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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52719 |
| Date | 03 1900 |
| Creators | Du Plessis, Keith R. (Keith Roland) |
| Contributors | Botha, A., Wolfaardt, G. M., Stellenbosch University. Faculty of Science. Dept. of Microbiology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 110 p. : ill. |
| Rights | Stellenbosch University |
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