2951 putative LoF variants obtained from 185 human genomes to determine their true prevalence and properties. We estimate that human genomes typically contain ~100 genuine LoF variants with ~20 genes completely inactivated. We identify rare and likely deleterious LoF alleles, including 26 known and 21 predicted severe disease-causing variants, as well as common LoF variants in nonessential genes. We describe functional and evolutionary differences between LoF-tolerant and recessive disease genes and a method for using these differences to prioritize candidate genes found in clinical sequencing studies.  相似文献   

The structure-activity relationship in herbicidal monosubstituted sulfonylureas   总被引：1，自引：0，他引：1  

Li ZM  Ma Y  Guddat L  Cheng PQ  Wang JG  Pang SS  Dong YH  Lai CM  Wang LX  Jia GF  Li YH  Wang SH  Liu J  Zhao WG  Wang BL 《Pest management science》2012,68(4):618-628

BACKGROUND: The herbicide sulfonylurea (SU) belongs to one of the most important class of herbicides worldwide. It is well known for its ecofriendly, extreme low toxicity towards mammals and ultralow dosage application. The original inventor, G Levitt, set out structure–activity relationship (SAR) guidelines for SU structural design to attain superhigh bioactivity. A new approach to SU molecular design has been developed. RESULTS: After the analysis of scores of SU products by X‐ray diffraction methodology and after greenhouse herbicidal screening of 900 novel SU structures synthesised in the authors' laboratory, it was found that several SU structures containing a monosubstituted pyrimidine moiety retain excellent herbicidal characteristics, which has led to partial revision of the Levitt guidelines. CONCLUSIONS: Among the novel SU molecules, monosulfuron and monosulfuron‐ester have been developed into two new herbicides that have been officially approved for field application and applied in millet and wheat fields in China. A systematic structural study of the new substrate–target complex and the relative mode of action in comparison with conventional SU has been carried out. A new mode of action has been postulated. Copyright © 2011 Society of Chemical Industry  相似文献