No description available.

No description available.

The objectives of this research were to evaluate reagents for use in a procedure to fractionate Cu in soils and to apply this methodology to soil incubated in the laboratory with added CuSO₄ or high-Cu swine manure. The evaluation procedure consisted of measuring desorption of Cu from a selection of clay minerals, organic materials, and hydrous oxides using reagents suggested in the literature. Adsorption of Cu by these materials was performed at pH 3.5 and 5.5 at two Cu concentrations, in the presence of 0.05 N CaCL₂. Despite the presence of excess electrolyte, 20-50% of the Cu adsorbed by montmorillonite was desorbed by N Ca(NO₃)₂, KCl, or Ca(ClO₄)₂. Less Cu was salt-exchangeable from humic acid and Fe oxides, and very little (<2%) from Mn oxides, reflecting the strength of bonding of Cu to these materials. Little effect of cation type on desorption was noted, but kinetic effects (up to 16 hours) and concentration effects (0.5 vs. 1 N) were noted. Specifically adsorbed (surface complexed) Cu was desorbed from these surfaces using 2.5% acetic acid and 0.1 N Pb(NO₃)₂, both reagents removing similar amounts (30-70%) of the adsorbed Cu, with Pb being slightly more efficient on some surfaces. Release of Cu from organics after Pb extraction was evaluated using 0.1 M K₄P₂O₇, 5% acetyl acetone, and 5% NaOCl. The former reagent was shown to be most effective, but also to have a solubilizing effect on Mn oxides. In a sequential scheme, therefore, removal of Mn oxideoccluded Cu by 0.1 M NH₂OH·HCl(pH 2) was designed to precede K₄P₂O₇ extraction. Dissolution of poorly crystalline Fe oxides by 0.275 M oxalate (pH 3.2, in darkness) was found to be selective and efficient, while this reagent under uV irradiation solubilized most crystalline Fe oxides, except hematite, more effectively than dithionite. The final sequential procedure consisted of H₂O extraction, followed by N Ca(NO₃)₂, 0.1 N Pb(NO₃)₂ 2.5% acetic acid (to dissolve Cu precipitates and residual complexed Cu), 0.1 M NH₂OH·HCl, 0.1 M K₄P₂O₇, 0.257 M oxalate (pH 3.2, darkness), oxalate under uV light (85C, 3 hours), and residual HF digestion. This procedure was applied to three Virginia soils treated with high rates (45 dry t/a) of high-Cu swine manure, or equivalent rates of CuSO₄ (50 ppm, soil basis). Fractionation was performed after 1, 4, 12, and 29 days of incubation at 30C. Compared to untreated soils, Cu-manure increased soluble Cu over the whole incubation period, while CuSO₄ treatment increased exchangeable Cu initially, but this decreased to near control levels by day 12. Nearly 80% of the added Cu from both sources was Pb- or acetic acid-extractable, the CuSO₄ being more easily displaced by Pb and the manure Cu by the acid. The organic Cu (K₄P₂O₇-extractable) increased slightly with Cu-manure additions, and there were smaller gains in the Fe and Mn oxide fractions. Fractionation of the high-Cu manure suggested nearly all the Cu was in an organic form, possibly low molecular weight organics that associated with soil surfaces upon addition to soil. Although manure treatment resulted in increased soil organic matter levels, an initial Eh decrease (to near 0 mv), and a rise in pH (to 7-8), there was little difference in the distribution of Cu between the fractions due to Cu source or between the three soils. Specific adsorption was the major retention mechanism, although the reversion of Cu to organic and oxide forms was hypothesized over long time spans. / Ph. D.

LD2668 .T4 1941 B82 / Master of Science

Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The concentrations of copper (Cu) in vineyard soils of the Western Cape range from 0.1 to 20 ppm. However, more than 160 tons of the fungicide copper oxychloride are annually being sprayed on these vineyards. This has raised concerns that Cu may accumulate in these soils, resulting in a negative impact on the soil biological processes, especially since the soils in the Western Cape are slightly acidic, making Cu more mobile and available for soil organisms than would have been the case in alkaline soils. The goal of the initial part of this study was therefore to identify those soil microbial communities indigenous to the Western Cape, which are most susceptible to Cu-induced stress as a result of the addition of copper oxychloride. These potential bioindicators of Cu-induced stress were first searched for in uncultivated agricultural soil from Nietvoorbij experimental farm. Consequently, a series of soil microcosms was prepared by adding various concentrations of Cu as a component of copper oxychloride, to each of eight aliquots of soil: 0 (control), 10, 20, 30, 40, 50, 100, 500 and 1000 ppm. The resulting concentrations of exchangeable Cu in these microcosms were found to be 2 (control), 12,23,34,42,59, 126,516 and 1112 ppm. Selected microbial communities in each microcosm were subsequently monitored over a period of 245 days. It was found that the culturable microbial numbers did not provide a reliable indication of the effect of Cu on community integrity. However, analyses of terminal-restriction fragment length polymorphism (T-RFLP) community fingerprints and especially analyses of the whole community metabolic profiles, revealed that shifts in the soil microbial communities took place as the Cu concentration increased. Direct counts of soil protozoa also revealed that the addition of Cu to the soil impacted negatively on the numbers of these eukaryotes. To confirm these findings in other soil ecosystems, the impact of copper oxychloride on whole community metabolic profiles and protozoan numbers were investigated in soils from Koopmanskloof commercial farm and Nietvoorbij experimental farm. These potential bioindicators were subsequently monitored in a series of soil microcosms prepared for each soil type by adding the estimated amounts of 0 (control), 30, 100 and 1000 ppm Cu as a component of copper oxychloride to the soil. The results confirmed the fmdings that elevated levels of copper impact negatively on the metabolic potential and protozoan numbers of soil. Consequently, it was decided to investigate a combination of protozoan counts and metabolic profiling as a potential bioindicator for Cu-induced stress in soil. Data collected from all the microcosms containing exchangeable Cu concentrations ranging from 1 ppm to 1112 ppm was used to construct a dendrogram using carbon source utilization profiles in combination with protozoan counts. It was found that the microcosms grouped into clusters, which correlated with the concentration of exchangeable Cu in the soil. Under the experimental conditions used in this study, the combination of protozoan counts and metabolic profiling seemed to be a reliable indicator of Cu-induced stress. However, this bioindicator must be further investigated in other soil types using other types of stress inducing pollutants. In addition to the above fmdings it was also found that the numbers of soil protozoa was particularly susceptible to Cu-induced stress in soils with a low soil pH. This is in agreement with the fmdings of others on the bio-availability of heavy metals in low pH soils. In these soils, nutrient cycling as a result of protozoan activity, may therefore be particularly susceptible to the negative impact of copper to the soil. / AFRIKAANSE OPSOMMING: Die konsentrasies van koper (Cu) in wingerdgronde van die Wes-Kaap wissel tussen 0.1 en 20 dpm. Meer as 160 ton van die fungisied koper-oksichloried word egter jaarliks op dié wingerde gespuit, wat kommer laat ontstaan het oor die moontlike akkumulasie van Cu in dié grond en die gevaar van 'n negatiewe impak op die biologiese prosesse in die grond. Die gevaar word vererger deur die feit dat die Wes-Kaapse grond effens suur is, wat Cu meer mobiel en beskikbaar maak vir grondorganismes as wat die geval sou wees in alkaliese grond. Die eerste doelstelling van hierdie studie was dus om die mikrobiese gemeenskappe in die grond, wat inheems is aan die Wes-Kaap, te identifiseer wat die meeste vatbaar is vir Cu-geïnduseerde stres as gevolg van die toevoeging van koper-oksichloried. Hierdie potensiële bioindikatore van Cu-geïnduseerde stres is eerstens gesoek in onbewerkte landbougrond van die Nietvoorbij-proefplaas. 'n Reeks grondmikrokosmosse is gevolglik berei deur verskillende konsentrasies Cu, as 'n komponent van koperoksichloried, by elk van agt hoeveelhede grond te voeg naamlik 0 (kontrole), 10,20, 30, 40, 50, 100, 500 en 1000 dpm. Die gevolglike konsentrasies van uitruilbare Cu in hierdie mikrokosmosse was 2 (kontrole), 12, 23, 34, 42, 59, 126, 516 en 1112 dpm. Geselekteerde mikrobiese gemeenskappe in elke mikrokosmos is vervolgens oor 'n tydperk van 245 dae bestudeer. Daar is gevind dat die kweekbare mikrobiese tellings nie 'n betroubare aanduiding kon gee van die uitwerking van Cu op gemeenskapsintegriteit nie. Die ontledings van terminale-restriksie fragment lengte polymorfisme (T-RFLP) gemeenskapsvingerafdrukke en veral van die metaboliese profiele van die totale gemeenskap, het getoon dat verskuiwings in die grondmikrobiese gemeenskappe plaasgevind het met 'n toename in Cu-konsentrasies. Direkte tellings van grondprotosoë het ook aangedui dat die toevoeging van Cu tot die grond 'n negatiewe uitwerking op die getalle van hierdie eukariote gehad het. Om dié resultate te bevestig, is die impak van koper-oksichloried op die metaboliese profiele van totale gemeenskappe en protosoë-getalle in ander grond-ekosisteme vervolgens bestudeer deur grond van die kommersiële plaas Koopmanskloof en die Nietvoorbij-proefplaas te gebruik. Dié potensiële bioindikatore is vervolgens bestudeer in 'n reeks grondmikrokosmosse, wat vir elke grondtipe voorberei is deur die toevoeging van beraamde hoeveelhede van 0 (kontrole), 30, 100 en 1000 dpm Cu as 'n komponent van koper-oksichloried. Die resultate het die bevindings bevestig dat verhoogde vlakke van Cu 'n negatiewe uitwerking het op die metaboliese potensiaal en op die protosoëgetalle in die grond. Daar is gevolglik besluit om 'n kombinasie van protosoë-tellings en metaboliese profiele te ondersoek as 'n potensiële bioindikator van Cu-geïnduseerde stres in grond. Data van al die mikrokosmosse wat uitruilbare Cu bevat, wisselend van 1 dpm tot 1112 dpm, is gebruik om 'n dendrogram te konstrueer wat koolstofbronbenuttingsprofiele in kombinasie met protosoë tellings gebruik. Daar is gevind dat die mikrokosmosse groepe vorm wat korrelleer met die konsentrasie uitruilbare Cu in die grond. Onder die eksperimentele kondisies wat in dié studie gebruik is, wil dit voorkom of die kombinasie van protosoë-tellings en metaboliese profiele 'n betroubare indikator van Cugeïnduseerde stres is. Hierdie bioindikator moet egter verder in ander grondtipes en met ander tipes stres-induserende besoedeling ondersoek word. By bogenoemde bevindings is daar ook gevind dat die getalle grondprotosoë besonder gevoelig is vir Cu-geïnduseerde stres in grond met In lae pH. Dit is in ooreenstemming met die bevindings van andere met betrekking tot die bio-beskikbaarheid van swaar metale in grond met 'n lae pH. In dié tipe grond mag nutriëntsiklering as gevolg van protosoë aktiwiteit besonder gevoelig wees vir die negatiewe uitwerking van koper in die grond.

This thesis reports two new methods developed to study the free ion activity of aluminum and copper. Both methods could be applied to the study of other metals. The first method measures the apparent solubility of aluminum and sulfate in a dynamic, leached system. This system is believed to give a good representation of the field situation where soils are continuously leached and never at equilibrium. This study was done under three sulfate concentrations. The part of the experiment using low sulfate concentrations showed aluminum solubility control by a gibbsite-like solid phase with a log K$ sp circ$ of 7.49. It was also shown, however, that under natural soil solution concentrations of sulfate in acidic forest soils, an interaction with sulfate controls aluminum activity rather than gibbsite solubility equilibria. This interaction is either, an aluminum-sulfate solid phase or, a stoichiometric ion-pair co-adsorption of aluminum and sulfate. / The second method is a simple determination of free Cu$ sp{2+}$ in soils using a cupric ion-selective electrode. Free copper has been demonstrated to be the toxicity controlling component in aquatic studies and this study was undertaken to measure free copper activity in soils. The possible interference due to ionic strength variations or the presence of aluminum in the soil solution was checked and found to be negligible. The free activity of copper (pCu$ sp{2+}$) measured in a variety of pristine and contaminated soils varied between 6.33 to 12.20 pCu$ sp{2+}$ units. Total soil copper content and acidity were shown to strongly increase copper solubility and free Cu$ sp{2+}$ activity in the soil solution extracts. (Abstract shortened by UMI.)

No description available.

No description available.

Copper and Zn deficiencies of crops have been reported in various parts of the world. To prevent these deficiencies sulfate forms of Cu and Zn are generally used. In addition, Cu and Zn also are contributed to soils by manures, pesticides, and waste materials such as sewage sludge. An insufficient supply of Cu or Zn may reduce crop yield; whereas, excess Cu or Zn may be detrimental to both plant and animals. The field phase of this research was conducted on a Davidson silty clay to evaluate corn response to high levels of CuSO₄ and ZnSO₄ applications up to 338 kg Cu and 830 kg Zn ha⁻¹. The results of this research indicated that corn grain and stalk yields of corn were not affected (α= 0.05) by high levels of CuSO₄ and ZnSO₄ either alone or combined. Copper concentration in neither corn grain nor ear leaves was affected (α = 0.05) by the Cu application. Zinc concentrations in both grain (α = 0.01) and ear leaves (α= 0.001) were increased by ZnS04 application. Application of ZnSO₄ increased the Cu in the labile pool, whereas CuSO₄ fertilization did not affect Zn in the labile pool. A greenhouse experiment was conducted to examine the response of wheat to Cu application on 14 soils. Treatments in this study were a control and 5.35 mg Cu kg⁻¹ as CuSO₄. Dry matter yields were not affected (α = 0. 05) by Cu fertilization whereas tissue cu levels were increased (α = 0.001). Copper uptake was highly correlated with DTPA-Cu (r = 0.80, α = 0.001), but weakly correlated with Mehlich III-Cu (r = 0.28, α = 0.05). The DTPA-Cu showed high correlations with clay content (r = 0.98, α = 0.001) and SA (r = 0.93, α = 0. 001); whereas, Mehlich III-Cu did not correlate with these variables (α = 0.05). A second greenhouse experiment was conducted with 10 Virginia soils to evaluate the response of corn to Cu fertilization. Treatments were a control and 5.35 mg Cu kg⁻¹ as CuS0₄. Dry weights of corn on the 10 soils were not affected (α = 0.05) by Cu application; whereas, tissue Cu levels were increased by the applied Cu (α = 0. 001). Copper uptake by corn plant correlated with DTPA-Cu (r = 0.62, α= 0.001) and with soil pH (r = 0.35, α = 0.05). There was no correlation of organic matter with Cu uptake (α = 0.05). Both DTPA-Cu and Mehlich III-Cu were unrelated to either organic matter or soil pH (α = 0.05). / Ph. D.

Three field studies were established in 1978 and continued through 1985 in order to determine the effects of long-term Cu applications, as either CuSO₄ or Cu-enriched swine manure, at high application rates on corn (Zea mays L.) production. The studies were conducted on Bertie fine sandy loam (Aquic Hapludult), Guernsey silt loam (Aquic Hapludalf), and Starr clay loam (Fluventic Dystrochrept)-Dyke clay (Typic Rhodudult) soils in the Coastal Plain, Ridge and Valley, and Piedmont physiographic regions of Virginia, respectively. A laboratory incubation study was also conducted using the same soils to determine the effects of soil pH on the changes in forms of soil Cu present over a 256-day period following addition of CuSO₄ or Cu-enriched swine manure. Application of 336 kg Cu ha⁻¹ , as CuSO₄ , or up to 264 kg Cu, as Cu-enriched swine manure, from 1978 through 1985 had no adverse affects on corn grain yields or on Cu concentrations in corn ear leaves or grain. Copper concentrations in ear leaf tissue were increased only slightly (≤ 2.1 mg kg⁻¹) by the eight annual Cu additions with no increase in Cu content of grain being observed. Copper concentrations in both ear leaves and grain remained within normal levels. DTPA extractable Cu was linearly related to the cumulative amount of Cu applied to the three soils (r = 0.93 to 0.98, α= 0.01). Extractable soil Cu showed no relationship with Cu levels in grain or leaf tissue. Analysis of subsoil samples indicated little downward movement of the applied Cu due to leaching. Fractionation of the Cu in the three soils indicated increases in all fractions resulting from Cu treatments. Results of the laboratory incubation study showed that the distribution of applied Cu among soi 1 fractions was dependent on soil pH, length of time following Cu additions, and to some degree on the source of applied Cu. Levels of Ex-Cu and HOAc-Cu decreased with time and increasing pH. No consistent differences in Pyro-Cu were observed due to pH or length of incubation. Concentrations of Ox-Cu parallelled the levels of Fe and Mn in the soils and generally increased with time. Soils at low pH tended to contain less Ox-Cu than soils at higher pH levels. / Ph. D.