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Query: UMLS:C0205700 (ash)
 15,125 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A study of interception of chemicals at an ash plantation forest in southern-central England shows the modification of acidic pollution as it passes from precipitation, through the vegetation cover and the soil to generate surface runoff. Precipitation is highly acidic (pH 3.7-4.8, alkalinity -16 to -200 microEq/l) and it is enriched in the strong acid anions associated with acidification (sulfate and nitrate) as well as ammonium and the trace elements aluminium and zinc. The concentration of both sea-salt and pollutant components varies considerably over time and this is linked to washout from the atmosphere during precipitation events as marked by an inverse relationship between concentration and volume of catch. The catchment is also supplied by sea-salt and pollutant additions as dry deposition: gaseous inputs of SO(x) may also increase sulfate deposition. Through the vegetation, much of the acidity is neutralised and, particularly during the growth period, calcium, magnesium and potassium is cycled, while sodium and nitrate are partially removed. Within the catchment, weathering ensures that further base cation production occurs leading to enhanced neutralisation of acidity and the generation of positive alkalinities. As a result, surface runoff becomes buffered with alkalinity approximately 490 microEq/l and pH approximately 7.9. Thus, although the acidification input from the atmosphere is high, this does not translate to acidic runoff due to within-canopy and within-soil processes.
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PMID:Interception and attenuation of atmospheric pollution in a lowland ash forested site, Old Pond Close, Northamptonshire, UK. 1184 89

Anion exchangers were prepared from different agricultural residues (AR) after reaction with epichlorohydrin and dimethylamine in the presence of pyridine and N,N-dimethylformamide (EDM method). Agricultural residues anion exchangers (AR-AE) produced by the EDM method were inexpensive and showed almost the same NO3- removal capacities as Amberlite IRA-900. AR-AE produced from AR with higher hemicelluloses, lignin, ash and extractive contents resulted in the lower yields. Sugarcane bagasse with the highest alpha-cellulose contents of 51.2% had the highest yield (225%) and lowest preparation cost. The highest maximum adsorption capacity (Qmax) for nitrate was obtained from rice hull (1.21 mmol g(-1)) and pine bark natural exchangers (1.06 mmol g(-1)). No correlation was found between Qmax and alpha-cellulose content in the original AR. AR-AE produced from different AR demonstrated comparable Qmax due to the removal of non-active compounds such as extractives, lignin and hemicelluloses from AR during the preparation process. Similar preparation from pure cellulose and pure alkaline lignin demonstrated that the EDM method could not produce anion exchangers from pure lignin due to its solubilization after the reaction with epichlorohydrin.
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PMID:Preparation of agricultural residue anion exchangers and its nitrate maximum adsorption capacity. 1222 9

The objective of this study was to determine the effect of wood ash application on soil solution composition of three tropical acid soils. Calcium carbonate was used as a reference amendment. Amended soils and control were incubated for 60 days. To assess soluble nutrients, saturation extracts were analysed at 15 days intervals. Wood ash application affects the soil solution chemistry in two ways, as a liming agent and as a supplier of nutrients. As a liming agent, wood ash application induced increases in soil solution pH, Ca, Mg, inorganic C, SO4 and DOC. As a supplier of elements, the increase in the soil solution pH was partly due to ligand exchange between wood ash SO4 and OH- ions. Large increases in concentrations of inorganic C, SO4, Ca and Mg with wood ash relative to lime and especially increases in K reflected the supply of these elements by wood ash. Wood ash application could represent increased availability of nutrients for the plant. However, large concentrations of basic cations, SO4 and NO3 obtained with higher application rates could be a concern because of potential solute transport to surface waters and groundwater. Wood ash must be applied at reasonable rates to avoid any risk for the environment.
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PMID:Effect of wood ash application on soil solution chemistry of tropical acid soils: incubation study. 1236 2

A geographic information system was used to map and analyze nitrate, chloride, sulfate, and fluoride concentrations in 110 wells tapping the Woodbine Aquifer. The study area, covering nine counties in north-central Texas, includes large percentages of both urban and agricultural land uses. Land use maps were compared with solute concentration data, and statistics were applied to detect associations between solutes, well depth, and land use. Anthropogenic sources such as fertilizer applications and natural sources such as gypsum, lignite, and clay deposits controlled nitrate, chloride, and sulfate concentrations, each inversely correlated with well depth. However, only one nitrate observation--from a shallow well in the aquifer's outcrop zone--surpassed the maximum contaminant level (MCL) of 44.3 mg L(-1). By comparison, nearly half of the sulfate and several of the chloride observations surpassed the MCL of 250 mg L(-1) for each of those ions. Volcanic ash deposits influenced fluoride concentrations, which directly correlated with well depth. There were no statistically significant associations between solute concentrations and land use. Low recharge rates and confining layers have mitigated anthropogenic impacts on solute levels in the aquifer.
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PMID:Spatial patterns of nitrate, chloride, sulfate, and fluoride concentrations in the Woodbine Aquifer of north-central Texas. 1260 33

The aim of the present work was to investigate the influence of a number of heavy metals (Cd, Cr(III), Cu, Pb and Zn), as well as anions (Cl-, SO4(2-)) on the physical and mechanical properties of cementitious pastes, including setting time, bulk density and unconfined compressive strength. The above mentioned species and their concentrations were selected in order to simulate addition of 20% municipal solid waste incinerator ash to Portland cement. Spiking experiments were performed according to a 2IV(7-3) fractional factorial design by addition of pure compounds containing the contaminants of interest to Portland cement. The results from the experimental campaign, which were interpreted using statistical analysis techniques, showed that the investigated contaminants variously affected the hydration process of cement. The ranking for final setting time values was Zn(NO3)2 > K2SO4 > NaCl > mean response > Cr(NO3)3 > NaCl+Cr(NO3)3, Cd(NO3)2+Pb(NO3)2 or CuCl2+Zn(NO3)2 interaction, whereas the ranking for UCS values during hardening was Zn(NO3)2 > CuCl2 > NaCl+K2SO4, CuCl2+Pb(NO3)2 or Cd(NO3)2+Zn(NO3)2 interaction > mean response. Conversely, none of the selected contaminants was found to significantly influence ultimate strength.
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PMID:Modelling heavy metal and anion effects on physical and mechanical properties of portland cement by means of factorial experiments. 1266 92

The chemical composition of snow and terricolous lichens was determined along transects through the Subarctic towns of Vorkuta (130 km west-east), Inta (240 km south-north) and Usinsk (140 km, southwest-northeast) in the Usa river basin, northeast European Russia. Evidence of pollution gradients was found on two spatial scales. First, on the Inta transect, northward decreases in concentrations of N in the lichen Cladonia stellaris (from 0.57 mmol N g(-1) at 90 km south to 0.43 mmol N g(-1) at 130 km north of Inta) and winter deposition of non-sea salt sulphate (from 29.3 to 12.8 mol ha(-1) at 90 km south and 110 km north of Inta, respectively) were attributed to long range transport of N and S from lower latitudes. Second, increased ionic content (SO42-, Ca2+, K+) and pH of snow, and modified N concentration and the concentration ratios K+:Mg2+ and K+: (Mg2++Ca2+) in lichens (Cladonia arbuscula and Flavocetraria cucullata) within ca. 25-40 km of Vorkuta and Inta were largely attributed to local deposition of alkaline coal ash. Total sulphate concentrations in snow varied from ca. 5 micromol l(-1) at remote sites to ca. 19 micromol l(-1) near Vorkuta. Nitrate concentration in snow (typically ca. 9 micromol l(-1)) did not vary with proximity to perceived pollution sources.
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PMID:Regional variation in the chemical composition of winter snow pack and terricolous lichens in relation to sources of acid emissions in the Usa river basin, northeast European Russia. 1282 18

Trace metal selenium in milk cow serums has determined by graphite furnace atomic absorption spectrometry with matrix modifier. It's found that addition the solution of 0.1% Ni(NO3)2 as matrix modifier, the ash temperature will increase up to 1,000 degrees C. 600 degrees C is practically used for ash temperature. D2 lamp is used for background correction. Selenium in milk cow serums was directly determined after addition of 0.1% Ni(NO3)2 without digestion. The method is convenient to determine element in milk cow serum. The results show that the method has good precision and accuracy. The relative standard deviation of selenium. Determination was 4.9%, and the rates of recovery were 93.3%-104%.
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PMID:[Determination of trace selenium in milk cow serum with graphite furnace atomic absorption spectrophotometry]. 1293 3

Inorganic nutrients can be easily recovered from ALS crop residue solid wastes by aqueous leaching. However, oven drying and milling pretreatment of these residues has been frequently required to accommodate crop scientists and facility storage limitations. As part of a research study that will compare three different bioreactor technologies for processing these wastes, we realized that different drying and size-reduction pretreatments had been utilized for each technology. This paper compares the effects of residue pretreatment on recovery of nutrients by leaching. Pretreatments included three drying methods [fresh, oven-dried (70 degrees C overnight), and freeze-dried] and two size reduction methods [chopped (2 cm length) and milled (2 mm diameter)]. Determination of mass balances (dry weight and ash content of solids) before and after leaching indicated solubilization was least for fresh residues (23% dry weight loss and 50% for ash loss), and most for freeze-dried residues (41-47% dry weight loss and nearly 100% for ash loss). Mineral recovery of major elements (NO3, PO4, K, Ca, and Mg) in leachates was poorest for fresh residues. P and K recovery in leachates were best for oven-dried residues and Ca, Mg, and N recovery best for freeze-dried residues. The differences in recovery for N, P, and K in leachates were minimal between chopping and milling and slightly better for Ca and Mg from milled residues.
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PMID:The effect of drying and size reduction pretreatments on recovery of inorganic crop nutrients from inedible wheat residues. 1463 96

The potential risk of groundwater contamination by the excessive leaching of N, P and heavy metals from soils amended at heavy loading rates of biosolids, coal ash, N-viro soil (1:1 mixture of coal ash and biosolids), yard waste compost and co-compost (3:7 mixture of biosolids to yard wastes), and by soil incorporation of green manures of sunn hemp (Crotalaria juncea) and sorghum sudangrass (Sorghum bicolor x S. bicolor var. sudanense) was studied by collecting and analyzing leachates from pots of Krome very gravelly loam soil subjected to these treatments. The control consisted of Krome soil without any amendment. The loading rate was 205 g pot(-1) for each amendment (equivalent to 50 t ha(-1) of the dry weight), and the amounts of the cover crops incorporated into the soil in the pot were those that had been grown in it. A subtropical vegetable crop, okra (Abelmoschus esculentus L.), was grown after the soil amendments or cover crops had been incorporated into the soil. The results showed that the concentration of NO3-N in leachate from biosolids was significantly higher than in leachate from other treatments. The levels of heavy metals found in the leachates from all amended soils were so low, as to suggest these amendments may be used without risk of leaching dangerous amounts of these toxic elements. Nevertheless the level of heavy metals in leachate from coal ash amended soil was substantially greater than in leachates from the other treatments. The leguminous cover crop, sunn hemp, returned into the soil, increased the leachate NO3-N and inorganic P concentration significantly compared with the non-legume, sorghum sudangrass. The results suggest that at heavy loading rates of soil amendments, leaching of NO3- could be a significant concern by application of biosolids. Leaching of inorganic P can be increased significantly by both co-compost and biosolids, but decreased by coal ash and N-viro soil by virtue of improved adsorption. The leguminous cover crop, sunn hemp, when incorporated into the soil, can cause the concentration of NO3-N to increase by about 7 fold, and that of inorganic P by about 23% over the non-legume. Regarding the metals, biosolids, N-viro soil and coal ash significantly increased Ca and Mg concentrations in leachates. Copper concentration in leachate was increased by application of biosolids, while Fe concentration in leachates was increased by biosolids, coal ash and co-compost. The concentrations of Zn, Mo and Co in leachate were increased by application of coal ash. The concentrations of heavy metals in leachates were very low and unlikely to be harmful, although they were increased significantly by coal ash application.
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PMID:Effects of soil amendments at a heavy loading rate associated with cover crops as green manures on the leaching of nutrients and heavy metals from a calcareous soil. 1464 15

Co-composting of high moisture vegetable wastes (celery and cabbage) and flower wastes (carnation) were studied in a sequential fed bed. The preliminary materials of composting were celery and carnation wastes. The sequential fed materials of composting were cabbage wastes and were fed every 4 days. Moisture content of mixture materials was between 60% and 70%. Composting was done in an aerobic static bed of composting based temperature feedback and control via aeration rate regulation. Aeration was ended when temperature of the pile was about 40 degrees C. Changes of composting of temperature, aeration rate, water content, organic matter, ash, pH, volume, NH4(+)-N, and NO3(-)-N were studied. Results show that co-composting of high moisture vegetable wastes and flower wastes, in a sequential fed aerobic static bed based temperature feedback and control via aeration rate regulation, can stabilize organic matter and removal water rapidly. The sequential fed operation are effective to overcome the difficult which traditional composting cannot applied successfully where high moisture vegetable wastes in more excess of flower wastes, such as Dianchi coastal.
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PMID:[Co-composting high moisture vegetable waste and flower waste in a sequential fed operation]. 1476 84


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