The study analysed the spatial and temporal contamination levels of fresh water resources by saline intrusion in the Douala coastal area. Water samples were collected from 19 stations. 3 stations were selected from th...The study analysed the spatial and temporal contamination levels of fresh water resources by saline intrusion in the Douala coastal area. Water samples were collected from 19 stations. 3 stations were selected from the mangrove area and 16 stations were selected from the rest of the area partitioned into four transects (coastal transect, inner transect 1, inner transect 2 and inner transect 3). Sampling was done repeatedly during the wet and dry seasons. They were analyzed for physico-chemical parameters according to the American Public Health Association methods. Geostatistical analysis was used in mapping the water properties. Considerable levels of actual electrical conductivity values (208.91 to 660.63 and 45 to 7540 μS/cm for the wet and dry seasons, respectively);calcium (0.06 to 85 and 4 to 256 mg/L for the wet and dry seasons, respectively);sulphate (0 to 103 and 0 to 99 mg/L for the wet and dry seasons) and total dissolved solids (15.79 to 1467 and 20 to 3750 mg/L for the wet and dry seasons, respectively) were observed for ground water in the study area based on spatio-temporal assessment. From the output grid, it could be deduced that the south eastern region had a hint of salt water intrusion (SWI) contamination of fresh water resources with actual value highs of electrical conductivity (1790 and 820 μS/cm) for the dry and wet seasons, respectively. Calcium highs (140 and 16 mg/L) for the dry and wet seasons were obtained at the central part of the study area. The spatial distribution of calcium highs extends from the central zone of the study area in the dry season and the south eastern zone in the wet season. The southern region is more vulnerable to contamination by calcium ions during this season. An up to date scope for surveillance monitoring and forecasting regarding the deterioration of coastal aquifers is recommended. Modelling of aquifers shifts for the coastal zone should be instituted as a means of ensuring efficient fresh water resources evaluation and utilization. An indepth study of t展开更多
With the establishment of a well-off society in an all-round way,Chinese residents have put forward higher requirements for the quality and safety of fresh agricultural products.In recent years,domestic and foreign ac...With the establishment of a well-off society in an all-round way,Chinese residents have put forward higher requirements for the quality and safety of fresh agricultural products.In recent years,domestic and foreign academic circles have also paid more and more attention to the risk of fresh agricultural product supply chain.This article collects and sorts out the research findings of domestic and foreign scholars on the risk assessment of fresh agricultural product supply chain in recent years,and summarizes and discusses from three aspects:supply chain risk factors,risk assessment indicator selection,and risk assessment methods.It is intended to provide a reference for future new research ideas and research perspectives.展开更多
文摘The study analysed the spatial and temporal contamination levels of fresh water resources by saline intrusion in the Douala coastal area. Water samples were collected from 19 stations. 3 stations were selected from the mangrove area and 16 stations were selected from the rest of the area partitioned into four transects (coastal transect, inner transect 1, inner transect 2 and inner transect 3). Sampling was done repeatedly during the wet and dry seasons. They were analyzed for physico-chemical parameters according to the American Public Health Association methods. Geostatistical analysis was used in mapping the water properties. Considerable levels of actual electrical conductivity values (208.91 to 660.63 and 45 to 7540 μS/cm for the wet and dry seasons, respectively);calcium (0.06 to 85 and 4 to 256 mg/L for the wet and dry seasons, respectively);sulphate (0 to 103 and 0 to 99 mg/L for the wet and dry seasons) and total dissolved solids (15.79 to 1467 and 20 to 3750 mg/L for the wet and dry seasons, respectively) were observed for ground water in the study area based on spatio-temporal assessment. From the output grid, it could be deduced that the south eastern region had a hint of salt water intrusion (SWI) contamination of fresh water resources with actual value highs of electrical conductivity (1790 and 820 μS/cm) for the dry and wet seasons, respectively. Calcium highs (140 and 16 mg/L) for the dry and wet seasons were obtained at the central part of the study area. The spatial distribution of calcium highs extends from the central zone of the study area in the dry season and the south eastern zone in the wet season. The southern region is more vulnerable to contamination by calcium ions during this season. An up to date scope for surveillance monitoring and forecasting regarding the deterioration of coastal aquifers is recommended. Modelling of aquifers shifts for the coastal zone should be instituted as a means of ensuring efficient fresh water resources evaluation and utilization. An indepth study of t
文摘With the establishment of a well-off society in an all-round way,Chinese residents have put forward higher requirements for the quality and safety of fresh agricultural products.In recent years,domestic and foreign academic circles have also paid more and more attention to the risk of fresh agricultural product supply chain.This article collects and sorts out the research findings of domestic and foreign scholars on the risk assessment of fresh agricultural product supply chain in recent years,and summarizes and discusses from three aspects:supply chain risk factors,risk assessment indicator selection,and risk assessment methods.It is intended to provide a reference for future new research ideas and research perspectives.
