Search results
- Title
- Wetland ecological risk assessment and management
- Contributors
- Ge Xu (author), Jianbing Li (thesis advisor), University of Northern British Columbia (Degree granting institution), Min Zhao (committee member), Ron Thring (committee member)
- Abstract
- Based on the traditional framework of wetland ecological risk assessment, this thesis proposed a new method by considering two major pollution types faced by wetlands, including heavy metal pollution and water eutrophication. Artificial neural network (ANN) method was applied to evaluate the eutrophication risk level, while an improved potential ecological risk index was used to estimate the risk of heavy metals in surface sediments. Then, Fuzzy set theory was used to combine the two risk levels to obtain a general risk level, which could be used for recommending appropriate risk management actions. The Sanyang Wetland in Wenzhou, China was used as a case study to demonstrate the proposed wetland ecological risk assessment method. This thesis indicated that the new framework of wetland ecological assessment could provide a risk level of objectives and give corresponding suggestions to decision making.
- Discipline
- NRES-Environmental Science
- Date added
- 2019-03-28T22:18:26.13Z
- Title
- Multi-layer perceptron - markov chain based geospatial analysis of land use and land cover change
- Contributors
- Lei Shen (author), Jianbing Li (thesis advisor), University of Northern British Columbia College of Science and Management (Degree granting institution), Roger Wheate (committee member), Jun Yin (committee member)
- Abstract
- This thesis study analyzed the land use and land cover (LULC) changes in Stoney Creek Watershed, BC, Canada using the combination of remote sensing, GIS and modeling approaches. The Object-Based Image Analysis (OBIA) tool in PCI Geomatica 2017 software was applied to generate unsupervised classification LULC maps using Landsat TM and OLI images of the years 1986, 1999 and 2016. Various band ratio were computed to improve different classification results. Esri ArcMap 10.5 was used to produce all the LULC maps for subsequent modeling. A modeling method using Multi-layer perceptron (MLP) neural network and Markov Chain (MC) was performed to predict LULC changes in 2026, using hard and soft prediction results. The outcomes of this study could provide valuable information of LULC patterns and dynamics for supporting both environmental and economic development in this area.
- Discipline
- NRES-Environmental Science
- Date added
- 2019-07-09T18:39:10.427Z
- Title
- Novel treatment and value-added utilization of oily sludge using ionic liquid and pyrolysis
- Contributors
- Yuan Tian (author), Jianbing Li (thesis advisor), Todd Whitcombe (committee member), Ron Thring (committee member), William McGill (committee member), Liang Chen (committee member)
- Abstract
- The effective treatment of oily sludge has been a challenging problem faced by the petroleum industry worldwide. It is a semi-solid mixture of hydrocarbons, water, metallic ions, and suspended fine solids. The recalcitrant nature of oily sludge makes the treatment a difficult and costly task. The objective of this dissertation research was to develop environmentally friendly and economically competitive techniques for oily sludge treatment. Three different approaches were developed: ionic liquid (IL)-enhanced solvent extraction, co-pyrolysis with wood waste, and value-added utilization of oily sludge as sorbent to remove lead (Pb2+) and cadmium (Cd2+) from solution. Firstly, as compared to conventional solvent extraction, the IL-enhanced solvent extraction not only improved oil recovery efficiency but also greatly reduced solvent and energy consumption as well as shortening the treatment duration even at low IL concentration. Secondly, co-pyrolysis of oily waste and hog fuel was conducted in a fixed bed reactor. Three experimental parameters (pyrolysis temperature, reaction time, and hog fuel addition) were explored to optimize both oil recovery and metal ion immobilization. The latter was tested through sequential extraction techniques with high temperature pyrolysis leading to metal ions fixed within the residues. The addition of hog fuel had a significant synergistic effect on the distribution of metal ions in the various extraction fractions resulting in lower risk index (RI) values. Thirdly, the oily sludge-derived char (OS500) obtained at 500 °C could effectively remove Pb2+ from solution with the maximum sorption capacity of 373.2 mg/g (based on a Langmuir model). Sorption of Pb2+ by the OS500 was mainly attributed to its precipitation with carbonate (CO32‒) originating in OS500. The maximum sorption capacity for Cd2+, using a Langmuir model, was 23.19 mg/g. Complexation and metal ion exchange dominated Cd2+ sorption on OS500. The Pb2+ sorption capacity dramatically decreased as the iii pyrolysis temperature increased from 500 to 900 °C due to the decomposition of minerals which could release CO32‒ at high temperature. The activated OS500 showed a higher sorption capacity (90.06 mg/g) for Cd2+ than OS500 (23.95 mg/g) because conversion of barite (BaSO4) to witherite (BaCO3) after chemical activation favored the precipitation of Cd-carbonate.
- Discipline
- Natural Resources & Environmental Studies
- Date added
- 2019-12-19T23:01:08.966Z