Isotopic evidence of allogenic groundwater recharge in the Northern Ordos Basin

Large amount of groundwater recharge runs in opposite direction to the scarce surface water resources in the Northern Ordos Basin, and there are two controversial viewpoints. Hydrogen and oxygen stable isotopes are employed to identify the groundwater origin. Results show that surface water and soil water are mainly recharged by groundwater instead of local precipitation. The groundwater is not recharged by local rainfall, but is inferred to have originated from the Tibetan Plateau, based on isotopic (D, ¹⁸O, ³He/⁴He), hydraulics, geophysical, and geological evidence. It is consistent with the viewpoint of external groundwater recharging in North China.     

Use of isotope hydrology for groundwater resources study in Upper Chi river basin

The Upper Chi river basin is located in the vicinity of Chaiyaphum province, northeastern Thailand. Groundwater management in the drought affected area of fractured Mesozoic siliciclastic rocks groundwater system was challenged by the approaches of isotope and chemical techniques. The local meteoric water line (LMWL) of the study area provide lower slope (δD = 6.8508δ¹⁸O ? 0.8013) and more depleted average annual rainfall (δ¹⁸O = ?7.6 %ο) when compare to LMWL of Bangkok due to higher evaporation. The surface water mainly exhibits an evaporation effect and can be clearly divided into two groups, the upper reaches and the downstream areas, with approximate separated in δ¹⁸O by ?4.0 %ο. The groundwater system in the area can be divided into seven subareas based on the stable isotope characteristics and groundwater dating by radiocarbon and tritium methods. Nong Bua Deang subarea, Kang Kro subarea, and Thep Satit subarea, the most upstream system which were separated by thick aquitards of Phra Wihan sandstones, are classified as the upper reach area. The groundwater samples are characterized in two traits: the upstream group shows older groundwater ages (<80.0 % modern carbon, PMC) because of less interaction with surface water and the downstream group, near main channels and reservoirs, exhibit younger groundwater ages because of contribution of surface water in the recharge area. Bamnet Narong subarea and Muang Chaiyaphum subarea are classified as the middle reach area. The groundwater shows rapidly recharge from rainfall, the results of radiocarbon provide younger ages. The downstream characteristic which is closely interaction of extremely evaporated surface, were found in Kon Sawan-Mancha Kiri subarea and Ban Phai subarea. Almost all the groundwater samples are related to younger ages except the wells near the upper tributaries. The groundwater management can be proposed by attending to conservation policy in the upper reach area, and some parts of Ban Phai subarea in which groundwater is slowly replenished slowly, as well as groundwater exploration will be expanded in the Bamnet Narong subarea and the Muang Chaiyaphum subarea which is the most effective zones for groundwater developments.     

Using high-resolution in situ radon measurements to determine groundwater discharge at a remote location: Tonle Sap Lake, Cambodia

Tonle Sap Lake (Cambodia) is the largest freshwater lake in SE Asia, and is reported to have one of the highest freshwater fish productions anywhere. During the dry season (November–April) the lake drains through a tributary to the Mekong River. The flow in the connecting tributary completely reverses during the wet monsoon (May–October), adding huge volumes of water back to the lake, increasing its area about fourfold. We hypothesize that nutrients are at least partially delivered via groundwater discharge, especially during the draining portion of the annual flood cycle. We surveyed over 200 km in the northern section of the lake using a customized system that measures natural ²²²Rn (radon), temperature, conductivity, GPS coordinates and water depth while underway. Results showed that there were portions of the lake with significant enrichments in radon, indicating likely groundwater inputs. These same areas were generally characterized by lower electrical conductivities. Samples collected from nearby wells also showed a general inverse relationship between radon and conductivity. Our data suggest that groundwater pathways are important, accounting for roughly 10–20 % of the freshwater flow of the Tonle Sap tributary (connection to the Mekong River), the largest single source of fresh water to the lake. Nutrient inputs from these inputs, because of higher concentrations in groundwater, will be correspondingly higher.     

Application of 85Kr dating to groundwater in volcanic aquifer of Kumamoto Area, Japan

Groundwater age was determined by ⁸⁵Kr/Kr specific activity of gases dissolved in groundwater at Kumamoto Area, in which newly developed Kr extraction system and liquid scintillation counting technique for ⁸⁵Kr were applied. Apparent mean residence times observed were 8.2 ± 0.7 years and 20.7 ± 0.6 years for the groundwater taken from a well at the recharge area and that from an artesian borehole at the discharge area, respectively showing a consistent age trend estimated from the observed groundwater flow system of Kumamoto Area and also that determined using environmental tritium. Similar mean residence times of ⁸⁵Kr and tritium were observed at the discharge area but the mean residence time of ⁸⁵Kr at the recharge area was younger compared to that of tritium, probably due to mixing of river water containing recent ⁸⁵Kr high in concentration into groundwater flow coming from the northern upland??s recharge area. The mean residence time of the groundwater flow coming from northern upland area and a traveling time of the groundwater between two sampling points were estimated by a simple model assuming mixing the river water with the groundwater and a piston flow between two sampling points.     

The hydrological response of heavy clay grassland soils to rainfall in south‐west England using δ2H

Stable isotopes of water have been previously used in catchment studies to separate rain‐event water from pre‐event groundwater. However, there are a lack of studies at the smaller scale looking at the separation of event water from pre‐event water. This is particularly relevant for heavy clay soil systems through which the movement of water is uncertain but is thought to be rainwater‐dominated. The data presented here were collected at a rural site in the south‐west of England. The historic rainfall at the site was isotopically varied but similar to the global meteoric water line, with annual weighted means of ?37‰ for δ²H and ?5.7‰ for δ¹⁸O and with no seasonal variation. Drainage was sampled from the inter‐flow (surface runoff + lateral through‐flow) and drain‐flow (55 cm deep mole drains) pathways of two 1 ha lysimeters during two rainfall events, which had δ²H values of ?68‰ and ?92‰, respectively. The δ²H values of the lysimeter drainage water suggest that there was no contribution of event water during the first, small discharge (Q) event; however, the second larger event did show isotopic variation in δ²H values negatively related to Q indicating that rainwater was contributing to Q. A hydrograph separation indicated that only 49–58% of the inter‐flow and 18–25% of the drain‐flow consisted of event water. This was surprising given that these soil types are considered retentive of soil water. More work is needed on heavy clay soils to understand better the nature of water movement from these systems. Copyright © 2010 John Wiley & Sons, Ltd.     

Radon isotope assessment of submarine groundwater discharge (SGD) in Coleroon River Estuary,Tamil Nadu,India

Submarine groundwater discharge is the fresh groundwater discharge to sea that impacts the coastal regions. Radon (²²²Rn) isotope has been used to quantify SGD in coleroon river estuary, India. Continuous ²²²Rn analyses were attempted for 10 days in groundwater and pore water samples at three different locations. ²²²Rn in groundwater ranges between 35.0 and 222.0 Bq m^?3 and in pore water between 14.0 and 150.0 Bq m^?3 irrespective of locations. The radon mass balance estimated total SGD rate ranges between 2.37 and 7.47 m days^?1. The SGD increases with distance from coast, influenced by tides and hydrological features.     

Uranium isotopes in carbonate aquifers of arid region setting

Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of ²³⁸U and ²³⁵U in groundwater of four selected locations in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for ²³⁵U and ²³⁸ U at 3–39 ng L^?1 (average: 18 ng L^?1) and 429–5,293 ng L^?1 (average: 2,508 ng L^?1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium concentrations suggests that in lithologically comparable aquifers, climate may influence the concentration of uranium in subtropical to arid regions.     

Assessment of environmental radioactive elements in groundwater in parts of Nalgonda district,Andhra Pradesh,South India using scintillation detection methods

The objective of this work was to determine the radioactive element concentrations in groundwater in parts of the Nalgonda district. Results indicate that ²²²Rn activity is present in significant levels in deep groundwater compared to shallow groundwater and tank water. An increasing ²²²Rn activity trend is noticed along the well depth while electrical conductivity, uranium, and alkalinity levels showed inverse trends. Environmental tritium data indicates modern recharge to groundwater. Inter-elemental correlations suggest that high dissolved uranium is associated with high alkalinity and high electrical conductivity groundwater. The study also infers recharge sources and mechanisms to shallow and deep groundwater.     

Determination of cephalosporin antibiotics in water samples by optimised solid phase extraction and high performance liquid chromatography with ultraviolet detector

A reliable and robust analytical method based on solid phase extraction (SPE) and high performance liquid chromatography (HPLC) with ultraviolet (UV) detector was developed for the simultaneous determination of five cephalosporin antibiotics (Ceftazidime, Cefradine, Cefaclor, Cefotaxime and Cefoperazone) in various water samples. Under optimised conditions, it was applicable to preconcentrate up to 500?ml of water samples in the OASIS HLB cartridges with reasonable recoveries for all the cephalosporin antibiotics tested. Recoveries were as follows: deionised water, tap water and groundwater, between 84.2 and 98.9%; surface water, between 71.2 and 81.0%; influent and effluent of wastewater treatment plant (WWTP), between 56.9 and 72.1%. The method detection limits (MDLs) for different water samples were in the range of 26 to 59?ng?l^?1. Real water samples were analysed using the proposed approach to demonstrate the applicability and validation. Negative results were obtained for the tap water and groundwater. However, all the selected cephalosporin antibiotics were identified in the influent and effluent of a local WWTP at ng?l^?1–µg?l^?1 level. In addition, Ceftazidime was found in surface water with a concentration of 0.75–2.60?µg?l^?1. The results indicate that the ‘pseudo-persistent’ contamination of cephalosporin antibiotics in the water environment could not be neglected.     

Isotopes in groundwater as indicators of climate changes

Isotopes of the water molecule (δ¹⁸O and δ²H) are a well-used tool for investigating groundwater origin and history (i.e. tracing the recharge conditions over time, processes occurring during infiltration of rainwater towards aquifers and those involved in the water-rock interaction, and mixing of different waters).This review covers several large European aquifers (Portugal, France, UK, Switzerland, Germany, Hungary, and Poland), which were investigated in terms of their recharge conditions, and the story of the groundwater at a large scale, involving recent, Holocene and Pleistocene components and their eventual mixing.     

A simplified method of developing a local meteoric water line equation for Beijing,China

The local meteoric water line (LMWL) is a benchmark in regional isotope hydrology research. Because of the limitation in the number of monitoring stations, most sites cannot develop the LMWLs with the conventional method. A new simplified method of obtaining the LMWL is proposed. The principle is to get the δD and δ¹⁸O data from the groundwater recharged by the local precipitation and derive the LMWL. Compared with the conventional method, the new method is shown to have many advantages such as saving human and physical resources and monitoring time, simple to be implemented, more practical, and better fitting.     

Transport and sorption of <Superscript>85</Superscript>Sr and <Superscript>125</Superscript>I in crushed crystalline rocks under dynamic flow conditions

Transport and sorption of water-soluble ⁸⁵Sr²⁺ and ¹²⁵I⁻ in the columns with beds of crushed crystalline rocks from synthetic groundwater has been studied under dynamic flow conditions. Samples of crystalline rocks: diorite-I, diorite-II, gabbro, granite and tonalite, having the grain size between 0.25 and 0.80 mm, were used. Plastic syringes of 8.8 cm length and 2.1 cm in diameter were applied as columns. The synthetic groundwater was pumped downward through the columns with a seepage velocity of about 0.2 cm/min and the given radioactive nuclide was added into the water stream individually in a form of a short pulse. In case of ⁸⁵Sr, desorption from diorite-I was also studied using an artificial acid rainfall and then, the longitudinal distribution of the residual ⁸⁵Sr activity along the bed was measured. Retardation, distribution and hydrodynamic dispersion coefficients were determined by the evaluation of respective breakthrough curves. A corrected integral form of a simple advection–dispersion equation was derived and used for fitting the experimental data. The K _d-parameters resulting from dynamic experiments were also compared with the results of static sorption experiments.     

A highly sensitive and selective fluorescent probe for cyanide based on the dissolution of gold nanoparticles and its application in real samples

We report a simple fluorescence method for detection of cyanide sensitively and selectively based on the dissolution of polymer-coated gold nanoparticles by cyanide. The lowest concentration for quantification of cyanide ions was 3.0×10(-7) M, and other common anions nearly have no influence. Furthermore, several real water samples spiked with cyanide, including local groundwater, tap water, boiled water, and lake water, were analyzed, and the experimental results demonstrated that our sensing system worked well in the above water samples, with a good linear correlation.     

Radioactivity in groundwater along the borders of Oman and UAE

Characterizing the quality and radioactivity of groundwater is vital as it represents valuable resource in arid regions. Here we present radioactivity level in groundwater collected from wells in a region along the border between Sultanate of Oman and United Arab Emirates (UAE). The aquifers are alluvium deposits (silt, sand and gravel) and the measured groundwater radioactivity (including ²³²Th, ²³⁸U, ²³⁵U, ²²⁶Ra, ²²²Rn, gross-α and gross-β) indicates values below the WHO permissible limits for drinking water. The results also show large difference in radioactivity fingerprints, in particular for ²²⁶Ra and ²²²Rn within the investigated aquifers. The data further indicate lower radioactivity in groundwater of the alluviums compared to the carbonate aquifers in the region. This feature makes the alluvium aquifers valuable reservoirs that should be carefully exploited as a source of groundwater. As this is the first investigation on the radioactivity of groundwater in alluvial aquifers in the region, it suggests that other alluvial deposits, particularly those inland and far from the marine water intrusion or seepage from carbonate rocks would have low radioactivity fingerprints.     

双电极法现场快速检测地下水和湖水中碳酸氢根和碳酸根

地下水和湖水中碳酸氢根( HCO-3)和碳酸根( CO2-3)含量是地球化学碳行为和碳循环的重要表征,但两种离子的浓度易受环境影响而改变,因此,地下水和湖水中HCO-3和CO2-3真实含量的测定一直是个难题。实验利用CO2的水解平衡,通过pH电极和二氧化碳电极联用,建立了HCO-3和CO2-3现场快速测定的新方法,解决了地下水和湖水中HCO-3和CO2-3真实含量的测定难题。研究结果表明,在pH=4.8±0.1的底液中, HCO-3和CO2-3的线性范围分别为0.027~570 mg/L和1.25×10-8~39.7 mg/L。共存的金属离子、强酸阴离子(K+、Na+、Mg2+、Cl-、SO2-4,100 mg/L)、弱酸阴离子和弱酸(HSO-3、NO-2、HOAc,50 mg/L)对测定干扰小于5%。实际水样加标实验回收率在95.2%~99.2%之间,相对标准偏差为2.6%~3.7%。与酸碱滴定法进行对比,本方法的准确性良好。但方法受温度影响,因此标准溶液与样品应在同一温度下测量。总体而言,双电极法灵敏、快速、经济且电极携带方便、操作简单、对环境要求不高,十分适合现场和室内一般自然水体的快速检测。本方法已成功应用于青海省地下水和青海湖湖水中HCO-3和CO2-3的现场测定。实验表明,海东地区地下水样品pH在6.4~7.4之间,HCO-3含量为234~4096 mg/L,CO2-3含量为0.16~1.89 mg/L；青海湖湖水样品pH≈8.7,HCO-3含量范围在1.36~1.86 g/L,CO2-3含量在32.3~43.9 mg/L,与文献结果吻合。     

Polyethyleneimine Solubilized Luminescent Au(I)‐Thiolate Complexes for Highly Sensitive and Selective Cyanide Anion Sensing

Cyanide (CN^?) is a highly toxic anion to human beings, exploring efficient probes for sensitive and selective detection of it is very important. In this study, we explore a simple one‐pot reaction to synthesize polyethyleneimine (PEI) solubilized Au(I)‐MUA (11‐mercaptoundecanoic acid) complexes under mild condition. The as prepared Au(I)‐MUA complexes exhibit strong red photoluminescence (PL) and can act as sensitive and selective CN^? optical sensor in aqueous media based on the chemical reaction between CN^? and gold atom that quench the fluorescence, and the limit of detection is 10 nM, which is ～270 times lower than the maximum contamination level (2.7 μM) in drinking water permitted by WHO. Additionally, real water sample from a local lake is tested with these optical sensors, and the PL variation caused by 0.1 μ CN^? can be observed.     

Occurrence of the radionuclides in groundwater of crystalline hard rock regions of central Tamil Nadu,India

A study was conducted to understand the occurrence of the radionuclides in groundwater of crystalline hard rock region. Samples were collected to analyze major cations, anions, U, ²²²Rn and stable isotopes of oxygen, hydrogen. It was inferred that few samples have U and ²²²Rn concentrations higher than the permissible limit of drinking water standard. High degree of weathering of granitic rocks and long contact time of groundwater with the aquifer matrix could be the reason for enhanced U and ²²²Rn levels in groundwater. The association of U with SO₄ also proves that there exists anthropogenic influence in groundwater composition.     

Uranium isotopes as a tracer of groundwater transport studies

The activity concentrations of ²³⁴U and ²³⁸U in thermal groundwater, deep well water and river water samples from Central Poland were determined. Concentration of ²³⁴U and ²³⁸U in the examined waters varied from <0.013 (LLD) to 16.8 mBq/dm³ and from <0.013 (LLD) to 45.5 mBq/dm³ respectively. The highest uranium activity concentrations were measured in the thermal groundwater from Mszczonow and Cieplice, while the lowest were observed in thermal ground water from Uniejow and Poddebice. In thermal groundwater from Skierniewice, uranium activity concentrations were below lower limit of detection (0.013 mBq/dm³). The ²³⁴U/²³⁸U activity ratio varied from 0.37 (Cieplice) to 1.30 (Poddebice well water).     

The use of radium isotopic ratio in groundwater as a tool for pollution source identificatioin

Radium isotopes were measured in groundwater near a radioactive storage facility with contained pasty residues from monazite and industrial processing sealed in concerete reserouirs. The concentration of radium isotopes in the water was slightly higher than found in the normal drinking water. The measured²²⁸Ra to²²⁵Ra ratio in the groundwater is not compatible with calculations of radium isotopes ingrow and docay in cake II for different elapsed times, leaving mesothorium cake as the most likely source of contamination.     

Monitoring of environmental radiation and radionuclides around nuclear fuel cycle facilities from 1989 to 1995

Aomori Prefectural Govemment and Japan Nuclear Fuel Limited started environmental radiation monitoring around Nuclear Fuel Cycle Facilities in April 1989. External radiation is measured by NaI(TI) scintillator and Themoluminescence dosimeter. The level of external radiation is relatively low in the winter due to snow. We have collected terrestrial samples of drinking water, soil, agricultural products and marine samples of seawater, sea sediment, seafood, etc. periodically. We have measured many radionuclides and fluoride in these samples. In soil sample,^239+240Pu ratio to¹³⁷Cs was almost constant at all sampling points. A correlation was observed between salinity and concentration of tritium, uranium and fluoride in lake water of Lake Obuchinuma. The correlation between¹³⁷Cs and^239+240Pu in lake sediment was observed in each lake.