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351.
正The Sichuan Basin,with an area of about 20×104 km2,is situated at 102.5°~110°E and 27.67°~32.67°N.The underground brine resources in Sichuan basin are a type of comprehensive liquid mineral resource.Pingluo 相似文献
352.
The rainfall and infiltration elements of the hydrological cycle in arid regions are characterized by temporal and spatial variations that are random and sporadic. Consequently, the chloride concentration in rainfall has a similar behaviour. Despite this, the classical chloride mass balance (CMB) approach only employs arithmetic and weighted averages for recharge estimation. In this paper, the classical CMB method is modified by taking into account some perceived deficiencies in the methodology. The modified CMB method takes into consideration additional statistical parameters, namely variances and the correlation coefficient between variables concerned based on the application of the perturbation method. Strategic aquifer planning in the Kingdom of Saudi Arabia requires a quick method for estimating groundwater recharge in order to determine the temporal management of available water resources. To demonstrate the difference between the classical and the refined CMB methods, both were applied to a representative basin, i.e. Wadi Yalamlam, in the western part of Saudi Arabia. Based on the refined calculations, recharge to groundwater is found to be 11% of the effective annual rainfall. This refined method provides higher recharge rates because it takes into account the actual variability in the variables concerned and can, thus, improve the accuracy of future groundwater recharge estimation studies. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
353.
INTRODUCTIONAccumulatedevidencessuggestedaclosecorrelationbetweenneoplasticdiseaseofaquaticor ganismsandtheincreasingreleaseofgenotoxinsbyanthropogenicactivitiesintoaquaticenvironment(Mix ,1 986;Gardneretal.,1 991 ;GESAMP ,1 991 ) .Ithas,therefore,becomenecessarytoe… 相似文献
354.
Cryoturbated Upper Chalk is a dichotomous porous medium wherein the intra‐fragment porosity provides water storage and the inter‐fragment porosity provides potential pathways for relatively rapid flow near saturation. Chloride tracer movement through 43 cm long and 45 cm diameter undisturbed chalk columns was studied at water application rates of 0·3, 1·0, and 1·5 cm h?1. Microscale heterogeneity in effluent was recorded using a grid collection system consisting of 98 funnel‐shaped cells each 3·5 cm in diameter. The total porosity of the columns was 0·47 ± 0·02 m3 m?3, approximately 13% of pores were ≥ 15 µm diameter, and the saturated hydraulic conductivity was 12·66 ± 1·31 m day?1. Although the column remained unsaturated during the leaching even at all application rates, proportionate flow through macropores increased as the application rate decreased. The number of dry cells (with 0 ml of effluent) increased as application rate decreased. Half of the leachate was collected from 15, 19 and 22 cells at 0·3, 1·0, 1·5 cm h?1 application rates respectively. Similar breakthrough curves (BTCs) were obtained at all three application rates when plotted as a function of cumulative drainage, but they were distinctly different when plotted as a function of time. The BTCs indicate that the columns have similar drainage requirement irrespective of application rates, as the rise to the maxima (C/Co) is almost similar. However, the time required to achieve that leaching requirement varies with application rates, and residence time was less in the case of a higher application rate. A two‐region convection–dispersion model was used to describe the BTCs and fitted well (r2 = 0·97–0·99). There was a linear relationship between dispersion coefficient and pore water velocity (correlation coefficient r = 0·95). The results demonstrate the microscale heterogeneity of hydrodynamic properties in the Upper Chalk. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
355.
改性提高膨润土阳离子交换容量研究 总被引:2,自引:0,他引:2
研究了焙烧活化、酸活化、氯化钠活化、溴化十六烷基三甲铵活化等改性方法对膨润土阳离子交换容量的影响。结果表明,450℃焙烧2 h,膨润土阳离子交换容量可提高30%以上,0.01 mol.L-1氯化钠和0.3 mol.L-1溴化十六烷基三甲铵活化处理均可使膨润土阳离子交换容量提高10%以上,0.1 mol.L-1盐酸活化处理对提高膨润土的阳离子交换容量效果不明显,还深入讨论了改性提高澎润土阳离子交换容量的机理。 相似文献
356.
A continuous marine fish cell line RSBF(i.e.Red Sea Bream Fin)was utilized to screen the cytotoxicity and genotoxicity of polyethylenimine(PEI)and nickel cholride(NiCl2)in this study on the deleterious effects of aquatic genotoxins on fish.At the 0.01 to 1μgml concentration tested,PEI had acute toxicity to the treated RSBF cells(IC50=1.12,0.92,0.88 and 0.64μg/ml PEI for time 0 h,24 h,48 h and 72 h after treatment,respectively)and markedly inhibited their proliferation in a dose-dependent manner.At the 0.001 to 5 μmol/L concentration tested,NiCl2 posed no acute toxicity but significantly stimulated their growth(107?214?of control).Random amplified polymorphic DNA(RAPD)technique was used to detect the genotoxic effects of PEI and NiCl2 by comparing the RAPD banding patterns of the control and treated cells.RAPD analysis indicated that at the concentrations tested,PEI was more genotoxic than NiCl2 to RSBF cells;that there was a slight dose-dependent response in the genotoxic effect of PEI bue not NiCl2;and that RAPD technique might provide a sensitive,non-specif-ic gentoxic endpoint.And the potent cytotoxicity and genotoxicity of PEI on fish cells showed that we should be cautious in utilizing it as gene vector in fish gene transfer and human gene therapy. 相似文献
357.
Evaluation of low-rank coals as raw material for Fe and Ca organomineral fertilizer using a new EDXRF method 总被引:2,自引:2,他引:0
A rapid and reliable method for analyzing Fe and Ca in low-rank Greek coals was developed. The presence of Fe and Ca is of importance regarding the potential use of these coals as raw material for organomineral fertilizers. Samples were collected from the main Greek lignite deposits and standards were prepared using Atomic Absorption Spectroscopy (AAS), which were also employed in the Energy Dispersive X-ray Fluorescence (EDXRF) method. The new method offers the advantages of being timesaving, non-destructive and can be easily incorporated in a fertilizer production line. Analysis of low-rank Greek coals demonstrated a significant Fe and Ca content ranging from 0.15 to 1.97 wt.% for Fe and from 0.04 to 2.51 wt.% for Ca. When both EDXRF and AAS techniques were applied, the Fe and Ca concentration values differed less than 5%, demonstrating that both techniques are reliable for low-rank coals in the above concentration range. These EDXRF results may be used as a preliminary test regarding the application of Greek coals in organomineral fertilizer production, given that in these coals iron and calcium are the most abundant metals. 相似文献
358.
针对尼日利亚北部乍得湖盆地降雨入渗补给地下水的问题,选择典型区域开展土壤剖面取样工作,采用氯离子平衡法计算各剖面降雨入渗补给量,并结合野外调查、钻探等工作研究影响降雨入渗补给的主要因素。结果表明:4个取样点(Y1、Y2、Y3、Y4)土壤剖面年平均降雨入渗补给量分别为4.9、1.5、7.9、26.2 mm/a,平均值为10.1 mm/a,年平均降雨入渗补给率仅为0.72%、0.22%、1.17%、3.87%,平均值为1.49%;研究区降雨入渗补给量很少,降雨对地下水资源的补给有限,地下水的主要补给来源为Hadejia河;研究区蒸散发量大,植物根系发达、吸水能力强,地表入渗水分多在表层土壤中或泥质层与风积砂层交界面上消耗于蒸发蒸腾,最终散失到大气中。在人类活动严重改变Hadejia河水文情势的背景下,研究区这种独特的地下水补给特征导致地下水位快速下降,使得区内正面临较严重的地下水资源枯竭问题。 相似文献
359.
根据亚钛还原钒酸铵滴定法的测定原理,对样品溶样、过滤洗涤、还原氧化、滴定等操作方法做了改进。磷酸-盐酸-过氧化氢混合酸低温溶解样品,离心分离过滤,亚钛还原UO22+,过量亚钛用次溴酸钠氧化,尿素亚硝酸钠混合液进一步氧化未被次溴酸钠氧化的微量低价杂质。在小体积(10 mL)范围内,用低浓度钒酸铵标准溶液进行滴定操作测定微量铀,滴定终点清晰,相对标准偏差(RSD,n=5)为0.05%~0.07%,方法测定下限为0.001%,适于矿石和矿渣中0.001%~0.01%铀的测定。方法简便、快速,能满足生产和科研的需要。 相似文献
360.