Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Lake lowering in sulphide-rich areas is currently a major environmental impact for surface water. This study focuses on whether there is a relationship between a gradient of lake lowering and surface water impacts in areas of sulphide-rich sediments, in order to better understand their contribution of heavy metals and sulfuric acid. Also, is it a reasonable method to use the reduced lake area in order to quantify the gradient? The survey was conducted by collecting water samples from reference lakes and lowered lakes from south to north in coastal areas within the county of Västerbotten. Water samples were then analyzed for TOC, pH, conductivity, anions, base cations, alkalinity, acidity, sulfate, Al, Cd, Fe, Mn, Cu, Zn and Pb. These parameters were then compared statistically using regression analysis and t-tests. The results show that no gradient was discernible in response to the reduced lake area. However, significant differences (p < 0,05) between the reference lakes and all the reduced lakes were visible for pH, conductivity, Cd, Cu, Zn and Al. The study shows that there is a correlation between lake lowering and negative impacts on surface water. However, to calculate a gradient from the reduced lake area is deficient as it is limited by the lakes volume reduction, and how the area around the lake has been affected. Further studies on the subject are therefore necessary. / FLISIK (för livskraftiga småvatten i kvarkenregionen)

No description available.

Thesis (Ph.D.)--University of Adelaide, Depts. of Geology and Geophysics and Geographical & Environmental Studies, 2000? / Bibliography: leaves 223-266.

Thesis (M.Eng.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: leaf 206-219.

Acid sulfate soils covers an area area about 600 km-2 along the coast line of Northern Sweden. These soils originate from land uplift and oxidized sulfide soils. The oxidation process releases sulfur and Fe(III) and will lower the pH-value and mobilize metals that will cause toxic environments for water living organisms. Concerns of how higher occurrence of extreme weather conditions will affect the mobilization of metals has occurred. Understanding of the mobilizations of metals in different catchment conditions is therefore important knowledge for preparation of risk analyzes to protect ecosystems from toxic effects. The aim of this study is to compare accumulation of metals in sediments from marine and limnic environments to investigate how lakes effects the mobilization of metals in catchments consisting of acid sulfate soil. Answering the questions of accumulation differences between the catchments and how organic matter affects the mobilization and accumulation of metals. Sediment cores were collected in two different catchment areas, known to be affected by acid sulfate soils, in Västerbotten county. 22 different elements were analyzed by x-ray fluorescence spectroscopy and Loss-on-ignition (LOI) was used as a proxy for organic matter. The results indicate that draining of land areas, often due to agriculture and deforestation, increases mobilization and accumulation of metals correlated with both organic and lithogenic fractions to a large extent. However, elements such as S, Ni, Zn, Fe, Cu, Na, Mg, Al, Rb, Sr and Zr are derived from mobilization from acid sulfate soils where elements with high correlation with organic matter accumulates in limnic environment conditions.

No description available.

The primary soil limitations to crop yield in the Senegalese "Peanut Basin" include salinity, acidity, and fertility. Crop yield may be increased by use of soil amendments and salt-tolerant cultivars. Objectives of this research were to evaluate salt tolerance of various millet (Pennisetum glaucum (L.) R.Br.) cultivars and compare effects of soil amendments on millet growth and yield in greenhouse and field studies. The research included two greenhouse experiments (i) comparing the salt tolerance of seven pearl millet cultivars (IBMV 8402, SOSAT C88, ICMV-IS 88102, IKMP1, IKMP2, IKMV 8201 and GAWANE) using five levels of electrical conductivity (0.3. 2.1, 4.2, 5.2 and 6.3 dS m-1) and (ii) assessing SOSAT C88 responses to various organic (compost and peanut shells) and inorganic (phosphogypsum; PG) amendments in manufactured saline soils (4.2 dSm-1); and (iii) a two-year (2014-2015) field experiment in Senegal evaluating the effects of local organic amendments (peanut shells and compost) on the responses of three millet cultivars (SOSAT C88, GAWANE and IBMV 8402) under low and high soil salinity. Cultivars SOSAT C88 and IBMV 8402 performed best in saline greenhouse media. The soil amendments that elicited the best millet plant responses in the greenhouse experiment were yard waste compost and peanut shells. Phosphogypsum exacerbated salinity effects by increasing electrical conductivity. In the field study, there were no differences among treatments. Cultivars IBMV 8402 and SOSAT C88 could be cultivated in saline soils amended with peanut shells. / Master of Science

This thesis describes the use of different DNA sequencing technologies to investigate the structure and function of microbial communities in two extreme environments, boreal acid sulfate soil and the terrestrial deep biosphere. The first of the two investigated environments was soils containing un-oxidized metal sulfides that are termed ‘potential acid sulfate soil’ (PASS) materials. If these materials are exposed to atmospheric oxygen by either natural phenomena (e.g., land uplift) or human activities (e.g., drainage) then the metal sulfides become oxidized and the PASS becomes acidic and is defined as an ‘acid sulfate soil’ (ASS). The resulting acid and metal release from metal sulfide oxidation can lead to severe environmental damage. Although acidophilic microorganisms capable of catalyzing acid and metal release have been identified from many sulfide mineral containing environments, the microbial community of boreal PASSs/ASSs remains unclear. This study investigated the physicochemical and microbial characteristics of PASSs and ASSs from the Risöfladan experimental field in Vasa, Finland. Sanger sequencing of 16S rRNA gene sequences of microorganisms present in the PASSs and ASSs were mostly assigned to acidophilic species and environmental clones previously identified from acid- and metal-contaminated environments. Enrichment cultures inoculated from the ASS demonstrated that the acidophilic microorganisms were responsible for catalyzing acid and metal release from PASSs/ASSs. Lastly, the study investigated how to mitigate metal sulfide oxidation and the concomitant formation of sulfuric acid by treating ASSs in situ with CaCO3 or Ca(OH)2 suspensions. The DNA sequencing still identified acidophilic microorganisms after the chemical treatments. However, the increased pH during and after treatment suggested that the activity of the acidophiles might be inhibited. This study was the first to identify the microbial community present in boreal PASSs/ASSs and suggested that treatment with basic compounds may inhibit microbial catalysis of metal sulfide dissolution. The second studied environment was the deep, dark terrestrial subsurface that is suggested to be both extremely stable and highly oligotrophic. Despite the scarcity of carbon and energy sources, the deep biosphere is estimated to constitute up to 20% of the total biomass on earth and thus, represents the largest microbial ecosystem. However, due to the difficulties of accessing this environment and our inability to cultivate the indigenous microbial populations, details of the diversity and metabolism of these communities remain largely unexplored. This study was carried out at Äspö Hard Rock Laboratory, Sweden and utilized second-generation sequencing to identify the taxonomic composition and genetic potential of planktonic and biofilm populations. Community DNA sequencing of planktonic cells from three water types at varied age and depth (‘modern marine’, ‘undefined mixed’, and ‘old saline’) showed the existence of ultra-small cells capable of passing through a 0.22 μm filter that were phylogenetically distinct communities from the >0.22 μm fraction. The reduced cell size and/or genome size suggested a potential adaptation to the oligotrophic environment in the terrestrial deep biosphere. The identified planktonic communities were dominated by Proteobacteria, Candidate divisions, unclassified archaea, and unclassified bacteria. Functional analysis of the assembled genomes showed that the planktonic population from the shallow modern marine water demonstrated a predominantly anaerobic and heterotrophic lifestyle. In contrast, the deeper, old saline water was more closely aligned with the hypothesis of a hydrogen-driven deep biosphere. Metagenomic analysis of subsurface biofilms from ‘modern marine’ and ‘old saline’ water types suggested only a subset of populations were involved in initial biofilm formation. The identified biofilm populations from both water types were distinct from the planktonic community and were suggested to be dominated by hydrogen fed, chemolithoautotrophic and diazotrophic populations.

Global environmental concerns arise when marine deposits with fine-grained iron sulfide-rich sediments (FeS and FeS2), now situated above sea level, oxidize from anthropogenic lowering of the groundwater table. The oxidation of iron sulfides decreases the soil pH and the acidic environment of these Acid Sulfate Soils (AS) soils increase weathering and mobilization of metals into adjacent watercourses, lakes and estuaries. Low pH and enhanced concentrations of metals are known to influence water quality negatively, causing fish kills and reduced aquatic diversity. Sulfide rich sediments were deposited in the Baltic Sea after the last glaciation and are now abundantly found along the coasts of for example the Bothnian Bay as a result of isostatic rebound. Recent studies from Finland have stated associations between leached (AS) soils and increased concentrations of metals in estuary sediments, thus the effects are likely to be similar in Sweden. With financial support from the Interreg Nord project “Ecological restoration in coastal river basins in the Bothnian Bay” in cooperation with the Geological Survey of Sweden (SGU), sediments from three lakes and two estuarine sites in the Rosån catchment in Norrbotten county, northern Sweden, were sampled and analyzed with fpXRF, ICP-MS and LOI methods. Elemental concentrations and organic contents were compared to establish accumulation trends over time and relationships between metal concentrations in recently deposited sediments and potential influence from previously sampled (AS) soils. Correlations in time, to anthropogenic activity, such as ditching were also considered. A primary allover trend with increasing concentrations of Aluminum (Al), Arsenic (As), Cadmium (Cd), Cobalt (Co), Cupper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni), Lead (Pb), Rare Earth Elements (REE) and Zinc (Zn), was noticed in a majority of the lake and estuary sediment samples. With some site variation, also two discrete peaks at different depth, were found in the upper 20 to 30 cm of the sampled sediments. Significant correlations to organic matter were also found for a considerable amount of the elements. Soil samples from (AS) soils in areas related to Rosån show pH values as low as 2.62 and oxidation depths down to 170 cm. Substantial elemental depletion in the oxidized zone suggest increased weathering, leaching and mobilization of Al, Cd, Co, Mn, Ni, REE, Zn and to some extent As, Cu, Fe and Pb from the soil, as a consequence of the acidic environment. A relationship between (AS) soils and increased metal concentrations is therefore likely. The sedimentation rate of roughly 0.2 cm/year was calculated from the separation age of the lakes and the sediment depth to an interpreted transition from more marine environment to lake settings. Consequently the distinct peaks of increased metal concentrations are thus suggested to be related to anthropogenic activities as for example improved drainage methods after the Second World War, but proper dating of the sediments is needed to establish any certain correlations. / På senare tid har man uppmärksammat de miljöproblem som uppstår när finkorniga sediment, innehållande järnsulfider, oxiderar på grund av mänsklig påverkan, t ex. dikning, eller annan typ av aktivitet som sänker grundvattennivån. När järnsulfiderna oxiderar bildas svavelsyra som gör att pH- värdet i marken blir väldigt lågt. Den sura miljön i dessa så kallade sura sulfatjordar, gör i sin tur att mineraler i marken vittrar fortare med påföljden att både surt vatten och ökade mängder metaller, sprids till närliggande vattendrag, sjöar och hav. Lågt pH och höga halter av metaller i vatten påverkar även vattenkvalitén negativt och har rapporterats orsaka fiskdöd och minskad akvatisk mångfald. Sura sulfatjordar är globalt förekommande och återfinns bland annat längs Bottenvikens kuster. De har kunnat bildas genom att sulfidhaltiga sediment, som avsattes i Östersjön efter den senaste istiden, nu befinner sig ovan havsnivån på grund av landhöjningen. I Finland har man i flera studier sett ett samband mellan sura sulfatjordar och ökade metallhalter i nyligen avsatta kustsediment och man kan anta att liknande förhållande gäller även i Sverige. Med finansiellt stöd från EU-projektet “Kustmynnande Vattendrag i Bottenviken-Metodutveckling och Ekologisk Restaurering” (Interreg Nord) genom Sveriges geologiska undersökning (SGU) och i samarbete med Länsstyrelsen i Norrbotten, har bottensediment från tre sjöar och två fjärdar i Rosåns avrinningsområde i Norrbotten provtagits och analyserats. För att fastställa hur koncentrationerna har förändrats över tiden har metallhalterna i de nyligen avsatta sedimenten jämförts med koncentrationerna i äldre sediment. Även jordprofiler från sura sulfatjordar i området har studerats för att kunna utvärdera ett ev. samband mellan urlakade ämnen i jordarna och ökade halter i sedimenten. Granskning av hur långt metallerna transporteras i systemet har gjorts, liksom försök att hitta kopplingar i tiden till mänsklig påverkan som t.ex. dikning. I de översta sedimenten kan man, förutom en generellt ökande trend av aluminium (Al), arsenik (As), kadmium (Cd), kobolt (Co), koppar (Cu), järn (Fe), mangan (Mn), nickel, (Ni) bly (Pb), sällsynta jordartsmetaller (REE) och zink (Zn), också se tydliga toppar med ökade halter av dessa ämnen på minst två specifika djup. De sura sulfatjordarna, som uppmätte pH-värden ner till 2,62, visade tecken på urlakning av Al, Cd, Co, Ni, Mn, REE, Zn och till viss del också As, Cu, Fe och Pb, varpå en trolig relation mellan sura sulfatjordar och ökade metallhalter i nyligen avsatta sediment kan fastställas. En uppskattning av ackumulationshastigheten, som gjordes utifrån när de provtagna sjöarna skiljdes från havet, och sedimentdjupet som visar övergången från hav till sjö, visar att de observerade topparna av ökade metallkoncentrationer i sedimenten skulle kunna vara förknippade med dikning i början av 1900-talet och efter andra världskriget. För en säker bestämning av sambandet till specifika händelser behövs dock en riktig datering.