Brick tea and its health impact

Tea bush is one of the plants cultivated in acidic soil, and is a typical hyper-accumulator of F and Al. Brick tea is a kind of brick-formed tea compressed using the older and coarse leaves and branches of tea trees. Brick tea mixed with milk is drunk as a daily indispensable beverage for Mongols, Ewenki, and other minority nationalities in the pastoral and semi-pastoral areas of Northwest China. It is reported that drinking brick tea can result in dental and skeletal fluorosis due to the high F content in it. Because Alzheimer＇s disease （AD） is related with Al in human brain, and Al has potential toxicities for skeletal and neural systems,     

Possibility of degradation of phenylarsonic acid in the presence of ferrihydrite

Although inorganic species are predominant in natural systems, but there are many kinds of organoarsenic species such as methylated and phenylated arsenic compounds. Phenylarsonic acid （PA） is a degradation product of organoarsenics used for chemical warfare agents, which has been detected in well water at the disposal site of the agents in Japan. There are few reports studying behavior of PA in soil. In this study, PA was adsorbed onto ferrihydrite and its chemical forms were determined using high performance liquid chromatography connected to inductivity-coupled plasma mass spectrometry （HPLC-ICP-MS）. 100 mg/kg of PA was mixed with 0.03 g of 2-line ferrihydrite. For each suspension, pH was adjusted by HNO3 or NaOH. Each sample was incubated for more than 19 hours and the final pH was measured. After filtration, the chemical form of arsenic in the filtrate was measured using HPLC-ICP-MS. In addition, ferrihydrite separated by filtration was dissolved by 3 ml of 0.5 M HCI and the arsenic species in the solution was detected by HPLC-ICP-MS （column： Tosoh TSKgel SuperlC-AP, eluent： 0.01 M HNO3）. It was verified that PA is not degraded by heating in 0.5 M HCl solution. At pH 3.1, any arsenic compounds were not detected from the solution, because almost all arsenic species were adsorbed onto ferrihydrite at lower pH. At pH= 12, however, 7%-10% of inorganic arsenic was detected in the solution. In solid phase, there are some problems to determine the precise ratio of inorganic and organic species. When the solution includes Fe ion at 0.01 M level, the retention time of arsenic species drifted compared to those in standard solution, which makes it difficult to determine precisely the arsenic species adsorbed on ferrihydrite. Therefore, more study is needed to determine the ratio of inorganic and organic species in the system.     

The acid neutralizing capacity （ANC） of South Africa＇s freshwater ecosystems

Acidification is considered the most important one of the primary chemical stress factors that impact on freshwater ecosystems. In unpolluted freshwater systems, the primary controls on the degree of acidification are factors such as the geological substrate of the catchment area, the presence of organic acids secreted by vegetation in the river system, and equilibrium exchange of carbon dioxide with the atmosphere. Anthropogenic factors that can impact on the degree of acidification of freshwater systems include agricultural, mining and industrial activities, either through direct runoff into river systems or through deposition of atmospheric pollutants from these sources. The capacity factors alkalinity and acidity, which represent the acid- and base-neutralizing capacity （ANC and BCN） of an aqueous system, have been used as more reliable measures of the acidic character of freshwater systems than pH. Unlike pH, ANC and BNC are not affected by parameters such as temperature and pressure. Therefore, ANC has been employed as a predictor of biological status in critical load assessments. Freshwater systems with ANC＇s eq/L isμeq/L are considered sensitive to acidification, ANC=0 μbelow 150 commonly used as the predictor for fish species such as trout in lakes, and an eq/L as more realistic for streams. Acid-neutralizing capacity μANC value of 40 （ANC） can be determined by titration with a strong acid to a preselected equivalence point. Alternatively, it can be calculated as the difference between base cations （[BC]） and strong acid anions （[SAA]）： ANC=[BC]- [SAA]=[Ca^2＋]＋[Mg^2＋]＋[Na^＋]＋[K^＋]-[SO4^2-]-[NO3^-]-[Cl^-] To date, there has been no attempt to establish the ANC of South Africa＇s freshwater ecosystems or variability therein, despite the fact that long-term water quality monitoring data exist for all the parameters needed to calculate it according to the above equations. As a result, the relationship between the acid neutralizing capacity of freshwater ecosystems in South Africa and biodiversity factors, such as fish status, is unknown. Results of the first comprehensive （country-wide scale） evaluation of the acid neutralizing capacity of river systems in South Africa will be presented. Long-term monitoring data obtained from the Department of Water Affairs and Forestry （DWAF） from most of South Africa＇s river systems were used to establish geographic and temporal variabilities in ANC. The results show that the Berg and Breede River systems are most susceptible to acidification, and that geological substrate appears to explain most of the geographic variabilities observed.     

The concentration and distribution of different mercury species in the water columns and sediment of Aha Lake

In order to find out whether Aha Lake was polluted by the acid mining waste water or not, the concentration and distribution of different mercuryspecies in the water columns and sediment profile collected from Aha Lake were investigated. It was found that discernible seasonal variation of different mercury species in water body were obtained in the Aha Reservoir. With regards to the whole sampling periods, the concentrations of HgP in the Aha Reservoir water body were evidently correlated to the concentrations of total mercury, showing that total mercury was mostly associated with particle mercury. The concentrations of methylmercury in water body were also evidently correlated to the concentrations of dissolved mercury. The dissolved mercury evidently affects the distribution and transportation of methylmercury. However, there is no correlation between methylmercury and total mercury. The dissolved mercury, reactive mercury, dissolved methylmercury levels in the water body of high flow period were much higher than those in low flow period. The distribution, speciation and levels of mercury within the Aha Reservoir water body were governed by several factors, such as the output of river, the release of sediment . Discernible seasonal variation of total mercury and methylmercury in porewater was described during the sampling periods, with the concentrations in high flow period generally higher than those in low flow period. The methylmercury in pore water column was evidently correlated to that of the sediment. The results indicated that highly elevated MeHgD concentrations in the porewater were produced at the depths from 2 to 5 cm in the sediment profile, and decreased sharply with depth. A positive correlation has been found between MeHgD formation and sulfate reducing bacterial activity. These highly elevated concentrations of MeHgD at the intersurface between waters and sediments suggest a favorable methylation condition. Moreover,     

Treatment of high fluoride concentration wastewater by layered double hydroxides： Mechanism studies

An appropriate concentration of fluoride in drinking water is required to prevent dental cavities, but long-term ingestion of water that contains more than a suitable level of fluoride can cause bone disease and mottling of the teeth. Fluoride ions can be found in wastewater from the fluoride chemical industry, as well as the semiconductor, metal processing, fertilizer, and glass-manufacturing industries. The discharge standard for fluoride in industrial wastewater in China is 10 mg/L. Efficient treatment of fluoride-containing wastewater is therefore of major concern in China, following the rapid development of the fluoride chemical industry. Several methods have been used to remove fluoride from water, such as adsorption, chemical precipitation, electrodialysis, ion exchange and electrochemical processes. Layered double hydroxides （LDHs） are anionic clays with high anion exchange capacities which are effective adsorbents for removal of a variety of anionic pollutants. LDHs have been studied as potential adsorbents for removing toxic anionic species such as CrO4^2-, TcO4^-, SeO3^2-, pesticides, and anionic surfactants from aqueous systems. One of the main attractions of using LDHs for fluoride removal, is that unlike other chemical treatment methods, no chemical sludge should be produced. In the present study, an attempt was made to investigate the mechanism of fluoride removal by LDHs under different conditions using batch methods. In addition, the release of fluoride adsorbed on LDHs by treatment with an aqueous solution of Na2CO3 was studied. The residual fluoride was found to be 10 mg/L in a solution with an initial concentration of 1000 mg/L, which meets the discharge standard for fluoride in industrial wastewater in China.     

The effect of acid deposition on base cation cycling in a karstic-forested catchment： Evidence from strontium isotopes

Bedrock weathering and atmospheric deposition are the two primary sources of base cations （K^＋, Na^＋, Ca^2＋ and Mg^2＋） to forest ecosystems. Therefore, the key problem is to understand the relative inputs from these two sources and the cycling in the ecosystem. This study focuses on the effects of acid deposition on cation cycling in a small-forested karstic catchment in Guizhou Province. Sr isotope ratios were used as a tracer for understanding the transport process between the different cation pools： rock, soil, surface water, atmospheric deposition and plant. The samples of wet deposition, total deposition, throughfall, surface and ground waters, vegetation, and soil were monthly collected. The exchangeable Sr^2＋ and Ca^2＋ in soil samples were extracted by using 1 M ammonium acetate. The leaf-tissue samples were ashed at 550℃, and the residue was digested in ultrapure HClO4 and HNO3. All water samples were filtrated through 0.45 μm aperture filter paper. Base cation concentrations and Sr isotopic composition were analyzed for all the samples. The results show that acid deposition （average pH 4.9） frequently occurred in the studied region. Cation abundance follows an increasing manner from rainwater, throughfall, to surface water or ground water samples, suggesting that acid deposition at first eiuviates Ca^2＋ , Mg^2＋ and Sr^2＋ from leaf, then the exchangeable cations from soil, and at last cations accumulate in surface water or ground water.     

High resolution profiles of trace metals in pore waters of marine and riverine sediments assessed by DET and DGT

In polluted aquatic systems, toxic metals are often accumulated in bottom sediments. They are, however, not necessarily stored definitively because diagenetic processs can modify redox, pH and even the amount of complexing ligands, releasing the trace metals back into the pore waters and the water column. Especially the labile metal fraction in the pore waters is important since this is the bioavailable fraction determining the bio-toxicity of the sediments. The goal of our study was therefore to assess, with novel sampling techniques, this bioavailable metal fraction in the pore waters as well as the flux towards the overlying water column. High-resolution profiles of trace metals in pore waters of marine and riverine sediments were assessed by DET （diffusive equilibrium in thin films） and DGT （diffusive gradients in thin films） gel techniques. The DET technique uses a diffusive gel layer that equilibrates with the aquatic system and with this technique the concentrations of total dissolved trace metals are obtained directly. The DGT technique uses an acrylamide diffusive gel backed by a resin gel （Chelex） which binds trace metals. With the DGT technique only labile species of selected metals can be captured. According to the redox potential measurements, the marine sediments were suboxic （200 mV to -220 mV versus Ag/AgCl electrode）, while the riverine sediments were completely anoxic （-160 mV to -220 mV versus Ag/AgCl electrode）. This redox potential was apparently controlling the trace metals species in the pore waters： for example a strong correlation between Mn and Co was found in the riverine sediments （for DET and DGT sampling）, while in the marine sediments trace metals presented various behaviors.     

Improved reliability in the interpretation of geochemical measurements by the quantification of uncertainty from sampling

All geochemical measurements require the taking of field samples, but the uncertainty that this process causes is often ignored when assessing the reliability of the interpretation, of the geochemistry or the health implications. Recently devised methods for the estimation, optimisation and reduction of this uncertainty have been evaluated by their application to the investigation of contaminated land. Uncertainty of measurement caused by primary sampling has been estimated for a range of six different contaminated land site investigations, using an increasingly recognized procedure. These site investigations were selected to reflect a wide range of different sizes, contaminants （organic and metals）, previous land uses （e.g. tin mining, railway sidings and gas works）, intended future use （housing to nature reserves） and routinely applied sampling methods. The results showed that the uncertainty on measurements was substantial, ranging from 25% to 186% of the concentration values at the different sites. Sampling was identified as the dominant source of the uncertainty （〉70% of measurement uncertainty） in most cases. The fitness-for-purpose of the measurements was judged using the optimized contaminated land investigation （OCLI） method. This identifies the optimal level of uncertainty that reduces to overall financial loss caused by the measurement procedures and the misclassification of the contamination, caused by the uncertainty. Generally the uncertainty of the actual measurements made in these different site investigations was found to be sub-optimal, and too large by a factor of approximately two. The uncertainty is usually limited by the sampling, but this can be reduced by increasing the sample mass by a factor of 4 （predicted by sampling theory）. It is concluded that knowing the value of the uncertainty enables the interpretation to be made more reliable, and that sampling is the main factor limiting most investigations. This new approach quantifies this problem for the first time, and allows sampling procedures to be critically evaluated, and modified, to improve the reliability of the geochemical assessment.     

Geochemistry of recent hydrothermal systems of Mendeleev Volcano （Kuril Islands） and surrounding waters

On the Kuril Islands there are 85 volcanoes, 39 of which are active. Hot springs and mud pots are wide spread in this area and have significant inputs on the chemical composition of the surrounding surface waters and environment. We present results of trace elements as well as data on H, O, S, and He isotope ratios for hydrothermal systems of the Mendeleev Volcano （Kunashir Island） and surrounding surface waters. Water and gas samples were taken from springs and holes as well as creeks and the Lesnaya River. Among the thermal water types, three main groups can be distinguished. The first group includes the waters, in which SO4^- ion predominant. The water temperature on the surface reaches 97℃, and TDS varies from a few g/L to 7 g/L. These waters are acid to superacid with pH values ranging 0.6 to 2.3. The second group is sodium-chloride waters. A maximum TDS is 14.2 g/L. The waters are neutral or alkaline; pH varies from 6.9 to 8.2. The third group is the sodium-chloride-sulfate-bicarbonate water. The Stolbovskie springs, located in the periphery of the Mendeleev Volcano are representative of this type. The pH of these waters is close to neutral. TDS is 1.9 g/L. They are rather the derivatives of sodium-chloride waters arisen from dilution of them by subsurface waters. The Kuslyi Creek and Lesnaya River are located near the Mendeleev Volcano. The most acid springs discharge into the Kislyi Creek as a result pH of this creek being 2.5, and contents of most elements rather high. For example, the contents of dissolved solids of Si, Fe, Al, Mn, Zn, in waters of the Kislaya Creek are 22.1, 8.1, 6.2, 1.29, and 0.28 mg/L, and correspondently. The water of the Lesnaya River, （Before the Kislyi Creek, pH is about 8 with TDS 102 mg/L, but after the Kuslyi Creek, pH decreases and the concentrations of chemical elements increase. Debit of the Kislayi Creek in summer season is about 370 L/sec. It means that every day only this small creek inputs in the Lesnay River about 706 kg of Si;