Environmental science, engineering & technology Technology: general issues 45 History of engineering & technology 27 Science: general issues 13 climate change 10 machine learning 10 Civil engineering, surveying & building 8 adsorption 7 modeling 7 sustainable development 7 artificial intelligence 6 sustainability 6 wastewater 6 water quality 6 COVID-19 5 Sentinel-1 5 circular economy 5 forecasting 5 groundwater 5 kinetics 5 water 5 SAR 4 agriculture 4 biomass 4 deep learning 4 drinking water 4 feature selection 4 heavy metals 4 land use 4 nitrogen 4