A standardized method to examine soil microbial health incorporating biomass, activity, and diversity measurements is currently lacking, limiting the use of this ecologically relevant endpoint in ecological risk assessments. The soil microbial health of a petroleum hydrocarbon-contaminated boreal forest soil, relative to a reference soil, was examined using a suite of tests. Microbial health impacts in the contaminated soil were observed using nitrification, organic matter decomposition, bait lamina, denaturing gradient gel electrophoresis, community level physiological profiling, and most enzyme assays. Results of heterotrophic plate count and respiration tests indicated higher culturable numbers and activity in the contaminated soil. A data integration technique was developed to incorporate the results from individual tests into an overall conclusion, indicating that soil contamination at the site moderately to severely impacted microbial health. The research presented lays the foundation for the development of a soil microbial health standardized method.

The study of acid rock and mine (ARD and AMD) environments mainly focused on the mineralogical and microbiological conditions and responses of such systems. Most of the research that involved some organic viewpoint was related to the amelioration of the environmental conditions, sometimes with contradictory results. How organic matter (OM) participates and which organic fractions are involved in ARD and AMD processes remain unclear. In this work we have applied organic geochemistry tools combined with mineralogical ad molecular microbiology techniques to study of ARD and AMD environments. The main objectives were to identify and characterise the natural sources of OM occurring both at ARD and AMD sites, and to determine whether the OM sources identified are involved in the generation or amelioration of AMD/ARD. This study shows that multiple OM sources occur naturally in acid drainage environments, included plant derived material and mature, petroleum-derived hydrocarbons, originating from the source rocks, apparently have not directly influence on the processes. This suggests that the generation of ARD and AMD is a completely chemoautotrophic process. Particle size of the iron phases present at ARD sites seems to be involved in the iron bioavailability. The presence of goethite in ARD/AMD systems may have a relationship with the presence of OM. Stimulation of ARD sediments using plant derived OM, abundantly present in and around ARD and AMD ponds systems does not result in the neutralisation of ARD or AMD. This suggests that plant material is not used by Fe(III)-reducing bacteria. However, it fuels fermentation processes and it is likely that fermentation products such as acetate, detected in microcosms and in situ, could limit Fe(III)-reduction. In contrast, the stimulation of ARD sediments using manure (particularly sheep manure) raises the pH up to near neutral conditions. Although it remains unclear which OM fraction from the manure is actively involved in the neutralisation of ARD; these results suggest that manure may make an interesting and non-expensive electron donor in AMD/ARD treatments.

Contaminated land is a widespread, global issue affecting millions of people. Atrazine is a commonly used herbicide which often contaminates groundwater and drinking water supplies and is associated with adverse health outcomes. Biochar is the solid product of pyrolysis and is associated with several environmental benefits. It may be an effective remediation tool when used as a soil amendment. This thesis investigates the mechanisms through which biochar can immobilise atrazine, and the implications of the mechanisms for remediating contaminated land. Nine biochar samples were obtained from the United Kingdom Biochar Research Centre , which were produced from softwood pellets (SWP), wheat straw pellets (WSP), miscanthus straw pellets (MSP), rice husk (RH) and oil seed rape (OSR) each at pyrolysis temperatures of 550°C and 700°C (excluding OSR at 700°C). The sorption mechanisms controlling atrazine sorption to these biochars were determined through various characterisation methods and batch sorption experiments. The sorption tests showed that sorption to each of the standard biochars occurs via multiple simultaneously occurring mechanisms, which are each promoted under certain conditions. Studies investigating sorption kinetics, isotherms and interactions with humic acids showed that for all biochars in this study, pore filling was a significant process through which atrazine is transported to adsorption sites, although poor intraparticle diffusion for softwood and oil seed rape biochars can prevent efficient transport. Wheat straw and rice husk biochars showed effective pore diffusion, resulting in high sorption capacities. Partitioning was associated with poor remediation outcomes and was significant to softwood biochars, although adsorption dominated overall sorption for all other biochars. pH was shown to significantly influence the occurrence of various sorption mechanisms. At low pH values, most biochars showed evidence of electrostatic repulsion between positive atrazine species and the positively charged biochar surface. At intermediate pH values, all biochars showed strong hydrogen bonding between H+ groups on the surface of the biochar and atrazine. A meta-analysis of previous relevant studies provided further evidence for hydrogen bonding of atrazine to biochar and showed that hydrophobic effects likely play little role in adsorption after accounting for the effects of surface area. Varying contributions of π-π EDA interactions, hydrogen bonding involving biochar O- groups, and interactions with ash minerals resulted in different sorption profiles for each biochar at high pH values. In order to further determine the mechanisms controlling sorption at high pH, surface compositions of SWP550, RH700 and OSR550 biochars were modified using hydrofluoric acid. Modification with hydrofluoric acid successfully removed the ash contents of rice husk and oil seed rape biochars and reduced atrazine removal at high pH values. This suggested that the ash fraction increases atrazine removal at high pH through complexation or catalytic hydrolysis. The roles of the various mechanisms are related to remediation outcomes in a novel manner allowing for the improved design of biochar for environmental remediation.

Successive applications of Bordeaux syrup, a copper fungicide widely used to control diseases on the vine, contributed to the increase in copper in large areas of vineyards in the Serra Gaúcha. Phytoremediation is a soil remediation technology that provides low environmental impact, low cost and wide public acceptance. The objective of this study is to select soil cover plants of winter and summer that are promising for phytostabilization and phytoextraction of copper in soil of Serra Gaúcha. A 'Cambissolo', was collected in the Serra Gaúcha and added different copper concentrations of 0, 100, 200, 400, 500 and 600 mg kg-1 in the form of copper chloride (66.66%) and copper sulfate (33 , 34%). In this soil, in a greenhouse were grown nine genotypes of winter cover plants: black oat (Avena stringosa Schreb) With four genotypes ("UPFA 21 Moreninha", "Vacaria", "Passo Fundo" and "IPFA 99009"), cover oat (Avena brevis L.) with genotype ("BRS Centauro"), white oat (Avena sativa L.) with three genotypes ("URS 21", "UPF 18" and "UPF 22") and hairy vetch (Vicia villosa Roth) with a 'cultivate' ("SS esmeralda") and nine genotypes of summer cover plants: pearl millet (Pennisetum glaucum L.), jack bean (Canavalia ensiforms DC), black mucuna bean (Mucuna aterrima L.), dwarf pigeonpea (Cajanus cajan L.), bahiagrass (Paspalum notatum L.), sunn hemp (Crotalaria juncea L.), gray mucuna bean (Mucuna cinereum L.), dolichos bean (Dolichos lablad L.) and sunn hemp (Crotalaria spectabilis Roth). When grown in soils with high concentrations of copper, black oat genotypes "UPFA 21 Moreninha" and white oat "URS 21" and plants jack bean and black mucuna bean produce large amounts of dry, these soils can be used as ground cover plants. The genotype "Vacaria" oat, black mucuna bean and gray mucuna bean produce high amounts of dry matter and accumulate high concentrations of copper in the root system, with potential to be used in programs phytostabilization of copper. / Aplicações sucessivas de calda bordalesa, um fungicida cúprico muito utilizado no controle de doenças na videira, contribuíram para o aumento dos teores de cobre em extensas áreas de vinhedos na Serra Gaúcha. A fitorremediação é uma tecnologia de remediação de solos que apresenta reduzido impacto ambiental, baixo custo e grande aceitação pública. O objetivo deste estudo é selecionar plantas de cobertura de solo de inverno e verão que sejam promissoras para a fitoestabilização e fitoextração do cobre em um solo da Serra Gaúcha com altos teores de cobre. Um Cambissolo foi coletado na Serra Gaúcha e foram adicionadas diferentes doses de cobre 0, 100, 200, 400, 500 e 600 mg kg-1 na forma cloreto de cobre (66,66%) e sulfato de cobre (33,34%). Neste solo, em casa de vegetação foram cultivados nove genótipos de plantas de cobertura de inverno: aveia preta (Avena strigosa Schreb.) com quatro genótipos ( Vacaria , UPFA 21 Moreninha , Passo Fundo e IPFA 99009 ), aveia para cobertura (Avena brevis L.) com o genótipo BRS Centauro , aveia branca (Avena sativa L.) com três genótipos ( URS 21 , UPF 18 e UPF 22 ) e ervilhaca peluda (Vicia villosa Roth.) com uma cultivar ( SS Esmeralda ); e nove genótipos de plantas de cobertura de verão: milheto (Pennisetum glaucum L.), feijão de porco (Canavalia ensiforms DC.), mucuna preta (Mucuna aterrima L.), feijão guandu anão (Cajanus cajan L.), pensacola (Paspalum notatum L.), (crotálaria (Crotalaria juncea L.), mucuna cinza (Mucuna cinereum L.), labe-labe (Dolichos lablad L.) e crotálaria (Crotalaria spectabilis Roth.). Quando cultivados em solos com altas concentrações de cobre, os genótipos de aveia preta UPFA 21 Moreninha e de aveia branca URS 21 e as plantas de feijão de porco e mucuna preta produzem elevadas quantidades de massa seca, podendo ser utilizadas nestes solos, como plantas de cobertura de solo. O genótipo Vacaria de aveia preta, a mucuna preta e a mucuna cinza produzem elevadas quantidades de massa seca e acumulam elevadas concentrações de cobre no sistema radicular, apresentando potencial para serem utilizadas em programas de fitoestabilização de cobre.