Can oyster restoration reverse cultural eutrophication in Chesapeake Bay?     

Carl F. Cerco  Mark R. Noel 《Estuaries and Coasts》2007,30(2):331-343

We investigated the hypothesis that effects of cultural eutrophication can be reversed through natural resource restoration via addition of an oyster module to a predictive eutrophication model. We explored the potential effects of native oyster restoration on dissolved oxygen (DO), chlorophyll, light attenuation, and submerged aquatic vegetation (SAV) in eutrophic Chesapeake Bay. A tenfold increase in existing oyster biomass is projected to reduce system-wide summer surface chlorophyll by approximately 1 mg m⁻³, increase summer-average deep-water DO by 0.25 g m⁻³, add 2100 kg C (20%) to summer SAV biomass, and remove 30,000 kg d⁻¹ nitrogen through enhanced denitrification. The influence of osyter restoration on deep extensive pelagic waters is limited. Oyster restoration is recommended as a supplement to nutrient load reduction, not as a substitute.  相似文献   

安徽宣城矿集区长山铅锌多金属矿床成矿流体特征及成因     

王静  张达玉  黄家龙  孟翔  张飞  侯舒雅  易洪  WHITENoelClarence 《矿床地质》2023,42(4):791-810

长山铅锌多金属矿床位于长江中下游成矿带宣城矿集区东北部,文章在对该矿床开展详细的地质调查和岩相学研究基础上,对代表性矿化蚀变矿物(石英、方解石)开展了流体包裹体测温、激光拉曼光谱和氢、氧、碳稳定同位素分析。长山铅锌多金属矿床矿化蚀变组合从早到晚可以分为矽卡岩-氧化物阶段、早硫化物阶段和晚硫化物阶段。矿物流体包裹体温度和盐度测算显示,长山矿床的成矿流体温度和盐度从矽卡岩-氧化物阶段(315～382℃,w(NaCl)_eq为14.04%～16.24%)→早硫化物阶段(220～347℃,w(NaCl)_eq为4.49%～15.86%)→晚硫化物阶段(163～306℃,w(NaCl)_eq为1.40%～11.10%)逐渐降低。石英和闪锌矿中包裹体的δD和δ¹⁸O值分别为-89.5‰～-67.8‰和-3.2‰～7.62‰,方解石中δ¹³C和δ¹⁸O值分别是-6.8‰～-1‰和10.6‰～17.1‰,同位素特征指示长山矿床的成矿流体为岩浆水与海相碳酸盐中富含有机质流体混合,...  相似文献   

Petrographic and geochemical characterization of weathered materials developed on BIF from the Mamelles iron ore deposit in the Nyong unit,South-West Cameroon     

Teutsong  Tessontsap  Temga  Jean Pierre  Enyegue  Armelle Ayissi  Feuwo  Nicodème Noel  Bitom  Dieudonné 《中国地球化学学报》2021,40(2):163-175

Acta Geochimica - Iron ore deposits hosted by Precambrian banded iron formation (BIF) are the most important source of mineable iron. In Cameroon, they are located in the southern part of the...  相似文献   

Dust pollution caused by an extreme Santa Ana wind event     

Álvarez  Christian A.  Carbajal  Noel  Pineda-Martínez  Luis F. 《Natural Hazards》2022,110(3):1427-1442

In arid and semiarid regions from the southwestern USA and vast areas of northwestern Mexico, Santa Ana wind events modify the environment with high temperatures, very low humidity, and dust storms representing a recurrent phenomenon that triggers asthma and other respiratory diseases. While research has emphasized Santa Ana wind effects on the USA side, northwestern Mexico has been less investigated. Numerical modeling of a severe dust storm in November 2018, applying the Weather Research and Forecasting model coupled with a chemistry module (WRF-Chem), revealed that erosion, transport, and dust storms extend along the peninsula and the Gulf of California. Santa Ana winds eroded large areas, transported desert conditions to urban zones, causing high dust concentrations and reducing the relative humidity below 10%, deteriorating climatic conditions favorable to wellness. In Tijuana, Mexicali, Ensenada, San Diego, and Los Angeles, PM10 and PM2.5 concentrations (particle matter with diameter below 10 µm and 2.5 µm) reached values over 2000 µg/m3 for PM10, with daily mean concentrations well above national standards, leading to poor air quality and representing a health threat even in short-term exposure. This Santa Ana event transported dust particles several hundreds of kilometers over urban areas, the Gulf of California, and the Pacific Ocean. Severe soil deterioration was simulated within the study area, reaching dust emissions above 700,000 t, including croplands from the northern part of Baja California and Sonora's coastal area.

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A note on tidal current rotation     

Noel?CarbajalEmail author 《Ocean Dynamics》2004,54(5):531-536

The rotational form of the vertically averaged equations of motion is applied to derive a formula, linear friction included, which establishes a direct connection between sense of rotation of tidal currents and features of tidal amphidromic systems. Two factors in the formula, called and , influence the sense of rotation of tidal currents; the factor involves the frequency of the tidal signal , the Coriolis parameter f, and the linear friction coefficient r. The sign of the cross-product of the logarithm of sea-surface elevation (), and phase () gradients determines whether the factor favors clockwise or anticlockwise sense of rotation. is a unit vector and is the angle between ln and . The limits ||0, ||0 and 0 lead to a clockwise sense of rotation in the Northern Hemisphere. 0 favors anticlockwise rotation in the Northern Hemisphere. Friction and low frequencies favor an anticlockwise sense of rotation. The theory works well in semi-enclosed regions like the North Sea. Although only linear friction and sea-surface elevation gradients were considered, there are ocean regions where the agreement between theory and observations is also good.Responsible Editor: Hans Burchard  相似文献   

DNA Repair in fish from polluted estuaries     

Noel G. Espina  Peddrick Weis   《Marine environmental research》1995,39(1-4)

A cancer-resistant fish, the mummichog Fundulus heteroclitus, was assayed for its ability to repair damage to its genome caused by an alkylating agent. Although DNA may be alkylated at several sites, the persistence of O⁶-alkylguanine has been correlated with carcinogenesis. O⁶-alkylguanine, if not repaired before the next round of replication, can lead to base transition mutations. The DNA repair protein, O⁶-alkylguanine transferase (O⁶-AGT), removes alkyl groups from the O⁶ position of guanine.Populations from polluted and relatively pristine estuaries were compared. O⁶-AGT activity was assayed by incubating extracts of liver from feral fish with previously methylated calf thymus DNA. After incubation, the DNA was depurinated by acid hydrolysis and the O⁶-methylguanine (O⁶-MeG) was separated and quantified by HPLC. Activity was measured by the reduction of O⁶-MeG in the incubated sample as compared to controls.Both populations demonstrated O⁶-AGT activity in their livers. Both had activity levels which were not as high as those seen in mammals. The reference population had O⁶-AGT levels inversely correlated with size, which is expected since younger fish have more DNA synthesis in their livers. The polluted population did not have a significant correlation with size, and generally exhibited less activity than the reference population. The lower O⁶-AGT activity in the polluted population suggests an environmental impact, and does not answer the question as to why this species is cancer resistant.  相似文献   

Remarkable Link between Projected Uncertainties of Arctic Sea-Ice Decline and Winter Eurasian Climate   总被引：1，自引：0，他引：1  

Hoffman H.N.CHEUNG  Noel KEENLYSIDE  Nour-Eddine OMRANI  Wen ZHOU 《大气科学进展》2018,35(1):38-51

We identify that the projected uncertainty of the pan-Arctic sea-ice concentration(SIC) is strongly coupled with the Eurasian circulation in the boreal winter(December–March; DJFM), based on a singular value decomposition(SVD) analysis of the forced response of 11 CMIP5 models. In the models showing a stronger sea-ice decline, the Polar cell becomes weaker and there is an anomalous increase in the sea level pressure(SLP) along 60°N, including the Urals–Siberia region and the Iceland low region. There is an accompanying weakening of both the midlatitude westerly winds and the Ferrell cell,where the SVD signals are also related to anomalous sea surface temperature warming in the midlatitude North Atlantic.In the Mediterranean region, the anomalous circulation response shows a decreasing SLP and increasing precipitation. The anomalous SLP responses over the Euro-Atlantic region project on to the negative North Atlantic Oscillation–like pattern.Altogether, pan-Arctic SIC decline could strongly impact the winter Eurasian climate, but we should be cautious about the causality of their linkage.  相似文献   

'Out there'?'In here'? Domesticating critical geography   总被引：1，自引：0，他引：1  

Noel Castree 《Area》1999,31(1):81-86

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Global climate change and the effect of conservation practices in US agriculture   总被引：1，自引：0，他引：1  

Noel D. Uri 《Environmental Geology》2000,40(1-2):41-52

 Increase in the use of conservation practices by agriculture in the United States will enhance soil organic carbon and potentially increase carbon sequestration. This, in turn, will decrease the net emission of carbon dioxide. A number of studies exist that calibrate the contribution of various individual, site-specific conservation practices on changes in soil organic carbon. There is a general absence, however, of a comprehensive effort to measure objectively the contribution of these practices including conservation tillage, the Conservation Reserve Program, and conservation buffer strips to an change in soil organic carbon. This paper fills that void. After recounting the evolution of the use of the various conservation practices, it is estimated that organic carbon in the soil in 1998 in the United States attributable to these practices was about 12.2 million metric tons. By 2008, there will be an increase of about 25%. Given that there is a significant potential for conservation practices, which could lead to an increase in carbon sequestration, there are a number of policy options that can be pursued. These include education and technical assistance, financial assistance, research and development, land retirement, and regulation and taxes. Received: 27 December 1999 · Accepted: 14 March 2000  相似文献   

Numerical experiments on the long-term morphodynamics of the Colorado River Delta     

Yovani Montaño  Noel Carbajal 《Ocean Dynamics》2008,58(1):19-29

The interaction among tidal currents, sediment transport, and long-term changes of the sea bottom in the Colorado River Delta have been investigated applying a two dimensional nonlinear hydrodynamic-numerical finite differences model. The system was forced by the dominant M ₂ tidal component at the open boundary. We carried out calculations to study the morphodynamics of the actual bathymetry caused by the bedload sediment transport. To investigate the origin of actual morphological features, we performed experiments using a smoothed bathymetry, in which the islands Montague, Gore, and Pelícano were eliminated. Under the imposed tidal hydrodynamics, the results indicate that the bedload transport contributes significantly in the genesis of sandbanks and in the formation and maintaining of the Montague and Gore Islands.  相似文献