Browsing by Author "Van Wyk, Mia"
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- ItemEvaluating the toxic effects of industrial waste from a historic landfarming site using bioassays(Stellenbosch : Stellenbosch University, 2011-12) Van Wyk, Mia; Reinecke, Sophie A.; Reinecke, Adriaan J.; Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology.ENGLISH ABSTRACT: Landfarming is a widely used method for the disposal of contaminants in the petrochemical industry. It involves ploughing the contaminants into the top soil layer allowing biological breakdown. A historically landfarmed site was identified at a South African petrol refinery. The refinery used to dispose so-called American Petroleum Institute (API) -sludge onto a landfarming site. API-sludge consisted of a mixture of oil and water soluble contaminants originating from a process of separating refinery waste from reusable water and oil. Landfarming on this site was discontinued after excessive quantities of sludge were ploughed into the soil over time and it became obvious that effective biodegradation could not take place. An environmental assessment had to be carried out to assess to what extent the soil has recovered from the contamination and after remediation was done over time. Bioassays together with chemical analyses were executed to determine the level of pollutants in the soil and to assess the integrated effects of their bioavailable fractions. The landfarming site of the refinery was divided into two sections namely, a more contaminated north-site and less contaminated south-site. Soil samples were collected from both sites as well as from an off-site (control site). The soils were analysed physically, chemically and used in the bioassays. Two additional control soils were also used, OECD-soil and LUFA2.2 soil. Chemical analysis of the site soils showed the presence of heavy metals and high levels of diesel range organic hydrocarbons. The north-site had higher levels of contaminants compared to the south-site. Three species of soil organisms were used in standardised tests: Eisenia andrei, Enchytraeus doerjesi and Folsomia candida were exposed to the respective soils to study their survival, growth, reproduction success and avoidance behavior. Exposures to both site-soils were not acutely toxic to any organisms. F. candida had a decrease in juvenile production in both north- and south-site soils (289.42 ± 58.62 and 253.33 ± 122.94 respectively) compared to the control soil (479.89 ± 30.42). E. doerjesi showed an increase in produced juveniles exposed to north- and south-site soil (339.75 ± 76.92 and 414.00 ± 17.78 ) compared to control soil (57 ± 34.39). E. andrei had similar cocoon production when exposed to south-site soil than in off-site soil (19.00 ± 5.3 and 18.5 ± 9.7 respectively) but significantly less in north-site soil (1.25 ± 0.7). Only E. doerjesi showed avoidance of north-site soil. To determine the sensitivity of the organisms to the API-sludge, they were exposed to concentration series of API-sludge-spiked control soils. The effect concentrations were calculated as the concentration of API-sludge that will decrease the studied endpoints by 50% of the control soil (EC50). The EC50s varied for each species exposed in the different control soils showing that the toxicity of the API-sludge is to a certain extent dependent on the physical soil properties of the substrate. The reproduction of F. candida were most sensitive to the API-sludge in off-site soil (EC50 = 90 mg/kg) and the E. doerjesi the least sensitive in LUFA2.2 soil (EC50 = 36000 mg/kg). Five plant species were exposed to API-sludge-spiked potting soil and the germination success, early growth rate and biomass were studied. The plants were not as sensitive to API-sludge as the soil animals. Lettuce and grass were affected the most by API-sludge and beans were the most resilient species. With the addition of low levels API-sludge to the substrate, the growth rate of beans was stimulated. This study showed that the south-site has been successfully remediated and most soil organisms exposed to these soils were not affected by the levels of toxicants present. However, exposures to north-site soil still had negative effects on soil organisms. It is recommended that hydrocarbon contamination should be further remediated in the north-site soil before landfarming should be allowed to continue.
- ItemDie geskiktheid van potwurms (Enchytraeidae) en plante om die toksisiteit van olieraffinadery-slik te toets(AOSIS Publishing, 2016-11-24) Reinecke, Adriaan J.; Reinecke, Sophia A.; Van Wyk, MiaGrondbewerking word in die petrochemiese nywerheid in suidelike Afrika gebruik as ’n metode om van besoedelstowwe ontslae te raak. ’n Historiese grondbewerkingsperseel is by ’n petroleumraffinadery geïdentifiseer waar die gedeponeerde slik uit ’n mengsel van olie en wateroplosbare chemiese besoedelstowwe bestaan wat verskeie gevaarlike chemikalieё insluit. Die doel met die studie was om die toksisiteit van die slik, sowel as grond, op die perseel te bepaal en vas te stel of plante en potwurms gebruik kan word in die bioassessering van die slik, aangesien daar ’n behoefte bestaan om ’n groter verskeidenheid toetsorganismes te gebruik wat verskillende ekologiese nisse verteenwoordig. Ons het eksemplare van ’n grondlewende potwurm (Enchytraeus doerjesi) aan die slik en aan slikbewerkte grond blootgestel en hulle oorlewing, groei, voortplantingsukses en vermydingsgedrag bestudeer. Vyf plantsoorte en hulle sade is aan verskillende konsentrasies van die slik in kommersiёle potgrond blootgestel en hulle ontkiemingsukses, groeikoers en biomassa is bepaal. Die grond van die landbewerkingsperseel was nie akuut toksies vir die potwurms nie en hulle het selfs ’n toename in voortplanting getoon in vergelyking met onbesoedelde grond. Hulle het wel in gedragstoetse erg besoedelde grond vermy. Die bevinding is dat potwurms nie so gevoelig is vir die slik soos erdwurms en springsterte, wat voorheen getoets is nie, maar dat hulle wel bruikbaar is en kan bydra om die toksisiteit en herstelstatus van sulke grond te evalueer, aangesien hulle ’n bykomende ekologiese nis verteenwoordig. Die plante was nie baie gevoelig vir die slik nie en gemengde resultate is verkry. Slaai en gras is die meeste deur die slik geaffekteer, terwyl boontjies die beste gevaar het en hulle groeikoers selfs deur die byvoeging van slik gestimuleer is.
- ItemKan die gevoeligheid van grondlewende organismes bydra om die volhoubaarheid van landbewerking van olieraffinadery afval te beoordeel?(AOSIS Publishing, 2015) Reinecke, Adriaan J.; Reinecke, Sophia A.; Van Wyk, MiaVoordelige grondlewende organismes lewer ekostelseldienste in gesonde grondtipes. Olieraffinaderye genereer groot hoeveelhede soliede afval wat verskeie tipes koolwaterstowwe en metale bevat wat in die grond geploeg word tydens landbewerking van die afval. Die bedoeling is om die afval deur die grond-ekostelsel te laat degradeer. Die kontaminante mag egter giftig wees vir die diverse verskeidenheid van grondorganismes. Vir die volhoubaarheid van dié praktyk is dit nodig om te weet of remediёring van die landbewerkte grond voldoende was vir die beoogde, voortgesette gebruik daarvan. Indikatore is nodig om die graad van herstel van sodanige grondtipes te bepaal. Die doel van hierdie studie was om die grond van ’n landbewerkte gebied chemies te ontleed en die toksisiteit en herstel te bepaal deur van gestandardiseerde bioassesserings met die komposteringswurm Eisenia andrei (Oligochaeta) en die springstert Folsomia candida (Collembola) gebruik te maak. Die organismes is blootgestel aan die gekontamineerde en kontrolegrond en hulle oorlewing, groei, voortplantingsukses en vermydingsgedrag is nagegaan. Die resultate het getoon dat die grond van die landbewerkte perseel steeds verskeie gevaarlike chemikalieё bevat, soos die dieselreeks organiese verbindings, maar dat die grond nie akuut toksies vir die organismes was nie. Dit het wel die groei en voortplanting van die erdwurms, asook die voortplanting van die springsterte nadelig beïnvloed. Die perseel benodig steeds remediёring alvorens grondbewerking van olieslik voortgesit word. Bioasessering het, aanvullend tot die chemiese analises, ’n meer volledige en meer ekologies relevante beeld van die remediëringstatus en toksisiteit van die grond verskaf. Die bevinding ondersteun die gebruik van bioassesserings as ’n eko-toksikologiese metode om landbewerkingsgrond te evalueer.