dissolved humus in soil waters

... changes in soil climate, (iv) the * Corresponding author: ranger@nancy.inra.fr chemical erosion due to losses in drainage waters, and (v) the physical erosion when the soil lays bare in a sloping ... solutions of the upper soil layers drastically fell down after the cutting. The limited increase in nutrients leached with drainage waters was only due to the increase in the water flux, which ... clear-cutting of a 70-year-old Douglas-fir plantation on the chemical composition of soil solutions and on leaching of nutrients in drainage waters were observed by a continuous monitoring, six

Ngày tải lên: 07/08/2014, 16:20

... obtained by inserting the coring tube into the bottom sediments; this core and its contents then are retrieved and inserted into the Shaker frame. The thickness of the sediment in the coring ... LLC 52 Sediment and Contaminant Transport in Surface Waters section with an open bottom through which a coring tube that contains sediment can be inserted. This coring tube has a rectangular ... and limiting, interpretations as to the appropriate mechanisms that describe the process as shown in Figure 3.2. In the rst interpretation, it is assumed that particles are uniform in size

Ngày tải lên: 18/06/2014, 22:20

... two concentric cylinders, with the outer cylinder rotating and the inner cylinder stationary. In this way, a reasonably uniform velocity gradient can be generated in the uid in the annular gap ... settling speed, then d = 0 and there is no contribution of differential settling to dN/dt in this limit As the difference in particle sizes increases, the difference in settling... on salinity ... particle size initially increasing with time and then approaching a steady state in which the median particle size remained approximately constant with time. For the conditions in these experiments,

Ngày tải lên: 18/06/2014, 22:20

... state In waters with variable salinity, a conservation equation for salinity is also needed In sufficiently general form for almost all modeling of surface waters, these equations are the following ... contaminant transport problems However, for a thorough understanding of the rich and fascinating field of fluid mechanics in surface waters, additional articles, texts, and conference proceedings ... and Sea Engineering, Inc., for the Fox River (Sea Engineering, 2004) For fully developed turbulent flow in a river, the near-bottom velocity profile is given by Trang 10Once u(z) is obtained from

Ngày tải lên: 18/06/2014, 22:20

... decreases in the inlet and beginning of the expansion region In the latter part of the expansion 20 Distance (m) 30 8 (d) 7 6 5 4 3 2 1 0 FIGURE 6.8 (CONTINUED) Transport in an expansion region Initial ... penetration of turbulence into the bed with increasing shear stress In calculations, d50 is often approximated by the average diameter of the sediments in the surficial layer In the modeling of sediment ... change rapidly and in a nonuniform manner in time and space (which is most of the time), the most accurate procedure for deter- mining erosion rates is by using Sedflume for existing in situ sediments

Ngày tải lên: 18/06/2014, 22:20

... ddiam-istribution of particle sizes in natural sediments (inevitably including some particles less than 1 µm in diameter), colloids are inherently present in any sample of natural sediments; ... ascertained whether the remaining sorption after strip-ping was due to sorption to the mineral surfaces of the sediments or due to sorption of HCB to a small amount of organic matter still remaining ... particles or flocs less than 1 µm in eter In pure water, no colloids are present However, they are always present in natural waters but vary widely in amount and character In addition, because there

Ngày tải lên: 18/06/2014, 22:20

... speed increases, the total amount of PCBs remaining in the water increases because of the very nonlinear increase of sediment and contaminant resuspension as the wind speed increases. In these ... two in the inner bay and by a factor of ve or more in the outer bay. At the end of the 14 days, the percentage of PCBs originally resuspended and still remaining in the water (dissolved in ... of C w in the overlying water and higher values of C s © 2009 by Taylor & Francis Group, LLC 322 Sediment and Contaminant Transport in Surface Waters in the overlying water and in the deposited

Ngày tải lên: 18/06/2014, 22:20

... and the soil. Soil was drilled with a stainless steel soil column cylinder with a cutting shoe and a removable cover (10 cm diameter, 1 m length; Eijkelkamp) and was inserted into the soil with ... changes in soil water content. These results indicate the importance of the edapho-climatic conditions in the interpretation of tree-pasture interactions. 4.2. Lateral water uptake by trees Thinning ... dense root system in order to adequately exploit wa- ter in unsaturated soils, since the difficulty of water movement in the soil is greater than the force with which it is retained. In- deed, root

Ngày tải lên: 07/08/2014, 16:21

... transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing ... for use in soils, which has grown lately into a multimillion dollar business, are addressed. These are issues of considerable interest to people studying, practicing, and producing medicines ... nucleic acids. Growth promoting substances. such as auxin, gibberellin, and vitamins are included in the latter group, and their biotic origin and decomposition are examined in relation to claims

Ngày tải lên: 11/08/2014, 12:21

... all kinds of soils since it is the major fraction of soil humus Though variations as to its content can be noticed due to differences in climate and drainage, humic matter can be found in soils ... By definition organic soils contain >80% organic matter and ~ 2 0 % mineral matter (Brady and Weil, 1996) A more complex definition, used in Soil Taxonomy (Soil Survey Staff, 1990), indicates ... dispersion, and is easily coagulated In Stevenson's opinion, it looks similar to the humic acid in mollisols With research interest declining among soil scientists facing resentment due to an apparent

Ngày tải lên: 11/08/2014, 12:21

... an important amino sugar in soils It is an epimer of glucosamine, differing from the latter only in placement of an OH group in the carbon chain According to Stevenson (1994) amino sugars have ... protein and amino acids For more details on the basics of amino acids and protein, see Tan (1998; 2000) Decomloosition o f Protein and Amino acids In contrast to lignin and phenols, protein and ... From the standpoint of soil physics, mention has been made in the literature on interaction reactions between amino sugars or polysaccharides and soil mineral particles encouraging soil aggregation,

Ngày tải lên: 11/08/2014, 12:21

... indicated in Chapter 1, the. .. well drained soils, underscoring the aerobic environment prevailing in soils affecting the oxidation of humic acids In contrast, the negative values for ... yet that these small phenol units originate from lignin, or pyridine units from protein It is a matter of believing and trusting only, since as discussed in Chapter 4, phenol or benzene-like ... process, involving now also partial oxidation and further losses of CH, groups. An increase or decrease in the number and length of aliphatic chains in the humic molecule is considered to be inherent

Ngày tải lên: 11/08/2014, 12:21

... differences in absorption in the fingerprint region Notwithstanding the many arguments on the usefulness of infrared analysis of humic substances, the method is capable of detecting and distinguishing ... to a molecule In the fingerprint region, single bond stretching and bending vibrations of polyatomic systems are major features Molecules similar in structure may absorb similarly in the group ... Since W-visible light spectra of humic compounds are generally featureless straight lines, Salfeld (1975) suggests modifying the analysis by measuring the absorbencies at intervals of 10 nm in

Ngày tải lên: 11/08/2014, 12:21

... are incorrect, they only mean that one has to use caution in accepting the facts on COOH content in humic substances The latter finds its origin in the considerable difficulties encountered in ... of the opinion that the presence of electric double layers surrounding individual colloidal particles is only possible in very dilute condition or very thin soil suspensions, containing only ... pKa is considered to be of intrinsic value and should apply to all the acidic or COOH groups in the humic molecule Use o f DK, i n Determining Negative Charges In soil chemistry, the magnitude

Ngày tải lên: 11/08/2014, 12:21

... above by interacting with the expanding clay is noted in mollisols to reduce the extent of shrinking and swelling. 8.1.2 EFFECT ON SOIL CHEMICAL PROPERTIES Humic matter can affect the soil chemical ... and inability to directly determine enzymes in soils cause many soil researchers to shy away from studying the issue Enzymes are proteinaceous compounds and can be determined indirectly ... the opinion in clay mineralogy is that most enzymes are too big to penetrate the intermicellar spaces of clay minerals According to the purpose of this book, in the following discussion

Ngày tải lên: 11/08/2014, 12:21

... transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing ... research into their environmental behavior and fate. Much of this concern has focused on the potential for contamination of the hydrologic system, including surface waters. Pesticides in Surface Waters ... studies-including laboratory studies and studies using microcosms and artificial streams and ponds-also were included in which factors affecting the behavior and fate of pesticides in the environment

Ngày tải lên: 12/08/2014, 05:21

... M parathion Dieldrin Endrin detection 40 19 14.5 Survey of dieldrin and endrin in water, sediments, and oysters Dieldrin detected in 70 percent of oysters, endrin detected in 100 percent of ... and Baker, 1993), that has been sampling the tributaries of Lake Erie and the drainage basins in Ohio and in parts of Indiana and Michigan continuously since 1981 This data set is probably the ... organisms were investigated The data set resulting from the Ciba-Geigy studies is one of the best available for examining Trang 1626 PESTICIDES IN SURFACE WATERS long-term trends in atrazine occurrence

Ngày tải lên: 12/08/2014, 05:21

... In many parts of the United States, building foundations and the soil surrounding them are routinely treated with insecticides for controlling termites or other destructive insects Controlling ... States In Spain, pesticides (trifluralin, atrazine, and simazine) and pesticide precursors have been measured in the waste effluent of a pesticide-manufacturing facility discharging directly into ... profile of the herbicide atrazine in the Minnesota River, which drains a large area Trang 3Factors Controlling the Behavior and Fate of Pesticides in Surface Waters 21 9 of intensive row-crop agriculture

Ngày tải lên: 12/08/2014, 05:21

... observed in the Moon Lake watershed in Mississippi, where increased total DDT concentrations in the water column occurred during the winter and spring rainy seasons (Cooper, 1991) Soil in this watershed ... concentrations are observed in streams draining agricultural areas for a few days to a few weeks, depending on the timing and number of rain events and the size of the drainage basin During this period, ... occur during periods of high flow resulting from spring or autumn rains, extremely large single-storm events, or large releases of irrigation or reservoir waters In Chesapeake Bay, increases in organochlorine

Ngày tải lên: 12/08/2014, 05:21

... concentrations in soil and other solid matrices include the following: 1. Samples should be handled as intact soil cores until being transferred into methanol or into the container that will ... VOCs in soil or other solid matrices are sampled and analyzed. These guidelines address methods for: (1) handling of samples as intact soil cores; (2) preserving samples; (3) storing samples in ... for decision making (e.g., in excavated soils and when determining disposal or treatment options, or for determining concentrations of VOCs that have a high affinity for the soil matrix). 7.0...

Ngày tải lên: 14/03/2014, 20:20