N—P—K复肥四元体系KCl—KH_2PO_4—CO（NH_2）_2—H_2O在

基于Ｎ—Ｐ—Ｋ三元复肥的物理化学基础．首次测定了四元体系ＫＣｌ—ＫＨ２ＰＯ４—ＣＯ（ＮＨ２）２在２９８．２Ｋ时的溶度及饱和溶液的折光率，绘制了体系的溶度图和折光率──组成图。该体系的溶度图属低共饱型，平衡固相为组份化合物，低共饱点组成为：１００ｇ饱和溶液中．ＫＣｌ１３．３１ｇ，ＫＨ２ＰＯ４３．３３ｇ，ＣＯ（ＮＨ２）２４７．２６ｇ，Ｈ２Ｏ３６．１０／１０ｇ。     

Simulation of chloride migration rates in Paleo Pennar Delta Region, Coastal Andhra Pradesh, India

 Quaternary alluvial aquifers in the paleo Pennar delta region of Andhra Pradesh (Long. 80°0′ and 80°12′; Lat. 14°40′ and 14°20′) constitute an important coastal strip, with potential fresh groundwater resources and several well fields in operation. The lineament patterns and traces of paleo channels provide basic information on the configuration and boundaries of paleo delta and the possible neotectonic movements in the region. The paleo delta region is essentially characterized by freshwater aquifer systems at the near-surface depths, (up to 50 m from ground level) with transmissivity values in the system ranging from 1200 to 2500 m²/day. This groundwater system has been subjected to heavy draft situation over the last two decades, parlicularly near the outer rim of the delta where an unlined brackish-water canal runs parallel to the coast imparting chloride contamination to the adjoining fresh aquifers. A two-dimensional solute transport model solution was applied to assess chloride migration rates inland under different hydraulic stresses, combining finite difference solution of flow equation and the method of characteristic solution of solute transport equation. Groundwater flow and chloride migration patterns/rates were obtained for different simulated stress events in the delta system, and measures required to protect the freshwater resources ara outlined. Received: 2 January 1997 · Accepted: 4 November 1997     

恒离子强度下KCl+K_2SO_4+H_2O溶液中氯化钾活度系数的测定

我们已用钾离子敏感膜电极和银—氯化银电极组成无液界电池,通过测量其电动势的方法测定了25℃时恒定离子强度(I=0.1,0.3,0.5和0.7)条件下,KCl—K_2SO_4水溶液中KCl的平均质量摩尔浓度活度系数。结果表明,KCl的平均活度系数的对数与混合溶液中每个电解质的离子强度分量,在该条件下服从哈内特线性关系。已用最小二乘法计算了相应的哈内特系数。在相应恒离子强度(I=0.1,0.3,0.5和0.7)条件下,其值分别为0.0430,0.0356,0.0329和0.0320。     

在恒离子强度下KCl+KNO_3水溶液中KCl的活度系数及KNO_2~0的缔合常数测定

作者用无液界电池电动势法测定了25℃恒离子强度(I=0.1,0.3,0.5和0.7)条件下KCl+KNO_3水溶液中KCl的平均质量摩尔浓度标度的活度系数,发现其活度系数的对数与混合溶液中KNO_3的浓度服从下列公式的关系: Lgγ1±=Lgγ_(1±)~0-a_(12)m_2-β12m_2~2且用最小二乘法求得了各离子强度条件下相应的哈奈特系数。还用Pitzer公式计算了混合溶液中KCl的平均活度系数及超额自由能,计算的活度系数与实验值之间的标准偏差为±0.006。较高的超额自由能表明该体系有较大的混合效应,同时表明在低浓度下K~+-NO_3离子对也可能发生较强的相互作用。已用简单的循环逼近法求算了KNO_3~0的化学计量缔合常数,其结果可用下列经验公式表示: LnK~*=a+bI_e已求得在海水离子强度(I_c=0.68)下KNO_3~0之K~*=2.4,用外推法求得25℃时KNO_3~0的热力学缔合常数值K_a=0.40。     

Semi‐Micro Reflux Procedure for Minimization of Chloride Interference by COD Determination

In this study, a semi‐micro procedure for the COD (Chemical Oxygen Demand) was undertaken to allow the measurement of effluent samples with a high chloride content. It was found that the COD values for standard and effluent samples, corresponded closely to those obtained using the standard method of Burns and Marshall. When the method was applied to samples of industrial wastewater, with a very high chloride content, the recommended procedure proved to be accurate and precise, with RSDs of 6% and 4.3% for the standard and effluent solutions, respectively. The required amount of hazardous reagents was similar to that found in the standard closed reflux method. It was also possible to determine the total amount of oxidized halides. The use of this low‐cost, laboratory‐made system made it unnecessary to acquire an expensive, imported analytical system, while maintaining a high level of accuracy in the determinations.     

On the history of chloride concentrations in the River Lippe (Germany) and the impact on the macroinvertebrates

The River Lippe is situated at the northern part of the rhenish-westphalian coal mining area, Germany and has a long history of being affected by mining water discharge. There has, however, been a massive decrease in the discharge of mining water over the past few decades. While early in the last century concentrations of up to 3500 mg l⁻¹ of chloride were observed, the mean concentration is now below 400 mg l⁻¹. At the same time the water quality has improved greatly so factors other than chloride concentration may be influencing the macroinvertebrate community.Macroinvertebrate data collected from three sites along the River Lippe was analyzed for a change in the occurrence of salt tolerant species in an area where mining water discharge ended in 2000. It was found that also during the period of discharges the macroinvertebrate community was dominated by freshwater species and therefore the impact of mining water discharges in the upper River Lippe is considered to be minor.It was also found that for some species (Nais elinguis, Bithynia tentaculata and Gammarus tigrinus) their proposed salinity preference did not correlate with their occurrence in the field. This may be an area that requires further research.     

Profiles of chloride and stable isotopes in pore-water obtained from a 2000 m-deep borehole through the Mesozoic sedimentary series in the eastern Paris Basin

Water stable isotopes and chloride profiles in pore-water through more than 800 m of sediments were obtained from a 2000 m-deep borehole (EST 433) drilled by Andra in the eastern Paris Basin. Vapour exchange method and aqueous leaching were used to obtain the stable isotope and chloride concentrations of pore-water from 24 rock samples. Petrophysical measurements included water contents, grain densities and porosities of the studied formations. Pore-water and some groundwater samples collected during the drilling are mainly of meteoric origin: they plot near the Global Meteoric Water Line, distributed between heavy-isotope depleted Oxfordian groundwater and enriched Triassic groundwater, in good agreement with previous data. The δ²H and δ¹⁸O values describe curved profiles in the Callovo-Oxfordian formation, and show an increase with depth below this formation (Dogger and Liassic). Similar trends were observed for the chloride concentrations, except in the Liassic formation where they are more or less constant. The low chloride concentrations in the basal Jurassic layers indicate that the source of salinity to the Dogger aquifer is likely the middle Liassic formation and not the Triassic salt as previously suggested. A preliminary modelling exercise showed that currently available diffusion parameters (diffusion coefficients and accessible porosities) might be used to properly simulate these exchanges for deuterium. This is not the case for chloride, perhaps because the used values for anion accessible porosity were not relevant and/or the applied modelling conditions were unsuitable.     

Hand dug wells in Namibia: An underestimated water source or a threat to human health?

The rural population of parts of northern and western Namibia uses hand dug wells for their domestic water supply, partly because no other source (e.g., deep tube wells) is available, but also as a substitute for pipeline water that is often perceived as being too expensive. The water quality of these wells is usually not monitored or controlled, thus a study has been carried out in four study areas in Namibia: southern Omusati/Oshana area, Okongo/Ohangwena area, Omatjete/Omaruru area, Okanguati/Kunene area. Hand dug wells have been tested for on-site parameters: electric conductivity, pH and temperature while samples were taken for major inorganic constituents and several minor and trace constituents including fluoride and nitrate. In addition a sampling campaign in 2010 included the determination of coliform bacteria and Escherichia coli. Results were classified according to the Namibian Water Guidelines. The constituents making the water unfit for human consumption are fluoride, nitrate, sulphate and total dissolved solids. Contamination by E. coli was indicated in nearly all wells that are used for livestock watering. For the Omatjete/Omaruru study area an isotope based study on the source of nitrate has indicated manure as a source. The range of recharge values obtained for the studied villages ranges from 1 mm/a to locally more than 100 mm/a. Overall the water resource in the shallow perched aquifers in the study areas is in many places inappropriate for human consumption. Treatment to improve the quality or introduction of protection measures is necessary to bring this resource to an acceptable quality according to national and/or international standards.     

Impact of tectonic erosion by subduction processes on intensity of arc volcanism

Abstract According to new estimates, more than 2 km³ of terrestrial material is transported every year with the subducting lithospheric plates to depths greater than 20-30 km. A comparable amount of subducted material is partly restored to the nearby margins through underplating, diapirism or forearc volcanism; partly rejuvenated through arc and back-arc magmatism; and the rest is recycled into the deep mantle. This study emphasizes the connection between the consumption of some arcs and the intensity of arc volcanism. In many cases (Japan, Peru, Izu-Bonin, Guatemala), interruption in tectonic erosion of the margin is followed by a hiatus of arc volcanism. The delay between the presumed cause (i.e. absence of subducted arc-type crust) and the response (i.e. lack of explosive volcanism) corresponds to the time required for the subducting slab to reach the melting depth (i.e. 2-4 million years). Alternately, intense tectonic erosion of the margin is followed by paroxysms of arc volcanism. Crustal contamination of volcanic rocks may be caused directly by magma sources which may contain arc material derived from the subcrustal erosion of the margin.     

Solubility of the assemblage albite+K-feldspar+andalusite+quartz in supercritical aqueous chloride solutions at 650 °C and 2 kbar

The solubility of the high grade pelite assemblage albite+K-feldspar+andalusite+quartz at 650 °C and 2 kbar was determined in aqueous solutions over a total chloride range of 0.01–3 m_Cl^tot using rapid-quench hydrothermal technique. The concentration of Na, K, Si, and Al was determined in the fluid phase after quench. The K/Na ratio was determined by approaching the equilibrium from below and above. It is 0.34 at low chloride concentrations and decreases slightly to 0.31 with increasing total chloride. Silica and aluminum concentrations were determined only from undersaturation. The silica solubility is found to be independent of chloride concentration and is 0.13 molal. Aluminum is nearly independent of chloride concentration decreasing only slightly from 0.0015 to 0.0007 molal. Comparison of the experimental data with thermodynamic model calculations demonstrates that the silica concentrations are well predicted, while significant differences exist between individual databases for Al speciation and its total concentration. Al concentrations are underestimated by up to 10 to 15 orders of magnitude using the SUPCRT92 database. Predicted K/Na ratios are underestimated by up to 30%. The best predictions achieved for this simplified high-grade pelite assemblage are those using the SUPCRT92 database with revised thermodynamic data for feldspars and K- and Na-species (J. Phys. Chem. Ref. Data 24 (1995) 1401) and additional Al-species (Am. J. Sci. 295 (1995) 1255; Geochim. Cosmochim. Acta 61 (1997) 2175). The use of ideal mixing for neutral complexes in combination with the extended Debye–Hückel activity model for the charged species yields the most compatible speciation model.