Fluoride and health hazards: community perception in a fluorotic area of central Rajasthan (India): an arid environment

India is among the 23 nations around the globe where health problems occur due to excess ingestion of fluoride (>1.5 mg/l) by drinking water. In Rajasthan, 18 out of 32 districts are fluorotic and 11 million of the populations are at risk. An exploratory qualitative survey was conducted to describe perception of the community regarding fluoride and related health problems in Central Rajasthan. A study on distribution and health hazards by fluoride contaminate in groundwater was performed in 1,030 villages of Bhilwara district of Central Rajasthan. One thousand thirty water samples were collected and analyzed for fluoride concentration. Fluoride concentration in these villages varies from 0.2 to 13.0 mg/l. Seven hundred fifty-six (73.4%) villages have fluoride concentration above 1.0 mg/l. Sixty (5.83%) villages have fluoride concentration above 5.0 mg/l with maximum numbers (24, 19.5%) from Shahpura tehsil. A detailed fluorosis study was carried out in 41 villages out of 60 villages having fluoride above 5.0 mg/l in the study age, sex, and occupation data were also collected. Four thousand, two hundred fifty-two individuals above 5 years age were examined for the evidence of dental fluorosis, while 1998 individuals above 21 years were examined for the evidence of skeletal fluorosis. The overall prevalence of dental and skeletal fluorosis was found to be 3,270/4,252 (76.9%) and 949/1,998 (47.5%), respectively. Maximum of 23.9% (1,016) individuals have mild grade of Dean’s classification. Three hundred seventy-four (8.8%) individuals have severe type of dental fluorosis. The Dean’s Community Fluorosis Index for the studied area in total is 1.62. Maximum CFI 3.0 was recorded from Surajpura of Banera Tehsil. Five hundred sixty-six (28.3%) individuals have Grade I type of skeletal fluorosis while only 0.6% (12) individuals have Grade III skeletal fluorosis. In conclusion, the prevalence and severity of fluorosis increased with increasing fluoride concentration. It was interesting to note that in some villages, the prevalence and severity of fluorosis were highest in subjects belonging to the economically poor community. Similarly, male laborers showed highest prevalence of fluorosis. Prevalence and severity of fluorosis were observed higher in subjects using tobacco, bettle nuts, and alcoholic drinks. In contrast, subjects using citrus fruits and having good nutritional status showed low prevalence.     

Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials

The Standards, Measurements and Testing Programme (formerly BCR) of the European Commission proposed a three-step sequential extraction procedure for sediment analysis, following extensive expert consultations and two interlaboratory studies. This scheme was recently used to certify the extractable trace element contents of a sediment reference material (CRM 601). Although this procedure offers a means to ensure the comparability of data in this field, some difficulties concerning the interlaboratory reproducibility still remain, and a new project is currently being conducted to determine the causes of poor reproducibility in the extraction scheme. The final objective of the project is the certification of new sediment and soil reference materials for their extractable contents of Cd, Cr, Cu, Ni, Pb and Zn. This paper presents the results of a small-scale interlaboratory study, which aimed to test a revised version of the extraction schemes by comparing the original and the modified protocols using the CRM 601 sample. This work offers an improvement to the BCR sequential extraction procedure through intercomparison exercises. This improved procedure will allow the obtaining of CRMs to validate analytical data in the analysis of soils and sediments, and it will also facilitate comparability of data in the European Union.     

The Influence of pH on Mobility of Heavy Metals from Municipal Solid Waste Incinerator Fly Ash

Incineration has become one of the principal methods for municipal solid waste disposal particularly in all large cities throughout the world. Currently, the municipal solid waste incinerator fly ashes (MSWIF) are disposed of by landfill. The metal speciation of cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) in MSWIF after been extracted with water at different pH values were examined using a sequential extraction procedure. The extraction sequence was as follows: (1) Exchangeable (NaOAc, pH 8.2), (2) Bound to Carbonates (NaOAc, pH 5.0), (3) Bound to metal oxides (HONH3Cl), (4) Bound to organic matters (HNO3, H2O2), and (5) Residual (HNO3, HCl, H2O2, HF, 1:3:1:3). The heavy metal contents in the extraction solutions were determined by inductively coupled plasma atomic emission spectrometry. The heavy metal concentrations in the different fractions obtained by sequential extraction show distinct distribution trends. The extractable fraction ranges from 25.5 to 88% of the total element content. With the pH of the extractant fall below the neutral and acidic ranges, the concentrations of heavy metals rise substantially due to the released of metals bound to carbonate fraction.     

An Automated Technique for Delineating and Characterizing Valley-Bottom Settings

Accurate delineation and characterization of valley-bottom settings is crucial to the assessment of the biological and geomorphological components of riverine systems; yet, to date, most valley-bottom mapping endeavors have been done manually. To improve this situation, we developed automated techniques in a Geographic Information System (GIS) for delineating and characterizing valley-bottom settings in river basins ranging in size from approximately 1,000–10,000 km². All procedures were developed with ARC/INFO GIS software and fully automated in Arc Macro Language (AML). The GRID module is required for valley-bottom delineation and slope calculations; whereas characterization (i.e., measuring the width of the valley-bottom zone) requires Coordinate Geometry (COGO) in the ARCEDIT module. The process requires three inputs: a polygon coverage of the analysis area; an arc coverage of its hydrography, and a grid representing its digital elevation. The AML is designed to operate within a wide range of computer memory/disk space options, and it allows users to customize several procedures to match the scale and complexity of a given analysis area with available computer hardware.     

Landfill leachate treatment methods: A review

Landfilling of municipal waste is still a major issue of the waste management system in Europe. The generated leachate must be appropriately treated before being discharged into the environment. Technologies meant for leachate treatment can be classified as follows (i) biological methods, (ii) chemical and physical methods. Here we review briefly the main processes currently used for the landfill leachates treatments.     

堆肥处理对污泥腐殖物质组成和光谱学特征的影响

采用凝胶(Sephadex G-75)色谱、荧光光谱和红外光谱法研究了污泥堆肥的HA和FA在堆制前后的组成与结构特征变化．凝胶色谱分析表明,污泥经过63d堆腐后,HA中大分子组分含量明显提高;而FA则由不同分子量物质组成,其中小分子量物质占主要部分,在堆腐以后,FA中大分子物质含量下降30％,小分子量物质含量则相对增加．同时,荧光光谱、红外光谱的结果表明：随着污泥堆肥的进行,HA中有机物不饱和结构的多聚化或联合程度增大,芳香结构物质含量增加;但经过堆制的FA具有更多的结构简单的低分子量物质和更低的芳构化水平．     

Nitrogen export from an agriculture watershed in the Taihu Lake area, China

Temporal changes in nitrogen concentrations and stream discharge, as well as sediment and nitrogen losses from erosion plots with different land uses, were studied in an agricultural watershed in the Taihu Lake area in eastern China. The highest overland runoff loads and nitrogen losses were measured under the upland at a convergent footslope. Much higher runoff, sediment and nitrogen losses were observed under upland cropping and vegetable fields than that under chestnut orchard and bamboo forest. Sediment associated nitrogen losses accounted for 8-43.5% of total nitrogen export via overland runoff. N lost in dissolved inorganic nitrogen forms (NO(3-)-N + NH4+-N) accounted for less than 50% of total water associated nitrogen export. Agricultural practices and weather-driven fluctuation in discharge were main reasons for the temporal variations in nutrient losses via stream discharge. Significant correlation between the total nitrogen concentration and stream discharge load was observed. Simple regression models could give satisfactory results for prediction of the total nitrogen concentrations in stream water and can be used for better quantifying nitrogen losses from arable land. Nitrogen losses from the studied watershed via stream discharge during rice season in the year 2002 were estimated to be 10.5 kg N/ha using these simple models.     

Inhibition of attachment of larval barnacles,Balanus amphitrite,by bacterial surface films

Films of bacteria on solid substrata can positively or negatively influence the attachment of marine invertebrate larvae. Effects of marine bacteria on the attachment of cypris larvae of the barnacle Balanus amphitrite Darwin were examined in the laboratory. Bacteria, grown to mid-exponential phase and allowed to adsorb irreversibly to polystyrene petri dishes, attached in densities of 10⁷ cells cm^-2. Assays (22h) were used to compare the effects of adsorbed cells of 18 different bacterial species on larval barnacle attachment. Most of the adsorbed bacteria either inhibited or had no effect on larval attachment compared to clean surfaces. Experiments testing the effect of larval age on barnacle attachment were conducted with six species of bacteria and showed that older larvae attached in higher percentages to clean surfaces and that bacterial films generally inhibited larval attaschment. Both the species of bacteria and the in situ age of the adsorbed bacteria affected barnacle attachment response: older films of Deleya (Pseudomonas) marina were more inhibitory. Bacterial extracellular materials may be involved in the inhibitory process.     

An evaluation of two diffusion culture techniques for estimating phytoplankton growth rates In situ

In comparative tests, acrylic diffusion chambers (voltume=42 ml) with polycarbonate filter membranes (1 m pore diameter) consistently supported higher cell yields and faster growth rates of summer phytoplankton populations and species from Narragansett Bay than did dialysis bags (volume=50 ml, 0.24–0.48 nm pore diameter) or bottle cultures (with or without added nutrients). Stirring of diffusion chambers or dialysis bags had less effect on growth responses than did the choice of the containment membrane. Exchange measurements showed the polycarbonate filters (0.49 ml cm^-2 h^-1) to be five times more permeable than dialysis membranes (0.09 ml cm^-2 h^-1) per unit area. The mean of measured half-life times for water in diffusion chambers was less than one hour while comparable half-life times for dialysis bags were approximately 3 h. Diatoms from the <10 m size fraction had higher growth rates than assemblages of microflagellates and non-motile ultraplankton. Stirring of diffusion chambers did not adversly effect the growth of microflagellates or non-motile ultraplankton. Growth responses in diffusion chambers moored in situ were generally similar to those measured in diffusion chambers incubated in outdoor tanks connected to a running seawater system.     

Colloid-enhanced ultrafiltration in removal of traces amounts of borates from water

The use of colloid-enhanced ultrafiltration for boron removal from water is investigated. Biodegradable surfactant, 1,4-sorbitol oleate, was applied to obtain micelles and high molecular weight chitosan to reinforce their stability. Two kind of membranes were compared: neat porous polysulfone membrane and charged porous sulfonated polysylfone membrane; both with similar average pore diameter of 5 nm. The studies revealed that two key factors affect the boron rejection: presence of surfactant in the colloidal mixture and a repulsion effect of sulfone groups on the membrane surface. Both have a positive effect on boron removal.