A comparison of RT-PCR and Northern blot analysis in quantifying metallothionein mRNA levels in killifish exposed to waterborne cadmium     

Lisa Ann Elizabeth Kaplan  Kathleen Van Cleef  Isaac Wirgin  Joseph F. Crivello 《Marine environmental research》1995,39(1-4)

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Selected chemical contaminants in surface sediments of Commencement Bay and the Tacoma Waterways, Washington, USA     

Donald W. Schults  Steven P. Ferraro  George R. Ditsworth  Kathleen A. Sercu 《Marine environmental research》1987,22(4)

Eight metals, 21 organic priority pollutants, and 11 other contaminants and contaminant-related sediment characteristics were measured in surface sediments (upper 2 cm) at 21 locations in Commencement Bay and the Tacoma Waterways, Washington. Summary statistics were calculated and statistical approaches (analysis of variance, multiple comparisons tests, cluster analysis and principal component analysis) were applied to subsets of the data to classify sediment contamination. Overall sediment contamination was highest in the Sitcum, City and Hylebos Waterways, intermediate in Commencement Bay, at the entrances to the Tacoma Waterways and in the outer reaches of the Blair and Hylebos Waterways, and lowest at the Blair Waterway turning basin, the mouth of the Puyallup River and at a reference site near Browns Point. High concentrations of some contaminants appeared to be related to proximity to sources of contaminants. Depositional vectors, and chemical adsorption processes may also influence the spatial distribution of sediment contamination in the study area.Results of simple and partial correlation analyses indicate that arsenic, iron and manganese may be more closely associated with the clay fraction, while cadmium, copper and polynuclear aromatic hydrocarbons may be more closely associated with the total organic carbon content of sediments. We were unable to discriminate statistically between the affinity of chromium, lead, zinc and phthalates with the % clay or the total organic carbon content of sediments.  相似文献   

The distribution of geothermal fields along the East Pacific Rise from 13°10′ N to 8°20′ N: Implications for deep seated origins     

Kathleen Crane  Frank Aikman III  Jean-Paul Foucher 《Marine Geophysical Researches》1988,9(3):211-236

In 1983 a combined SeaMARC I, Sea Beam swath mapping expedition traversed the East Pacific Rise from 13°20 N to 9°50 N, including most of the Clipperton Transform Fault at 10°15 N, and a chain of seamounts at 9°50 N which runs obliquely to both the ridge axis and transform fault trends. We collected temperature, salinity and magnetic data along the same track. These data, combined with Deep-Tow data and French hydrocasts, are used to construct a thermal section of the rise axis from 13°10 N to 8°20 N.Thermal data collected out to 25 km from the rise axis and along the Clipperton Transform Fault indicate that temperatures above the rise axis are uniformly warmer by 0.065°C than bottom water temperatures at equal depths off the axis. The rise axis thermal structure is punctuated by four distinct thermal fields with an average spacing of 155 km. All four of these fields are located on morphologic highs. Three fields are characterized by lenses of warmed water 20 km in length and 300 m thick. Additional clues to hydrothermal activity are provided in two cases by high concentrations of CH₄, dissolved Mn and ³He in the water column and in another case by concentrations of benthic animals commonly associated with hydrothermal regions.We use three methods to estimate large-scale heat loss. Heat flow estimates range from 1250 MW to 5600 MW for one thermal field 25 km in length. Total convective heat loss for the four major fields is estimated to lie between 2100 MW and 9450 MW. If we add the amount of heat it takes to warm the rest of the rise axis (489 km in length) by 0.065.°C, then the calculated axial heat loss is from 12,275 to 38,525 MW (19–61% of the total heat theoretically emitted from crust between 0 and 1 m.y. in age).  相似文献   

Marine vs. terrigenous organic matter in Louisiana coastal sediments: The uses of bromine:organic carbon ratios     

Lawrence M. Mayer  Linda L. Schick  Mead A. Allison  Kathleen C. Ruttenberg  Samuel J. Bentley 《Marine Chemistry》2007

Recent data on the sources of organic carbon buried in the ocean have emphasized the probable importance of terrigenous organic matter in burial budgets of deltaic depocenters. The many markers used to assess relative importance of marine vs. terrestrial sources each have ambiguities. We use the ratio of bromine to organic carbon (Br:OC) as a source indicator for organic matter in the Mississippi delta. Progressive increases in bromine concentrations from the river to the slope indicate increasing content of marine-derived organic matter. Quantitative estimates of marine vs. terrigenous organic matter using Br:OC ratios in a two-endmember mixing model are consistent with recent estimates using a combination of three other source markers [Gordon, E.S., Goñi, M.A. 2003. Sources and distribution of terrigenous organic matter delivered by the Atchafalaya River to sediments in the northern Gulf of Mexico. Geochim. Cosmochim. Acta, 67:2359–2375]. The Br:OC vs. δ¹³C relationship indicates seaward increase in δ¹³C without proportionate incorporation of marine organic matter, consistent with recent arguments that isotopically depleted terrestrial detritus derived from C3 plants is separated from C4-derived terrigenous organic matter during transport. Decreasing Br:OC ratios downcore at many sites that have significant amounts of marine organic matter indicate that the marine organic matter is preferentially lost during burial diagenesis. This preferential loss constrains the contribution of organic matter burial in deltaic environments to global removal of Br.  相似文献   

Corrigendum to: Why is the relative abundance of Asterionella formosa increasing in a Boreal Shield lake as nutrient levels decline?     

Branaavan Sivarajah  Kathleen M. Rühland  Andrew L. Labaj  Andrew M. Paterson  John P. Smol 《Journal of Paleolimnology》2016,56(1):93-93

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Beyond techno-science: Transgenic maize in the fight over Mexico’s future     

Kathleen McAfee 《Geoforum》2008,39(1):148-160

Disputes about genetically engineered crops are linked to wider debates about the globalization of agro-food systems and its consequences for food security, social equity, and rural life. Biotechnology expert discourse rarely addresses these wider issues. An exception is the assessment of transgenic maize by the NAFTA Commission on Environmental Cooperation (CEC), which recommended a moratorium on Mexican imports of US-grown maize. Controversy about “contamination” of indigenous maize varieties by US-grown transgenic corn has been intensified by rising Mexican discontent with the terms of regional economic integration. In this context, scientists and officials were pressured to consider not only risks to maize biodiversity but also the ecological, and cultural characteristics of maize in its Mexican settings and the implications of asymmetric power in North American agricultural trade. In contrast to most narrowly-framed biotechnology risk assessments, the review took account of interventions by rural social movements. While the new moratorium was not adopted by the state, continuing conflicts over GMOs in Mexico have blocked introduction of transgenic maize and have enlarged the political space for debate over Mexico’s development direction. These conflicts reflect the differing interests of various state actors and economic sectors with regard to trade liberalization. They also reveal contrasting food-system paradigms: further agricultural modernization, export competition, and food-import dependence versus an alternative vision of revitalized rural life, farmers’ rights, and national food sovereignty.  相似文献   

Geochemical characteristics of gold-related granitoids in southwestern New Brunswick, Canada     

Xue-Ming Yang  David R. Lentz  Guoxiang Chi  Kathleen G. Thorne 《Lithos》2008,104(1-4):355-377

Two groups of granitoids associated with gold mineralization in the Appalachian orogen of southwestern New Brunswick are recognized: a Late Silurian to Early Devonian (423–396 Ma) granodioritic to monzogranitic series (GMS), and a Late Devonian (370–360 Ma) granitic series (GS). The GMS granitoids are relatively low in silica, calc-alkaline, metaluminous to weakly peraluminous, and show characteristics of normal (oxidized) to reduced I-type granites depending on the properties of country rocks. They may have been derived from partial melting of lower crustal rocks triggered by underplated basaltic magmas; and country rocks bearing reduced organic carbon and/or graphite may have played an important role in the reduction of normal I-type intrusions to reduced I-type, which is essential in the formation of intrusion-related gold systems. In contrast, the GS granites, although calc-alkaline and metaluminous to peraluminous, are relatively rich in silica, incompatible elements, and high field strength elements. They are fractionated I-type granites, and are probably related to the coeval Mount Douglas granite in the Saint George batholith through fractional crystallization. Their parental magmas may have been derived from partial melting of quartzofeldspathic sources at relatively low temperatures. Both GMS and GS intrusions are orogenic, although some of them display the affinity of those emplaced into a within-plate environment. The origin of intrusion-related gold systems in this region appears to be controlled by several factors, including magma sources, magmatic processes, redox conditions (country-rock nature), and local structural regimes.  相似文献   

Quechua II contraction in the Ayacucho intermontane basin: Evidence for rapid and episodic Neogene deformation in the Andes of central Perú     

James M. Wise  Donald C. Noble  Kathleen A. Zanetti  Terry L. Spell 《Journal of South American Earth Sciences》2008,26(4):383-396

In the Ayacucho basin of central Perú the regional Quechua II contractional deformation is bracketed by ⁴⁰Ar/³⁹Ar isotopic age determinations to a maximum duration of about 300,000 years, and probably less than 150,000 years, centered on 8.7 Ma. The strongly deformed Huanta Formation beneath the Quechua II angular unconformity was deposited during a period of extension that began before 9.05 ± 0.05 Ma. Deposition of a thick succession of alluvial fan deposits interbedded with flows of basaltic andesite in the Tingrayoc Member continued up to about 8.76 ± 0.05 Ma with the later part of the sedimentary record reflected by lacustrine deposits of the Mayocc Member. The upper limit on contractional deformation is constrained by an age of 8.64 ± 0.05 Ma on a unit of tuff near the base of the Puchcas volcanics, which in places was deposited upon near-vertical beds of the Huanta Formation. The Ayacucho Formation was deposited, locally unconformably, upon the Puchcas volcanics beginning slightly before 7.65 ± 0.10 Ma.Extended periods of neutral to tensional stress interrupted by rapid well-developed pulses of contractional deformation demonstrate the episodic behavior of Andean orogeny in Perú. The very short duration for the Quechua II event implies that driving forces for episodic deformation may be related to coupling along the orogen boundaries and strain accumulation and release mechanisms in the continental crust instead of much longer-term variations in the configuration of converging plates.  相似文献   

Response of closed basin lakes to interannual climate variability     

Kathleen Huybers  Summer Rupper  Gerard H. Roe 《Climate Dynamics》2016,46(11-12):3709-3723

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Correspondence     

Mrs Kathleen Sherrard  Dr Hermann Jaeger 《Australian Journal of Earth Sciences》2013,60(2):351-352

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