Emissions from cargo unloading and handling activities in sea ports can be of special importance, particularly in case of proximity to dense urban populations. In this sense, the main purpose of this work was to develop and implement a set of technical solutions intended to reduce the emissions and dispersion of particles resulting from scrap-metal handling on one of the most important Portuguese sea ports.The analysis of the atmospheric flow within the discharging berth was carried out in the Wind Tunnel Laboratory of the Department of Environment and Planning, at the University of Aveiro (Portugal). Laser sheet and hot wire anemometry techniques were applied. Two possible solutions were proposed, consisting in the use of windbreaks located upwind of the scrap-metal piles and a barrier of containers positioned downwind. Both flow visualisation and velocity-measuring techniques confirm a higher efficiency in the reduction of suspended particulate matter by using the containers plus the windbreaks. This combined solution is responsible for an important reduction on the emissions from the scrap-metal piles under typical meteorological conditions for this area, offering a good compromise between cost, time needed for implementation and efficiency. 相似文献
In this study, the marine microalgae Skeletonema costatum and Nitzschia closterium were exposed to different forms of copper, such as a metal salt (Cu2+), a nano-metal (nano-Cu), and nano-metal oxide (nano-CuO). During a 96-h exposure to nanoparticles (NPs) and salt, the cell number, Cu2+ concentration in the culture medium, morphology, and intracellular amino acids were measured to assess the toxicity of the copper materials and the toxicity mechanism of the NPs. As results, the toxicity of Cu2+, nano-Cu, and nano-CuO to marine phytoplankton decreased in order. The EC50 values of Cu2+ and nano-Cu for S. costatum and N. closterium ranged from 0.356 to 0.991 mg/L and 0.663 to 2.455 mg/L, respectively. Nano-Cu inhibits the growth of marine phytoplankton by releasing Cu2+; however, nano-CuO is harmful to microalgae because of the effect of NPs. The secretion of extracellular polymeric substances by microalgae could also affect the toxicity of nano-Cu and nano-CuO to microalgae. S. costatum was more sensitive to copper than N. closterium. Cu2+, nano-Cu, and nano-CuO all reduced per-cell amino acids and the total output of algae-derived amino acids by affecting the growth of the phytoplankton. This study helps to understand the risk assessment of nano-Cu and nano-CuO to marine microalgae.
Environmental Science and Pollution Research - As one of the main food crops in the world, the yield of maize directly affects the food security of the world. The optimization of irrigation and... 相似文献
