Concentrations Of Major Anions Research Articles

Assessment of the environmental impacts of utilizing coal ashes and OPC for soil stabilization applications: Leachate analysis in response to rainfall interaction

The construction industry is a leading sector for coal ashes utilization, including in cement manufacturing and soil stabilization applications. In soil stabilization, coal ashes, alongside Ordinary Portland Cement (OPC), are the most commonly used materials. However, the environmental impact of coal ashes, particularly the leaching of heavy metals from stabilized soil when exposed to rainfall, remains underexplored. There is a notable gap in assessing the environmental impacts of this utilization, particularly when the stabilized soil interacts with rainfall in real-world scenarios. Therefore, this study aimed to contribute to filling this gap. Accordingly, in this study, peat soil was stabilized by using fly ash, bottom ash, and OPC. The characterization of soil mixture materials, including physicochemical and engineering properties, was established and studied first. Following the environmental impact, simulations were conducted using a column to study soil leachate under different conditions and seasons (dry and wet) in response to its interaction with rainfall. The leachate was analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to measure the concentrations of heavy metals, including copper (Cu), aluminum (Al), manganese (Mn), iron (Fe), and zinc (Zn). Additionally, Ion Chromatography (IC) was employed to determine the concentrations of major anions, including fluoride (F⁻), chloride (Cl⁻), nitrate (NO₃⁻), phosphate (PO₄³⁻), and sulfate (SO₄²⁻). The findings revealed the complex interaction of the chemical stabilization processes and environmental factors with the leaching behavior of heavy metals and anions, highlighting the significant impact of stabilization on leaching patterns. To conclude, this study provides a valuable contribution to understanding the environmental and engineering implications of utilizing coal ashes in soil stabilization.

Podejście do jakości wody w zlewni osadzonej w krajobrazie rolno-leśnym nieznacznie zdegradowanym przez działalność rolniczo-hodowlaną

The headwater streams constitute landscapes with their own entity and are strongly influenced by their environment. They have a large impact on health and integrity, both for water quality and wildlife downstream. Studies on water quality from atlantics agroforestry catchments are scarce. Knowledge about water quality in agroforestry headwater catchments is important for assessing downstream effects and as a baseline for net impacts of land-use change. We analyzed physicochemical water variables of a headwater stream framed in a rural-agroforestry catchment with very little agricultural area, low livestock density and very little human population in NW Spain. Stream water samples were collected at the catchment outlet at approximately biweekly intervals over three years. All water samples were analyzed for the following quality parameters: pH, water temperature (T), electrical conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), major cations (Ca, Mg, Na, K), anions (Cl, SO4), nutrients [total dissolved carbon (TDC), dissolved organic carbon (DOC), nitrites nitrogen (NO2-N), nitrate nitrogen (NO3-N), ammonium nitrogen, Kjeldahl nitrogen (KN), total nitrogen (TN), dissolved, particulate and total phosphorus (DP, PP, TP)], and suspended solids (SS). Discharge was also measured. The mean concentrations of major anions, cations and different forms of carbon, nitrogen and phosphorus were rather low compared to global “average” values. Overall, the mean values of the main physicochemical water quality indicators offers similar values to those found in other rural catchment in humid temperate climates with low agricultural activity and demography, although such concentrations could have been underestimated as they mostly correspond to regular sampling and therefore ignore the influence of rainfall-runoff events.

Groundwater geochemistry and hydro-geochemical processes in coastal area South Phan Thiet, Binh Thuan Province, Vietnam

As one of the largest dragon fruit areas and many tourism projects, the southern coastal area of Phan Thiet (including three communes: Tien Thanh, Thuan Quy, and Tan Thanh) has been a bright spot in the economy of Binh Thuan. Economic development puts pressure on water resources, especially groundwater resources, the main supply for irrigation and domestic water in the region. In this research, 19 groundwater samples from the Holocene and Pleistocene aquifers were collected in February 2023 and analyzed for the concentration of Ca2+, Mg2+, Na+, K+, NH4 +, NO3 −, PO4 3-, Cl−, HCO3 –, and SO4 2-, thereby evaluating groundwater geochemistry, hydro-geochemical processes, and the suitability for irrigation purposes. The rank of cations in the aquifers of the region is Na+ > Ca2+ ∼ Mg2+, and Ca2+ ∼ Mg2+ > Na+ respectively. The concentrations of major anions in the study area are in order Cl− > HCO3 − > SO4 2- respectively. The predominant processes in the aquifer involve the interplay between rock and water as well as anthropogenic activity. The saturation indices of dolomite, gypsum, and halite are under-saturated in all collecting sample sites. According to the quality evaluation for irrigation, 14 of the 19 samples with % sodium levels less than 60 are suitable, while the others should be treated before use. The study area also indicated nitrate pollution (4/19 groundwater samples exceeding 15 mgN L−1 of the Nitrate limited for groundwater, National technical regulation on underground water quality). It is recommended that local authorities have strategies to supply water for different purposes, control pollution sources, and treat water waste to protect these aquifers.

Groundwater Contamination in Arid Coastal Areas: Qatar as a Case Study

AbstractThe Arab region is located in an arid environment and suffers from water scarcity and poor water quality which are expected to become more severe in coming years due to global warming. In this study, the groundwater quality of 205 wells in Qatar was investigated. The physical parameters of pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, inorganic carbon (IC), and organic carbon (OC) were determined. The study characterized the concentrations of major anions of Cl, F, Br, NO3, PO4, and SO4, and major cations of Ca, K, Mg, and Na. Importantly, metals and metalloids including V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Pb, and U were determined. The results revealed that the groundwater of all wells is not drinkable due to high salinity (average TDS 4598 mg/L and salinity 0.4%, respectively). Additionally, average concentrations of major anions Cl, SO4, and F were 1472, 1064, and 1.9 mg/L, respectively, and all exceed the World Health Organization (WHO) guidelines for drinking water. However, NO3 concentration in 11 out of 205 wells was above the WHO guidelines of 50 mg/L due to intensive agriculture and fertilizer applications. Major cations of Ca, K, Mg, and Na were higher than WHO guidelines with average concentrations of 345, 63, 127, and 923 mg/L, respectively. All trace metals were much lower than the WHO guidelines for drinking water; however, the vanadium (V) average concentration in groundwater of all wells was 31 μg/L, which is five times higher than the Dutch guidelines (whereas the WHO has no guidelines for V). The groundwater of Qatar is dominated by Ca and Mg sulfates in Sabkha environments and dominated by NaCl in the coastal zones from evaporate environments consisting of coastal salt flats, salt pans, estuaries, and lagoons supersaturated by salts and the influence of sea water intrusion.

How do major ions and fulvic acid affect dissolved inorganic phosphorus adsorption onto suspended particulate matter in estuarine environment?

The adsorption and desorption of Dissolved Inorganic Phosphorus (DIP) onto Suspended Particulate Matter (SPM) are of key importance for the biogeochemistry in estuarine system. These processes are susceptible to changes in environmental factors, especially the inherent changes in levels of major ions, fulvic acids and salinity. As anthropogenic organic contamination in estuaries increases, aniline was chosen to investigate the influence of anthropogenic organic matter on DIP adsorption The influence of these factors on adsorption and desorption of phosphate onto SPM in estuarine aquatic system was examined using batch experiments in single and combined systems. The study showed that the adsorption of DIP onto SPM in estuaries was mainly controlled by salinity, especially the concentration of calcium (Ca2+), magnesium (Mg2+), sulfate (SO42−) and bicarbonate (HCO3−). Increased concentrations of major cations (Ca2+ and Mg2+) enhance DIP adsorption, while increased concentrations of major anions (SO42− and HCO3−) reduce adsorption. The amount of DIP adsorbed to SPM was mainly governed by the concentration of Ca2+, while the effect of differences in salinity was mainly dictated by the concentration of major anions. The facilitating effect of fulvic acid on DIP adsorption was generally negatively affected by increased salinity, as the fulvic acid increasingly reduced the enhancing effect of Ca2+ on DIP adsorption by forming stable complexes. Fulvic acids had no significant influence on the effect of Mg2+ and HCO3− on DIP adsorption to SPM. Aniline slightly inhibited DIP adsorption by competing with DIP for active sites on SPM. Aniline had no significant influence on the effect of cations on DIP adsorption to SPM, while slightly increasing inhibitory influence on anions.

Hydrogeological characteristics of groundwater and surface water associated with two small lake systems on King George Island, Antarctica

Although groundwater is an important component of the water cycle in the polar regions, groundwater in Antarctica has rarely been studied. This study evaluated the physical and chemical characteristics of groundwater, surface water, and snow in two lakes on the Barton Peninsula, King George Island, Antarctica, with a particular focus on groundwater. Influxes/outfluxes of groundwater were measured using seepage meters, and hydraulic conductivities were calculated based on grain size analysis for the sediments. A total of 41 water samples were used to determine the chemical compositions and isotopic ratios of oxygen and hydrogen. The groundwater fluxes measured in one lake (referred to as “Lake A”) were −9.9 × 10−10 ~ 2.7 × 10−9 m/s (average of −9.1 × 10−10 ± 3.6 × 10−9 m/s) and in a second lake (referred to as “Lake B”) were 2.2 × 10−9 ~ 3.0 × 10−9 m/s (average of 2.6 × 10−9 ± 4.0 × 10−10 m/s). This indicates that groundwater flux is highly dynamic in Lake A, whereas groundwater influx in Lake B is relatively stable. Hydraulic conductivity for the lake sediments ranged between 1.7 × 10−6 m/s and 2.1 × 10−4 m/s. Oxygen and hydrogen isotopic compositions followed the global meteoric water line (GMWL) and local meteoric water line (LMWL), indicating that groundwater and surface water in the study area originate from the atmosphere. Evaporation may not be an influential factor probably due to the relatively humid climate during the summer season in the study area. Groundwater and surface water might partially experience isotopic exchange fractionation during and after the snow melting process. The chemical composition of groundwater was distinguished from that of surface water and snow by higher concentrations of major anions (Cl, SO4, and alkalinity), major cations (Ca, Mg, K, and Na), and trace elements (Si, Li, Sr, Mn, Zn, and Cu), resulting from water-rock interactions. To the best of our knowledge, this is the first study to directly measure groundwater fluxes in lake systems in Antarctica, and to evaluate the characteristics of groundwater in the Barton Peninsula. It may therefore serve as a basis for studying the role of groundwater in the water cycle of Antarctica.

ГИДРОХИМИЧЕСКИЙ СТОК РЕЧНЫХ ВОД ЮГА ХАБАРОВСКОГО КРАЯ В ПЕРИОД ЛЕТНЕГО ПАВОДКА

Актуальность: изучение гидрохимического стока рек как одного из основных индикаторов экологического состояния водных объектов. Цель: получение новых знаний о гидрохимическом стоке рек юга Хабаровского края, которые необходимы для объективной оценки экологического состояния поверхностных вод края и проведения эффективных водоохранных мероприятий. Объекты: р. Амур и семь рек бассейна р. Уссури (одного из наиболее значимых притоков Амура): Бикин, Хор, Подхоренок, Бира, Кия, Малая Чирка и 2-ая Седьмая. Методы. Концентрaции мaкро-aнионов (Cl–, SO42–) измерялись методом ионно-обменной хромaтогрaфии; макро-катионов (Nа+, K+, Cа2+, Mg2+), микроэлементов и редкоземельных элементов ‒ методом ICP‒MS (Agilent, 7500с). В качестве концентрации гидрокарбонатного иона (HCO3–) принималась величина щелочности. Результаты. В июле 2011 г. проведены комплексные гидрохимические исследования в р. Амур и семи реках бассейна р. Уссури (одного из наиболее значимых притоков Амура): Бикин, Хор, Подхоренок, Бира, Кия, Малая Чирка и 2-ая Седьмая. В пробах речной воды были определены параметры основного солевого состава, микроэлементов и редкоземельных элементов. В период высокого расхода воды в высоко увлажненных южных районах Хабаровского края речные воды очень схожи по типу и величине минерализации: среди катионов доминирует Ca2+, основным противо-анионом является HCO3–; воды ультрапресные, ∑i не превышает 50 мг/л. В поверхностных водах всех исследованных рек обнаружены высокие концентрации растворенных форм Al, Fe и Pb. В р. Малая Чирка ‒ высокие концентрации растворенных Co, Cu, Mn и экстремально высокие Cd, превышающие средние глобальные концентрации в 40 раз. Содержание остальных микроэлементов в исследуемых реках в целом соответствовало их средним глобальным концентрациям и является характеристикой природного регионального фона в период летних паводков. Установлен региональный уровень суммарных концентраций растворимых форм редкоземельных элементов (1,44‒5,44 мкг/л). Величины концeнтрaций редкоземельных элементов в иccлeдуeмых реках укaзывaют нa однотипноcть иcточникa их поcтуплeния. Рассчитанные суммарные суточные потоки макро-ионов, микроэлементов и редкоземельных элементов, поставляемые реками Бира, Кия, Подхоренок, Бикин, Хор и Амур, равны 61894, 377 и 2,21 т/сут, соответственно.

Ion Concentrations and Their Spatial Variability in Underground Water and Surface Water in Typical Terrestrial Ecosystems in China

The water chemistry data monitored during 2010-2015 by 33 terrestrial ecological stations from the Chinese Ecosystem Research Network (CERN) and the National Ecosystem Research Network of China (CNERN) were used to characterize ion concentrations and their spatial variability in underground water, still surface water, and flowing surface water from typical terrestrial ecosystems. The results showed the presence of mass-based concentrations of major anions, including HCO3- > SO42- > Cl- > CO32-. Among them, HCO3- and SO42- were dominant, and their sums accounted for 71.7%, 75.3%, and 74.9% of the total anions in underground water, still surface water, and flowing surface water, respectively. Cations were mainly Ca2+ and Na+, and their sums accounted for 69.7%, 64.8%, and 68.9% of the total cations in underground water, still surface water, and flowing surface water, respectively. The ion concentration and ion ratio in the underground water, still surface water, and flowing surface water differed largely among the studied regions. The hydrochemical type varied regionally, e.g., Na-Mg-SO4-Cl type, usually with high content of salinity, was found in the underground water of ecological systems in the Northwest arid and semiarid areas and in the East Huanghuaihai Plain; Ca-SO4-HCO3 type in underground water and Ca-HCO3-SO4 type in surface water were found in hilly areas with subtropical red soil; Na-Ca-HCO3-Cl type was present in underground water of south hilly areas with subtropical latosolic red soil; and Ca-HCO3 and Ca-Mg-HCO3 types were found in other ecological systems. Hydrochemical types had low inter-annual variation for both underground water and surface water.

Groundwater quality in open-defecation-free villages (NIRMAL grams) of Kurukshetra district, Haryana, India.

Groundwater is an indispensable natural resource for drinking water, generally in rural areas due to unavailability of treated water. The study was designed to investigate the groundwater quality in nine open-defecation-free (ODF) villages (Nirmal Grams) of Kurukshetra district, Haryana, India. For the research, 81 groundwater samples were collected from different borewells of Nirmal Grams during pre-monsoon (PRM), monsoon (MON), and post-monsoon (POM) seasons and were analyzed for 13 water quality parameters, i.e., pH, EC, TDS, Cl-, TH, Ca2+, Mg2+, Na+, K+, HCO3-, F-, SO42-, and PO42-, using standard methods. The Water Quality Index (WQI) was calculated from the analyzed parameters and the results were compared with the World Health Organization (WHO 2011) and the Bureau of Indian Standards (BIS 2012) in order to have an overview of the groundwater quality. The concentration of major anions and cations was found to be in the order of HCO3- > Cl- > SO42- > F- > PO42- and Ca2+ > Na+ > K+ > Mg2+, respectively. Statistical Package of Social Sciences (SPSS) version 23 was used for statistical analysis, Aquachem 2014 software (trial version) was used for Piper diagram, Box-Whisker plot, Schoeller, and Gibbs diagram, whereas WQI was calculated manually. The values of WQI in the study area were ranged between 32.08 and 88.38 in PRM, 46.62 and 102.33 in MON, and 34.99 and 79.81 in POM seasons, respectively. Groundwater quality index reveals that the majority of the samples fall under 'good' to 'excellent' water category. It indicates that the groundwater is suitable for drinking and other domestic uses.

Unique Pit Lake Created in an Opencast Potassium Salt Mine (Dombrovska Pit Lake in Kalush, Ukraine)

We studied the physicochemical and biological characteristics of the Dombrovska pit lake in Ukraine. The lake formed in an abandoned opencast potassium salt mine and is one of the most saline inland water bodies in the world. It is 85 m deep (November 2015) and an annual inflow of about 2 Mm3 of water. The lake has two distinct layers. The mesohaline surface (0–5 m) layer is well oxygenated and slightly alkaline (pH = 7.5–8.8). Its mineralization, expressed as dry mass, was 50–134 g dm− 3, and its electrical conductivity (EC) was 58–134 mS cm− 1. The underlying layer consists of hypersaline water with low amounts of dissolved oxygen, a neutral pH (6.7–7.4), high mineralization (179–420 g dm− 3), high EC (169–215 mS cm− 1), and higher concentrations of major anions and cations (except Ca2+) and nutrients than the overlying water. The vertical relationship between major ions and metals and the future salinity of the lake are discussed. In terms of zooplankton, in July we found living specimens of the rotifer Brachionus plicatilis and the ciliates Paradileptus elephantinus and Tindinnidium sp. as well as dead rotifers, cladocerans, and copepods (in total, 19 species), but only live B. plicatilis and 9 dead species in November. In the littoral part of the pit lake, we found the diatoms Nitzschia pusilla and some Halamphora species (H. borealis, H. tenerrima, H. acutiuscula), which favour highly saline waters.

Inter-comparison of Chemical Composition and Originality of Atmospheric PM10 at Coastal Regions and Offshore Islands in the Subtropical East Asia

Inter-comparison on the chemical characteristics, spatiotemporal variation, and source originality of atmosphere PM10 at the coastal regions and offshore islands of subtropical region in East Asia was investigated. A total of six sampling sites including three coastal and three island sites over the Minjiang estuary were selected for simultaneously manually sampling PM10 to investigate the differences of coastal and island PM10 concentration, chemical properties, and emission sources. After sampling, an ion chromatographer (IC) was used to analyze the concentration of major anions (F−, Cl−, SO42−, and NO3−) and cations (NH4+, K+, Na+, Ca2+and Mg2+). The metallic elements (Na, Ca, Al, Fe, Mg, K, Zn, Cr, Ti, Mn, Ni, Pb, and Cd) of PM10 were measured with an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The carbonaceous contents, including elemental, organic, and total carbons (OC, EC, and TC), of PM10 were analyzed with an elemental analyzer (EA). The source apportionment of PM10 was further resolved by a receptor model based on chemical mass balance (CMB). Field measurement results showed that high concentrations of PM10 (102 ± 25 μg/m3) were commonly observed from late fall to early winter. The PM10 concentration showed a consistently descending trend from the west coastline to the far east islands, with the highest PM10 concentration at the coastal site (Site HQ) and the lowest at the far east island site (Site DY) in all seasons. Secondary inorganic aerosols (SIAs) and crustal materials were two most abundant compounds in PM10. Increasing anthropogenic trace elements was commonly observed in spring and winter, while northern monsoons were blown. High OC/EC ratios showed that secondary organic aerosols (SOAs) could be formed in the atmosphere of Minjiang estuary. Results from CMB receptor modeling indicated that the major sources of atmospheric PM10 at the coastal and offshore island regions of the Minjiang estuary were soil dusts (13–33%), secondary aerosols (15–30%), transport emissions (11–17%), sea salts (8–27%), and agricultural debris burning (2–8%). Particularly, during the poor air quality periods, a rising contribution of industrial emissions (1–16%) was resolved, suggesting that atmospheric PM10 over the Minjiang estuary was mainly attributed to cross-boundary transport rather than local emissions.

Evaluation of groundwater quality in parts of the Southern Gangetic Plain using water quality indices

In India, persistent dependence on groundwater for intensively irrigated agriculture, industrial use and domestic activities imposes substantial threat to the quality and quantity of groundwater. This study assesses the suitability of groundwater for drinking purposes in parts of the Southern Gangetic Plain based on samples collected from 33 dug wells. In this scope, two robust indices are utilized, namely Groundwater Quality Index (GQI) and the Canadian Council of Ministers of the Environment (CCME) Water Quality Index (CCME_WQI), to assess the overall quality of groundwater by integrating observed water quality determinants like pH, TDS and major ion concentration. The concentration of major anions and cations is observed to be in the order of HCO3 − > Cl− > SO4 2− > NO3 − and Na+ > Ca2+ > Mg2+ > K+, respectively. The pH values of the analyzed samples vary between 6.2 and 7.37 during the post-monsoon (POM) period and between 6.6 and 7.9 during the pre-monsoon (PRM) period. Similarly, TDS concentrations are observed to vary between 6.7 and 1535 mg/l (POM) and 1.43 and 1327 mg/l (PRM). The values of GQI in the study area range between 10.41–108.56 and 16.03–130.06 for the PRM and POM periods, respectively. Among the groundwater samples collected during the PRM period, about 21, 73 and 6% are found to be excellent, good and poor quality, respectively. While the percentage of poor quality water for POM period is exactly the same as that of PRM, about 42 (52%) of the samples are found to be of excellent (good) quality for drinking purposes. The analysis of CCME_WQI for groundwater samples reveals that 3 (21%), 42 (36%), 33 (18%), 21 (24%) of the samples collected during PRM (POM) are classified to be of excellent, good, fair and marginal category, respectively. The spatial distribution of GQI and CCME_WQI illustrates that excellent quality water occurs primarily in the northeast part of the study area during the POM period. However, some localized patches with excellent quality are also observed in both the seasons. Results from this study will be crucial for proper utilization and management of already depleted groundwater resources of the study area.

Major anion and cation fluxes from the Central SiberianPlateau watersheds with underlying permafrost

The subarctic rivers of the Central Siberian Plateau have specific fed-characteristics due to the permafrost distribution and the active layer thawing dynamics. Two watersheds with different types of permafrost (from insular to continuous) are studied. Different data sources (Roshydromet and our own observations) are used for receiving anions’ (HCO3-, SO42-, Cl-) and cations’ (Ca2+, Mg2+) fluxes from the Nizhnyaya Tunguska river (1960-2011) and the Tembenchi river (1970-2011). The annual discharge of N. Tunguska for 1939-2011 is characterized by an increase of 0.3 km3/year/year, and for Tembenchi, 0.04 km3/year/year. The major part of the increase (about 60%) is due to spring flooding (May - June). The volume-weighted mean concentrations of major anions and cations in the N. Tunguska river water increased three times in the spring period (40.7 - 116.8 mg/l) and in the summer-fall period (74-212.9 mg/l). On the contrary, such concentrations decreased sharply during the winter mean water period. Due to these results, the total export of main anions and cations from the N. Tunguska river basin rose more than 4,5 times. Two possible reasons can be identified: 1) a water discharge increase of the Subarctic rivers (Peterson et al., 2002); 2) permafrost degradation induced by global climate warming (Frey and McClelland 2009).

AN ANALYSIS OF THE GROUNDWATER CHEMISTRY OF THERMAL SPRINGS IN THE SOUTPANSBERG BASIN IN SOUTH AFRICA: RECENT DATA

Investigations were carried out in order to assess the groundwater chemistry of aquifers in the Soutpansberg Basin. Water samples were collected from Sagole, Tshipise, Mphephu, Dopeni and Siloam thermal springs during the winter and summer seasons of May 2013 and October 2013, respectively. Water temperature, pH, electrical conductivity, dissolved oxygen and total dissolved solids were determined on-site, using a multiparameter meter. The concentrations of major anions (Cl − , NO 3 − , SO 4 2− and PO 4 3− ,) were determined using ion chromatography. Cations (Na + , Ca 2+ , Mg 2+ , K + , Al 3+ and Fe 2+ ) were analysed using optical emission spectrometry. The highest water temperatures during both the summer and winter seasons were recorded at Siloam (59.4°C and 59.0°C), Tshipise (51.2°C and 51.2°C) and Dopeni (46.0°C and 46.5°C), respectively. The thermal spring water samples were found to be rich in sodium, bicarbonate and chlorine with very low concentrations of other element species. The chemical composition of Sagole and Siloam thermal springs indicates the same origin of Na-Cl-HCO 3 waters, typical of deep circulating groundwater. None of the thermal springs exhibited any evidence of groundwater pollution. The seasonal variations in the chemical composition of winter and summer samples were found to be negligible and consequently show that the source of the hot water was deep and therefore not affected by seasonal rainfall recharge.

Chemical composition of the inorganic fraction of cloud-water at a high altitude station in West India

Data from a ground-based cloud-water collection system intercepting water from clouds at a mountain field station, Sinhagad near Pune in India are presented. This study was part of an Indo-Swedish Collaboration Project on Atmospheric Brown Cloud-Asia (ABC-A). Cloud-water and rainwater (wet-only) samples were collected during June 2007–Dec. 2010. Concentrations of major anions and cations were determined. Ion concentrations were generally higher (NO3−, about 8 times; SO42− and K+, 5 times; NH4+, 4 times and Cl−, Na+, Ca2+, Mg2+ 3 times) in cloud-water samples than in rainwater samples collected during the same days. The average pH of cloud-water samples was 6.0 with about 20% of the values below 5.6 and only 4% less than 5.0. Despite high concentrations of SO42− and NO3− the cloud water samples were on average not more acidic than rainwater samples. This is different from most of the other studies of cloud-water composition which have noted a substantially higher acidity (i.e. lower pH) in cloud-water than in rainwater. The slightly alkaline (pH > 5.6) nature of the cloud-water samples is mainly due to the presence of soil derived calcium carbonate in quantities more than enough to neutralize the acids or their precursors. A separation of the cloud-water data into trajectory groups showed that samples in air-masses having spent the last few days over the Indian sub-continent were in general more acidic (due to anthropogenic emissions) than those collected during days with air-masses of marine origin. A high correlation mutually between Ca2+, Na+, NO3− and SO42− makes it difficult to estimate the contribution to SO42− from different sources. Anthropogenic SO2-emissions and soil dust may both give important contributions.

Analysis of water-soluble ions and their precursor gases over diurnal cycle

A detailed description of an interactive relationship is made between water-soluble ionic components in PM2.5 and their precursor gases using the hourly resolution data measured at an urban monitoring site in Seoul during the year of 2010. Their diurnal variability was found to be correlated with their precursor gases (HNO3 and NH3). In the case of NO3− and NH4+, a close similarity was seen in their diurnal trends, especially during spring. There were no noticeable differences in the formation pathway of NO3−, SO42−, and NH4+ aerosols between day and night. For NO3− formation, heterogeneous hydrolysis of N2O5 might play a significant role in the nighttime enhancement of the oxidation rate. In addition, the concentrations of major anions (e.g. NO3−, SO42−, and Cl−) exhibited highly diverse seasonal patterns with their maximum values occurring in spring, summer, and winter, respectively. The overall results of this study suggest that the formation pathway of NO3− and SO42− aerosols should be regulated by a competing relationship between the NH3-lean (spring and winter) and NH3-rich conditions (summer and fall).

Evaluation of commonly used filter substrates for the measurement of aerosol trace element solubility

The published literature describing aerosol trace element fractional solubility measurements is characterized by a wide range of observed fractional solubilities. Whereas some of this variability is derived from natural differences in the chemical characteristics of the aerosol source material, the use of different sample collection and processing protocols by the scientific community has also confounded efforts to understand aerosol solubility. Bulk aerosol samples were collected at a coastal site over a nine‐month period and used to assess the influence of filter material on aerosol solubility measurements. Two hundred samples were extracted with ultrapure deionized water and focused on the solubility of ten trace elements (Al, P, Ti, V, Mn, Fe, Ni, Cu, Zn, and Pb) of interest to the GEOTRACES program. Aerosol samples were collected on eight different filter types and extracted using a flow‐through “instantaneous” extraction method. In many cases, the operationally defined aerosol trace element solubility differed depending on filter type. Major anion concentrations and trace element fractional solubility were found to differ 58% and 60% of the time, respectively. Filter blank concentrations are also reported for the various filter types. This work, in conjunction with the 2008 GEOTRACES Aerosol Intercalibration study, should aid the design of future research efforts by the wider marine aerosol community and allow better comparisons among published data.

Influence of depth and time on diversity of free-living microbial community in the variably saturated zone of a granitic aquifer

We investigated the temporal and vertical changes in the microbial communities related to hydrological variations an aquifer (Brittany, France). Five water samplings were carried out, spanning three hydrological cycles in the variably and the permanently saturated zones. Seasonal variations in the major anion concentrations (NO3 -, SO4 2- and Cl(-) ) indicated that different physical processes occurred during the recharge process in the two zones. The variably saturated zone is mainly dominated by diffusion and advection processes from the soil, whereas the permanently saturated zone is controlled by moderate advective transfer from the variably saturated zone. Bacterial diversity was investigated by flow cytometry, 16S rRNA and narG genes analyses. Part of this diversity was new in that 6 of the 27 16S rRNA gene sequence phylotypes were unknown even at the class or phylum level. The narG gene analysis did not reveal any clear variation in time or depth within the nitrate reducers' community. In contrast, 16S rRNA gene analyses showed modifications of community composition that could be related to the hydrologic and chemical contrast between the two zones. It was concluded that the physical processes of water transfer could influence bacterial diversity at the soil-aquifer interface.

Transport and fate of mercury under different hydrologie regimes in polluted stream in mining area

Abstract Seepage from Hg mine wastes and calcines contains high concentrations of mercury (Hg). Hg pollution is a major environmental problem in areas with abandoned mercury mines and retorting units. This study evaluates factors, especially the hydrological and sedimentary variables, governing temporal and spatial variation in levels and state of mercury in streams impacted by Hg contaminated runoff. Samples were taken during different flow regimes in the Wanshan Hg mining area in Guizhou Province, China. In its headwaters the sampled streams/rivers pass by several mine wastes and calcines with high concentration of Hg. Seepage causes serious Hg contamination to the downstream area. Concentrations of Hg in water samples showed significant seasonal variations. Periods of higher flow showed high concentrations of total Hg (THg) in water due to more particles being re-suspended and transported. The concentrations of major anions (e.g., Cl −, F −, NO 3 − and SO 4 2-) were lower during higher flow due to dilution. Due to both sedimentation of particles and dilution from tributaries the concentration of THg decreased from 2100 ng/L to background levels (< 50 ng/L) within 10 km distance downstream. Sedimentation is the main reason for the fast decrease of the concentration, it accounts for 69% and 60% for higher flow and lower flow regimes respectively in the upper part of the stream. Speciation calculation of the dissolved Hg fraction (DHg) (using Visual MINTEQ) showed that Hg(OH) 2 associated with dissolved organic matter is the main form of Hg in dissolved phase in surface waters in Wanshan (over 95%).

Denitrifying bacteria and hydrogeochemistry in a natural wetland adjacent to farmlands in Chiba, Japan

AbstractThis study combined bacterial incubation and hydrogeochemical methods to investigate denitrification in the surface water, top soil (0–20 cm), and shallow groundwater of the Ochi wetland in Japan. Surface water was rich in nitrate (40 mg/l) and denitrifying bacteria (700 per ml). Three functional zones in the wetland were identified in the top soil and shallow groundwater. In the upstream portion of the wetland (Zone I), the counts of denitrifying bacteria in top soil increased from 5200 to 14 970 per ml and nitrate decreased from 25·4 to 1·8 mg/l. Organic carbon concentrations decreased as sulfate increased from 4·0 to 9·6 mg/l in this zone. In the middle‐stream of the wetland (Zone II), all concentrations of major anions, iron, organic carbon, and total nitrogen content in top soil were relatively constant, but the counts of denitrifying bacteria increased up to 70 200 per ml. In the downstream portion of the wetland (Zone III), complete removal of nitrate resulted in sharp reduction of counts of denitrifying bacteria. Correspondingly, dissolved oxygen (DO), organic carbon, and total nitrogen increased in this zone. Counts of denitrifying bacteria were lower in shallow groundwater than in top soil; nitrate concentrations in shallow groundwater were also very low in this zone. DO and the oxidation/reduction potential data suggest that groundwater flows to the surface along an extended flow path, thus providing nitrate for the denitrifying community. Copyright © 2011 John Wiley &amp; Sons, Ltd.