Mititgation and Management Strategies for Reducing Eutrophication in Tropical Humid Regions

Extensive growth of algal blooms as a consequence of eutrophication may bring serious health effects to humans including fatalities. Several attempts in reducing the eutrophication or algal blooms in waterbodies have been implemented in past few decades. However, most of the control methods were focused on temperate systems rather than tropical systems. Therefore, this study was aimed to develop a mitigation framework for reducing eutrophication and algal blooms in tropical regions. This work focusses more on humid tropic systems because there is a lack of research resources in this region. The study involved four main work packages: (a) systematic review study to track the available eutrophication control techniques; (b) development of eutrophication framework; (c) assessment of seasonal water quality in Durian Tunggal Reservoir (DT) and Jus Reservoir (Jus); and (d) evaluation of eutrophication management framework using DT and Jus reservoir as case study. The study starts with systematic review study to track the available eutrophication control techniques. Findings from the systematic review were used to develop the eutrophication framework by providing the established method that can be used to mitigate the eutrophication problem. The framework consists of two stages; a pre-selection stage and a selection stage. The pre-selection stage requires the decision maker to evaluate the condition of the waterbody. Meanwhile, the selection stage is where suitable control techniques are suggested based on Multiple Criteria Analysis (MCA). The performance of the framework was demonstrated by using a case study of two reservoirs in Malaysia. The results presented in this thesis show that the framework that is proposed using MCA as a decision support tool allows for the selection of robust investments in eutrophication and algal bloom management. The integration of scenario analysis can provide complementary insights into sustainability and cost efficiency for eutrophication management and policy for developing countries by giving the best available techniques according to the selected criteri

Long term chemical and ecological recovery of Kinghorn Loch (Scotland, UK) following red mud pollution

The estimated global production of red mud, a by-product of alumina production, is ~120 million t per year. Little is known about the long-term chemical, physical and ecological responses in aquatic ecosystems following pollution with red mud. To date, no whole-lake assessment of the impact of red mud and recovery trajectories has been conducted. Kinghorn Loch, Fife, Scotland, is an important example of a red mud polluted aquatic ecosystem. This is due mainly to the availability of long-term data documenting changes in the lake during the pollution and recovery following diversion of red mud leachate in 1983 to date. Long-term data were assessed to determine the time scale of recovery for a range of specific pollutants in the surface waters of Kinghorn Loch, and field surveys and a laboratory controlled experiment were conducted to investigate lake sediment-pollutant interactions and arsenic (As) species bioaccumulation in aquatic plants. Results showed recovery of the lake water column, with a significant decrease of pH and the concentrations of all red mud constituents in surface water since the cessation of pollution. Using generalised additive models the chemical recovery period was 5 years for pH and from 22 to 26 years for As, vanadium (V) and phosphorus (P), with aluminium (Al) still not reaching the end-point recovery following this period. A 12- month field survey showed that concentrations of phosphate (PO4-P), total phosphorus (TP), dissolved and total As and V in lake water varied significantly throughout the year, with depth of overlying water contributing to variation in P concentrations in water above sediment. A range of physico-chemical factors, including dissolved oxygen (DO), pH and concentrations of pollutant binding element controlled seasonal and spatial variations in water column contaminant concentrations. The behaviour of V differed from As and P concentrations in water, with maximum V concentrations occurring in spring and the highest concentrations of As and P in surface water and dissolved As and PO4-P in water above sediment observed in summer. With the exception of V in deeper layers of the water column in spring and winter, observed total As and V concentrations met standards for Protection of Aquatic Life in the UK (50 and 20 μg L-1, respectively). Sediment in Kinghorn Loch is still contaminated 30 years into the lake recovery period. The highest seasonal mean concentrations in the upper (0-4 cm) sediment layer were 231 mg kg-1 for V and 185 mg kg-1 for As, the latter considerably exceeding Canadian Sediment Quality Guidelines for the Protection of Aquatic Life for As (17 mg kg-1). Evidence from the laboratory experiment and the field observations suggests that the lake still processes red mud contaminants, with seasonal mobilisation of As and P from lake sediment under reducing conditions. In contrast, release of V from sediment into overlying water appeared not to be driven predominantly by redox conditions, but instead by interactions between pH, competitive ion concentrations and DO. Higher pollutant concentrations observed throughout the year in deeper layers of the water column compared to surface water indicated that the impact of sediment on the water column is generally confined to the bottom waters of the lake. Macrophytes in Kinghorn Loch contained relatively high concentrations of As, predominantly in the inorganic form which is most toxic to organisms. The highest As content measured in roots of Persicaria amphibia (L.) Gray (40.4 – 218 mg kg-1) greatly exceeded the 3 – 10 mg kg-1 range suggested as a potential phytotoxic level. Accumulation of toxic As species by plants suggested toxicological risk to higher organisms in the food web and indicated that ecological recovery of the lake is still in progress. The results of this research at Kinghorn Loch will help water resource managers to understand not only the environmental and human health effects of multiple pressures related to red mud pollution, but also the likely recovery time scales in relation to water quality targets

Our phosphorus future: towards global phosphorus sustainability

Global food security remains threatened as many farmers struggle to afford sufficient phosphorus fertiliser for their crops. Meanwhile, overuse of fertilisers and sewage pollution pump millions of tonnes of phosphorus into lakes and rivers each year, damaging biodiversity and affecting water quality. This report is a comprehensive global analysis of the challenges and possible solutions to the phosphorus crisis. The report calls on governments across the world to adopt a '50, 50, 50' goal: a 50 per cent reduction in global pollution of phosphorus and a 50 per cent increase in recycling of the nutrient by the year 2050. The report has been written by a team of 40 international experts from 17 countries led by the UK Centre for Ecology & Hydrology (UKCEH) and the University of Edinburgh