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991.
992.
Fresh applications of phosphorus (P) may cause ‘incidental’ losses of dissolved and particulate P forms in land runoff when rainfall interacts directly with fertilizers and manures which are spread, or excreted, onto the soil surface. Research indicates that when incidental P losses (IPL) occur, they often make the dominant (50–98 %) contribution to measured P loads in surface and sub‐surface runoff from field plots, with increased risk of eutrophication where P‐enriched runoff is routed directly to the watercourse. Rates of P loss are temporally and spatially very variable (< 1 to 25 % of total P applied) depending on the amount of P applied; the P release properties of the materials applied (% P extractable in water), the timing of storm events after application and the amounts of runoff generated. Large P applications left on the surface of wet, frozen, compacted, and intensively underdrained soils in high rainfall areas are particularly vulnerable to IPL. Concentrations of P in runoff are often greatest during the first storm event following P application, but can remain high for several weeks, or even months after application. Catchment scale impacts are more difficult to quantify due to the effects of dilution with runoff from fields without IPL, and the contributions of P from other sources. Approaches to predicting IPL are discussed and need to be improved in order to assess the contribution of IPL to catchment P loads in river basin management planning. Strategies to control IPL should focus on adoption of more sensitive management practices in fields with a high risk of rapid runoff or preferential flow, and are likely to very effective. 相似文献
993.
Ryan D Antolovich M Herlt T Prenzler PD Lavee S Robards K 《Journal of agricultural and food chemistry》2002,50(23):6716-6724
A methodological approach to phenolic profiling making extensive use of LC-MS with extracted ion chromatograms was applied to extracts of five different olive tissues: pulp, seed, stone, new-season leaves, and old-season leaves. Tissue extracts of the cultivars Hardy's Mammoth, Corregiola, Verdale, and Manzanillo were analyzed by HPLC with UV and ESI MS detection. Chromatograms of samples of green Hardy's Mammoth drupes, a uniquely Australian olive cultivar, were dominated by a large, broad peak. This peak was not attributable to oleuropein, which is usually the dominant phenolic compound in green olive fruit, but the phenolic compound I. This compound was isolated by semipreparative HPLC and characterized by 1D- and 2D-NMR. Extraction studies showed that the compound was not likely to be an artifact of an enzymatic degradation process. Tritium labeling studies were used to establish a possible relationship between the biosynthesis of I and oleuropein. 相似文献
994.
Nives Ogrinc Tjaša Kanduč Bor Krajnc Urša Vilhar Primož Simončič Lixin Jin 《Journal of Soils and Sediments》2016,16(2):382-395
Purpose
Soil carbon dynamics were studied at four different forest stands developed on bedrocks with contrasting geology in Slovenia: one plot on magmatic granodiorite bedrock (IG), two plots on carbonate bedrock in the karstic-dinaric area (CC and CD), and one situated on Pleistocene coalluvial terraces (FGS).Materials and methods
Throughfall (TF) and soil water were collected monthly at each location from June to November during 2005–2007. In soil water, the following parameters were determined: T, pH, total alkalinity, concentrations of Ca2+ and Mg2+, dissolved organic carbon (DOC), and Cl? as well as δ13CDIC. On the other hand, in TF, only the Cl? content was measured. Soil and plant samples were also collected at forest stands, and stable isotope measurements were performed in soil and plant organic carbon and total nitrogen and in carbonate rocks. The obtained data were used to calculate the dissolved inorganic carbon (DIC) and DOC fluxes. Statistic analyses were carried out to compare sites of different lithologies, at different spatial and temporal scales.Results and discussion
Decomposition of soil organic matter (SOM) controlled by the climate can explain the 13C and 15?N enrichment in SOM at CC, CD, and FGS, while the soil microbial biomass makes an important contribution to the SOM at IG. The loss of DOC at a soil depth of 5 cm was estimated at 1 mol m?2 year?1 and shows no significant differences among the study sites. The DOC fluxes were mainly controlled by physical factors, most notably sorption dynamics, and microbial–DOC relationships. The pH and pCO2 of the soil solution controlled the DIC fluxes according to carbonate equilibrium reactions. An increased exchange between DIC and atmospheric air was observed for samples from non-carbonate subsoils (IG and FGS). In addition, higher δ13CDIC values up to ?19.4?‰ in the shallow soil water were recorded during the summer as a consequence of isotopic fractionation induced by molecular diffusion of soil CO2. The δ13CDIC values also suggest that half of the DIC derives from soil CO2 indicating that 2 to 5 mol m?2 year?1 of carbon is lost in the form of dissolved inorganic carbon at CC and CD after carbonate dissolution.Conclusions
Major difference in soil carbon dynamics between the four forest ecosystems is a result of the combined influence of bedrock geology, soil texture, and the sources of SOM. Water flux was a critical parameter in quantifying carbon depletion rates in dissolved organic and inorganic carbon forms.995.
Samuel Raj Babu Arulmani Vimalan Jayaraj Solomon RobinsonDavid Jebakumar 《Journal of Soils and Sediments》2016,16(3):831-841
Purpose
This study was conducted to determine the existence of soil bacteria in soil by soil microbial fuel cell (SMFC). The main objectives were (1) to differentiate the type of soil which will influence the electricity production, (2) to demonstrate the impact of different volume of soil in the MFC and feeding MFC for long-term electricity production, and (3) to conclude that electricity production is directly proportional to the biofilm formation on the anode surface.Materials and methods
MudWatt kits were purchased from Keego Technologies USA, and 22 identical SMFCs were designed to study the electricity production from agricultural soil (S1) and vermicompost soil (S2). Ten milliliters of bioslurry is fed in SMFC to study the stability of electricity production at different stages. Microbes were isolated and characterized from the surface of the electrode. Biofilm analyses were done by high-content screening (HCS) system using 10 μl of acridine orange (100 μg/ml) at different stages of biofilm, and scanning electron microscopy is applied to confirm the matured biofilm on the surface of the anode.Results and discussion
Application of bioslurry at different stages of electricity production conquers the normal energy recovery of the SMFCs and S2 soil with bioslurry sample produced the highest open circuit voltage (OCV) of 2.8 V (460 days) and S1 soil sample with bioslurry produced 1.7 V (364 days). The difference between SMFCs and MudWatt kits significantly confirms that increasing the volume of soil in the anode part increases the electricity production. The maximum OCV of S1 and S2 in MudWatt kits were 1.5 V (90 days) and 1.8 V (190 days), respectively. Increased volume of soil in our SMFCs produce maximum OCV of 1.8 V (S1 for 173 days) and 2.2 V (S2 for 240 days), and HCS analysis of biofilm at different stages reveals that electricity production is directly proportional to the biofilm formation.Conclusions
Thus, it was concluded that the nature of soil and soil bacterium is important for the electricity production, and S2 soil sample produces maximum electricity than the S1 soil sample. Feeding of SMFCs with bioslurry aids the long-term and stabilized electricity production in both the soil samples.996.
Purpose
The aim of the present study was to investigate the effects of visitors’ activities on soil properties in parks of Tel Aviv-Jaffa city, Israel.Materials and methods
The city was divided into three geographical regions: south, central, and north. This division reflects the course of development of the city from south to north and encompasses various socioeconomic levels of residents. In each region, 9–15 parks were randomly chosen and classified into three groups according to their size (in m2): 2?×?103 to 10?×?103, 11?×?103 to 20?×?103, and 21?×?103 to 50?×?103. In each park soil, 0–2 cm of depth layer was sampled in areas under various levels of visitor pressure from July to August 2011, and organic matter, electrical conductivity, and sodium and chlorine contents were determined. Lawns and path and picnic areas represented low and high visitor pressure, respectively. Observations were conducted to characterize the various land uses of the parks and to estimate the numbers of visitors. Also, questionnaires were used at selected parks to assess visitors’ motivations or reasons for visiting the parks.Results and discussion
Socioeconomic indicators, such as the number of residents, the apartment areas, and the percentages of family households, differed among the regions. Soil properties differed between the areas of high and low visitor pressure: they were influenced by type of human activity, size of the park, and number of visitors.Conclusions
Soil properties are affected by variations in the intensity of park use by visitors and by the type of activities enjoyed by these visitors, both of which depend on the socioeconomic status of the park area.997.
An experiment and a numerical scheme which combine previously given methods for the dispersion and seepage phenomena have been presented to describe the dispersion of a pollutant in porous media beneath a triangular channel. The combined effect of longitudinal and lateral dispersion was considered. Numerical concentration profiles are given along with a comparison of experimental and numerical data. The technique suggested herein can be extended to other channel shapes and flow fields accounting for the capillary fringe. 相似文献
998.
An isocratic liquid chromatographic (LC) technique is described for the determination of benzoic acid and sorbic acid in foods such as beverages, fruits, seafood, vegetables, sauces, and dairy, bakery, and confectionery products. A C18 column is used with methanol-phosphate buffer (5 + 95) as mobile phase and 4-hydroxyacetanilide or 3,5-dinitrobenzoic acid as internal standard. Sample preparation is simple, rapid, and produces a sample extract that has a minimum effect on the column performance and life. Specificity of the method was checked against common food additives such as L-ascorbic acid, caffeine, artificial sweeteners (saccharin, cyclamate, aspartame), antioxidants (BHT, BHA) and artificial colors. Also described are 2 procedures for confirmation of the preservatives, using either redox reaction of sorbic acid with potassium permanganate or gas chromatography/mass spectrometry. Mean recoveries of 90-105% were obtained with a precision of 1-6% and a detection limit of 20 mg/kg for the 2 preservatives. 相似文献
999.
P. Guerrier J. -P Weber R. Coté M. Paul M. Rhainds 《Water, air, and soil pollution》1995,80(1-4):1199-1202
In Canada, medical instruments containing mercury (Hg) are still widely used in hospitals. These are mostly thermometers and sphygmomanometers. Mercury present in these instruments does not in itself constitute a risk of contamination since this metal is contained within a closed system. However, breakage, inadequate maintenance and disposal of such instruments can expose workers and the public to this toxic substance. In Quebec, 80% of the 28 hospitals surveyed still use Hg sphygmomanometers and 45% Hg thermometers. Besides, 35% do not have any recovery procedures in case of spillage and most mercury spills are apparently not reported. Two main courses of action are recommended: the gradual replacement of these medical instruments by aneroid sphygmomanometers and electronic thermometers, and the establishment and communication, in the form of a handbook, of guidelines to handle and dispose of mercury safely. 相似文献
1000.
Fenet H Beltran E Gadji B Cooper JF Coste CM 《Journal of agricultural and food chemistry》2001,49(3):1293-1297
The fate of fipronil, a phenylpyrazole insecticide, and its metabolites under tropical conditions was studied in soil and in vegetation after treatment for locust control. Two different plots were treated with a formulation of fipronil at doses of 5 and 10 g of active ingredient ha(-)(1), respectively. Vegetation and soil at depths of 0-5 and 5-20 cm were sampled for up to 2 months after treatment. After extraction and purification on fipronil immunoaffinity cartridges, residues were analyzed by gas chromatography using electron capture and mass detectors. In soil, a rapid initial decrease of fipronil was observed with a rapid formation of the sulfone and the photodegradate; the amide and the sulfide were not detected. In vegetation, a rapid initial decrease of fipronil was also observed with a rapid formation of mostly the sulfone; the photodegradate and the sulfide were also detected but at much lower concentrations. The metabolites resulting from the degradation of fipronil were similar in both soil and vegetation, but their relative concentrations were different. 相似文献