PREDICTING IMPACTS FROM WATER CONSERVATION AND ENERGY DEVELOPMENT ON THE SALTON SEA,CALIFORNIA1

ABSTRACT: An input-output model was developed to predict changes in Salton Sea salinity and water level until the year 2000 due to proposed water conservation efforts and geothermal and solar pond energy developments. The model SALINP provided good agreement with the observed salinities for 1960–80. While SALINP was not overly sensitive to one-year changes in any of the major inputs, a change in the historical means of the Imperial Valley runoff and evaporative loss inputs produced a significant effect on future predictions. The proposed water conservation measures caused the predicted Salton Sea salinity for 2000 to greatly exceed 40,000 ppm, the level at which adverse effects to wildlife are believed to occur. The possible geothermal development also produced predicted salinities considerably above 40,000 ppm. The salinity predictions for solar ponds by themselves and in conjunction with geothermal development were below 45,000 ppm for 2000. The solar pond and geothermal combination also resulted in a predicted lowering of the “natural” water level by 5 to 7 feet by 2000.     

南昌市名特优农产品生产基地布局规划

本文通过对南昌市名特优农产品资源、生产现状和市场条件的综合分析，确立了发挥地区资源优势，重点发展的名特优农产品，并进行了科学合理的规划和布局。     

FACTORS AFFECTING HERBICIDE YIELDS IN THE CHESAPEAKE BAY WATERSHED,JUNE 19941

ABSTRACT: Median concentrations and instantaneous yields of alachlor, metolachlor, atrazine, cyanazine, and simazine were generally highest at sites in the Lower Susquehanna River Basin and in agricultural subbasins. Instantaneous herbicide yields are related to land use, hydrogeologic setting, streamflow yield, and agricultural row cropping practices. The significance of these relations may be affected by the interdependence of the factors. The percentage of basin area planted in corn is the most influential factor in the prediction of herbicide yield. Instantaneous yields of all five herbicides measured in June 1994 related poorly to averaged 1990–94 herbicide use. Annually averaged herbicide-use data are too general to use as a predictor for short-term herbicide yields. An evaluation of factors affecting herbicide yields could be refined with more-current land use and land cover information and a more accurate estimate of the percentage of basin area planted in corn. Factors related to herbicide yields can be used to predict herbicide yields in other basins within the Chesapeake Bay watershed and to develop an estimate of herbicide loads to Chesapeake Bay.     

基于岭估计的青海省东部农业区ET_0遥感反演研究

论文利用青海东部农业区内的12个气象站2003—2005年气象资料,应用Penman-Monteith公式计算得到各站逐旬的ET_0值,并进一步研究其与高程(DEM)、地表温度(LST)及归一化植被指数(NDVI)3个因子之间的关系,提取遥感数据并耦合到时间分辨率为旬,空间分辨率为1 km,将其与计算所得ET_0建立多元反演模型。由于3个自变量因子之间存在着很强的相关关系,LST与NDVI间判定系数R2平均在0.7左右,不能直接用最小二乘回归方法建立模型。为有效避免自变量间相关性对模型的影响,研究中采用岭估计方法建模。结果表明,通过岭估计建立2003年10~33旬区域二元模型反演最低精度达76.19%,区域三元模型反演最低精度也有83.54%。与传统方法所建模型相比,检查点均方根误差减小约1.1,反演最低精度提高11%左右,能满足实际应用需求。     

农业区旱地垂直剖面土壤中重金属赋存形态与生态风险评价

用ICP-OES测定了厦门市农业区某旱地垂直剖面土壤中10种重金属元素的含量,并用改进的BCR四步连续提取法分析了垂直剖面土壤中6种重金属的赋存形态。结果表明,剖面土壤中Cd富集较严重,Pb主要以还原态为主,而Mn、Cu、Fe、V、Zn主要以残渣态存在;重金属生物有效性系数排序为Pb(0.514)Mn(0.398)Cu(0.221)Fe(0.165)V(0.100)Zn(0.059 7),Pb和Mn的生物有效性较高,对环境存在较大的潜在生态危害。次生相与原生相分布比值法对重金属潜在生态风险评价的结果表明,Co、Zn、Fe、V、Cu和Mn处于无污染水平,Pb处于中度污染水平。潜在生态危害指数表明,垂直剖面土壤中潜在生态危害顺序为CdCuPbCrZn,Cd的生态危害系数对多元素综合潜在生态风险的贡献最大,即Cd表现为首要的潜在生态风险因子。     

Trace elements in sediments in a city with agricultural development

The objective of this study was to determine the concentrations of trace elements in sediment samples taken from impermeable urban areas of a city with predominantly agroindustrial development characteristics. For this, samples were taken every month from paved streets in the city of Toledo, Paraná State (PR), Brazil. Thus, trace element levels were obtained through analysis performed by optical emission spectrometry with inductively coupled plasma. Levels of total organic carbon were also obtained through the dry combustion method. When compared to local background levels, the trace element levels were shown to be enriched in the following percentage proportions: barium (Ba) (45.4%), copper (Cu) (48.6%), chromium (Cr) (37.2%), manganese (Mn) (81.6%), nickel (Ni) (0%), lead (Pb) (40%), zinc (Zn) (283.7%), magnesium (Mg) (34.3%), and sodium (Na) (250.2%), whereas the carbon (C) percentages were around 1%. The most significant enrichment factors occurred for Ba, Cr, Pb, Zn, Mg, and Na. The highest rates occurred in geoaccumulation where the sediments were enriched by zinc. According to the principal guidelines, the concentrations obtained for cadmium (Cd), Cr, Cu, Ni, and Zn can cause adverse environmental impacts.     

湛江市农业土壤与作物铬含量及其健康风险

在湛江市采集了106个农业土壤表层样品和43个农作物样品,分析了土壤和农作物中铬的含量,研究铬的分布特征和富集能力,评价其健康风险。结果表明:土壤中铬平均含量为87.13mg/kg,超过国家土壤二级标准的样品占20.75%,徐闻、雷州等地超标较严重。湛江市种植面积及产量最大的4大类农作物蔬菜、水果、甘蔗和水稻铬平均含量介于0.014～0.160mg/kg之间,均符合我国《食品中铬限量卫生标准》(GB 14961-1994)。蔬菜类的芥菜铬的富集能力相对较强,青瓜、菜心、生菜等蔬菜品种和菠萝、香蕉、橙子、甘蔗等水果类铬的富集能力则较低;水稻铬的富集能力容易受土壤复合污染影响,富集系数介于0.0001～0.0048。依据中国营养学会推荐的RfD值和广东省居民平均食物消费结构进行计算,湛江市蔬菜、水稻和水果(含甘蔗)三大类作物通过土壤-植物-人体途径日平均摄入量为78.9μg/d,若考虑其它的摄入途径,农产品中的铬对人体潜在一定的健康风险。     

工程菌生物强化处理高浓度农药废水的试验研究

利用悬浮生物废水处理系统及固定化菌体废水处理系统,对预处理后的高浓度农药废水进行了生化处理的试验研究。在最佳工艺条件下运行,固定化菌体处理系统COD去除率可达96.8%,出水COD降至208mg/L,满足排放要求。     

资源和环境约束下的城市产业结构优化——以徐州市为例

徐州在传统工业化进程中取得了较大进展,但也存在着较大问题。徐州需要加快实现工业化进程的路径转换,坚定走新型工业化道路。应当寻求工业化与信息化互动的结合点和切入点;推进产业结构优化升级;强化科技创新和扩大对外开放。要牢固确立新的发展观,切实转变经济增长方式,大力发展循环经济,加强环境保护和生态建设,营造一流人居环境。按照新型工业化的要求,实现徐州城市的可持续发展。     

基于能值理论的福建省农业系统动态研究

运用能值理论和方法,对福建省农业系统1981～2004年的能值投入和产出以及能值使用强度、能值货币比率、净能值产出率等9个指标24年来的变化趋势进行了分析。结果表明,24年来能值总投入和总产出都有较大增长;能值使用强度、能值投资率、能值生产率、系统优势度、环境承载力不断上升,表明农业系统经济开发程度不断提高,生产效益已远超过全球平均水平,农产品具有明显价格竞争优势,农业系统结构有所优化,同时对环境资源的压力也有所增大;能值货币比率和能值可持续发展指数不断下降,系统稳定度略有下降,表明由于农业系统集约化程度增强及开发强度加大,系统可持续性和稳定性有所降低。将各能值指标与其他地区比较,福建省农业生产的资源环境条件较为优越,农业系统生产环境仍处于较为良好状态。