A study was undertaken to determine the manganese status of some Lower Fraser Valley soils developed from alluvial and marine deposits. Mn fractions in six soils and in their particle size separates were determined by atomic absorption spectrophotometry. Water soluble Mn ranged from 0.5 to 1.4 ppm; Exchangeable Mn from 0.5 to 15.0 ppm; Hydroquinone reducible from 0.7 to 119.5 ppm; Total Mn from 82.0 to 957.5 ppm; and "Active Mn" from 3.2 to 129.8 ppm. These ranges were similar to reported values, except that.the study failed to find the high levels of total Mn reported by Baker on some soils from the same area. Generally water soluble and exchangeable Mn showed little variation within profile or between soils. In four out of the six profiles reducible and total Mn were higher in the parent material than in the surface horizons. However, there was no satisfactory fit for a number of the profiles to the four distribution patterns suggested by Leeper. Values for EDTA extractable and "active" Mn in two profiles suggest that both fractions of Mn represent the same chemical form. However, further results suggest that the two Mn fractions are different. In nearly all samples with high organic matter content EDTA extracted more Mn after removing "active Mn" than direct extraction with EDTA, supporting suggestions that EDTA extracts chelated Mn and also causes some dispersion of soil particles. Sonic dispersion led to increased recovery of all forms of Mn, more especially reducible and total Mn. The results suggest that until more is known about sonic dispersion it is unwise to assume that no modification of soil constituents takes place. Statistical techniques were used to examine the relationship between Mn distribution and parent materials, pH, organic matter content and cation exchange capacity. These analyses showed that the level of Mn fractions in the soil cannot be predicted by any single factor, but only by a number of soil factors in combination. The possibility of building up a computer model to predict Mn distribution is suggested. The significance of soil Mn distribution in terms of plant requirements is discussed. Plant available Mn in these soils, estimated by 0.02 M CaCl₂ extraction, ranged from 0.5 to 10.7 ppm. This was very similar to that for exchangeable. Based on data in the literature these soils were classified into manganese-deficient and-sufficient categories. Using extraction techniques only, various Mn pools were established for these soils according to the chemical pool concept proposed by Viets. These pools and their possible relation to Mn availability are discussed. It was suggested that a further study was necessary to establish a correlation between these Mn pools and plant Mn requirements and also to reveal the equilibria and rates of interconversion existing between the established pools as found under the soil conditions of the Lower Fraser Valley. / Land and Food Systems, Faculty of / Graduate

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Environmental Health Faculty of Applied Sciences Cape Peninsula University of Technology / Soil contamination by metals is a serious environmental problem that has significant implications for human health. Roadside soils have been shown to have considerable contamination due to depositions of metals by vehicles. Metal pollution poses significant environmental concerns because most metals are not biodegradable and often have long half-lives, thus predicating far reaching effects on biological systems, including the soil. Unleaded petrol has been available in South Africa since 1996. The conversion from leaded to unleaded petrol has been a slow process. Leaded petrol has been totally phased out since January 2006. The manganese-containing fuel additive methylcyclopentadienyl manganese tricarbonyl (MMT) that was introduced to automobile fuel formulae as an octane boosting and “anti-knock” agent, to replace or reduce the lead content in petrol, was officially approved in some developed countries. Despite the fact that metal contamination of soil has long been known, few studies have been carried out into its vertical distribution in the soil. The objectives of this investigation were: firstly, to assess the accumulation of lead and manganese in soil along the N1 highway; secondly, to determine the vertical distribution of lead and manganese in soil along the N1 highway; and thirdly, to compare the concentrations of lead and manganese in soil along the N1 highway, before and after the banning of leaded petrol in South Africa. Six soil samples were taken at each site approximately two meters from the road verges and at a depth of approximately 0-2cm of surface soil. The sampling period commenced on the 16th of February 2011 and ended on the 28th of December 2011. Once-off soil samples were also collected at sites 1, 5 and 6 at depths of 0-2cm, 30cm and 60cm, respectively. Samples were digested with 10 ml 55% nitric acid. Lead and manganese concentrations were determined by using Inductively Coupled Plasma Mass Spectrophotometer (ICP–MS). The mean concentrations of lead found in the roadside soils of the N1 highway ranged between 7.32mg/kg and 2068.31mg/kg and these were of high concentrations when compared to studies done in other countries. Results from the vertical distribution of lead investigation showed that lead concentrations ranged from 52.72mg/kg to 215.94mg/kg at surface level, from 15.80mg/kg to 164mg/kg at a depth of 30cm and from 14.06mg/kg to 216.07mg/kg at a depth of 60cm from the surface. It was also shown that there is a positive correlation between lead concentration and the amount of organic content (although not statistical), concluding that as the amount of organic content increases lead concentrations also increase. The mean manganese concentrations found in the roadside soils of the N1 ranged between 12.17mg/kg and 221.47mg/kg. The levels of manganese in the soil were found to be relatively low when compared to other studies an indication of mild to low metal contamination of the sampled soils. Results from the vertical distribution of manganese concentrations showed that concentrations in the soil ranged from 39.23 mg/kg to 63.32 mg/kg at surface level, from 14.4mg/kg to 310.86mg/kg for depths of up to 30cm, and from 4.42mg/kg to 343.96mg/kg for depths of up to 60cm. No relationships of manganese levels in the soil were found at any of the sites when sites were compared prior to the banning of lead and after the banning of lead despite the increased traffic volumes and, thus, increased MMT usage over the years, indicating that manganese contribution from MMT is very low and does not significantly increase soil contamination along the N1 highway. However, further investigations are needed into the future to monitor manganese contamination that may possibly occur.

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[Truncated abstract] Industrial processing to refine alumina from bauxite ore produces millions of tonnes of refining residue each year in Australia. Revegetation of bauxite residue sand (BRS) is problematic for a number of reasons. Harsh chemical conditions caused by residual NaOH from ore digestion mean plants must overcome extremely high pH (initially >12), saline and sodic conditions. At such high pH, manganese (Mn) is rapidly oxidised from Mn2+ to Mn4+. Plants can take up only Mn2+. Thus, Mn deficiency is common in plants used for direct BRS revegetation, and broadcast Mn fertilisers have low residual value. Added to this, physical conditions of low water-holding capacity and a highly compactable structure make BRS unfavourable for productive plant growth without constant and large inputs of water as well as Mn. However, environmental regulations stipulate that the residue disposal area at Pinjarra, Western Australia, be revegetated to conform with surrounding land uses. The major land use of the area is pasture for grazing stock. Hence, pasture revegetation with minimum requirement for fertiliser and water application is desirable. This thesis investigates a number of avenues with potential for maintaining a productive pasture system on BRS whilst reducing the current level of Mn fertiliser and irrigation input. Emphasis was placed on elucidation of chemical and physical factors affecting Mn availability to plants in BRS