Mineralogical characterization of the Tournemire argillite after in situ interaction with concretes

This study aims to investigate, through mineralogical characterization (SEM, XRD) and mass-balance calculations, the effects of contact time, concrete types and presence of free water on the Tournemire argillite under in situ conditions. Three sampling zones from Excavation Disturbed Zone (EDZ) areas have been chosen: (1) dry contacts, collected at the tunnel masonry/argillite interface (contact time - 125 years), (2) wet contacts, taken close to drained areas below the tunnel roadbed in contact with the canal draining the Cernon fault water (contact time - 15 and 7 years) and at the tunnel masonry/argillite interface over 70 m from the Cernon fault (contact time - 125 years). This study shows that: in the absence of water, no significant modification of argillite is observed after 125 years, except for pyrite dissolution and gypsum precipitation; in the presence of water, precipitation of gypsum, recrystallization of mixed-layer clays, neoformation of zeolites and K-feldspars overgrowths are observed. At the concrete/argillite interface near the Cernon fault, important dolomite neoformation and leaching of chlorite and kaolinite occur. These processes are enhanced with contact time, low flow rate and the nature of the concrete (compound cement Portland CEM II 32.5). Evidence for oxidation processes linked to the EDZ (pyrite oxidation, Fe-oxy-hydroxide and gypsum precipitation) is observed.     

Factors affecting TCLP lead leachability from computer CPUs

The factors impacting lead leachability from computer central processing units (CPUs) during the toxicity characteristic leaching procedure (TCLP) were investigated. Several CPUs were disassembled and their component materials were decreased in size to meet the requirements of the TCLP. The impact of CPU composition was examined by leaching different combinations of the CPU components. The ferrous metal content of the mixture greatly impacted lead leaching. TCLP lead concentrations of CPUs predicted by leaching the lead-bearing printed wire boards alone were much greater than those measured when the ferrous metal of the CPU was included in the mixture. The leaching of iron and zinc from the galvanized steel components of the CPU created electrochemical conditions where lead was less soluble. Additional size reduction beyond that required by the TCLP did not result in additional lead leaching. As the volume of head space above the leaching solution increased, the concentration of lead measured increased as well.     

Effect of temperature and organic nutrients on the biodegradation of linear alkylbenzene sulfonate (LAS) during the composting of anaerobically digested sludge from a wastewater treatment plant

Limits on the application of biosolids (anaerobically processed sludges from wastewater treatment plants) as fertilizers for the amendment of soil are becoming greater because of the accumulation of recalcitrant substances, making necessary the use of techniques that bring the concentration of xenobiotics to lower concentrations than those permitted. In general, the biosolids composting process is sufficient to reduce the usual concentration of linear alkylbenzene sulfonates (LAS) to low levels. In this work, an assessment is made on the effect of temperature in the capacity of enriched bacterial populations to biodegrade LAS, together with the influence that the available nutrients may have in the biodegradation of these compounds. The results show that the microbial metabolism of LAS was not observed in the thermophilic range. The optimum temperature for the biodegradation of LAS appears to be around 40 degrees C, this is, the lowest assayed here, and at this temperature the differences in the biodegradation of LAS among the nutritionally supplemented cultures are small.     

Influence of dairy manure addition on the biological and thermal kinetics of composting of greenhouse tomato plant residues

A laboratory-scale bioreactor was used to investigate the influence of dairy manure addition (as an inoculum and a carbon source) on the biological and thermal kinetics of the composting process of tomato plant residues-wood shavings mixture. Urea was added (as a nitrogen source) to correct the initial C:N ratio to 30:1 and the initial moisture content was also adjusted to 60%. The result of this study indicated that manure addition to the tomato residues-wood shavings mixture is a good source of macro and micronutrients required for supporting the composting microorganisms. Manure addition increased the rate of temperature increase and the duration of maximum temperature and reduced the lag and the peak time, all of which resulted in a significant reduction in the retention time. However, thermophilic temperature (> or = 40 degrees Celsius) was only achieved with 30%, 40% and 50% manure addition for 3, 7 and 9h. Total carbon reductions were in the range of 9.4-10.8% and TKN reductions were in the range of 3.4-6.0%. Neither the nitrogen nor the moisture content were limiting factors as the C:N ratio remained in the range of 26:1 to 28:1 and the moisture content remained within the optimum range of 58-61%. The maximum temperature of each mixture correlated with the reduction of total carbon, but carbon availability was a limiting factor in these experiments. In order to attain and sustain a thermophilic phase during the composting process, the addition of a readily available carbon source to the tomato should be investigated and carbon type (carbohydrates, proteins and fats) should be taken into account.     

Impacts of land cover on stream hydrology in the West Georgia Piedmont, USA

The southeastern United States is experiencing rapid urban development. Consequently, Georgia's streams are experiencing hydrologic alterations from extensive development and from other land use activities such as livestock grazing and silviculture. A study was performed to assess stream hydrology within 18 watersheds ranging from 500 to 2500 ha. Study streams were first, second, or third order and hydrology was continuously monitored from 29 July 2003 to 23 September 2004 using InSitu pressure transducers. Rating curves between stream stage (i.e., water depth) and discharge were developed for each stream by correlating biweekly discharge measurements and stage data. Dependent variables were calculated from discharge data and placed into 4 categories: flow frequency (i.e., the number of times a predetermined discharge threshold is exceeded), flow magnitude (i.e., maximum and minimum flows), flow duration (i.e., the amount of time discharge was above or below a predetermined threshold), and flow predictability and flashiness. Fine resolution data (i.e., 15-min interval) were also compared to daily discharge data to determine if resolution affected how streams were classified hydrologically. Urban watersheds experienced flashy discharges during storm events, whereas pastoral and forested watersheds showed less flashy hydrographs. Also, in comparison to all other flow variables, flow frequency measures were most strongly correlated to land cover. Furthermore, the stream hydrology was explained similarly with both the 15-min and daily data resolutions.     

Use of beryllium-7 to document soil redistribution following forest harvest operations

Rapid and reliable methods for documenting soil erosion associated with forest harvest operations are needed to support the development of best management practices for soil and water conservation. To address this need, the potential for using 7Be measurements to estimate patterns and amounts of soil redistribution associated with individual post-harvest events was explored. The 7Be technique, which was originally developed for use on agricultural land, was employed to estimate soil redistribution associated with a period of heavy rainfall within a harvested forest area located in the Lake Region of Chile (39 degrees 44'7' S, 73 degrees 10'39' W; 22% slope; and mean annual rainfall 2300 mm yr(-1)). The results provided by the 7Be technique were validated against direct measurements of soil gain or loss during the same period obtained using erosion pins. The information produced by the two approaches was similar. The results of this study demonstrate the potential for using 7Be measurements to document event-based erosion in recently harvested forest areas.     

Phosphorus fractions in manure from growing pigs receiving diets containing micronized peas and supplemental enzymes

Different livestock feeds manipulations have been reported to reduce the total P concentration in manure. Information on the influence of these dietary manipulation strategies on the forms of P in manure is, however, limited. This study was, therefore, conducted to investigate the effect of diet manipulation through feed micronization and enzyme supplementation on the forms of P in swine manure. Eight growing pigs were fed four diets: barley-raw pea (BRP), barley-micronized pea (BMP), barley-raw pea with enzyme (BRPE), and barley-micronized pea with enzyme (BMPE) in a 4 x 4 Latin square design. Because we are interested in the effect of enzyme cocktail and pea micronization on manure P, we did not reduce the non-phytate P with enzyme addition in this study. The fecal material and urine were collected and analyzed for total P. Fecal material was fractionated to determine the total P in H2O-, NaHCO3-, NaOH-, and HCl-extractable fractions. The total P in the residual fractions was also determined. About 98% of the total P excreted by the pigs was found in the fecal material. Inclusion of micronized pea in pig diet did not have any significant effect (p > 0.1) on either the total P or the different P fractions in the manure. The labile P (the sum of H2O-P and NaHCO3-P) was significantly reduced (p < 0.05) by the addition of enzyme to swine diets. Pigs fed the BRPE and BMPE had 14 and 18% lower labile P, respectively, compared with pigs fed the BRP. Enzyme addition to pig diets reduced not only the total P in manure, but also the labile P fraction, which is of great environmental concern. Thus, the potential of P loss to runoff and the subsequent eutrophication can be reduced by enzyme addition to pig diets.     

Diuron in surface runoff and tile drainage from two grass-seed fields

The typical method of cool-season grass-seed production in Mediterranean climates briefly exposes surface waters to potentially high concentrations of the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethyl urea] during the initial season of growth. To better understand the process, and the degree, of diuron transport from agricultural fields, two grass-seed fields in the Willamette Valley of Oregon were monitored for diuron loss in surface runoff and tile drainage during the first wet season after planting. Initial diuron concentrations in surface runoff were high (>1000 microg L(-1) in one field and >100 microg L(-1) in the other), though they decreased by two orders of magnitude by the end of the season. Concentrations in the tile drains were as much as 1000 times lower than in the surface runoff during the first few weeks of runoff events, and they remained lower than surface water concentrations throughout the season. Total losses in surface runoff were between 1.3 and 3% of the amount applied-much higher than losses via the tile drains. It is also shown by means of a simple first-order decay model that, when little information is available, it may be best to describe diuron depletion in runoff water as a function of cumulative rainfall during the wet season.     

Carbon and nitrogen mineralization rates after application of organic amendments to soil

The objective of this study was to quantify C and N mineralization rates from a range of organic amendments that differed in their total C and N contents and C quality, to gain a better understanding of their influence on the soil N cycle. A pelletized poultry manure (PP), two green waste-based composts (GWCa, GWCb), a straw-based compost (SBC), and a vermi-cast (VER) were incubated in a coarse-textured soil at 15 degrees C for 142 d. The C quality of each amendment was determined by chemical analysis and by 13C nuclear magnetic resonance (NMR). Carbon dioxide (CO2-C) evolution was determined using alkali traps. Gross N mineralization rates were calculated by 15N isotopic pool dilution. The CO2-C evolution rates and gross N mineralization rates were generally higher in amended soils than in the control soil. With the exception of GWCb all amendments released inorganic N at concentrations that would be high enough to warrant a reduction in inorganic N fertilizer application rates. The amount of N released from PP was high indicating that application rates should be reduced, or alternative amendments used, to minimize leaching losses in regions where ground water quality is of concern. There was a highly significant relationship between CO2-C evolution and gross N mineralization (R2= 0.95). Some of the chemically determined C quality parameters had significant relationships (p < 0.05) with both the cumulative amounts of C and N evolved. However, we found no significant relationships between 13C NMR spectral groupings, or their ratios, and either the CO2-C evolved or gross N mineralized from the amendments.     

Performance characteristics of sequential separation and quantification of lead-210 and polonium-210 by ion exchange chromatography and nuclear spectrometric measurements

A selective separation and quantitative determination procedure for 210Pb and 210Po in various environmental matrices from different sources such as IAEA-326 soil, phosphate rocks (PR), and phosphogypsum (PG) was developed. The tested samples were digested sequentially using concentrated mineral acids (HF, HNO3) by a programmable high-pressure microwave digestion system. The sample solution was loaded onto a preconditioned ion exchange column (Sr-resin) for chromatographic separation. Polonium-210 was eluted by 6 M HNO3 then spontaneously deposited onto polished silver discs to be measured using low-background alpha spectrometry. Lead-210 was sequentially eluted using 6 M HCl solution, precipitated as lead oxalate, dissolved in HNO3 solution, and mixed with scintillation cocktail to be measured by liquid scintillation counting (LSC). Performance of the developed procedure was tested using a reference soil (IAEA-326), with recommended isotope values, that was used as a quality control to assess separation and quantification efficiency (recovery %). The minimum detectable activities of 210Pb and 210Po were found to be 24 and 0.28 Bq kg(-1) for the measurements using LSC and alpha spectrometry, respectively. The recoveries (%) of 210Pb and 210Po were found to be 80 and 60%, respectively. To test the validity of the proposed LSC method, a comparative study was performed by measuring 210Pb activity concentration in test samples by nondestructive gamma-ray spectrometry.