Three types of zeolite (NaP1 zeolite, analcime and chabazite) were hydrothermally synthesized by reacting fly ash with NaOH solution. The maximum conversion rate from fly ash to single zeolite is about 40%-75%, and the total conversion rate 60%-80%. The synthesis experimental results indicate that factors including vortex, viscosity, temperature, reaction time, and NaOH concentration in the reaction system strongly affect the type and conversion rate of zeolites. The batch experiments of removing Cu2+, Pb2+ and Cd2+ from wastewaters show that the adsorption capacity of zeolites synthesized is higher than that of fly ash. Keywords: coal fly ash, hydrothermal synthesis, zeolite, heavy metal, wastewater, adsorption.

Geomaterials can be cost-effective sorbents for use in water treatment. In this study, a heavily-weathered Tertiary soil from Xinzhou, China was used as a sorbent for defluoridation of high-fluoride drinking water. The soil is com-posed of quartz, feldspar, illite and goethite, with an Fe oxide content of 6.75%. Batch and column experiments were done to characterize the F-removal properties and to develop an optimal activation and regeneration procedure. The soil can be regenerated following a simple base-acid rinsing procedure. This can be performed in situ, i.e., by passing the rinsing solutions directly through the treatment column. The same regeneration procedure can be used to activate the pristine soil. Fluoride sorption is described by a Freundlich isotherm model and the bulk of the uptake occurs within 1.5h. Iron oxide coatings on soil particles and perhaps≡FeOH surface groups at particle edges of illite grains are likely responsible for the soil's F-sorption property. As collected in the field, the soil has a low permeability and is thus unsuitable for direct use in a fow-through column. Heat-treatment at 400-500℃ for 2h, however, produces a granular and permeable sorbent. Although the soil's sorption capacity (150µg/g) is about a quarter of the low end range of values reported for commercially-available activated alumina, the sorption for F-is specific. A batch sorption experiment in the presence of Cl-, SO42- and HCO3- shows little or no competition from these other anions.

A two-column reactor was designed to remove dissolved As and Cd from comtaminated water. The reactor functions by equilibrating the targered water with CO2 and directing it via saturated flow through acolumn of crushed siderite. This results in siderite dissolution and an increase in dissolved Fe(Ⅱ). The feedwater is them directed into the top of a second, aerated cloumn of crushed limestone, where it passes by unsaturated flow. The Fe2+ ion oxidizes quickly to Fe3+ and precipitates as Fe(Ⅲ) oxyhydroxide, which is an effective sorbent of AsO34-. The aeration that occurs in the second column also removes dissolved CO2 from the feedwater. This causes precipitation of Ca and Cd carbonates. Together, the processes reduce As and Cd concentrations from 1 and 3mg/1, respectively, to below detection (respectively<0.005and <0.01mg/1). A time-limited reduction in Cr conentration also occurred. Much of the As was removed in the first column of the reactor, because Fe(Ⅲ) oxyhydroxides also formed there. This was due to oxidation of Fe(Ⅱ) by Cr(Ⅵ) and other oxidants present on the input wastewater. Although As is removed in the reactor columns by a sorption mechanism, the sorbent responsible, Fe(Ⅲ) oxyhydroxide, is continuously produced during the operation of the reactor. Thus, unlike attenuation in a system with a fixed amount of sorbent, breakthrough of the As contaminant should never occur.

The response of carbonate aquifer to climate changes and ground water exploitation was studied at Shentou Springs. The springs consist of about 100 spring points. The long-term (1958-1999) annual average discharge of the springs is 6.86m3/s. The discharge has diminished since the early 1960s. In 1993, the discharge (3.81m3/s) was the smallest during the period of record. Data of restored spring discharge and precipitation during 1958-1999 were analyzed using a seasonal decomposition method. The result of analysis shows that the discharge of Shentou Springs responds remarkably to precipitation change. Lowering of ground water table and attenuation of spring discharge at Shentou in the last several decades are largely a response of the ground water system to the deficiency in regional precipitation in northern China. As compared with the effect of climate, human activities (mostly in the form of ground water abstraction) are secondary in affecting spring discharge. When the volume of exploited Quaternary ground waters that are partly recharged by karst waters exceeds 6400

The response of carbonate aquifer to climate changes and ground water exploitation was studied at Shentou Springs. The springs consist of about 100 spring points. The long-term (1958-1999) annual average discharge of the springs is 6.86m3/s. The discharge has diminished since the early 1960s. In 1993, the discharge (3.81m3/s) was the smallest during the period of record. Data of restored spring discharge and precipitation during 1958-1999 were analyzed using a seasonal decomposition method. The result of analysis shows that the discharge of Shentou Springs responds remarkably to precipitation change. Lowering of ground water table and attenuation of spring discharge at Shentou in the last several decades are largely a response of the ground water system to the deficiency in regional precipitation in northern China. As compared with the effect of climate, human activities (mostly in the form of ground water abstraction) are secondary in affecting spring discharge. When the volume of exploited Quaternary ground waters that are partly recharged by karst waters exceeds 6400

A two-column limestone reactor has been designed to reduce fluoride concentrations from wastewaters to below the maximum contaminant level (MCL limit) of 4mg/L. The reactor functions by forcing calcite (CaCO3) to dissolve and fluorite (CaF2) to precipitate in the first column. The second column is not necessary to remove fluoride but is used to precipitate the calcite dissolved in the first column. This returns the treated water to its approximate initial composition. In laboratory experiments, the fluoride concentration of the effluent from feedwaters containing initial F amounts of up to 109mg/L were brought below the MCL limit of 4mg/L with a porewater residence time within the column of 2h. Profile sampling shows that fluoride is reduced from 109 to 8mg/L after only 35min within the reactor. The major advantage of this potential technology over existing liming and ion exchange methods is that system monitoring is minimal, regular column regeneration is not required, and chemicals are not permanently added to the water. Because the CaCO3 dissolved in the first column is precipitated in the second, the reactor has potential application to reduce the concentrations from wastewaters of contaminants similar in charge and size to Ca2+ and CO32- through coprecipitation reactions. In a pilot experiment where fly ash leachate was spiked with mg/L levels of Cd, As, Cr, and Se and directed through the reactor, reductions in all elements except Cr occurred. Cd was the most notable. Influent concentrations from 2 to 30mg/L were reduced to below detection (<0.01mg/L)

In Shanyin, Shanxi province, China, As concentration in shallow groundwater exceeds guide concentrations, set internationally and nationally at 10-50mg/L, and may reach 1932.0mg/L, which has resulted in severe clinical symptoms of arsenic toxity. In this article, chemical characteristics of groundwaters containing anomalous As and mechanisms of arsenic release to shallow groundwaters were studied. Groundwaters containing anomalous As in the study area were characterized by higher pH, higher concentration of phosphate, higher concentration of naphthenic acid, and lower concentrations of sulfate and nitrate. Microbial metabolism of sedimentary organic matter, which is present as high as 1.0% organic C, results in the lower concentrations of sulfate and nitrate. The reactions decrease Eh and produce CO2, which promotes the dissolution of carbonates and increases pH. The clay minerals and colloids including organic matters scavenging arsenic would release arsenic to groundwater in higher pH and lower Eh environment. In addition, the competitive absorption between As and anions (such as phosphate and fluoride) contributes to the release of As from kaolinite, montmorillonite, illite, and Fe oxyhydroxides. Naphthenic acid also promotes mobilization and translocation of As in groundwater systems.

水文地质学在解决人类面临的众多资源-环境问题中发挥着关键作用，近40年得到快速发展。水文地质研究中带共性的关键科学问题包括：地下水系统中的物理-化学过程、场地评价方法和耦合模拟方法。为加快水文地质研究的创新进程，应当建立三种类型的研究项目平衡资助机制：小型的单个研究者主持的研究项目，多学科项目和多机构项目。

Groundwater is the most important source of water supply in Datong city. However, the levels of shallow Quaternary groundwaters from urbanized areas have been declining continuously and groundwater quality deteriorating in recent years. Understanding the geochemical evolution of groundwater is important for sustainable development of the water resources in Datong. Mineral hydrolysis of alumino-silicate minerals such as plagioclase and clinopyroxene, is the primary process controlling the concentration of H4SiO4 in the study area. Speciation calculations using the geochemical modeling code PHREEQC indicated that hydrolysis of bedrock, mainly composed of asalt and metamorphic rocks, is the major hydrogeochemical process controlling groundwater chemistry. The study area can be divided into 3 hydrogeochemical zones: A. Recharge (unimpacted) zone, B. Intermediate (industry-impacted) zone, and C. Discharge (agriculture-impacted) zone. Ion exchange and industrial and/or agricultural contamination contribute to the increase of Na+ from Zone A to Zone C, where the concentration of NO3-is up to 461.5mg/l with a mean value of 101.5mg/l, indicating that agricultural practice seriously affects groundwater. Sulfate concentration in groundwaters in an alluvial fan at Datong is extremely high, up to 1172.9mg/l, and shows a close relationship with the concentrations of trace elements, especially Ni and Co, indicating that coal mining is the main contamination source for groundwater from the alluvial fan, in addition to agricultural activities.