Environmental impact Natural Resource Economics, (New March 2000) 17 Tourism and Travel 14 Leisure, Recreation and Tourism Economics, (New March 2000) 12 Pollution and Degradation 12 Sustainability 12 Policy and Planning 11 Economic impact 9 Social Psychology and Social Anthropology, (New March 2000) 9 Case studies 8 Agricultural Economics 7 Land Resources 7 Management 7 Pollution 7 Tourism 7 Ecotourism 6 Plants 6 Social impact 6 Agriculture 5 Tourism impact 5 Water Resources 5 Animal Wastes 4 Aquatic Biology and Ecology 4 Crops 4 Environmental policy 4 Environmental protection 4 Forests 4 Genetic Engineering, Gene Transfer and Transgenics, (New June 2002) 4 Genetically engineered organisms 4 Meteorology and Climate 4