An anticlastogenic in vivo micronucleus assay for tea

Common use of antimutagens and anticarcinogens in everyday life is an effective measure for preventing human cancer and genetic diseases. Antioxidant properties of tea have vast potential as protective agents against diverse toxic effects. The present study was aimed to evaluate the role of aqueous clonal tea extracts (green tea, oolong tea and black tea) in modulating the genotoxic damage induced by cyclophosphamide (CP), a commonly used chemotherapeutic drug and a well-known mutagen and clastogen. All the three tea extracts at 1 and 2% concentration did not increase the frequency of micronucleated polychromatic erythrocytes (MPE) in bone marrow cells of mice when administered individually. The tea extracts decreased the micronuclei (MN) induced by CP. Therefore, regular intake of tea may improve the antioxidant status in in vivo and thereby reduce the risk of cancer and coronary heart disease.     

Implications of fluoride--an endless uncertainty

Fluorosis has become pandemic and it has assumed global status in the public health point of view. The paper deals with the health issues pertaining to fluorosis with special emphasis in the Indian context. It explains the equivocal evidences of fluoride-related problems and discusses the control measures of fluorosis. In general, it reveals how fluoride is useful at very low concentrations and at the same time brings forth manifestation of clinical abnormalities at higher concentrations that are the basis of the principles of toxicology.     

Effect of cadmium individually and in combination with other metals on the nutritive value of fresh water fish,Channa punctatus

Impact of metal cadmium on the nutritive value of Channa punctatus on exposure to a sublethal concentration (1.12 mg/l) of cadmium (Cd2+) for 15 and 60 days has been studied. Among the various parameters selected, the level of moisture in liver and muscle was increased, while decrease was noted in the level of ash, total proteins and inorganic constituents like iron, calcium, inorganic phosphate, sodium and potassium in both liver and muscle in the two types of exposure. The total lipid level of liver increased, while muscle lipid level was decreased. On the other hand, calcium, iron, inorganic phosphate, sodium and potassium levels showed increase in blood. Zinc and selenium decreased the percentage alterations in all the parameters selected for study. In the two types of exposure, zinc was most effective to counteract the cadmium toxicity to fish as in almost all the parameters insignificant alterations were recorded. In combination studies, protection against cadmium toxicity by the two chemicals became more marked with increase in the tenure of exposure.     

The impact of handpump corrosion on water quality in rural areas of West African sub-region

Water, even in its natural environment, contains some level of impurities. Water is nearly a universal solvent. It contains dissolved solids and gases, and hosts a number of micro-organisms. The exploitation of groundwater by means of boreholes for supplying small user groups and rural communities with water has been widely applied in certain parts of the world for several decades. In recent years this practice has spread all over the globe, and hundred of thousands of boreholes have beendrilled to tap low-yield aquifers. It is evident that such boreholes require pumps for lifting thewater. In developing countries these are usually handpumps, butsolar as well as other systems with submersible pumps are also used, depending upon the energy sources available and the financial means of the beneficiaries. This article gives a general overview of groundwater quality with regard to itsphysico-chemical composition. The results presented originatefrom the experience gained from handpump equipped boreholes within the UNICEF through German Centre for Technical EducationTransfer executed inter-regional UNDP-Handpumps Project inWest African Regions. Particular attention is paid to presenting corrosion onthe water quality of wells in terms of iron concentrationand other parameters. Furthermore, the corrosion attack ongalvanised iron, the effect of biofilms on the corrosionrate, and the difference between internal and externalcorrosion of rising mains are shown.     

Wet oxidative regeneration of activated carbon loaded with reactive dye

Wet Oxidative Regeneration (WOR) of powdered activated carbon (PAC) and granular activated carbon (GAC) loaded with the reactive dyes, namely chemictive brilliant blue R and cibacron turquoise blue G, was studied. Attempts were made to regenerate the loaded carbons designated now as spent carbon. A slurry (10% w/v) of spent carbon in distilled water was oxidized by wet oxidation in the temperature range of 150-250 degrees C using oxygen partial pressures between 0.69-1.38 MPa in an 1 1 SS 316 autoclave. The percent regeneration was determined from a ratio, X(RC)/X(VC), corresponding to an equilibrium adsorption capacity of regenerated carbon/equilibrium adsorption capacity of virgin carbon from an initial adsorption period of 3 h. It was observed that the regeneration mainly occurred due to the oxidation of the adsorbates taking place on the surface of carbon. It was possible to regenerate the spent GAC and PAC to the extent of more than 98% (approximately X(RC)/X(VC) > 0.98) by wet oxidation. After four consecutive cycles of adsorption and regeneration using the same stocks of GAC, carbon weight loss observed at 200 degrees C was about 40%. SEM studies of the regenerated carbon showed widening of the pores and loss of structure between the adjacent pores as compared with the virgin carbon. PAC was found to be more suitable as compared with GAC for the adsorption and wet oxidative regeneration processes to treat the aqueous solution containing lower concentration of unhydrolyzed reactive dye. The suitability of wet oxidative regeneration is demonstrated at a bench scale to treat the synthetic reactive dye solution.     

Cadmium accumulation and metallothionein synthesis in freshwater bivalves (Pyganodon grandis): relative influence of the metal exposure gradient versus limnological variability

The relative influence of limnological confounding factors on cadmium (Cd) bioaccumulation and metallothionein (MT) synthesis was quantified in natural populations of freshwater bivalves (Pyganodon grandis) living in lakes along a Cd concentration gradient. During the ice-free period, we measured 15 environmental variables in the water compartment and determined total concentrations of Cd and MT in the gills of bivalves at 37 littoral stations in 20 lakes distributed across the mining area of Rouyn-Noranda in northwestern Quebec. A multiple linear regression model including pH (+), dissolved Ca concentrations (-) and free Cd2+ concentrations at the sediment-water interface (+) explained 74% of the variability in Cd concentrations in the bivalve gills. Dissolved Ca (-) and free Cd2+ (+) together explained 62% of the variation in MT concentrations in the bivalve gills. Partial linear regression analyses indicated that the limnological factors' pure and shared effects together accounted for 48 and 45% of the total variation in Cd and MT concentrations in the gills, respectively. A lake selection procedure that could be applied in monitoring programs is proposed to minimise the relative influence of these confounding variables.     

Preferential bromide and pesticide movement to tile drains under different cropping practices

Subsurface drainage systems are useful tools to study chemical leaching in soils. Our objective was to compare the breakthrough behavior of bromide, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamid] to tile drains under two fall tillage practices (conventional tillage [CT] with a moldboard plow, and reduced tillage [RT] with a chisel plow) in field plots cultivated with corn (Zea mays L.). Leachate volume were greater in RT than in CT, with no statistical differences. Soil analysis showed that bromide migrated deeper in the soil profile than both herbicides, with little tillage effect. All chemicals were detected in drainage water at the same time and followed an event-driven behavior. Tillage had no effect on atrazine and metolachlor found in drainage water, while bromide concentration peaks were higher in RT than in CT in 1999. Concentration peaks were recorded earlier for atrazine and metolachlor than for bromide. Plots of cumulative relative chemical mass (cumulative mass divided by total mass measured in drainage) as a function of cumulative drainage were mostly linear for bromide, while they were S-shaped for both herbicides. Drainage that corresponded to 50% of relative cumulative mass ranged from 40 to 55% for bromide and from 5 to 28% for both herbicides. Rapid chemical movement to tile drains suggested that preferential flow was important in both CT and RT, and that these tillage practices had little influence on this phenomena.     

Soil testing to predict phosphorus leaching

Subsurface pathways can play an important role in agricultural phosphorus (P) losses that can decrease surface water quality. This study evaluated agronomic and environmental soil tests for predicting P losses in water leaching from undisturbed soils. Intact soil columns were collected for five soil types that a wide range in soil test P. The columns were leached with deionized water, the leachate analyzed for dissolved reactive phosphorus (DRP), and the soils analyzed for water-soluble phosphorus (WSP), 0.01 M CaCl2 P (CaCl2-P), iron-strip phosphorus (FeO-P), and Mehlich-1 and Mehlich-3 extractable P, Al, and Fe. The Mehlich-3 P saturation ratio (M3-PSR) was calculated as the molar ratio of Mehlich-3 extractable P/[Al + Fe]. Leachate DRP was frequently above concentrations associated with eutrophication. For the relationship between DRP in leachate and all of the soil tests used, a change point was determined, below which leachate DRP increased slowly per unit increase in soil test P, and above which leachate DRP increased rapidly. Environmental soil tests (WSP, CaCl2-P, and FeO-P) were slightly better at predicting leachate DRP than agronomic soil tests (Mehlich-1 P, Mehlich-3 P, and the M3-PSR), although the M3-PSR was as good as the environmental soil tests if two outliers were omitted. Our results support the development of Mehlich-3 P and M3-PSR categories for profitable agriculture and environmental protection; however, to most accurately characterize the risk of P loss from soil to water by leaching, soil P testing must be fully integrated with other site properties and P management practices.     

Phosphorus saturation in spodosols impacted by manure

Significant amounts of phosphorus (P) accumulate in soils receiving animal manures that could eventually result in unacceptable concentrations of dissolved P loss through surface runoff or subsurface leaching. The degree of phosphorus saturation (DPS) relates a soil's extractable P to its P sorbing capacity, and is reportedly a predictor of the P likely to be mobilized from a system. A DPS value (DPS-1) was derived that expressed the percentage of Mehlich 1-extractable P to the sorbing capacity of a Spodosol (expressed as the sum of oxalate-extractable Fe and Al). Values of DPS-1 were determined in various horizons of soil in current and abandoned dairy systems in South Florida's Lake Okeechobee watershed to assess P release potential. Land use within the dairies was classified as highly impacted by cattle (intensive and holding), and minimally impacted by cattle (pasture, forage, or native) areas. The A and E horizon of soils in heavily manure-impacted intensive and holding areas for both active and abandoned dairies generally had higher DPS-1 values than the pasture, forage, and native area soils, which were minimally impacted by manure. Degree of P saturation was also calculated as a percentage of Mehlich 1-extractable P to the sum of Mehlich 1-extractable Fe and Al (DPS-2). Both DPS-1 and DPS-2 were shown to be significantly (P = 0.0001) related to water-extractable P for all soil horizons, suggesting that either index can be used as an indicator for P loss potential from a soil.     

Natural uranium and thorium distributions in podzolized soils and native blueberry

Plant uptake of radionuclides is one of many vectors for introduction of contaminants into the human food chain. Thus, it is critical to understand soil-plant relationships that control nuclide bioavailability. Our objectives in this study were to (i) determine the extent of U and Th uptake and cycling by blueberry (Vaccinium pallidum Aiton) in native habitat and (ii) identify the soil properties and processes that contribute most to U and Th bioavailability in this system. We collected composite samples of plant leaves and stems, and samples from surface (AE) horizons and from the upper part of the Bs horizon at two sites. Concentration ratios (CRs) for U and Th were calculated for all plant tissues, using both the AE and Bs horizons as the base. Soil concentrations of U ranged from 16 to 25 microg g(-1), with a mean of 21.1 microg g(-1). Soil concentrations of Th ranged from 14 to 97 microg g(-1), with a mean of 41.8 microg g(-1). Mean U concentrations were 8.65 x 10(-3) microg g(-1) in leaf tissue, and 7.95 x 10(-3) microg g(-1) in stem tissue. Mean Th concentrations were 1.59 x 10(-1) microg g(-1) in leaf tissue, and 9.10 x 10(-2) microg g(-1) in stem tissue. Blueberry plants are cycling both U and Th in this system, with Th cycling occurring to a greater extent than U. In addition, Th was translocated preferentially to plant leaves while U concentrations showed little preferential translocation. Uranium uptake, however, seemed more sensitive than Th uptake to soil properties.