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991.
As part of the environmental recovery plan for the Mar Piccolo (Ionian Sea), a basin suffering especially from urban pollution, a study was planned on the modifications induced by the human activities to distinguish them from those due to the alternation of the seasons and the exchanges with the neighbouring basin of Mar Grande. The present paper deals with the chemical-physical characteristics of sea water and its particulate matter content is investigated as a part of this study. The physical, chemical and biological variables (stochastic variables for the model) are: chlorophyll a, proteins, carbohydrates, organic matter, dry weight, temperature, salinity, dissolved oxygen, pH, ultraviolet absorbance, phosphate, nitrite, nitrate, ammonia, silicate, photosynthetically available radiation (PAR) and energy. These variables have been sampled at 15 different stations during one year of monthly sampling. A preliminary analysis was carried out on the variables for detecting possible interactions among all the investigated parameters. To this purpose, and for all the variables, an original computer program for non-parametric statistical-evaluation and data-correlation was used to find correlation-guided hierarchy of variables. The relations among: Prot and Chl-a, Carb and Chl-a and OM and DW have been studied. The slopes of linear regression of (Prot, Chl-a) and (Carb, Chl-a) allowed us to detect different relations at different space-time areas. A nonlinear relation between OM and DW has been found as well. This treatment is a first approach to the construction of a mathematical model of the basin. Different areas, for sea water characteristics, were observed to occur in the basin, despite its small extension. This may be due to the reduced water exchanges and the different residential development along the coast. Innermost areas, less involved in the water mass circulation, were more affected by eutrophication.  相似文献   
992.
In the reconstruction of past climate using stable carbon isotope composition (δ13C) in tree ring, the responses of the stable carbon composition (δ13C) of multiple tree species to environmental factors must be known detailedly. This study presented two δ13C series in annual tree rings for Chinese hemlock (Tsuga chinensis Pritz) and alpine pine (Pinus densata Mast), and investigated the relationships between climatic parameters and stable carbon discrimination (Δ13C) series, and evaluated the potential of climatic reconstruction using Δ13C in both species, in a temperate-moist region of Chuanxi Plateau, China. The raw δ13C series of the two species was inconsistent, which may be a result of different responses caused by tree's inherent physiological differences. After removing the low-frequency effects of CO2 concentration, the high-frequency (year-to-year) inter-series correlation of Δ13C was strong, indicating that Δ13C of the two tree species were controlled by common environmental conditions. The Δ13C series of the species were most significantly correlated with temperature and moisture stress, but in different periods and intensity between the species. During the physiological year, the impacts of temperature and moisture stress on Δ13C occur earlier for Chinese hemlock (previous December to February for moisture stress and February to April for temperature, respectively) than for alpine pine (March to May for moisture stress and April to July for temperature, respectively). In addition, in temperatemoist regions, the control on Δ13C of single climatic parameter was not strongly dominant and the optimal multiple regressions functions just explained the 38.5% variance of the total. Therefore, there is limited potential for using δ13C alone to identify clear, reliable climatic signals from two species.  相似文献   
993.
在时序方差分析周期外推预测、双重检验逐步回归预测及其他相关问题的分析中,需要从若干因子的F-统计量中选取最大值进行 F-检验来确定这类问题的显著性.研究发现这种检验方法是有问题的、不准确的和会影响气候预测的准确性.这是由于 F-检验是对 F-分布的分位数的检验,其检验标准受到两个自由度的制约而成为变数;存在 F-统计量最大的因子与显著性最高的因子不对应问题.为此提出 F-信度检验法,它是对 F-分布的分布函数的检验.定义因子达到的 F-信度为 F-分布的分布函数值的百分数Pi=(1-α)×100%,它必须利用 F-统计量和两个自由度去计算.设显著性水平为α,则临界 F-信度值为Pα=(1-α)×100%.在理论上这种检验法的临界 F-信度值是唯一的,因而可从若干 F-信度值中选取最大值进行检验.实践证明这种检验法可明显提高对因子显著性问题的判别能力和气候预测水平.  相似文献   
994.
The Mianning-Dechang REE metallogenetic belt is among the most important of its kind in China. The typical geologic features and multiple economically- valuable components in this belt have caught attention from more and more geologists. Wide investigations from petrology, petrochemistry to rare earth and trace element geochemistry, have been carried out recently, and a large quantity of geochemical data have already been obtained[1―11]. Maoniuping REE deposit is the largest of this belt,…  相似文献   
995.
吉林省四平市山门中生代流纹岩柱状节理特征及成因意义   总被引:5,自引:0,他引:5  
赵明  刘福臣 《吉林地质》2003,22(3):57-61
四平市山门中生代流纹岩发育完整的柱状节理,这一独特的地质景观倍受众多游客和地学工作者的瞩目。本文通过理论分析结合野外实际观测资料,论述了流纹岩及柱状节理特征,并阐述了其成因方面的特殊意义。  相似文献   
996.
塔什库尔干碱性杂岩体形成时代及其地质意义   总被引:11,自引:0,他引:11  
帕米尔构造结是青藏高原变形最强烈的地区之一,区内新生代岩浆侵入活动发育,既有壳源岩浆侵位,也有幔源岩浆广泛分布。根据岩石学和地球化学研究,侵入岩可分为幔源碱性正长岩和壳源花岗岩2个系列。幔源碱性正长岩总体上由暗色正长岩、浅色正长岩和碱性花岗岩组成,其成因为岩浆不不混溶作用。壳源花岗岩类成分单一,具有低共熔岩浆属性,其成因可能与幔源岩浆对地壳加热有关。利用碱性正长岩的钾长石进行^40Ar-^39Ar法获得3个分别为大约23Ma、13Ma和8Ma坪年龄数据,结合岩体地质特征,认为它们分别代表了碱性正长岩和花岗岩的侵位时间以及后期构造热事件。研究结果表明,岩浆活动是帕米尔构造结形成和帕米尔强烈变形的主要因素之一。  相似文献   
997.
河南省三门峡市曲里石英闪长斑岩中锆石的阴极发光图像显示其具有两种类型,即具有细微震荡环带的自形锆石和具有继承核与生长边的浑圆状锆石。具有细微震荡环带岩浆锆石的SHRIMPU-Pb年龄(117.7±1.6Ma)显示该石英闪长斑岩体的形成时间为早白垩世;浑圆状锆石核部SHRIMPU-Pb谐和年龄为620Ma和219Ma,这表明该石英闪长斑岩的母岩浆可能起源于经历了超高压变质作用改造的华南地块基底物质的部分熔融。  相似文献   
998.
生物成因煤层气的生成及其资源意义   总被引:13,自引:1,他引:13  
生物成因煤层气一般可分为原生和次生生物成因,它们在生成机理上有许多相似之处,但也有所不同,导致后期保存和同位素组成上的差异。研究指出,原生生物成因气不能被大量保留在煤层中,气田中的生物成因气多为次生生物成因气;次生生物成因煤层气分布比较普遍,含量较为丰富,且生物成因煤层气埋藏深度浅,勘探成本低,因此次生生物成因煤层气具有不容忽视的巨大资源潜力。  相似文献   
999.
宣达盐盆富钾富矿卤水产于四川盆地东北部黄金口背斜群南段付家山构造近高点,以深层卤水形式赋存于3260m左右的下三叠统嘉陵江组五段和中统雷口坡组一段(T1j5-T2L1)盐系的碳酸盐岩储层中。卤水与海水蒸发系列相比,K+含量异常高,达25 96g L,超过海水钾盐沉积阶段,也超过综合利用和单独开采品位,为国内外罕见的液态钾矿资源。且富含I-,B3+,Li+,Rb+,Sr2+等多种有用组分,品质优异,构成优质化工原料水,为一种综合性富钾富矿液态矿藏,经济价值极高。卤水为沉积变质水和固态钾盐溶滤水的复合成因。开发利用将可为农业提供优质钾肥,缓解我国钾盐资源不足,并可提供多种短缺的化工产品,对固态钾盐找矿具有重要现实意义。  相似文献   
1000.
By means of SEDEX, ASPILA and XRF, depth-dependent changes of different phosphorus forms in sediment cores from specific areas of the offshore Changjiang Estuary (Yangtze Estuary) in 1998 were analyzed. Results show that contents of total phosphorus (TP), organic-phosphorus (OP) and iron-phosphorus (Fe-P) decreased down-core, while those of absorbed-phosphorus (Ad-P) and calcium-phosphorus (Ca-P) increased. The distribution tendency of detritus-phosphorus (De-P) is not obvious. Results also show that TP, Fe-P and OP contents at Meso station of the Changjiang Estuary and Hangzhou Bay are higher than that of the other stations. This suggests that the pollutants carried by the Changjiang and the Qiantang rivers from inland have affected the natural environment in offshore area. TP, Fe-P and OP contents of each station become higher from bottom to top, indicating the amount of the terrestrial pollutants carried by the two rivers has been enhanced since the last 30-50 years. Ad-P, Ca-P, Fe-P and OP are all active phosphorus in sediments, and their re-cycling in sediment is closely related to each other.  相似文献   
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