Monitoring of percolation water to discriminate surficial inputs in a karst aquifer

 A long-term study on the chemistry of percolating waters in a very large touristic karst cave (Grotta Gigante, northern Italy) was carried out in order to define recharge zones, flowpaths, and possible anthropogenic contamination from the neighboring area. On the basis of a multivaried analysis of the chemical parameters, a discrimination of the dripping points was attempted. Percolation waters whose recharge zone is in the northernmost sector of the cave appeared permanently affected by the anthropic settlements and agricultural activity on the ground surface. Received: 28 April 1997 · Accepted: 3 February 1998     

Hydrogeochemistry and reservoir characterization of the Konya geothermal fields,Central Anatolia/Turkey

A conceptual model with water samples from ten geothermal fields (?smil, Ilg?n (Çavu?cugöl), Tuzlukçu-Ak?ehir, Seydi?ehir and Kavakköy, Hüyük, Ere?li-Akhüyük, Kad?nhan?, Cihanbeyli, Karap?nar and Bey?ehir) in the province of Konya defined the geothermal system. Carbonates, quartzite and marbles of Paleozoic metamorphics are the reservoir rocks and the heating sources are igneous rock intrusions and geothermal gradient. The variable thermal water (CaMgHCO₃, CaSO₄, NaSO₄, CaHCO₃, CaNaHCO₃, NaCl and CaNaClHCO₃) had EC and temperature between 177.8 and 56,100 μS/cm and between 18.3 and 44 °C, respectively. Ca²⁺ in geothermal fluids are associated with marble and carbonate rocks and the high chloride shows direct connection with deep geothermal system, and prolonged contact with evaporite rocks. Sulphate originates from dissolution of and oxidation of sulphate and sulphur-bearing minerals. The high As, B, F and Mn concentration in some thermal water samples were determined as 85 μg/l, 148.56 mg/l, 3.01 mg/l and 208.13 mg/l, respectively. Reservoir temperatures computed by Na/K geothermometers were between 85.37–158.89 °C for Ak?ehir thermal waters and 58.78–90.45 °C for Ere?li thermal waters. The maximum reservoir temperature of other geothermal waters was 75 °C by the silica geothermometers.     

九孔鲍养殖水体中产酶菌群的研究

为了解九孔鲍养殖环境中细菌生理菌群的生态作用,对分离自养殖水体的33株菌株的产酶能力和种类进行了研究。结果表明,具有分泌胞外蛋白酶、脂肪酶和纤维素酶能力的菌株分别为39.4%、57.6%和30.3%;在这33株菌中,产至少一种胞外酶的菌株比例高达63.6%。API鉴定结果表明,在有能力分泌胞外蛋白酶、脂肪酶和纤维素酶的菌株中,弧菌菌群所占的比例分别为46%、42%和40%,而其中河流弧菌又占各弧菌菌群比例的83.3%、62.5%和100%。充分阐明弧菌,尤其是河流弧菌为优势菌,在鲍鱼养殖微生物态中起的重要作用。     

Detecting subtle hydrochemical anomalies with multivariate statistics: an example from ‘homogeneous’ groundwaters in the Great Artesian Basin,Australia

The major ion composition of Great Artesian Basin groundwater in the lower Namoi River valley is relatively homogeneous in chemical composition. Traditional graphical techniques have been combined with multivariate statistical methods to determine whether subtle differences in the chemical composition of these waters can be delineated. Hierarchical cluster analysis and principal components analysis were successful in delineating minor variations within the groundwaters of the study area that were not visually identified in the graphical techniques applied. Hydrochemical interpretation allowed geochemical processes to be identified in each statistically defined water type and illustrated how these groundwaters differ from one another. Three main geochemical processes were identified in the groundwaters: ion exchange, precipitation, and mixing between waters from different sources. Both statistical methods delineated an anomalous sample suspected of being influenced by magmatic CO₂ input. The use of statistical methods to complement traditional graphical techniques for waters appearing homogeneous is emphasized for all investigations of this type. Copyright © 2006 John Wiley & Sons, Ltd.     

Kinetics of phosphate adsorption by iron oxyhydroxides in aqueous systems

The rate of uptake of phosphate onto synthetic Fe(III)- and Fe(II)-derived oxyhydroxides has been studied using reaction conditions similar to those encountered in natural waters. Kinetic analyses were carried out on the adsorption profiles and both first-order and second-order conditional rate constants were obtained. The temperature dependence of some of the rate constants was investigated and corresponding apparent activation energies calculated. Similar experiments and analyses were undertaken using Fe from natural sources and in general the conditional rate constants obtained in seawater were in agreement with the synthetic ones. The results of this study are of value when comparing the time scales of adsorption processes in natural waters with the time scales of mixing and advection.     

Chlorinated hydrocarbons in the seawater and surface sediments of Blanca Bay,Argentina

In order to characterize our study area and to provide reference values to be used in the future to measure the changes produced by an increase in contamination, the concentrations of chlorinated hydrocarbons have been investigated in fifty-one samples of seawater, taken at four different depths: air-sea interface, surface, one metre and bottom waters, and in twenty-three samples of surface sediments from Blanca Bay, Argentina. Of eleven organochlorine compounds we were looking for (α BHC, lindane, heptachlor, δ BHC. aldrin, heptachlor epoxide, dieldrin, o-p′DDD, p-p′DDD, o-p′DDT and p-p′DDT), seven could be detected in seawater and three in surface sediments with the following mean concentrations: α-BHC=48·2 ng l^?1; lindane=54·2 ng l^?1; heptachlor=45·0 ng l^?1; δ BHC=12·5 ng l^?1; aldrin=61·8 ng l^?1 and ΣDDT=67·0 ng l^?1; and δ BHC=3·2 ng g^?1; lindane=4·2 ng g^?1 and heptachlor=1·0 ng g^?1 for seawater, regarding the surface waters, and sediment samples, respectively.Concentration factors among the different water layers were also studied to see if there was any correlation between chlorinated hydrocarbon contents and the water depths from which the samples were taken. As a mean value, the air-sea interface water contains 18 times more of these compounds than that of the water near the bottom. A comparison of the values corresponding to seawater and surface sediments from our study area with those levels measured in samples from other geographic locations is also presented.With the purpose to detect a relationship between chlorinated hydrocarbon concentrations and the contents of particulate matter (PM) on the one hand, and particulate organic material (POM) on the other hand, four groups of samples containing different amounts of PM and POM, respectively were formed. From a comparison of the results obtained, lindane, heptachlor and δ BHC showed a tendency to lower concentrations in those samples containing little PM whereas α BHC and aldrin remained without important changes. No significant correlation was found between organochlorine levels and contents of POM.     

The hydrogeothermal basin of Sofia graben (Bulgaria)

Abstract In the Mesozoic basement and Neogene filling of Sofia tectonic graben a non-homogenous system of thermal water reservoirs connected to a united hydrogeothermal basin occurred. The basin contains and reproduces five types of low mineralized thermal waters and four types of mineralized thermal waters with exotic composition. The water temperatures are 30–80(90) ^°C. The total potential of the basin is assessed at 500 l/s thermal waters and 48 MWt thermal power. The utilization of thermal waters in the area of the Bulgarian capital has its roots and traditions in antiquity, and a promising future. The new town plan of Sofia provides construction of 35 centers for developing a versatile and prosperous hydrothermal business.     

Trace elements in medium-temperature (40–80 °C) thermal waters from the Mura basin (North-Eastern Slovenia)

Medium-temperature thermal waters in the Mura basin occur in hydrogeological systems different in age, burial depth, temperature, porosity and permeability, and the presence of free carbon dioxide which penetrates through the fractures from pre-Tertiary basement. The waters commonly belong to sodium-bicarbonate hydrogeochemical facies, but may have significantly different amounts of total dissolved solids, including trace elements. Thermal waters occurring in low-permeable, well-compacted and moderately fractured Tertiary sediments older than Upper Pliocene are the richest in trace elements, although their abundance may be very variable from one aquifer to another. The ratios of major alkaline and alkaline earth elements (Na, K, Ca) and trace elements (Li, Rb, Cs, Ba, Sr) commonly show relative enrichment in highly mineralised waters with respect to the waters with lower mineralisation. Rare earth elements (REEs) and Y show only minor fractionation in the highly mineralised waters, whereas in the waters with lower mineralisation strong fractionation of heavy rare earth elements (HREEs) over light rare earth elements (LREEs) occurs, along with a pronounced positive europium anomaly. Positive Th/U ratios are commonly observed, although both actinide elements occur in the range of some hundredths of ppb to some ppb. Trace elements were particularly useful in the study of well cycling in two hydraulically interconnected geothermal wells in the town of Murska Sobota, which produce a mixture of low- and high-mineralised waters.     

内陆水体叶绿素a浓度反演的区域化三波段模型研究

以太湖和石头口门水库为例,建立了一种可直接计算水体叶绿素a浓度的区域化三波段模型。该模型通过对研究水体的光学特性分析,明确三波段组合与叶绿素a浓度间的函数关系参数,不仅可较好指示研究水体叶绿素a浓度水平,而且大大减小了回归算法所带来的模型不确定性。利用高精度、长时间序列的水体光学特性观测数据,建立针对不同研究水体的区域化三波段模型可为实现内陆水体叶绿素a浓度遥感监测业务化运行提供方法借鉴。     

Biogeochemistry of dissolved carbon,major, and trace elements during spring flood periods on the Ob River

Detailed knowledge of the flood period of Arctic rivers remains one of the few factors impeding rigorous prediction of the effect of climate change on carbon and related element fluxes from the land to the Arctic Ocean. In order to test the temporal and spatial variability of element concentration in the Ob River (western Siberia) water during flood period and to quantify the contribution of spring flood period to the annual element export, we sampled the main channel year round in 2014–2017 for dissolved C, major, and trace element concentrations. We revealed high stability (approximately ≤10% relative variation) of dissolved C, major, and trace element concentrations in the Ob River during spring flood period over a 1‐km section of the river channel and over 3 days continuous monitoring (3‐hr frequency). We identified two groups of elements with contrasting relationship to discharge: (a) DIC and soluble elements (Cl, SO₄, Li, B, Na, Mg, Ca, P, V, Cr, Mn, As, Rb, Sr, Mo, Ba, W, and U) negatively correlated (p < 0.05) with discharge and exhibited minimal concentrations during spring flood and autumn high flow and (b) DOC and particle‐reactive elements (Al, Fe, Ti, Y, Zr, Nb, Cs, REEs, Hf, Tl, Pb, and Th), some nutrients (K), and metalloids (Ge, Sb, and Te), positively correlated (p < 0.05) with discharge and showed the highest concentrations during spring flood. We attribute the decreased concentration of soluble elements with discharge to dilution by groundwater feeding and increased concentration of DOC and particle‐reactive metals with discharge to leaching from surface soil, plant litter, and suspended particles. Overall, the present study provides first‐order assessment of fluxes of major and trace elements in the middle course of the Ob River, reveals their high temporal and spatial stability, and characterizes the mechanism of river water chemical composition acquisition.