基于MODIS模拟的辽东湾叶绿素a的遥感反演模型

叶绿素a浓度对于水质和富营养化评价、赤潮探测及海洋生产力研究有重要意义.利用卫星遥感反演获取叶绿素a浓度弥补了传统采样方法的数据离散化、耗时长且费用高的缺陷,可以实时和全面地观测大尺度海洋叶绿索a分布.通过实测光谱模拟卫星波段,可以在一定程度上削除大气干扰,有助于准确地确定特征波段和建立遥感反演模型.本文以辽东湾为研究区,利用现场实测光谱模拟了MODIS波段,并在光谱特征分析基础上进行叶绿素a的特征波段选择,通过比较单波段和波段比值法等算法,建立了2个具有区域特色的叶绿素a遥感反演模型,并进行了模型验证.结果表明:在辽东湾海域,运用红光附近特征波段667和678 nm来反映叶绿素特征比传统蓝绿光波段(440和550nm)似乎更能削弱其它水体组分的干扰,突出辽东湾水体的特点.利用667、678和551nm的三波段模型要比单纯考虑667和678nm波段比值的模型要好一些,该模型r为0.856,标准差为0.190.模型验证预测值和实测值的相关系数为0.93(p<0.01),表明了模型良好的预测能力.模型具有明显的区域特色,结果是否具有普适性,还需进一步验证.     

公共资源可持续利用的微观影响因素分析

草地被称为世界性的公共资源。以往对于草地退化的关注多侧重在技术研究和推广上。为揭示微观行为对公共资源利用的影响,以寻求有效途径保护具有重要生态战略意义的草地资源,论文利用2005年西部6省区17县231个农户数据以及2006和2007年环青海湖地区的实地调查经验,采用农户模型和计量分析方法,研究现有产权制度下牧民的草地管理行为对草地资源退化的影响。结果表明,牧民参与非农就业、扩大牧户的草场规模以及进行围栏和舍棚建设有利于减轻草场的退化。据此,提出以下政策建议:目前政府提供围栏和舍棚建设方面的相关政策扶持,同时,制定有利于牧民参与非农就业机会的政策,降低牧区的人口压力,可有效促进草地公共资源的可持续利用。     

基于ANN分类的农田遥感动态监测模型研究

保护基本农田是我国农业可持续发展的基础和前提,动态监测基本农田在时间和空间上的变化能够为农业开发政策的制定,农业经济发展的规划与管理提供有效的辅助决策手段。论文利用人工神经网络的BP算法实现了对两个时期的遥感影像进行基本农田类型的分类提取,在保证精度的前提下,探索了一条把单要素监测和多要素监测相结合的遥感动态监测模型,并详细描述了模型实现的算法与步骤。最后利用该模型对实验区进行了监测,并对监测结果进行了分析,结果表明模型很好地评估了研究区基本农田的数量和发展潜力,定性、定量、定位地揭示了研究区基本农田类型在时空上的变化规律。     

基于复配胶团的强化超滤处理含镉废水

在胶团强化超滤法(MEUF)水处理中,为减少表面活性剂十二烷基硫酸钠(SDS)用量,降低渗透液二次污染,采用非离子表面活性剂十二烷基聚氧乙烯(23)单醚(brij35)、辛基酚聚氧乙烯(9)醚(Tritonx-100)与SDS分别复配,考察了复配情况下表面活性剂胶团特性参数的变化规律,对2种复配胶团的强化超滤过程进行了比较.结果表明,MEUF处理含镉废水时,brij35、Tritonx-100均对体系具有良好的复配效应.从对Cd2+的截留率看,当复配摩尔比<0.5时,brij35的复配效应优于Tritonx-100;当复配比>0.5时,两者的复配效应接近.从降低渗透液中表面活性剂的残留量和保持较高的渗透通量、较小的膜污染阻力3方面考虑,采用Tritonx-100复配优于brij35.     

矿山开采沉陷可视化系统设计开发及岩移参数求取

依据矿山开采沉陷相关理论,以概率积分法数学模型为基础、运用基于实测数据求参原理与方法,结合相关软件设计开发了矿山开采沉陷可视化系统。为研究矿区地表移动变形分布及岩移参数求取提供了技术支持。结合系统应用实例,利用地表观测数据拟合求参,对该矿其他工作面及类似地质条件矿区开采沉陷预计提供借鉴作用。     

北京市典型溶剂使用企业VOCs排放成分特征

通过罐采样-GC-MS/FID采集及分析系统,测定了北京市工业区内典型溶剂使用企业挥发性有机物(VOCs)的排放成分.结果表明:在汽车喷涂企业中,芳香烃(22%~55%)和烷烃(13%~44%)是重要的VOCs排放组分,印刷企业排放的主要组分为烷烃(43%~71%)和含氧VOCs(17%~19%),电子光刻企业排放的特征组分是丙酮(10%~18%),但不同电子光刻企业VOCs其它组分比例相差较大;企业中采用的VOCs处理装置对VOCs排放组成有重要影响;与已有研究的源谱比较,印刷行业源谱较相似,主要以烷烃为主,也有部分芳香烃.汽车喷涂行业的源谱有很大变化,可能是由于汽车涂料成分改变而造成.     

Comparing the adsorption behaviors of Cd,Cu and Pb from water onto Fe-Mn binary oxide,MnO2 and FeOOH

The adsorption potential of FMBO, FeOOH, MnO₂ for the removal of Cd²⁺, Cu²⁺ and Pb²⁺ in aqueous systems was investigated in this study. Comparing to FMBO and FeOOH, MnO₂ offered a much higher removal capacity towards the three metal ions. The maximal adsorption capacity of MnO₂ for Cd²⁺, Cu²⁺ and Pb²⁺ were 1.23, 2.25 and 2.60 mmol·g^-1, respectively. And that for FMBO were 0.37, 1.13, and 1.18 mmol·g^-1 and for FeOOH were 0.11, 0.86 and 0.48 mmol·g^-1, respectively. The adsorption behaviors of the three metal ions on the three adsorbents were all significantly affected by pH values and heavy metal removal efficiency increased with pH increased. The Langmuir and Freundlich adsorption models were used to describe the adsorption equilibrium of the three metal ions onto the three adsorbents. Results showed that the adsorption equilibrium data fitted well to Langmuir isotherm and this indicated that adsorption of metal ions occurred on the three metal oxides adsorbents limited to the formation of a monolayer. More negative charged of MnO₂ surface than that of FMBO and FeOOH could be ascribed by lower pH_iep of MnO₂ than that of FMBO and FeOOH and this could contribute to more binding sites on MnO₂ surface than that of FMBO and FeOOH. The higher metal ions uptake by MnO₂ than FMBO and FeOOH could be well explained by the surface charge mechanism.     

Species distribution of arsenic in sediments after an unexpected emergent discharge of high-arsenic wastewater into a river

The unexpected emergent discharge of high-arsenic wastewater into water environments results in significantly increased levels of arsenic in water; however, the species distribution of arsenic in sediments has never been reported before for such cases. This study focuses on an As pollution accident in the Dasha River, and uses sequential extraction procedures with deionized water, 1?mol·L^-1 MgCl₂ at pH= 8, 1?mol·L^-1 NaH₂PO₄ at pH= 5, and 1?mol·L^-1 HCl to investigate four binding phases of arsenic (i.e., water soluble, ion-exchangeable, strongly-bound, and precipitates) in sediments at different layers in different cross-sections along the river. The average ratio of arsenite (As(III)) to arsenate (As(V)) was found to decrease from 0.74:1 in river water to 0.48:1 in sediment, owing to its higher affinity toward As(V) than As(III). The content of arsenic in the sediments was relatively low and the maximum content was observed to be 36.3?mg·kg^-1 for As(III) and 97.5?mg·kg^-1 for As(V). As(III) and As(V) showed different binding phases in sediments, and the average fractions of these four species were determined to be 0.09, 0.11, 0.17, and 0.63 for As(III) and 0.03, 0.14, 0.63, and 0.20 for As(V), respectively. For all the sediment samples, the content of arsenic showed no relationship with the characteristics of the sediments such as the particle diameter, the content of organic carbon, Fe, and Mn, although a negative correlation with particle diameter was observed for the sediments in the uppermost 2-cm layer. The unexpected emergent As incident results in the high content of total arsenic in the surface sediment, which may be potential secondary source to the elevated As levels in surface water.     

陕西省苹果花期冻害风险评估及预测技术研究

苹果花期冻害风险评估及预测对促进苹果产业合理规划布局,减轻气象灾害损失有十分重要的意义。以冻害风险灾损率为指标,对陕西苹果基地县的冻害发生风险进行了评估,开发了基于数值预报模式和G IS技术的花期冻害中短期预测模型,将冻害温度预报扩大到乡镇级并实现了业务化解释应用。     

高液限土路堤直接填筑质量控制参数研究

为减小高液限土弃方处理或改良填筑造成的经济损失,通过室内试验研究了高液限土的基本特性,并结合现场路填筑试验,研究了其直接填筑性能和相应的质量控制参数。研究结果表明:高液限粘土和含砂高液限粘土可用于路堤直接填筑,填筑质量宜通过含水率、压实度、空气率3个参数控制;填筑过程中含水率应满足-2%≤ω-ωop≤6%;填筑碾压后的压实度应大于90%;高液限粘土空气率控制范围为4%≤va≤8%,含砂高液限粘土空气率控制范围为va≤13%。