In North America, the acceleration of the eutrophication of surface waters due to nutrient pollution is still present. Soil studies have not entirely succeeded in linking nutrient and sediment losses to field hydrology because relationships between discharge and dissolved ions/sediments are complicated by a hysteresis effect which has been only described qualitatively. The objective of this thesis was to better understand the effects of hydrology on N, P, and sediment transfer from agricultural and forest soils to surface waters. This was done by developing a technique, called the H index, to quantify the hysteretic behaviour of ion and sediment transport in stream/overland water. The chemical and sediment concentrations in a stream of a forested watershed in the Sierra Nevada during snowmelt and in overland runoff of two agricultural fields during rain events in the Montreal area were examined. In the stream of the forested watershed, H indices for suspended sediment increased (looser hysteresis loop) with the availability of sediments and the lag between peaks in suspended sediment concentrations and discharge. In agricultural fields, nutrient concentrations increased with time during each event with presence of counterclockwise and clockwise hysteresis. The hysteretic behaviour of suspended sediments was not significantly related with either prior soil moisture content or rainfall characteristics. In order to simultaneously monitor P and N in the stream and soils of the forested watershed, a laboratory study was conducted to investigate the efficacy of various mixedbed exchange resins in absorbing dissolved organic and inorganic N and P. Results showed that mixed-bed resin was adequate for characterizing P on a short-time scale but longer exposure periods were required for N. Results from the resin exchange reveal the possibility that the spring time pulse of NOs'-N in stream water was due to the melting of the snowpack.

The Saint-Esprit watershed project was initiated to address the issue of nonpoint source agricultural pollution and relies on the adoption of sustainable practices tested on-farm by willing farmers. To study the economic impact of an increasing erosion constraint at the farm and the watershed scales, four Mixed Integer Linear Programming (MILP) models, corresponding to three selected farms and the watershed, were built. The models maximize the sum of field net margins subject to singleness of field use, animal nutrient requirements, and erosion. / Scenario results show that increasing the erosion constraint: (1) reduces soil loss from agricultural production; (2) forces cropping patterns and farming practices to change; (3) reduces profits; and (4) induces marginal and average costs to increase at an increasing rate. Also, with comparable average soil losses per hectare, farms with lower net margins would be worse off if the erosion target was set at the watershed level.

This study assesses the contribution of agricultural non-point source pollution, to poor water quality of the Vaal River within the Grootdraai dam catchment area. The study evaluates agricultural pollutants affecting the quality of water within the study area. The impact of agricultural non-point source pollution on the water quality of the Vaal River was evaluated by establishing a correlation between the quantity of polluted runoff reaching the River and the quantity of measured nitrates and phosphates in its waters. A questionnaire using random sampling was used to capture data from 15 commercial farmers 35 local residents and the Department of Water Affairs management. The results of the study show that agricultural nutrients are heavily impacting and compromising the water quality of the Grootdraai Dam. The mean concentrations of Nitrogen and Phosphorus were found to be well above the water quality guidelines there by promoting eutrophication. / Environmental Sciences / M. Sc. (Environmental Management)

The pressing global demand to transform to a low-carbon business community, which is required by the urgency of mitigating climate change, significantly alters the operating procedures for carbon emitters and carbon revenue generators alike. Although agricultural activities are not considered as heavy carbon emission source, the increased public focus on climate change has catapulted the exploitation of sustainable agricultural land management mitigating strategies as intervention by the sector. Additionally, the focus on market-based mechanism to address climate change, which has led to the evolution of cap-and-trade schemes, makes the agricultural sector become a source of low-cost carbon offsets. However, the fact that cap-and-trade schemes in the agricultural sector are voluntary has resulted into not only very diverse farming practices but also diverse accounting practices. The consequences of the diversity practices are that, the impacts on financial performance and position are not comparable. Therefore, the overall objective of this study was to investigate the recognition, measurement and disclosure for cap-and-trade schemes in the agricultural sectors This study was conducted through literature reviews and empirical test. A qualitative research approach utilising constructivist methodology was employed. Primary data was collected in Kenya by administering three sets of semi-structured questionnaires to drafters of financial statements, loan officers and financial consultants. Secondary data involved content analysis of financial statements and reports of listed entities across the globe. It was established that proper accounting for cap-and-trade schemes adaptation activities is critical to the success of an entity’s environmental portfolio. Additionally, a model for valuing an organisation's carbon capture potential as suggested by this study enables entities to better report the impact of the adaptation activities on the financial performance and financial position. The outcome of this study enables entities to integrate the carbon capture potential on an entity sustainability reporting framework. / Colleges of Economic and Management Sciences / D. Phil. (Accounting Science)

The Kat River is an agricultural catchment that drains salt rich geology. Potential salinity impacts on ecological condition of the river were investigated. Monthly salt concentrations and flow discharges were monitored at ten sites along the Kat River below the Kat Dam. Monthly salt loads were computed to relate salinity to land use and ionic data used to assess the toxicity of major salts using the TIMS model. Concentration duration curves for sodium chloride were derived from flow concentration relationships, representing sodium chloride concentrations to which the aquatic ecosystem had been exposed. The ecological condition was assessed at nineteen sites using SASS5 biotic index over four seasons. Finally, the modelled instream salt concentrations and bioasessments were evaluated in terms of the modelled level of species protection afforded at different salt concentrations. Species Sensitivity Distributions (SSDs) were used for this exercise. There was a general downstream increase in salinity with the minimum concentrations recorded at the Fairbain tributary (84 mg/L) and maximum levels at the sewage outfall in Fort Beaufort (1222 mg/L). There was evidence that citrus irrigation upstream of Fort Beaufort increased salinisation. Sodium chloride, and to a lesser extent magnesium sulphate, were the dominant salts in the Kat River catchment, with the latter being more toxic. However these had little or no impact on the aquatic ecosystem. Flow-derived sodium chloride concentrations showed that both the Balfour and Blinkwater tributaries were in a fair/ poor condition. However with regard to ecological condition, it was demonstrated that the river is generally in a good state except for the Blinkwater River and the lower catchment. Degraded habitat condition at the Blinkwater was responsible for poor ecological condition. Integrating SSD derived classes, sodium chloride classes and ecological condition indicated that sodium chloride is a driver of ecological condition at the sewage treatment works and the subsequent site (only two of nineteen biomonitoring sites).

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No description available.