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51.
沂水龙泉站金矿与成矿有关的主要地质体以新太古代泰山岩群与燕山期花岗岩金含量较高。对黄铁矿地球化学的研究资料表明:早期黄铁矿为金矿物的主载矿物。稀土元素分布特征反映了成矿流体由早期相对中偏高温(260—330℃)和还原的环境向晚期低温和氧化环境演变的趋势。对方解石、石英包裹体的研究表明:包裹体均一温度变化范围较宽,在107~550℃之间,可分为125—160℃,177—230℃和260—330℃3个温度峰值集中区,分别反映了以中温石英为代表的早期成矿阶段(260~330℃),以中低温石英和方解石为代表的中期成矿阶段(177—260℃)和以低温方解石为代表的晚期成矿阶段(125—160℃)。其冰点温度变化于-2- -8.6℃之间,盐度在3.39wt%-12.39wt%之间。 相似文献
52.
EXPERIMENTAL STUDIES ON THE ROLE OF PLANKTIVOROUS FISHES IN THE ELIMINATION OF MICROCYSTIS BLOOM FROM DONGHU LAKE USING ENCLOSURE METHOD 总被引:11,自引:0,他引:11
谢平 《中国海洋湖沼学报》1996,(3)
The hypertrophic subtropic Donghu Lake's dense water bloom(of mainly Microcystis Anaabaena andOscillatoria)that occurred annually from the beginning of the 1970s, has disappeared since 1985. The infiuenceof planktivorous fishes (silver and bighead carps) on the water bloom was studied for three years usingthe enclosure method. The enclosures stocked densely with bighead and/or silver carp were free of waterbloom during the experimental period. The water bloom that appeared in the fish-free enclosures was completelyeliminated in 10-20 days by introduction of silver and/or bighead carp(grass carp was not effectivein controlling water bloom).This study showed clearly that grazing pressure by planktivorous fishes is a keyfactor in eliminating water bloom from the lake. 相似文献
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The measurement of natural sulfur emissions from soils and vegetation: Three sites in the Eastern United States revisited 总被引:6,自引:0,他引:6
Paul D. Goldan William C. Kuster Daniel L. Albritton Fred C. Fehsenfeld 《Journal of Atmospheric Chemistry》1987,5(4):439-467
Sulfur fluxes from bare soils, naturally vegetated surfaces and from several agricultural crops were measured at two mid-continent sites (Ames, Iowa and Celeryville, Ohio) and from one salt water marsh site (Cedar Island, North Carolina) during a field program conducted jointly by the NOAA Aeronomy Laboratory, Washington State University Laboratory for Atmospheric Research and University of Idaho Department of Chemistry during July and August 1985. The sites were chosen specifically because they had been characterized by previous studies (Anejaet al., 1979; Adamset al., 1980, 1981). The NOAA gas chromatographic/dynamic-enclosure measurements yielded bare soil surfaces fluxes from the mid-continent sites composed predominantly of COS, H2S, CH3–S–CH3 (DMS) and CS2, all of which were strongly correlated with air temperature. Net fluxes of approximately 5 and 15 ng S/m2 min were observed in Iowa and Ohio, respectively, at appropriate weighted mean July temperatures. These fluxes are roughly a factor of 10 smaller than the earlier measurements, the greatest difference being in the measurement of the H2S flux. The presence of growing vegetation was observed to measurably increase the flux of H2S, significantly increase that of DMS and to decrease that of COS. Sulfur fluxes in the Cedar Island environs were observed to be both spatially and temporally much more variable and to include CH3SH as a measurable contributor. Net fluxes, composed predominantly of DMS and H2S, were estimated to be about 300 ngS/m2min during August; again about a factor of 10 lower than previous estimates. All measurements were corroborated to within about a factor of 2 by those of the other participating laboratories. 相似文献
58.
通过制作生态系围隔实验装置,采用模拟围隔实验的方法,测定N、P营养盐的降解系数.基于夏秋两季杭州湾北岸近岸海域的现场水样采集,测出杭州湾北岸近岸海域无机氮的生物降解系数在0.121~0.269 d-1范围内,均值为0.225 d-1,测得活性磷酸盐的降解系数在0.031~0.179 d-1,均值为0.08 d-1.考虑到实验室静态模拟环境与真实海区状况的差异,采用保守估计法和 Bosko 公式进行处理,最终计算得出的0.21 d-1和0.05 d-1可分别作为杭州湾北岸海域无机氮和活性磷酸盐的实际降解系数. 相似文献
59.
利用箱式法对科尔沁地区围封和放牧条件下的沙质草地净生态系统碳交换量(NEE)进行研究,以探讨围封、放牧对NEE的影响。结果显示:(1)围封17年样地的NEE显著小于围封22年样地的,围封22年样地的显著小于放牧样地的(P<0.01)。(2)在植物生长季内,围封样地总体表现出碳汇功能,放牧样地表现出碳源功能。(3)从碳净固定的量来看,围封17年沙质草地的净碳固定能力强于围封22年的;而围封22年比围封17年的沙质草地的在净碳固定方面持续的时间较长。(4)不同环境因子对不同处理NEE的影响程度不尽相同,其线性组合最大可解释NEE的变异依次为围封22年(39.5%)>围封17年(32.1%)>放牧(21.2%)。 相似文献
60.
放牧及围封是引起沙质草地生态系统变化的重要因素。对科尔沁地区放牧和围封不同年限的沙质草地进行土壤呼吸动态测定与分析,结果表明:(1)植物生长初期土壤呼吸速率日平均值,围封样地的显著大于放牧样地的(p<0.05);植物生长末期土壤呼吸速率日平均值,放牧样地的显著大于围封样地的(p<0.05)。围封17年和围封22年样地的土壤呼吸速率日平均值相比较,7月上旬之前,围封17年样地的较围封22年样地的大,而7月中旬以后,围封22年样地的较围封17年样地的大,且差异均显著(p<0.05)。(2)土壤呼吸速率的季节动态对放牧和围封的响应过程相似,但围封引起的变异相对较小;土壤呼吸速率季节平均值,围封22年样地的显著大于围封17年的(p<0.05)和放牧的(p<0.01),围封17年样地的大于放牧的(p>0.05),故围封可以增强土壤CO2的排放,且在一定的时间内,土壤CO2的排放速率与围封时间正相关。(3)土壤温度和土壤体积含水率可解释土壤呼吸速率的变异从大到小依次为放牧(58%)>围封22年(39%)>围封17年(28%)。 相似文献