Browsing by Author "Reinecke, S. A."
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- ItemThe concept of bioavailability and establishing uniform standards for permissible chemical contamination of soil(AOSIS OpenJournals, 2006-09) Reinecke, A. J.; Reinecke, S. A.Soils are very heterogeneous substrates providing an environmental matrix with varying spatial and temporal gradients of pH, organic carbon, particle size distribution, moisture content as well as biological factors associated with soil organisms. These chemical, physical as well as biological factors determine the bioavailability of chemicals to soil-dwelling invertebrates. This review of recent literature on the use of the bioavailability concept in soil ecotoxicology indicates that the concept is often used unqualified and indiscriminately to mean different things to different authors. A clear understanding of the concept is crucial for toxicity testing, environmental monitoring, risk assessment and the setting of soil quality criteria since knowledge of the actual exposure of organisms, and not merely the total amount of the chemical, is required. The aim of this paper is to contribute towards a clarification of the concept. Apart from defining or describing bioavailability, the problems related to the comparability of toxicity data between soils and species, inter-soil and inter-species comparisons of toxicity data are discussed. The potential role that biomarkers can play in assessing bioavailability, is touched upon. In an effort to prescribe uniform criteria or standards for environmental quality, both biotic and abiotic characteristics, which determine the bioavailablity of contaminants should be considered. This requires a dynamic approach which takes both uptake processes as well as a variety of other biological factors into consideration. It is concluded that bioavialiblity should be interpreted qualitatively and that the rate of uptake of a contaminant could possibly serve as a measure of bioavailability. The development of standardised protocols for exposure of selected species and the measurement of biological responses with the aid of biomarkers could serve to refine and take risk assessment a step further.
- ItemDie inkorporering van biomerkers in die assessering van die ekologiese risiko van chemiese bodemkontaminante(AOSIS Publishing, 2007) Reinecke, A. J.; Reinecke, S. A.; Maboeta, M. S.; Odendaal, J. P.; Snyman, R.Soil is an important but complex natural resource which is increasingly used as sink for chemicals. The monitoring of soil quality and the assessment of risks posed by contaminants have become crucial. This study deals with the potential use of biomarkers in the monitoring of soils and the assessment of risk resulting from contamination. Apart from an overview of the existing literature on biomarkers, the results of various of our field experiments in South African soils are discussed. Biomarkers may have potential in the assessment of risk because they can indicate at an early stage that exposure has taken place and that a toxic response has been initiated. It is therefore expected that early biomarkers will play an increasing role as diagnostic tools for determining exposure to chemicals and the resulting effects. They may have predictive value that can assist in the prevention or minimising of risks. The aim of this study was to investigate the possibilities of using our results on biomarker responses of soil dwelling organisms to predict changes at higher organisational levels (which may have ecological implications). Our recent experimental results on the evaluation of various biomarkers in both the laboratory and the field are interpreted and placed in perspective within the broader framework of response biology. The aim was further to contribute to the development and application of biomarkers in regulatory risk assessment schemes of soils. This critical review of our own and recent literature on biomarkers in ecotoxicology leads to the conclusion that biomarkers can, under certain conditions, be useful tools in risk assessment. Clear relationships between contamination loads in soil organisms and certain biomarker responses were determined in woodlice, earthworms and terrestrial snails. Clear correlations were also established in field experiments between biomarker responses and changes at the population level. This indicated that, in spite of the fact that direct mechanistic links are still not clarified, biomarkers may have the potential to provide early indications of forthcoming changes at higher organisational levels. Ways are proposed in which biomarkers could be used in the future in risk assessment schemes of soils and future research directions are suggested.
- ItemKadmium in Valsbaai : moniteringspotensiaal van die mariene slak, Oxystele tigrina (Mollusca)(AOSIS, 2009-06) Reinecke, A. J.; Mdzeke, N. P.; Reinecke, S. A.’n Opname is onderneem van die kadmiumvlakke in die tussengetygebied van Valsbaai, Suid- Afrika. Kadmiumkonsentrasies is seisoenaal bepaal in die water en sediment in verskillende lokaliteite. Die metings is oor ’n periode van een jaar gedoen deur seisoenaal monsters te versamel by ses verskillende versamelpunte in en een buite die baai. Dit is met behulp van atoomabsorpsiespektrofotometrie ontleed vir kadmium en die hoogste kontaminasievlakke is by die noordelike kusstreek gevind tussen Strand en Muizenberg waar die digsbevolkte gebiede en die meeste industriële aktiwiteit voorkom. Betekenisvolle variasie in konsentrasies van kadmium het seisoenaal en ruimtelik voorgekom. Die gemiddelde konsentrasies in die water en sediment was in sommige gevalle effens hoër as die vlakke wat deur die Suid-Afrikaanse waterkwalitetisriglyne aanbeveel is. Kadmiumkonsentrasies is ook in versamelde eksemplare van die mariene slak Oxystele tigrina vir verskillende seisoene vir drie lokaliteite bepaal. Laboratoriumeksperimente is uitgevoer om die opname, akkumulasie en verlies van kadmium in verskillende organe van die tussengetyslak, Oxystele tigrina te ondersoek. Weefselspesifi eke kadmiumkonsentrasies in kontrolesowel as blootgestelde lewende eksemplare is vergelyk oor ’n blootstellingsperiode van veertien dae. Die eksperimentele slakke is aan twee subletale konsentrasies van onderskeidelik 0.20 en 0.40 μg/ml watergedraagde kadmium in die vorm van CdCl2 blootgestel. Die proefdiere is gereeld gemonitor en kadmiumkonsentrasies is in verskillende organe, na suurvertering, atoomabsorpsiespektrofotometries bepaal. Die resultate het ’n algemene toename van kadmium in die liggame van die slakke uitgewys. Kadmium is in variërende konsentrasies in alle weefsel gevind. ’n Ongeveer liniêre patroon van akkumulasie het aangetoon dat die metaal waarskynlik nie deur O. tigrina gereguleer is nie. Die metaal se teenwoordigheid het verskil tussen die sagteweefsel en skulp op so ’n wyse dat die sagteweefsel normaalweg ’n hoër opnamekoers van die kadmium weerspieël het. Nadat die blootgestelde organismes in kadmiumvrye seewater oorgeplaas is, het gedeeltelike kadmiumverlies wel plaasgevind. Die variasie in kadmiumverlies van die verskillende organe dui moontlik daarop dat slegs ’n gedeelte van die geakkumuleerde kadmium sterk gebind was in sekere weefsels of organe. Die behoud van kadmium in beide sediment en diereliggame was sodanig dat afgelei kan word dat kadmium teen huidige omgewingskonsentrasies in sekere dele van Valsbaai, wat algemeen as laag beskou word, steeds met verloop van tyd in hierdie tussengetydiere kan akkumuleer tot vlakke wat nadelig is vir die spesies self, maar ook vir hulle predatore. Dit sal veral kan gebeur indien fi siese toestande verander om die biobeskikbaarheid te verhoog.
- ItemDie konsep van biobeskikbaarheid en die neerlê van eenvormige standaarde vir toelaatbare chemiese kontaminante in die grond(AOSIS OpenJournal, 2006) Reinecke, A. J.; Reinecke, S. A.Soils are very heterogeneous substrates providing an environmental matrix with varying spatial and temporal gradients of pH, organic carbon, particle size distribution, moisture content as well as biological factors associated with soil organisms. These chemical, physical as well as biological factors determine the bioavailability of chemicals to soil-dwelling invertebrates. This review of recent literature on the use of the bioavailability concept in soil ecotoxicology indicates that the concept is often used unqualified and indiscriminately to mean different things to different authors. A clear understanding of the concept is crucial for toxicity testing, environmental monitoring, risk assessment and the setting of soil quality criteria since knowledge of the actual exposure of organisms, and not merely the total amount of the chemical, is required. The aim of this paper is to contribute towards a clarification of the concept. Apart from defining or describing bioavailability, the problems related to the comparability of toxicity data between soils and species, inter-soil and inter-species comparisons of toxicity data are discussed. The potential role that biomarkers can play in assessing bioavailability, is touched upon. In an effort to prescribe uniform criteria or standards for environmental quality, both biotic and abiotic characteristics, which determine the bioavailablity of contaminants, should be considered. This requires a dynamic approach which takes both uptake processes as well as a variety of other biological factors into consideration. It is concluded that bioavialiblity should be interpreted qualitatively and that the rate of uptake of a contaminant could possibly serve as a measure of bioavailability. The development of standardised protocols for exposure of selected species and the measurement of biological responses with the aid of biomarkers could serve to refine and take risk assessment a step further.
- ItemOu en nuwe tendense in die ekotoksikologie : die relevansie van stresekologie en ekotoksikogenomika(AOSIS OpenJournal, 2005) Reinecke, S. A.Die relatief jong wetenskapsgebied van die ekotoksikologie het in die afgelope dekade heelwat veranderinge ondergaan – vanaf ’n meer praktykgerigte, toetsgesentreerde vakgebied, na ’n basiese navorsingsveld waarin meer klem gelê word op probleemoplossing en die soeke na oorsake van effekte wat verkry word. In hierdie artikel word die ontstaan van die vakgebied in die wetenskap ontleed, asook die invloed van nuwe ontwikkelings op die gebiede van die bio-informatika en genetika. Die meriete hiervan word bespreek en die gevolgtrekking is dat die vakgebied besliste voortbestaansreg het as afsonderlike wetenskap, ongeag die multidissiplinêre aard daarvan. ’n Oorsig word gegee van die historiese ontwikkeling van die vakgebied en die skakeling daarvan met die breë ekologie, as ’n voorbeeld van stresekologie. Die belang van die inkorporering van die mees resente navorsingsontwikkelinge soos bio-informatika, multivariasie-statistiek en genomika in die biologie binne die ekotoksikologie, word bespreek. Die mening word uitgespreek dat ekotoksikologie in die nabye toekoms toenemend ’n gedaanteverwisseling sal ondergaan om ook die ekotoksikogenomika in te sluit. Dit sal die gevolg wees van die wisselwerking tussen ekotoksikologie en ekologie op ’n kruispad met genomika en bio-informatika.
- ItemThe protection of biological diversity by using the variation in sensitivity of species for toxic substances(AOSIS OpenJournals, 2004) Reinecke, A. J.; Reinecke, S. A.Efforts to develop generally applicable criteria or standards for environmental quality for the purpose of protecting South Africa’s rich biodiversity are normally hampered by the fact that species can differ considerably in their sensitivity to toxic substances. Direct extrapolation from one species to another is therefore not possible. By actually using this variation in sensitivity of species, the assessment of risk posed by contaminants may be placed on a more rigorous scientific footing. This concept holds that if quality criteria are accepted which would protect the most sensitive species, all other species are automatically protected. This article focuses on the use of sensitivity distributions of species as method and critically reviews the nature and applications of extrapolation models which are based on these distributions. Their possible use and arguments for and against such use are discussed. The conclusion is drawn that species sensitivity distributions have useful applications but data on the sensitivities of local species are scarce. Although already useful, this methodology can find more general application in South Africa if more research is undertaken to obtain reliable toxicity data for different species. In order to do that standardized toxicity tests for local species will have to be developed.
- ItemSellulêre biomerkerresponse as maatstaf van gevoeligheid van klipmossels (Mollusca) vir kadmiumbesoedeling(AOSIS OpenJournals, 2008-06) Reinecke, A. J.; Schoeman, W.; Reinecke, S. A.Die bioakkumulasie van kadmium in tussengetyspesies kan stres veroorsaak wat op sellulêre vlak meetbaar is. Verskeie klipmosselspesies kom volop op rotse aan die Suid-Afrikaanse kuslyn voor en kan moontlik vir ekotokiskologiese monitering gebruik word. Die oogmerk van die studie was om sensitiwiteitsdata te verkry wat kan bydrae tot die kies van ’n geskikte spesie vir monitering en die uiteindelike daarstelling van ’n model vir spesie sensitiwiteitsverspreiding (SSV) wat ’n biomerkerrespons as eindpunt gebruik. Die klipmossels Cymbula oculus, Scutellastra longicosta, Cymbula granatina en Scutellastra granularis en watermonsters is in Valsbaai versamel. Analises van kadmium in water en biologiese monsters is met behulp van atoomabsorpsiespektrofotometrie uitgevoer. Blootstellings van organismes aan subletale vlakke van kadmium is uitgevoer in statiese vloeitenks oor ’n periode van drie dae. Daar was ’n matige toename in liggaamskonsentrasies van kadmium oor tyd. Resultate wat by drie blootstellingskonsentrasies gekry is, het geen betekenisvolle verskille in metaalkonsentrasies tussen die verskillende C. oculus monsters uitgewys nie. Betekenisvolle verskille tussen die kontrole en die blootstellingsgroepe vir elke individuele blootstellingstyd is vir die spesie verkry behalwe tussen die kontrole en die 1mg/L CdCl2 blootstellingsgroep na 24 en 72 uur van blootstelling. Cd liggaamskonsentrasies (sagteweefsel) het tussen 4.56 en 21.41μg/g (nat massa) gevarieer. Gemiddelde Cd konsentrasies in sagteweefsel van S. longicosta was aansienlik laer (variërend tussen 1.18 en 19.58 μg/g Cd ) as in weefsel van C. oculus. Die kontrolegroep van hierdie spesie het betekenisvol verskil van die 0.8 en 1 mg/L CdCl2 blootstellings na 48 en 72 uur. Gemiddelde Cd liggaamskonsentrasies in S. granularis was die hoogste van al die blootgestelde spesies en het ’n vlak van 148 μg/g Cd by die hoogste blootstellingskonsentrasie bereik en het betekenisvol verskil van die ander monsters se gemiddeldes met die uitsondering van die 0.8 mg/ L CdCl2 blootstellingsgroep by 72 uur en die 1 mg/L CdCl2 groep by 24 uur. Betekenisvolle verskille is ook verkry vir die liggaamskonsentrasies van Cd van C. granatina tussen die drie verskillende blootstellingskonsentrasies en drie blootstellingstye. Integriteit van lisosoommembrane is bepaal met behulp van die neutraalrooi retensiemetode. Drie van die vier spesies het ’n betekenisvolle afname in retentsietye getoon met ’n toename in Cd konsentrasie. Tussenspesieverskille in gevoelighede vir omgewingsrelevante kadmiumkonsentrasies is deur die biomerkerresponse uitgewys. Gebaseer op die verlaging in NRR tye, is die volgorde van relatiewe gevoeligheid vir kadmium as volg: S. granularis > C. oculus> S. longicosta.> C. granatina.
- ItemSperm abnormalities associated with high copper levels in impala (Aepyceros melampus) in the Kruger National Park, South Africa(1999) Ackerman, D. J.; Reinecke, A. J.; Els, H. J.; Grobler, D. G.; Reinecke, S. A.The morphology of spermatozoa may be affected by very low concentrations of pollutants in the environment, and sublethal effects of toxic substances can be detected by studying the sperm of an animal. Sperm were collected from 50 impala (Aepyceros melampus) from a conservation area in South Africa and studied ultramicroscopically. Thirty-two samples were obtained from animals close to a copper mine, while 18 represented animals from an unpolluted area and held in captivity. Liver samples from all these animals were analyzed for their copper content. The findings from 12 animals kept in captivity and fed on a diet to which copper was added correlated with the findings from the field study. The general condition of the animals as expressed by the fat content of the bone marrow from the area exposed to copper contamination was affected detrimentally in comparison to the animals from the uncontaminated area. High percentages of sperm with neck vacuoles were found in all animals with high liver copper levels. A statistically significant correlation is demonstrated between the percentage of impala sperm with vacuoles in the neck region and the copper concentrations in this group of animals.