This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn and Fe in a wetland area of southern Guam. The research sites are within an area covered with saporite, a soil type deriv...This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn and Fe in a wetland area of southern Guam. The research sites are within an area covered with saporite, a soil type derived from volcanic deposits on the island. Leaf tissue of Pandanus tectorius was extracted and analysed to determine the bioaccumulation of the target metals. Metal accumulation at sites considered aerobic and anaerobic was investigated together with an attempt to correlate actual accumulation of the target metals in the plant tissue with a recognised bioavailability indicator, in this case, three step sequential extraction scheme. Manganese was found to be accumulated in relatively high concentrations and to a lesser extent Cu was also accumulated. Chromium, Ni and Fe however exhibited very low accumulation factors. Accumulation of Mn in particular was significantly affected by aerobic conditions whereas the converse effect was experienced by Cu. Significant correlation between various steps of a Sequential Extraction Scheme and actual accumulation was not achieved although the degree of aerobic conditions at each site and soil pH did affect concentrations of metals extracted by differing steps of SES. Results obtained suggest that further research in the area should be undertaken using different plant species and tissues.展开更多
The soils of southern Guam are formed from very deep;well-drained Saprolite derived from volcanic based tuff and tuff breccias.These soils suffer severe erosion as the result of rapid overland flow,wind and intensive ...The soils of southern Guam are formed from very deep;well-drained Saprolite derived from volcanic based tuff and tuff breccias.These soils suffer severe erosion as the result of rapid overland flow,wind and intensive rain events typical of southern Guam.An integrated approach to control the accelerated soil erosion was designed to include conservation tillage,crop rotation with leguminous plant,and residue management for soil surface cover.The objectives of this study are;1)to evaluate the use of crop rotation and tillage management for increasing organic-matter content to improve the overall quality of these severely eroded soils,2)to evaluate the effect of conservation practices on harvested yield and crop productivity of these eroded soils and,3)to assess the effects of conservation techniques including no-tillage systems on water runoff and infiltration.This paper discusses the effect of conservation strategies and techniques on these severely eroded soils of southern Guam.展开更多
【目的】对比分析海水和淡水养殖关岛红罗非鱼的品质特性和营养成分,为红罗非鱼配合饲料研制和罗非鱼肉质产品深加工提供参考依据。【方法】采用国家相关检测标准的生物化学方法和质构仪对海水养殖和淡水养殖关岛红罗非鱼肌肉的一般营...【目的】对比分析海水和淡水养殖关岛红罗非鱼的品质特性和营养成分,为红罗非鱼配合饲料研制和罗非鱼肉质产品深加工提供参考依据。【方法】采用国家相关检测标准的生物化学方法和质构仪对海水养殖和淡水养殖关岛红罗非鱼肌肉的一般营养成分、氨基酸、脂肪酸及质构特性进行测定和分析,并评价两种养殖模式下关岛红罗非鱼肌肉的营养价值。【结果】海水养殖关岛红罗非鱼肌肉的咀嚼性(12.63 m J)及水分(79.83%)、粗脂肪含量(1.29%)显著高于淡水养殖模式(7.74 m J、77.84%和1.05%)(P<0.05,下同),粗蛋白含量(18.13%)显著低于淡水养殖模式(20.46%)。海水和淡水养殖的关岛红罗非鱼肌肉均检测出17种氨基酸,必需氨基酸含量分别占其氨基酸总量的41.30%和41.38%,必需氨基酸与非必需氨基酸的比值(EAA/NEAA)分别为70.36%和70.59%,均符合联合国粮农组织/世界卫生组织(FAO/WHO)的评价标准,必需氨基酸指数(EAAI)分别为92.43和86.30。海水养殖模式下关岛红罗非鱼的脂肪酸总量、饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸含量均显著高于淡水养殖模式。【结论】两种养殖模式下的关岛红罗非鱼均具有较高营养价值,其中海水养殖模式下的关岛红罗非鱼在口感和营养价值方面优于淡水养殖模式,可作为主要养殖模式进行推广。展开更多
文摘This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn and Fe in a wetland area of southern Guam. The research sites are within an area covered with saporite, a soil type derived from volcanic deposits on the island. Leaf tissue of Pandanus tectorius was extracted and analysed to determine the bioaccumulation of the target metals. Metal accumulation at sites considered aerobic and anaerobic was investigated together with an attempt to correlate actual accumulation of the target metals in the plant tissue with a recognised bioavailability indicator, in this case, three step sequential extraction scheme. Manganese was found to be accumulated in relatively high concentrations and to a lesser extent Cu was also accumulated. Chromium, Ni and Fe however exhibited very low accumulation factors. Accumulation of Mn in particular was significantly affected by aerobic conditions whereas the converse effect was experienced by Cu. Significant correlation between various steps of a Sequential Extraction Scheme and actual accumulation was not achieved although the degree of aerobic conditions at each site and soil pH did affect concentrations of metals extracted by differing steps of SES. Results obtained suggest that further research in the area should be undertaken using different plant species and tissues.
文摘The soils of southern Guam are formed from very deep;well-drained Saprolite derived from volcanic based tuff and tuff breccias.These soils suffer severe erosion as the result of rapid overland flow,wind and intensive rain events typical of southern Guam.An integrated approach to control the accelerated soil erosion was designed to include conservation tillage,crop rotation with leguminous plant,and residue management for soil surface cover.The objectives of this study are;1)to evaluate the use of crop rotation and tillage management for increasing organic-matter content to improve the overall quality of these severely eroded soils,2)to evaluate the effect of conservation practices on harvested yield and crop productivity of these eroded soils and,3)to assess the effects of conservation techniques including no-tillage systems on water runoff and infiltration.This paper discusses the effect of conservation strategies and techniques on these severely eroded soils of southern Guam.
文摘【目的】对比分析海水和淡水养殖关岛红罗非鱼的品质特性和营养成分,为红罗非鱼配合饲料研制和罗非鱼肉质产品深加工提供参考依据。【方法】采用国家相关检测标准的生物化学方法和质构仪对海水养殖和淡水养殖关岛红罗非鱼肌肉的一般营养成分、氨基酸、脂肪酸及质构特性进行测定和分析,并评价两种养殖模式下关岛红罗非鱼肌肉的营养价值。【结果】海水养殖关岛红罗非鱼肌肉的咀嚼性(12.63 m J)及水分(79.83%)、粗脂肪含量(1.29%)显著高于淡水养殖模式(7.74 m J、77.84%和1.05%)(P<0.05,下同),粗蛋白含量(18.13%)显著低于淡水养殖模式(20.46%)。海水和淡水养殖的关岛红罗非鱼肌肉均检测出17种氨基酸,必需氨基酸含量分别占其氨基酸总量的41.30%和41.38%,必需氨基酸与非必需氨基酸的比值(EAA/NEAA)分别为70.36%和70.59%,均符合联合国粮农组织/世界卫生组织(FAO/WHO)的评价标准,必需氨基酸指数(EAAI)分别为92.43和86.30。海水养殖模式下关岛红罗非鱼的脂肪酸总量、饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸含量均显著高于淡水养殖模式。【结论】两种养殖模式下的关岛红罗非鱼均具有较高营养价值,其中海水养殖模式下的关岛红罗非鱼在口感和营养价值方面优于淡水养殖模式,可作为主要养殖模式进行推广。
