Stable isotope and hydrogeochemical studies of Beaver Lake and Radok Lake, MacRobertson Land, East Antarctica

Beaver Lake and Radok Lake, the largest known epishelf lake and the deepest freshwater lake on the Antarctic continent, respectively, were isotopically (δ(2)H, δ(18)O) and hydrogeochemically studied. Radok Lake is an isothermal and non-stratified, i.e. homogeneous water body, while Beaver Lake is stratified with respect to temperature, salinity, and isotopic composition. The results for the latter attest to freshwater (derived from snow and glacier melt) overlying seawater.     

Seasonal variation of oxygen-18 in precipitation and surface water of the Poyang Lake Basin,China

Based on the monthly δ¹⁸O value measured over a hydrology period in precipitation, runoff of five tributaries and the main lake of the Poyang Lake Basin, combined with hydrological and meteorological data, the characteristics of δ¹⁸O in precipitation (δ¹⁸O_PPT) and runoff (δ¹⁸O_SUR) are discussed. The δ¹⁸O_PPT and δ¹⁸O_SUR values range from?2.75 to?14.12 ‰ (annual mean value=?7.13 ‰ ) and from?2.30 to?8.56 ‰, respectively. The seasonal variation of δ¹⁸O_PPT is controlled by the air mass circulation in this region, which is dominated by the Asian summer monsoon and the Siberian High during winter. The correlation between the wet seasonal averages of δ¹⁸O_SUR in runoff of the rivers and δ¹⁸O_PPT of precipitation at the corresponding stations shows that in the Poyang Lake catchment area the river water consists of 23% direct runoff (precipitation) and 77% base flow (shallow groundwater). This high proportion of groundwater in the river runoff points to the prevalence of wetland conditions in the Poyang Lake catchment during rainy season. Considering the oxygen isotopic composition of the main body of Poyang Lake, no isotopic enrichment relative to river inflow was found during the rainy season with maximum expansion of the lake. Thus, evaporation causing isotopic enrichment is a minor component of the lake water balance in the rainy period. During dry season, a slight isotopic enrichment has been observed, which suggests a certain evaporative loss of lake water in that period.     

Radioactivity levels in surface water of lakes around Izmir/Turkey

The aim of this study is to determine the radioactivity levels as a baseline for further studies and to obtain the distribution patterns of radioactivity in lake surface water around Izmir/Turkey. In this study, surface water samples were collected from three lakes around Izmir–Turkey. Surface water samples were analyzed for pH, mV conductivity and alkalinity content. The gross alpha/beta and uranium concentrations were investigated in the collected lake water samples. Mean gross alpha and gross beta activity concentrations in the surface water were found to be between (0.03 and 2.62) Bq l⁻¹ for Karagol Lake, (0.75 and 2.35) Bq l⁻¹ for Golcuk Lake, (0.03 and 1.77) Bq l⁻¹ for Cakalbogaz Lake, respectively. Uranium concentration varied between (0.05 and 900) μg l⁻¹ for Karagol Lake, (0.05 and 0.95) μg l⁻¹ for Golcuk Lake and (3.33 and 10) μg l⁻¹ for Cakalbogaz Lake. Radioactivity contour maps were produced and their data were evaluated statistically.     

Gordon Research Conference: Isotopes in Biological and Chemical Sciences, 14–19February 2010, Galveston,TX, USA

The natural flow properties of the Yangtze River have been changed completely following the construction of the Three Gorges Dam. The dam's operation has affected the resources and environment in the middle and lower reaches of the Yangtze River, changing the hydrological conditions and ecological environment of the Dongting Lake. During three different dispatching periods of the reservoir, we took triplicate samples of the river and lake water. All the samples were analysed for δ²H and δ¹⁸O to determine the relationship between the lake and the Yangtze River (and other rivers), and to evaluate objectively the influence of the dam's operation on the lake. During the period of water-supply dispatch, the Four Rivers and Miluo River are the main recharge sources of the lake. During the flood-storage dispatching period, the Dongting Lake is recharged largely by the Three Outlets and the Four Rivers, whereas during the period of water-storage dispatch, most of the lake's water originates from the Miluo, Xiang, Zi, and Yuan rivers. Although the Yangtze River only contributes significantly to the lake's recharge through the Three Outlets during the flood-storage dispatching period, the lake discharges large amounts of water into the Yangtze River during all three periods. Through the operation of the reservoir, it should be ensured that the water level of the Dongting Lake is not too low during the dry season, nor too high during the wet season, thus preventing the lake region from future flood and drought disasters.     

Dating problems with selected mining lakes and the adjacent groundwater body in Lusatia,Germany

This study presents selected results, applying environmental tracers to investigate lake water–groundwater interactions at two study sites located in Lusatia, Germany. The focus of the investigations were two meromictic pit lakes and their adjacent aquifers. In order to follow hydrodynamic processes between lake and groundwater, mixing patterns within the lakes as well as ages of lake and groundwater, water samples of ground- and lake water were collected at three occasions, representing summer and winter conditions in the aquatic systems. The water samples were analysed for stable isotopes (deuterium, oxygen-18) and tritium and sulphurhexafluoride (SF₆ concentration). Lake water profiles of conductivity and ¹⁸O could validate the permanent stratification pattern of both the lakes. Groundwater data sets showed a heterogeneous local distribution in stable isotope values between rain and lake water. A two-component mixing model had been adopted only from ¹⁸O data to determine lake water proportions in the surrounding groundwater wells in order to correct measured tritium and SF₆ concentrations in groundwater samples. This procedure had been hampered by upstream-located wells indicating strong ¹⁸O enrichment in groundwater samples. However, rough groundwater ages were estimated. For both study sites, Piston flow ages between 12.9 and 27.7 years were calculated. The investigations showed the good agreement between two different environmental dating tools, considering the marginal data sets.     

Isotopic fingerprints of the Lake Żabińskie (NE Poland) hydrological system on contemporary carbonates precipitated in the lake

An isotopic monitoring was undertaken in 2012–2014 at Lake ?abińskie (Mazurian Lakeland, NE Poland). The aim was to identify the factors and processes controlling an isotopic composition of the lake water and to explore the mechanism responsible for recording the climatic signal in stable isotope composition of deposited carbonates. δ¹⁸O and δ²H in the precipitation, lake water column, inflows and outflow, δ¹⁸O and δ¹³C in the carbonate fraction of sediments trapped in the water column were recorded with monthly resolution. A relationship between δ¹⁸O and δ²H in local precipitation was used to estimate the local meteoric water line. The dataset obtained for the water enabled to identify the modification of the water’s isotopic composition due to evaporation, connected with seasonal lake water stratification and mixing patterns. Statistically significant correlation coefficients suggest that the δ¹⁸O of the carbonate fraction in the sediment traps depends on the δ¹⁸O of rainfall water and on air temperature. The fractionation coefficient α shows that in summer months the carbonate precipitation process is closest to equilibrium. As expected for an exorheic lake, no significant correlation was observed between δ¹⁸O and δ¹³C in precipitated carbonate.     

Spatial and seasonal variations in the stable C isotope composition of dissolved inorganic carbon and in physico-chemical water parameters in the Plitvice Lakes system

Plitvice Lakes waters were collected at 14 sampling points, including springs, tributaries and lakes, for the period 2002–2007. The results of the physical and chemical conditions of calcite precipitation as well as the δ¹³C values of dissolved inorganic carbon (DIC) were used to study the processes influencing calcite precipitation. Significant differences between spring, lake and stream waters as well as changes in the downstream direction were observed. The correlation between δ¹³C_DIC values and physico-chemical conditions for calcite precipitation showed that calcite precipitates in lake waters which are oversaturated with respect to CaCO₃ (I _sat values 4–10) and with δ¹³C_DIC values between?11.5 and?8.5 ‰. In spring waters, the δ¹³C_DIC values were more negative, from?14 to?12 ‰, and I _sat values of 1–2 indicated that equilibrium conditions for calcite precipitation were not attained. The downstream increase in δ¹³C_DIC correlated with the increase in the δ¹³C values of calcite in the lake sediments, suggesting that the freshwater calcite was mainly of autochthonous origin and precipitated within the water column in isotopic equilibrium with DIC.     

Mössbauer Spectroscopic Study on Vertical Distribution of Iron Species in Sediments from Qinghai Lake,China

In this study, ⁵⁷Fe Mössbauer spectroscopy has been applied to sediments collected from Qinghai Lake in Qinghai Province, China, to investigate the vertical distribution of iron species. Their Mössbauer spectra consisted of four doublets ascribable to one paramagnetic high-spin Fe³⁺, two paramagnetic high-spin Fe²⁺ with different quadrupole splittings, and one diamagnetic low-spin Fe²⁺ that corresponds to pyrite (FeS₂). The distribution of pyrite suggested climatic changes during the past nine thousand years. It was demonstrated that the iron speciation in the salt lake sediments by Mössbauer spectroscopy can be used to reconstruct the past environment.

     

Content and Isotope Ratios of Noble Gases in Congelation Ice of Lake Vostok

Isotope ratios of noble gases (He, Ne, Ar) were studied in samples collected by degassing of cores of water frozen over a glacier of Lake Vostok. The gases were collected into glass retorts during three days of degassing of cores, which have just been extracted from the borehole. Within the error, the isotope ³He/⁴He ratios of 0.28 ± 0.08 R_A (R_A = 1.38 × 10^–6 is the ratio for air) correspond to those from [1]. The ⁴He/²⁰Ne and ⁴⁰Ar/³⁶Ar ratios (12.4 ± 4.6 R_A and 1.0074 ± 0.0023 R_A, respectively) exceed their contents in air (⁴He/²⁰Ne_A = 0.29; ⁴⁰Ar/³⁶Ar_A = 298.6) and may indicate some contribution of terrigenous gas to the gaseous balance of the lake, as well as the high content of ancient ground waters in the lake. The ³He/⁴He ratio of 0.28 R_A means low mantle ³He flux typical of continental platforms far from active rift zones.     

Isotope Geochemical Studies on Carbonates of Quaternary Glacio-Lacustrine Lake Sediments as indicators of Paleoenvironment

Selected silty “summer” and argillaceous “winter” layers of profiles of the rhythmically bedded glacio-lacustrine ice-marginal lake sediment of the Dehlitz-Leipzig varved clay (Leipziger Tieflandsbucht, Central Germany) have been examined for isotope composition (¹⁸O/¹⁶O, ¹³C/¹²C) of carbonate and organic fraction. In addition, mineralogical and grain size compositions were determined. The results show 1) a change in source of carbonate sediment (provenance) through time; 2) the oxygen isotope ratios differed between the “summer” and “winter” layers of varves couplets due to different rates of sedimentation; 3) anoxic events occurred in the lake; 4) carbon isotope ratios suggest organics in lake sediments which were derived from land and the primary productivity was low in the lake itself. In the study of cold-climatic lake sediments, isotope investigations can efficiently be used as additional paleosedimentological and facies indicators.     

On the heavy elements content of sediments and rocks from two semiclosed ecosystems: Proglacial Lake Balea (Fagara Mountains) and Crater Lake St. Ana (Harghita Mountains)

The content of seven heavy elements (natural Sc and Cr, Co, As, Sb, Br and Se as possible pollutants) was determined by the Neutron Activation Analysis (NAA) in 29 samples of sediments and surrounding rocks collected from proglacial Lake Balea (Fagara Mountains) and crater St. Ana Lake (Harghita Mountains) to estimate the degree of anthropogenic pollution, as well as the sediments provenance. Consequently, we have found that, within experimental uncertainties, the content of the considered elements in sediments was close to those of surrounding rocks, and, at the same time, comparable with the normal environmental content as defined by the Romanian Regulations, which enabled us to consider them as normal, nonpolluting constituents of lake sediments. A further R-mode, Principal Component Analysis (PCA), performed for each lake, showed that Sc, Cr, and Co, on the one hand, and As, Sb, Br and Sb, on the other, form two distinct clusters, regardless of the lake, while the Q-mode analysis pointed to a different lake geochemistry with respect to sediments as well as rocks origin.     

湖泊沉积物溶解性有机氮组分特征及其与水体营养水平的关系

通过紫外-可见光吸收光谱,三维荧光光谱和气相色谱质谱联用(GC-MS)方法,比较研究了不同湖区与不同营养水平五个典型湖泊(洱海、滇池、鄱阳湖、武汉东湖、太湖)沉积物DON组分特征及其与水体营养水平间关系。结果表明：①与东部平原湖区相比,云贵高原湖泊沉积物DON结构较为稳定,生物可利用率较低;②同属云贵高原湖区,污染较严重的滇池,其沉积物DON来源和结构组分较复杂,生物可利用率较高;而污染程度相对较轻的洱海,其沉积物DON来源较简单,结构组分稳定性相对较高,有利于维持较好的水质;③东部平原湖区中,太湖和武汉东湖营养水平接近,其沉积物DON结构组分相近且相对复杂,但芳香度较低,芳香环取代基较少,对营养盐的固持能力较弱,对水污染的贡献较大,而鄱阳湖,其沉积物DON结构组分相对简单,但对营养盐的固持能力较强,对维持良好水质起积极作用;④P_{(Ⅲ+Ⅴ, n)}/P_{(Ⅰ+Ⅱ, n)}指数(类腐殖质与类蛋白质含量的比值)依次为滇池(33.14)>洱海(21.49)>太湖(15.65)>东湖(8.49)>鄱阳湖(5.21),E₄/E₆指数(465与665 nm处的吸光度比值)依次为滇池(27.00)>东湖(6.65)>鄱阳湖(5.47)>太湖(3.50)>洱海(2.31), 即P_(Ⅲ+Ⅴ,n)/P_{(Ⅰ+Ⅱ, n)}与E₄/E₆指数对不同营养水平湖泊的区分度较好,此外,两种指数与沉积物中多种氮具有较好的相关性,两者可在一定程度上指示湖泊营养水平。     

Conference and Research Reports

Groundwater discharge into an open pit lignite mining lake was investigated using radon-222 as a naturally occurring environmental tracer. The chosen study site was a meromictic lake, i.e., a water body that is divided horizontally into two separate layers – the upper mixolimnion (with seasonal mixing) and the lower monimolimnion (without seasonal mixing). For the estimation of groundwater discharge rates into the lake, a simple box model including all radon sinks and sources related to each layer was applied. Two field investigations were performed. During the October campaign, the total groundwater discharge into the lake was found to be 18.9 and 0.7 m³ d^?1 for the mixolimnion and monimolimnion, respectively. During the December campaign, the groundwater discharge into the mixolimnion was 15.0 m³ d^?1, whereas no discharge at all was observed into the monimolimnion. Based on the given water volumes, the residence time of lake water was 5.3 years for the monimolimnion and varies between 0.9 and 1.1 years for the mixolimnion. The investigation confirmed radon to be a useful environmental tracer for groundwater and surface water interactions in meromictic lake environments.     

Estimation of lake water—groundwater interactions in meromictic mining lakes by modelling isotope signatures of lake water

Abstract

A method is presented to assess lake water–groundwater interactions by modelling isotope signatures of lake water using meteorological parameters and field data. The modelling of δ¹⁸O and δD variations offers information about the groundwater influx into a meromictic Lusatian mining lake. Therefore, a water balance model is combined with an isotope water balance model to estimate analogies between simulated and measured isotope signatures within the lake water body. The model is operated with different evaporation rates to predict δ¹⁸O and δD values in a lake that is only controlled by weather conditions with neither groundwater inflow nor outflow. Comparisons between modelled and measured isotope values show whether the lake is fed by the groundwater or not. Furthermore, our investigations show that an adaptation of the Craig and Gordon model [H. Craig, L.I. Gordon. Deuterium and oxygen-18 variations in the ocean and the marine atmosphere. In Stable Isotopes in Oceanographic Studies and Paleotemperature, Spoleto, E. Tongiorgi (Ed.), pp. 9–130, Consiglio Nazionale delle Ricerche, Laboratorio di Geologia Nucleare, Pisa (1965).] to specific conditions in temperate regions seems necessary.     

Assessing the authenticity of commercial deep-sea drinking water by chemical and isotopic approaches

This study combines stable isotopes and chemical elements with statistical principal component analysis (PCA) to assess the authenticity of bottled commercial drinking water desalinized from deep seawater in the Taiwan market. Isotopic results indicate that true bottled deep-sea drinking water (DSDW) exhibits about 0?‰ for both δ²H and δ¹⁸O values, which are values similar to those of open seawater. By comparison, suspected counterfeit DSDW products display δ²H and δ¹⁸O values of around ?51?‰ and ?8?‰, respectively. These values are representative of terrestrial freshwater. In addition, suspected counterfeit DSDWs have δ and electrical conductivity values similar to a mixed water (MW) product that was manufactured by purifying terrestrial freshwater and adulterating this with small amounts of brine. Furthermore, PCA results indicate the chemical constitution of suspected DSDW products to be similar to the MW product which falls between purified terrestrial freshwater and desalinized open seawater. These similarities imply that suspected counterfeit DSDW products are manufactured in a similar manner to the declared MW product. This study demonstrates how combining knowledge of stable water isotopes and PCA can be used in assessing the authenticity of commercial DSDW products. The method should be of great interest to similar investigations elsewhere.     

Hydrology of the lakes in Central Wohlthat Massif,East Antarctica: new results

In 1983/1984, in the course of the 28th Soviet Antarctic Expedition, waterbody, ice cover, and surrounding glaciers of the lakes Untersee and Obersee were sampled along some depth profiles. The geochemical data of those samples, now available, show the homogeneity of both large lakes in vertical (down to the maximum depth) as well as in lateral directions. The comparison of isotope and chemical composition of lake water and adjoining glacier ice suggests strong differences in the long-term evolution between the lakes Untersee and Obersee. First data from a lakelet, embedded in the large morainic area to the west of Lake Untersee, are of special interest: the δ²H values of the lakelet water are lower than those of recent regional glacier ice by 50‰ SMOW. This fact indicates that the lakelet is fed episodically by Pleistocene dead ice, covered by the morainic material.     

A Mössbauer spectroscopic study of salt lake sediments from Qaidam basin

Mössbauer spectroscopy, X-ray diffractometry and chemical fractionation have been used to study the clay smaples in sediments of Charhan playa and Qinghai lake. The spectral components of the Mossbauer spectra of the samples are attributed to Fe²⁺ ions in chlorite and siderite, Fe³⁺ ions in clay minerals and hematite, and partly in amorphous ferric hydroxides. The essential difference in the mineral composition of the sediments of both lakes is the presence of siderite in the samples of Char han playa, whereas it is absent in the samples of Qinghai lake. The fraction of the amorphous ferric hydroxides is higher in the sediments of Qinghai lake. Total Fe²⁺/Fe³⁺ ratios increase with sediment depth of Charhan playa, whereas these ratios are altogether smaller and run through a maximum at a certain depth for Qinghai lake.     

Chemical and Isotope Investigations in Dissolved Gases of a Meromictic Residual Lake

Abstract

Lake Hufeisen near Halle/Saale has been formed in an old mining pit. Its deepest part is trench shaped and filled with water of sodium chloride content. Due to the density difference strong mixing processes in this part of the water body are prevented all over the year (meromictic lake). Therefore anoxic conditions have been established and the organic matter of the lake sediments is converted to carbon dioxide and methane. Over a period of more than one year gas samples were collected from different water depths. The investigations of the chemical composition (mainly nitrogen, carbon dioxide and methane) and the carbon isotope ratios show different relationships for individual species. The results are discussed with respect to the behaviour of the gases in the water column and to the stability of the density stratification in the saline bottom water.     

The study of distribution and forms of uranium occurrences in Lake Baikal sediments by the SSNTD method

Sediments of Lake Baikal drill cores VER-96-1 St8 TW2 (5332^′15^″E; 10756^′25^″N), (interval 181.8–235 cm from the sediment surface) were studied by means of SSNTD with the aim of defining uranium occurrence in the sediments and the uranium concentration. The neutron-fission ((n,f)-autoradiographic) method allowed a detailed study of uranium distribution of these Lake Baikal sediments within the Academicheskiy Ridge. Layered accumulations of uranium-bearing grained phosphorite, uranium-bearing particles of organic material, and abnormal uranium concentration in diatomite of unknown origin were discovered.