Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2017. / Surface water is used as a source of water supply in many countries, including South Africa. One of the sources of surface water pollution is leachate and surface runoff from landfills. In agricultural soils, the landfill runoff and leachate deteriorate the quality and affect the fertility of soil. The entry of metals and microorganisms from landfill leachate to adjacent environments is through surface runoff due to rainfall. Adverse effects on human- and environmental health triggers a need to monitor and control contaminants in the environment. The aims of the study are to determine the effect of landfill runoff and leachate on agricultural soil and river water (Veldwachters River) running adjacent to the Devon Valley landfill site and to identify potential metal-tolerant organisms in environmental samples collected in Stellenbosch, Western Cape, South Africa. Samples (agricultural soil, river water and sediments) were collected once a month for a period of six months from the study area for analysis. Physicochemical parameters that are known to have major effects on environmental samples were assessed and the concentrations of various metals (Al, Pb, Cr, Mn, Mo, Co, Ni, Cu, Zn, Fe, Cd and V) were also determined by means of inductively coupled plasma mass spectrometry (ICP-MS). Soil texture analysis was tested in order to monitor the metal distribution in soils under the influence of environmental factors.

Soil samples from 118 sites on 71 geologic units in southwest Oregon were collected and analyzed to determine the background concentrations of metals in soils of the region. Sites were chosen in areas that were relatively undisturbed by human activities. The U.S. Environmental Protection Agency approved total-recoverable method was used to recover metals from samples for analysis. The twenty six metals analyzed were: Ag, AI, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, La, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Tl, V and Zn. The Klamath Mountains followed by the Coast Range contain the highest soil concentrations of AI, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Ni, V and Zn. Soils of the Coastal Plain and High Lava Plains contain the lowest concentrations of these metals. Unusually high soil As concentrations are found at two sites in the Klamath Mountains. All Be and Cd values above laboratory's reporting limits are also from the Klamath Mountains and Coast Range. Concentrations of soil Ba and La are fairly uniform throughout the region. Soil Pb levels are generally low with a few exceptions in the Klamath Mountains, Coast and Cascade Ranges. The region west of the Cascade Range has higher soil Hg contents than in the east. Soil metal concentrations are generally much higher in the region west of the Cascade Range, excluding the Coastal Plain, than in the east with the exception ofNa, because of more ultramafic rocks and a wetter climate. Soil metal concentrations are directly related to soil development with the highest concentrations being found in well developed Alfisols and Ultisols and the lowest concentrations in poorly developed Entisols. Most metals have similar averages and ranges of concentration compared to the rest of the United States (U.S.). Metals with high values compared to the rest of the U.S. are Cr, Co, Cu, Mn and Ni. In general, AI, Co, Cr, Cu, Fe, La, Li, Mg, Na, Ni, and V are concentrated in the B horizon while Ba, Ca, Hg, K, Mn, Pb and Zn are concentrated in the A horizon.

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The research used dendro-chemical analysis of ash tree rings and current year leaf litter to track Cd, Pb, Zn, Cu, Mn, Cr, and Sn spread and cycling from a closed garbage dump-toxic waste site. This technique allowed for determination of areal extent, contaminant levels and time period of initial contaminant contact. Only Zn, Sn, and Cu were found in elevated quantities in the xylem wood and Pb in the leaf litter. Elemental concentrations of Pb, Sn and Cd in xylem wood and leaves of ash were positively correlated. Tin was the only element to demonstrate a clear initial contact period and elemental accumulation with age. Significant levels of Cu accumulated in the heartwood while Zn revealed significant but inconsistent accumulated patterns. Expected attenuation zones associated with municipal solid waste landfill leachate dispersion were not found; thus the pathway for contaminant dispersion was likely through groundwater flow. / An elemental index was developed to facilitate the use of dendro-chemical analysis in periods of suppressed tree growth resulting from environmental pollution.

Innovative means and methods were tested to develop an economical, pragmatic and environmentally sustainable soil remediation process for heavy metal contaminated soils. An unsaturated-flow soil washing procedure was devised to dissolve the soil-bound toxic heavy metals; the latter were extracted by a chemical washing solution that percolated through the soil matrix. Subsequently, the leached toxic heavy metals were selectively concentrated, by a chemical precipitation process, into a solid waste. Thereby, a fraction of the spent ethylenediaminetetraacetic acid (EDTA), within the washing and rinsing leachate, was theoretically regenerated and recycle-ready. / The unsaturated-flow washing procedure was perfected by applying different treatments to a soil from a secure landfill. This soil was contaminated with Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, S and Zn. The major contaminants were Fe, Pb, Zn, S, Cu and Mn, making up 25, 1.9, 1.0, 0.4, 0.4 and 0.2%wt of the soil. The extraction responses of the contaminants and those of Al, Ca, Mg and P were established for citric acid (0.5 M) and different molarities of diammonium EDTA ((NH4)2EDTA). The DOW Chemical Company supplied the (NH4)2EDTA (i.e. VERSENE), a 1.37M industrial cleaner, which roughly costs $1.85kg-1 in bulk. The affordability of VERSENE was a pre-condition for hoping to satisfy the economical feasibility of remediating trace metal contaminated soils. / Ultimately, the developed unsaturated-flow washing procedure was tested in a pilot-scale experiment, for its ability to remediate a soil from an abandoned car battery recycling facility. The latter soil was severely contaminated with Pb (3.9%wt). Drip irrigation was used to apply (NH4) 2EDTA and water-rinsing solutions to the surface of soil heaps that rested atop an impermeable barrier, which permitted the retrieval of the leachate. A cumulative EDTA input to the soil of 10.6% wt extracted 49.4% of the total Pb content of the soil. Alternatively, readily biodegradable citric acid barely extracted 2.2% of the total Pb content of the soil, for a cumulative input of 18.1% weight of soil. Different treatments were tested for their effectiveness in concentrating the leached toxic heavy metals into a solid waste. The Pb was best precipitated with Na2S alone, as it provided the most concentrated solid toxic waste. / The environmental sustainability of remediating trace metal contaminated soils was thoroughly examined, as per the amounts of chemical entrants and toxic waste by-products, and per the post-treatment leaching of toxic levels of the remaining and potentially toxic trace metals. (Abstract shortened by UMI.)

One of the most recognised values of tidal salt marshes is the ecosystem service they provide as natural sinks for contaminants such as metals. This study examines net accumulation of metals (As, Cr, Cu, Hg, Ni, Pb, Zn and V) over a 5-yr period, from 1997 to 2002, in surface sediments of salt marshes in the Bay of Fundy, Canada. Metal accumulation has been measured in seven sites that extend from outer to inner Bay and in low and high marsh areas within each site. Overall, sediment metal concentrations are at or near their natural levels. Concentrations of metals show variability among marshes but are not significantly different between low and high marsh. Concentrations of As, Hg, Pb and V appear to be influenced by anthropogenic inputs. Calculated sediment loading rates for these metals generally showed gradients of increased loading from outer to inner Bay. Variability in sediment deposition rate is the driving force behind this spatial pattern. Results of this study suggest that the value of salt marshes as a sink for metals may be enhanced by high sedimentation rates.

The adsorption behaviour of trace metals in soil may provide us with a way to more accurately predict and assess the toxicity of metals in the environment. This thesis reports efforts to apply surface complexation modeling to agricultural and forest soil and to relate model parameters to common soil properties. This study considered Ca, Cd, Cu, Pb and Zn but the methods here could be applied to other metals. In Chapter 2, the surface charge and adsorption behaviour of a set of Ap horizons was characterised using back-titration and batch adsorption techniques. With the objective of simplifying the application of the NICCA model to surface charge and cation adsorption in whole soils the parameters of the NICCA model were related to soil properties (Chapter 3). Four of the six surface charge parameters could be predicted from soil properties and this enabled me to reasonably predict the surface charge of a second group of soils from soil properties. These results suggest that it is possible to make reasonable predictions about the surface charge and adsorption behaviour of a given type of soil using some easily measurable soil properties and a set of generic NICCA adsorption parameters for that soil type. In Chapter 4 this idea is applied to the determination of lime requirement for the agricultural soils.

A major factor complicating the cleanup at many sites is co-contamination by both organic compounds and heavy metals. Whereas much research has focused on the removal of either organic compounds or metals, relatively few studies have investigated simultaneous removal of organic and inorganic pollutants from soil. / The studies reported in this thesis have evaluated a novel technique for the simultaneous mobilization of polychlorinated biphenyl (PCB) compounds and heavy metals (HMs) from a field contaminated soil. Soil extraction with washing aids {surfactants/cyclodextrin in combination with chelating reagent(s)} was optimized for mobilization efficiency, recovery/recycle of washing additives, and in parallel detoxification of mobilized contaminants. PCB extraction efficiencies were determined with a method that converted all the PCB congeners to dicyclohexyl by hydrogenation over palladium. Studies demonstrated that 10 minutes of ultrasonic mixing of field contaminated soil with a combination of surfactant (30 mL L-1) or cyclodextrin (100 g L-1) and a sparing quantity (2 mmoles) of EDTA, simultaneously mobilized appreciable quantities of PCBs and most analyte metals (Cd, Cu, Mn, Pb, Zn, Ni, Cr). / Relative to individual reagents, combinations of surfactant (Brij 98, Triton X-301, or Triton XQS-20) or cyclodextrin (RAMEB or HPCD) with EDTA did not influence PCB extraction efficiencies perceptibly. The presence of surfactant or cyclodextrin in admixture with EDTA did not appreciably change the efficiency of mobilization of most heavy metals (Al, Cd, Cr, Fe, Mn, Ni, and Zn) but did increase the recovery of Cu and Pb with nonionic surfactant and cyclodextrin. When coupled with PCB removal by hexane back-extraction and precipitation of the HMs (mediated by hydrolysis of zero-valent magnesium (Mg0)}, aqueous washing suspension was regenerated and recycled twice to mobilize more contaminants from the soil. Three sonication-washes with the same charge of reagent mobilized appreciable quantities of PCBs (68 - 83%) and virtually all of the available Cd, Cu, Mn, and Pb and lesser amounts of the Zn (56%), Ni (59%), and Cr (50%) but only small quantities of Al (28%) and Fe (30%). / The release of EDTA from heavy metals complexes was efficient for most metals (99%) but was influenced by the nature of surfactant. EDTA recovery (62-65%) post three cycles of soil washing, hexane back-extraction, and Mg 0 treatment was similar for all reagent combinations. Among surfactants and cyclodextrin, only anionic surfactants suffered losses to Mg0 treatment.