<p>Cape Town includes two vegetable farming areas within the city limits, the Joostenbergvlakte/Kraaifontein area and the Philippi area. Both areas supply produce to local markets and further afield. Sporadically, high levels of cadmium, copper, lead and zinc have been found to occur in some of the soils, irrigation water resources and crops. To find the sources of specifically Cd, Pb and Zn to these agricultural systems, extensive analysis of several heavy metals in inputs such as fertilizers, agrochemicals and supplementary water resources to these farming areas was undertaken. Heavy metal concentrations in soils, irrigation water resources and crops were also determined. Two mitigation techniques that could be used to remediate Cd, Pb and Zn contamination were investigated. The first mitigation method included immobilization of heavy metals as phosphate complexes by using a triple super phosphate fertilizer, while the second method involved mobilisation and thus leaching of heavy metals away from plant roots using EDTA. These mitigation methods were tested in a pot experiment using cabbage as the experimental crop and soil from these areas as growth medium. A survey of common farming practices in these two areas and farmers willingness to use remediation methods was conducted.</p>

<p>Cape Town includes two vegetable farming areas within the city limits, the Joostenbergvlakte/Kraaifontein area and the Philippi area. Both areas supply produce to local markets and further afield. Sporadically, high levels of cadmium, copper, lead and zinc have been found to occur in some of the soils, irrigation water resources and crops. To find the sources of specifically Cd, Pb and Zn to these agricultural systems, extensive analysis of several heavy metals in inputs such as fertilizers, agrochemicals and supplementary water resources to these farming areas was undertaken. Heavy metal concentrations in soils, irrigation water resources and crops were also determined. Two mitigation techniques that could be used to remediate Cd, Pb and Zn contamination were investigated. The first mitigation method included immobilization of heavy metals as phosphate complexes by using a triple super phosphate fertilizer, while the second method involved mobilisation and thus leaching of heavy metals away from plant roots using EDTA. These mitigation methods were tested in a pot experiment using cabbage as the experimental crop and soil from these areas as growth medium. A survey of common farming practices in these two areas and farmers willingness to use remediation methods was conducted.</p>

Philosophiae Doctor - PhD / Cape Town includes two vegetable farming areas within the city limits, the Joostenbergvlakte/Kraaifontein area and the Philippi area. Both areas supply produce to local markets and further afield. Sporadically, high levels of cadmium, copper, lead and zinc have been found to occur in some of the soils, irrigation water resources and crops. To find the sources of specifically Cd, Pb and Zn to these agricultural systems, extensive analysis of several heavy metals in inputs such as fertilizers, agrochemicals and supplementary water resources to these farming areas was undertaken. Heavy metal concentrations in soils, irrigation water resources and crops were also determined. Two mitigation techniques that could be used to remediate Cd, Pb and Zn contamination were investigated. The first mitigation method included immobilization of heavy metals as phosphate complexes by using a triple super phosphate fertilizer, while the second method involved mobilisation and thus leaching of heavy metals away from plant roots using EDTA. These mitigation methods were tested in a pot experiment using cabbage as the experimental crop and soil from these areas as growth medium. A survey of common farming practices in these two areas and farmers willingness to use remediation methods was conducted. / South Africa

Heavy metal contamination in the environment is a global issue that is likely to increase in the future. This report investigates a construction area in which increased concentrations of the heavy metals cadmium, cobalt, copper, nickel and zinc and a decreased pH-value has been observed in the surface water recipient. The focus is on assessing contamination characteristics and identifying suitable remediation methods to avoid a river protected by environmental quality standards further downstream from getting contaminated. The bedrock in the area is sulphide containing and releases acidic leachate when oxidising, which is assumed to have occurred due to plane blasting and filling of residual rock. The contamination characteristics were assessed with the statistical methods modified double mass analysis and principal components analysis. A water balance was established to obtain the flowrates, discharge volumes and to determine the masses of the released metals in the surface water. Identification of suitable remediation methods was performed through a literature study of available remediation methods and using the findings of the assessments as basis. The results showed that there was a significant increase in metal concentrations and decrease in pH-value roughly around the same time as blasting and filling of residual rocks in the area was begun and that there were elevated levels of sulphide and sulphur, but they could not be specifically linked to any media. The yearly masses of metals released from the area into the surface water were between 77-98 % higher than allowed by the established guidelines. By separating the water assumed to carry the majority of the contaminants from the remaining natural water in the watershed, the volume that needs to be treated can be halved. As the contamination is so extensive, a mixture of remediation methods was proposed, including installing green roofs to decrease the runoff from the area, confining the crushed rock with bentonite and installing a filter for fast, efficient reduction. For long-term remediation, it is suggested to optimise the existing sedimentation basins and wetlands. The conclusions were that it will be very expensive to remediate the contamination, due to the extent and magnitude, and that handling sulphide containing bedrock for construction purposes should be legally regulated in order to avoid negative environmental and economic impacts. / Förorening av tungmetaller i naturen är ett globalt problem som troligtvis kommer öka i framtiden. Den här rapporten undersöker en byggarbetsplats där ökade koncentrationer av metallerna kadmium, kobolt, koppar, nickel och zink samt ett minskat pH-värde har observerats i ytvattenrecipienten. Fokus ligger på att analysera föroreningskaraktärer och identifiera lämpliga åtgärdsmetoder för att undvika att en å nedströms som är skyddad av miljökvalitetsnormer ska förorenas. Berggrunden i området är sulfidförande och släpper ut surt lakvatten när den oxiderar, vilket är antaget har hänt till följd av plansprängning och utfyllnad av överblivet bergmaterial. Föroreningskaraktärerna analyserades med de statistiska metoderna modified double mass analysis och principalkomponentsanalys. En vattenbalans etablerades för att ta fram flöden, volymer och för att bestämma massorna av de frigjorda metallerna i ytvattnet. Identifiering av lämpliga åtgärdsmetoder gjordes med en litteraturstudie av tillgängliga metoder som grund. Resultaten visade att det är en signifikant ökning av metallkoncentrationer och minskning i pH-värde runt samma tid som sprängning och utfyllning av bergmaterial påbörjades samt att det är förhöjda halter av sulfid och svavel, men de kunde inte bli associerade med ett specifikt media. De årliga massorna av frigjorda metaller som släpps ut från området i ytvattnet är mellan 77-98 % högre än tillåtet av de etablerade riktlinjerna. Genom att separera vattnet som kan antas innehålla majoriteten av föroreningarna från det naturliga vattenflödet i avrinningsområdet kan volymen som behöver renas halveras. Eftersom föroreningen är så omfattande föreslås en kombination av åtgärdsmetoder; installation av gröna tak för att minska avrinningen från området, inneslutning av utfyllnadsmaterialet med bentonit och installation av ett filter för snabb, effektiv reduktion. För mer långsiktig rening föreslås det att optimera de existerande sedimentationsdammarna och våtmarken. Slutsatsen är att det kommer bli väldigt dyrt att åtgärda föroreningen på grund av dess omfattning, och hantering av sulfidförande berg för exploateringssyfte borde vara lagstadgat för att undvika miljömässiga och ekonomiska kostnader.

The aim of the project was to make a detailed risk assessment using Swedish guidelines for a factory site in Kodaikanal, South India, and a nearby village called Vellagavi. The study areas were chosen due to previous records of mercury contamination on the factory site and a possible spread to Vellagavi. A comparison between Indian and Swedish guidelines for risk assessment of contaminated areas was performed. The purposes of comparing the two systems were to locate if there were any differences in the legislation, or guidelines, and to find ways of improving the processes. The project also included an evaluation of possible remedial actions that could reverse or prevent environmental damage that might be caused by the former factory. Methods used for the project were literature studies, semi-structured interviews and surveys. The results from the risk assessment were that the Swedish Computer Program for Calculation of Guideline Values (CPCGV), with some adjustments, could be used in order to calculate site specific guideline values for mercury concentrations on sites similar to Swedish conditions, such as climate. The site specific guideline values in soil rangedfrom 0.1-2.4 mg/kg. An Indian court decision had stated that a guideline value of 20 mg/kg should be used for remediation at the factory site. The result from the forward dose calculation showed that when a soil contains 20 mg/kg,the tolerable daily intake of mercury would be exceeded, and therefore pose a risk to human health. The comparison of legislation systems between India and Sweden showed several differences. India did not have any legislation relating directly to polluted soil. Risk assessments in India commonly relied on several different international standards even though the standards were not regulated by law. The results from the remedial evaluation showed that there were several possible remediation methods that could beused on the factory site. Limited remedial actions were suggested for Vellagavi since there were no measurements taken on site. Preferably, remediation should take place at the source of the contamination, i.e. the factory site. / Det övergripande målet med projektet var att genomföra en detaljerad riskbedömning för en fabriksplats i Kodaikanal, södra Indien, samt för en närliggande by, Vellagavi. Tidigare genomförda mätningar uppvisade förhöjda halter av kvicksilver i området, varför det ansågs vara ett lämpligt område för studien. Studien innehöll en jämförelse av riktlinjer för riskbedömningar för förorenad mark mellan Indien och Sverige där syftet var att identifiera skillnader i lagstiftning och riktlinjer samt lokalisera eventuella förbättringsmöjligheter. Studien innefattades även av en åtgärdsutredning för fabriksplatsen och Vellagavi, vars syfte var att utreda vilka åtgärder som skulle kunna minska risken för fortsatt miljöförstöring eller återställa området. Metoderna som användes i studien var litteraturstudier, semi-strukturerade intervjuer och en enkätundersökning. Resultatet från riskbedömningen visade att beräkningsverktyget för platsspecifika riktvärden från Naturvårdsverket kunde användas på platser som liknar Sverige klimatmässigt, efter att diverse justeringar hade gjorts. Beräkningsverktyget användes för att ta fram ett platsspecifikt gränsvärde för kvicksilverkoncentrationen i marken. Det framtagna platsspecifika gränsvärdet för koncentrationen kvicksilver i jord varierade mellan 0,1-2,4 mg/kg. Ett beslut utfärdat av indisk domstol angav att fabriksplatsen skulle saneras så att kvicksilverkoncentationen i marken inte skulle överskrida 20 mg/kg. Resultatet från den här studien visade att den nivån av förorening i marken skulle innebära att det tolerabla dagliga intaget av kvicksilver skulle överskridas. En jämförelse av de juridiska systemen som anknöt till förorenad jord i Indien respektive Sverige visade på flertalet skillnader mellan länderna. Indien hade ingen lagstiftning som speficikt reglerade förorenad jord medan det i Sverige reglerades av Miljöbalken. Riskbedömningar i Indien baserades ofta på internationella standarder, med det fanns ingen lagstifting som reglerade vilka standarder som skulle användas. Resultatet från åtgärdsutredningen var att det fanns flera olika åtgärdsmetoder som skulle kunna användas för att sanera fabriksplatsen. Åtgärdsutredningen för Vellagavi var begränsad eftersom det inte fanns tillräckligt mycket mätdata för området. Företrädesvis bör saneringsåtgärderna vidtas vid föroreningskällan, vilket i detta fall är fabriksplatsen.