974 resultados para CH17-317


Relevância:

10.00% 10.00%

Publicador:

Resumo:

N, P and SiO3-Si in the Changjiang mainstream and its major tributaries and lakes were investigated in the dry season from November to December, 1997, and in the flood season in August and October, 1998. An even distribution of SiO3-Si was found along the Changjiang River. However, the concentrations of total nitrogen, total dissolved nitrogen, dissolved inorganic nitrogen, nitrate and total phosphorus, total particulate phosphorus increased notably in the upper reaches, which reflected an increasing impact from human activities. Those concentrations in the middle and lower reaches of the Changjiang River were relatively constant. Dissolved N was the major form of N and the particulate P was the major form of P in the Changjiang River. The molar ratio of dissolved N to dissolved P was extremely high (192.5-317.5), while that of the particulate form was low (5.6-37.7). High N/P ratio reflected a significant input of anthropogenic N such as N from precipitation and N lost from water and soil etc. Dissolved N and P was in a quasi-equilibrium state in the process from precipitate to the river. In the turbid river water, light limitation, rather than P limitation, seemed more likely to be a controlling factor for the growth of phytoplankton. A positive linear correlationship between the concentration of dissolved N and the river's runoff was found, mainly in the upper reaches, which was related to the non-point sources of N. Over the past decades, N concentration has greatly increased, but the change of P concentration was not as significant as N. The nutrient fluxes of the Changjiang mainstream and tributaries were estimated, and the result showed that the nutrient fluxes were mainly controlled by the runoff, of which more than a half came from the tributaries. These investigations carried out before water storage of the Three Gorges Dam will supply a scientific base for studying the influences of the Three Gorges Dam on the ecology and environment of the Changjiang River and its estuary.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The seasonal evolution of dissolved inorganic carbon (DIC) and CO2 air-sea fluxes in the Jiaozhou Bay was investigated by means of a data set from four cruises covering a seasonal cycle during 2003 and 2004. The results revealed that DIC had no obvious seasonal variation, with an average concentration of 2035 mu mol kg(-1) C in surface water. However, the sea surface partial pressure of CO2 changed with the season. pCO(2) was 695 mu atm in July and 317 mu atm in February. Using the gas exchange coefficient calculated with Wanninkhof's model, it was concluded that the Jiaozhou Bay was a source of atmospheric CO, in spring, summer, and autumn, whereas it was a sink in winter. The Jiaozhou Bay released 2.60 x 10(11) mmol C to the atmosphere in spring, 6.18 x 10(11) mmol C in summer, and 3.01 x 10(11) mmol C in autumn, whereas it absorbed 5.32 x 10(10) mmol C from the atmosphere in winter. A total of 1.13 x 10(11) mmol C was released to the atmosphere over one year. The behaviour as a carbon source/sink obviously varied in the different regions of the Jiaozhou Bay. In February, the inner bay was a carbon sink, while the bay mouth and the Outer bay were carbon sources. In June and July, the inner and Outer bay were carbon sources, but the strength was different, increasing from the inner to the outer bay. In November, the inner bay was a carbon source, but the bay Mouth was a carbon sink. The outer bay was a weaker CO2 Source. These changes are controlled by many factors, the most important being temperature and phytoplankton. Water temperature in particular was the main factor controlling the carbon dioxide system and the behaviour of the Jiaozhou Bay as a carbon source/sink. The Jiaozhou Bay is a carbon dioxide source when the water temperature is higher than 6.6 degrees C. Otherwise, it is a carbon sink. Phytoplankton is another controlling factor that may play an important role in behaviour as a carbon source or sink in regions where the source or sink nature is weaker.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Data collected from 12 marine monitoring stations in Daya Bay from 1982 to 2004 reveal a substantial change in the ecological environment of this region. The average N/P ratio increased from 1.377 in 1985 to 49.09 in 2004. Algal species changed from 159 species of 46 genera in 1982 to 126 species of 44 genera in 2004. Major zooplankton species went from 46 species in 1983 to 36 species in 2004. The annual mean biomass of benthic animals was recorded at 123.10 gm(2) in 1982 and 126.68 g m(2) in 2004. Mean biomass and species of benthic animals near nuclear power plants ranged froth 317.9 g m(2) in 1991 to 45.24 g m(2) in 2004 and from 250 species in 1991 to 177 species in 2004. A total of 12-19 species of hermatypic corals and 13 species of mangrove plants were observed in Daya Bay from 1984 to 2002. 2008 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In coastal ecosystems, suspension-cultured bivalve filter feeders may exert a strong impact on phytoplankton and other suspended particulate matter and induce strong pelagic-benthic coupling via intense filtering and biodeposition. We designed an in situ method to determine spatial variations in the filtering-biodeposition process by intensively suspension-cultured scallops Chlamys farreri in summer in a eutrophic bay (Sishili Bay, China), using cylindrical biodeposition traps directly suspended from longlines under ambient environmental conditions. Results showed that bivalve filtering-biodeposition could substantially enhance the deposition of total suspended material and the flux of C, N and P to the benthos, indicating that the suspended filter feeders could strongly enhance pelagic-benthic coupling and exert basin-scale impacts in the Sishili Bay ecosystem. The biodeposition rates of 1-yr-old scallops varied markedly among culture sites (33.8 to 133.0 mg dry material ind.(-1) d(-1)), and were positively correlated with seston concentrations. Mean C, N and P biodeposition rates were 4.00, 0.51, 0.11 mg ind.-1 d-1, respectively. The biodeposition rates of 2-yr-old scallops were almost double these values. Sedimentation rates at scallop culture sites averaged 2.46 times that at the reference site. Theoretically, the total water column of the bay could be filtered by the cultured scallops in 12 d, with daily seston removal amounting to 64%. This study indicated that filtering-biodeposition by suspension-cultured scallops could exert long-lasting top-down control on phytoplankton biomass and other suspended material in the Sishili Bay ecosystem. In coastal waters subject to anthropogenic N and P inputs, suspended bivalve aquaculture could be advantageous, not only economically, but also ecologically, by functioning as a biofilter and potentially mitigating eutrophication pressures. Compared with distribution-restricted wild bivalves, suspension-cultured bivalves in deeper coastal bays may be more efficient in processing seston on a basin scale.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

宁夏枸杞(Lycium barbarum L.)的果实为常用的传统中药,其有效成分主要为黄酮类化合物。研究发现,黄酮类成分具有止咳、平喘、祛痰之功效,并能扩张冠状动脉及降低血胆固醇,有增强心脏收缩、减少心脏搏动数及明显的抗氧化等作用。有研究表明,枸杞干叶中黄酮含量高于枸杞干果。因而,作者对不同采收时期青海产宁夏枸杞叶中总黄酮含量进行了测定和比较,以期为扩大黄酮类成分的药源及确定枸杞叶的最佳采收期提供一定的参考依据。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

通过对贵州省务川汞矿区土法炼汞的矿石、冶炼矿渣中汞含量的测定,运用质量平衡原理,计算土法炼汞过程中汞释放因子,估算土法炼汞过程中汞的年释放通量. 贵州务川汞矿区土法炼汞的回收率为7814 %~9316 % ,释汞因子为619 %~3211 % ,土法炼汞的年释汞量为317~916t . 结果表明,务川汞矿区土法炼汞是该地区大气的最主要人为释汞源.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

针对目前最常用的液- 液萃取、ICP- M S 测定法检测表生水体中微量稀土元素方法, 研究了不同pH值条件下, 酸性膦(65%HDEHP 和35%H2M EHP) 自表生水体中萃取稀土元素(REEs) 的回收率。结果表明, 在pH1~ 4 的范围内, 不同性质的水体(湖泊、河流、地下水) 有不同的REEs 回收率。其中湖水在pH 118~ 317 有90% 以上的回收率, 最高回收率为93164%; 河水在pH 211~ 315 范围内有90% 以上的回收率, 最高回收率为95152%; 地下水仅在pH 113~ 115 时回收率超过90% , 最高回收率为97161%。说明在萃取不同表生水体中稀土元素时, 需要调到特定的pH 值才能得到最好的萃取效果。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

On the basis of the geological field investigations and isotope geochronological studies the Sm-Nd isochron age (513 Ma?0 Ma), Rb-Sr isochron age (511 Ma? Ma) and K-Ar age (312-317 Ma) of the Dapingzhang spilite-keratophyre formation in Yunnan Province are presented. From these geochronological data it is evidenced that this suite of volcanic rocks was formed in the Cambrian and the parent magma was derived from a depleted mantle, which was influenced by crustal contamination and/or seawater hydrothermal

Relevância:

10.00% 10.00%

Publicador:

Resumo:

运用魔角旋转核磁共振结合红外光谱及X射线衍射等手段,研究了苏州高岭石的560-1600℃热转变产物,主要获得以下结论:(1)高岭石-偏高岭石-莫来石的转变系列的确存在结构上的连续性。其转变经历了几个阶段;脱羟阶段(400-600℃),偏高岭石阶段(600-800℃),相分离阶段(800-1100℃),莫来石阶段(1100-1600℃)。(2)莫来石形成过程没有出现Al2O3的大量分凝,但存在SiO2的分凝。(3)偏高岭石-莫来石转变过程的中间相为Al-Si尖晶石和准莫来石。(4)引起1000℃放热反应的主要因素是准莫来石的形成。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

济阳坳陷CO2气藏主要发育在高青-平南深断裂中南段和阳信次级凹陷西北缘及商店火山岩穹隆构造内。气藏中CO2气体浓度为69%~97%,δ^13CCO2值为-5.67‰~-3.35‰,CH4/^3He值为(1.01~5.65)×10^8,^3He/^1He值为(2.80~4.49)×10^-6,即R/Ra为2.00~3.21,^40Ar/^36Ar值为317~1791,CO2/^3He值为(0.25~2.61)×10^9。以上地球化学数据表明,济阳坳陷气藏中CO2主要来源于地慢,且慢源CO2在成藏过程中有损失,或者有壳源CO2的加入,特别是部分碳酸盐岩变质成因CO2的加入。在对CO2气来源定性分析的基础上,还需要在各来源的定量区分和CO2气藏的成藏及其与岩浆活动的时空匹配关系等方面作进一步的研究.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

济阳坳陷是自三叠纪以来欧亚板块、印度洋板块和库拉-太平洋板块相互作用形成的一个叠置在华北板块上的中、新生代坳陷,位于华北板块东部,东临著名的郯庐大断裂。在坳陷中部的高青-平南断裂地区和西部惠民凹陷发现了大量的CO2气藏,近年来受到很多地质学家和地学工作者的注意。本文在前人资料和自己研究成果的基础上,详细分析了济阳坳陷CO2气藏的气体地球化学特征和惠民凹陷地区火成岩中方解石脉的碳氧同位素特征,为厘定区域内二氧化碳气的来源提供理论依据。通过系统的研究,获得了以下成果和结论: 济阳坳陷CO2气藏中,13CCO2值为-5.67~-3.35‰,主频率段为-4.76~-4.32‰,指示CO2气的主体为无机成因;而气藏中CH4的13C为-54.39~-35.00‰,主频率段为-54.39~-51.55‰,显示以有机成因为主。 济阳坳陷CO2气藏中3He/4He比值为2.80~4.49×10-6,主频率段为3.55~4.49×10-6;40Ar/36Ar值为317~1791,变化较大,主要分布在770~1791;13CCO2值与3He/4He成正相关关系;CO2/3Hem值介于0.769~10.2×109之间,主体为1.86~3.51×109,且CO2/3Hem值与CO2含量一定程度地正相关;CH4/3He比值介于1.01~5.65×108之间,接近于幔源流体值,而远低于壳源特征值,且CH4/3He比值随3He/4He比值减少而增加。以上种种特征都说明,济阳坳陷非烃类气藏中气体具有多来源的特征,但CO2主体是无机成因,并主要来自地幔,少量来自有机成因;在成藏过程,幔源CO2通过转变为CH4或者碳酸盐岩而丢失了部分CO2,壳源CO2和其它烃类加入到气藏中;花沟地区的气体地球化学特征与众不同,可能存在碳酸盐地层变质脱气产生的CO2的混入,但具体原因尚待进一步研究。 济阳坳陷惠民凹陷地区火成岩中方解石脉的碳同位素数据-3.30~3.14‰,氧同位素数据12.64~16.97‰,二者成正相关关系,同时也位于前人所说的沉积混染趋势线上,具有较为典型的壳幔混合特征。这些方解石脉的碳同位素又明显的位于海相碳酸盐岩范围之内,说明脉体的主要碳源不是深源的,而是来自于海相底层。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

济阳坳陷位于渤海湾盆地东南部,是中国东部重要的含油气坳陷之一,同时也是重要的天然气气藏富集区。坳陷中部高青-平南断裂从孔店组沉积时开始发育,至明化镇末期断裂停止活动。岩浆活动导致断裂带两侧天然气的分布较为复杂:既有纯烃类气藏,也有纯非烃类气藏,还有混合气藏。已有的工作主要是着重气藏形成的地质条件、成藏模式以及盆地演化过程中的构造-热事件中的岩浆活动对CO2气藏形成的总体影响。对烃类气藏成因研究不足,仅简单的归于油型气;同时天然气藏与火山活动之间的关系研究不够,本论文在天然气、火山岩地球化学基础上,探讨天然气的来源,综合分析了火山活动对天然气形成的影响。论文获得的主要认识如下: 1. 根据花沟地区天然气碳及稀有气体地球化学特征结合该地区火山岩流体包裹体组分,认为高青、花沟地区烃类气藏应该是有机与无机成因相结合的混合气体,其有机来源主要是来自油型气;无机来源主要是地幔脱气以及发生氧化还原反应生成的无机成因气;而平南、平方王地区烃类气主要为油型气。 2. CO2气藏主要是无机幔源成因。据CO2体积百分含量、CO2碳同位素(δ13CCO2)表明CO2是无机成因,氦同位素R/Ra、40Ar/ 36Ar表明区内CO2成因与无机幔源成因密切相关。不同地区幔源包裹体中的CO2含量不同,研究表明后期火山岩浆更富CO2。高青地区CO2气以幔源岩浆脱气成因为主;平方王和平南地区为幔源岩浆脱气和壳源岩石化学混合成因。 3. 稀有气体同位素组成说明该地区He、Ar为壳幔混合成因。40Ar/36Ar值317~3178之间,氦同位素R/Ra在1.44~5.96之间;在3He/4He-40Ar/36Ar以及3He/4He-4He/20Ne图中均处于壳源与幔源混合成因区域。 4. 岩浆活动对天然气成藏效应体现在对天然气形成与成藏的影响。 5. 高青-平南断裂带幔源流体活动方式和活动强度存在时间和空间上的差异是造成高青-平南断裂带天然气分布不同最主要的原因。CO2气藏更容易在两个断裂的交汇处形成,说明了断裂为天然气的运移提供通道。