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971.
对东风盐场9个站位卤水中由藻类植物产生的可溶性糖浓度的变化规律及其与海盐产量和质量之间的关系进行了研究。结果表明,各站位可溶性糖含量的变化范围为0.7-124.3mg/L,以6月份最高,2月份最低;卤水中可溶性糖在111mg/L-215mg/L范围内,结晶盐的产量随卤水中可溶性糖含量的增加而提高,但同时降低了NaCl的含量,并增加了可溶性杂质及水分的含量,从而降低了盐质。初始可溶性糖浓度为111mg/L、137mg/L、160mg/L、193mg/L和215mg/L的25.4°Be’的卤水,在日照下实验12天,其对应结晶盐的NaCl含量分别为91.66%、90.63%、90.48%、90.23%和88.46%,可溶性杂质的含量分别为3.05%、3.32%、3.33%和4.54%。 相似文献
972.
973.
GB/T19000—ISO9000系列标准等同采用了国际通行的质量管理标准。贯彻该标准不仅能提高地勘单位质量管理水平、产品质量,也为地勘单位开展质量体系认证、产品质量认证提供技术依据,增强地勘单位参与国内、外市场竞争的能力。目前在贯标工作中制约因素主要有:地质成果形成特点及地质成果质量管理的特殊性、地质工作投入的减少及现有地质技术人员素质等。然而,贯标是我国经济体制改革深入的要求,是地勘队伍走出低谷、求生存和发展的基本手段。贯标和建立新的经济运行机制之间存在有相互依存、相互促进的关系。 相似文献
974.
Spectrum analyses of water quality time series have been carried out for five hydrometric stations including Wuhan hydrometric
station of the Changjiang(Yangtze) River, etc. The fluctuations of Ca2+, Mg2+ and HCO
3
−
concentrations in river water under different physical geography conditions have about two-year cycle which is corresponding
to hydrometeorological quasi-biannual-oscillation (QBO). Na+, Cl− SO
4
2−
have about two-year cycle in the area lightly affected by human activities while two-year cycle doesn’t exist in the area
heavily affected by human activities. All the fluctuations of major ions have about three-month cycle. The river diseharge
fluctuation accounts for 43.9%, 45.1%, 54.3%, 33.9%, 30.3% and 42.7% of the variance of Ca2+, Mg2+, HCO
3
−
, Na+, Cl−, SO
4
2−
, respectively, at Wuhan from 1962 to 1985. According to the spectrum characteristic of major ions, the duration of the time
series has to be at least 13 years for trend analysis of monthly water quality data.
Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 49671017).
Biography: XIA Xing-hui(1971-), female, a native of Hunan Province, Ph. D. Her research interest includes environmental chemistry. 相似文献
975.
Grazing is common in the foothills fescue grasslands and may influence the seasonal soil‐water patterns, which in turn determine range productivity. Hydrological modelling using the soil and water assessment tool (SWAT) is becoming widely adopted throughout North America especially for simulation of stream flow and runoff in small and large basins. Although applications of the SWAT model have been wide, little attention has been paid to the model's ability to simulate soil‐water patterns in small watersheds. Thus a daily profile of soil water was simulated with SWAT using data collected from the Stavely Range Sub‐station in the foothills of south‐western Alberta, Canada. Three small watersheds were established using a combination of natural and artificial barriers in 1996–97. The watersheds were subjected to no grazing (control), heavy grazing (2·4 animal unit months (AUM) per hectare) or very heavy grazing (4·8 AUM ha?1). Soil‐water measurements were conducted at four slope positions within each watershed (upper, middle, lower and 5 m close to the collector drain), every 2 weeks annually from 1998 to 2000 using a downhole CPN 503 neutron moisture meter. Calibration of the model was conducted using 1998 soil‐water data and resulted in Nash–Sutcliffe coefficient (EF or R2) and regression coefficient of determination (r2) values of 0·77 and 0·85, respectively. Model graphical and statistical evaluation was conducted using the soil‐water data collected in 1999 and 2000. During the evaluation period, soil water was simulated reasonably with an overall EF of 0·70, r2 of 0·72 and a root mean square error (RMSE) of 18·01. The model had a general tendency to overpredict soil water under relatively dry soil conditions, but to underpredict soil water under wet conditions. Sensitivity analysis indicated that absolute relative sensitivity indices of input parameters in soil‐water simulation were in the following order; available water capacity > bulk density > runoff curve number > fraction of field capacity (FFCB) > saturated hydraulic conductivity. Thus these data were critical inputs to ensure reasonable simulation of soil‐water patterns. Overall, the model performed satisfactorily in simulating soil‐water patterns in all three watersheds with a daily time‐step and indicates a great potential for monitoring soil‐water resources in small watersheds. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
976.
977.
安徽省淮北平原位于该省北部,平原西部阜阳市地面沉降中心最大沉降量1501mm,采水型地面沉降进一步扩大,推测平原西部地区已发生大范围的地面沉降.淮北平原区饮水型高氟地方病广布,地氟病区占全区总面积的40%.其中轻病村17942个,占病村总数79.5%;中度病村4529个,占20.0%;重病村148个,占病村总数0.65%.病区乡人口总数1344.4万人,占淮北平原总人口的66%.区域地下水水位持续下降,地下水质量不断劣化.本文通过对以上主要水环境问题的论述,提出了平原区今后工作方向的建议. 相似文献
978.
刘店煤矿岩浆侵入与煤质特征初探 总被引:1,自引:0,他引:1
岩浆侵入是煤矿常见的构造现象之一,岩浆侵入后对煤层与煤质的影响也十分明显,岩浆侵入不仅破坏了煤层的原生结构、厚度、构造,还改变了煤质.本文依据刘店煤矿的勘探资料,对淮北矿业集团公司筹建矿井--刘店煤矿的岩浆侵入与煤质特征进行了探讨,以期为刘店煤矿的生产提供有益的帮助. 相似文献
979.
980.