Hyperspectral Characteristics of Canopy Components and Structure for Phenological Assessment of an Invasive Weed

Spectral reflectance values of four canopy components (stems, buds, opening flowers, and postflowers of yellow starthistle (Centaurea solstitialis)) were measured to describe their spectral characteristics. We then physically combined these canopy components to simulate the flowering stage indicated by accumulated flower ratios (AFR) 10%, 40%, 70%, and 90%, respectively. Spectral dissimilarity and spectral angles were calculated to quantitatively identify spectral differences among canopy components and characteristic patterns of these flowering stages. This study demonstrated the ability of hyperspectral data to characterize canopy components, and identify different flowering stages. Stems had a typical spectral profile of green vegetation, which produced a spectral dissimilarity with three reproduction organs (buds, opening flowers, and postflowers). Quantitative differences between simulated flower stages depended on spectral regions and phenological stages examined. Using full-range canopy spectra, the initial flowering stage could be separated from the early peak, peak, and late flowering stages by three spectral regions, i.e. the blue absorption (around 480 nm) and red absorption (around 650 nm) regions and NIR plateau from 730 nm to 950 nm. For airborne CASI data, only the red absorption region and NIR plateau could be used to identify the flowering stages in the field. This study also revealed that the peak flowering stage was more easily recognized than any of the other three stages.     

The dynamic changes of arsenic biotransformation and bioaccumulation in muscle of freshwater food fish crucian carp during chronic dietborne exposure

Dietary uptake is the major way that inorganic arsenic (iAs) enters into benthic fish; however, the metabolic process of dietborne iAs in fish muscle following chronic exposure remains unclear. This was a 40-day study on chronic dietborne iAs [arsenite (AsIII) and arsenate (AsV)] exposure in the benthic freshwater food fish, the crucian carp (Carassius auratus), which determined the temporal profiles of iAs metabolism and toxicokinetics during exposure. We found that an adaptive response occurred in the fish body after iAs dietary exposure, which was associated with decreased As accumulation and increased As transformation into a non-toxic As form (arsenobetaine). The bioavailability of dietary AsIII was lower than that of AsV, probably because AsIII has a lower ability to pass through fish tissues. Dietary AsV exhibited a high potential for transformation into AsIII species, which then accumulated in fish muscle. The largely produced AsIII considered more toxic at the earlier stage of AsV exposure should attract sufficient attention to human exposure assessment. Therefore, the pristine As species and exposure duration had significant effects on As bioaccumulation and biotransformation in fish. The behavior determined for dietborne arsenic in food fish is crucial for not only arsenic ecotoxicology but also food safety.     

环氧丙烷生产废液中1,2 -二氯丙烷的回收

介绍了从环氧丙烷生产废液中回收1,2-二氯丙烷的新方法。采用常压精馏、减压精馏、共沸精馏工艺分离环氧丙烷生产废液中的1,2-二氯丙烷。实验结果显示,共沸精馏工艺的效果最好;在含有一定量的共沸剂、釜温100℃、顶温86℃、回流比为1的条件下,塔顶馏分中1,2-二氯丙烷的质量分数可达到98％以上,1,2-二氯丙烷的回收率可达到97％以上。     

新型聚硅氯化铁铝絮凝剂的制备及性能

以二甲基二氯硅烷为硅源,与氯化铁、氯化铝聚合制得新型的聚硅氯化铁铝（PSFAC）絮凝剂,考察了制备条件及PSFAC对含油废水和药厂废水的絮凝效果。制备PSFAC的最佳条件：nFc：nAl为0．4,nSi：n（Al＋Fe）为0．1,碱化度为2．0,C（Al,Fe）、为0．1mol／L,熟化时间为1-2d。当PSFAC加入量为10mg／L时,对含油废水、药厂废水的浊度去除率分别为84％和86％。PSFAC具有加入量少、沉降速度快、适用的pH范围较宽等优点。     

冬季动态槽式堆肥温度的空间变异

以鲜鸡粪、蘑菇渣和污泥按照体积比3∶1∶1混合进行动态堆肥模拟试验.堆肥槽沿物料前进方向分为7个部分,对每个部分按等间距分别做5个水平方向上切分和5个垂直方向上切分,在形成的125个交叉点上进行温度监测.研究结果表明,第1天的混合物料温度在同一层中变异很小,不同层之间略有差异.随着动态过程的进行,同一层温度变异逐渐增大,从第一天相差1～3℃,增加到相差30～40℃,靠近墙体的堆料温度较低,远离墙体的温度较高.随着堆肥时间延长,差异增大.机械翻堆能起到通风的作用,同时使每一个堆方的堆料在纵向方向上上下混合,但达不到横向混匀,因此,靠近墙体两侧的堆料始终处于较低的温度,只有中部能达到较高的温度,以堆肥温度50℃作为无害化指标,自墙体向中心方向的1m为没有达到无害化厚度,无害化体积占堆肥总体积50%.整个动态堆肥过程符合二级动力学方程.     

土地利用/覆盖变化对长江上游非点源污染影响研究

在国内外相关研究的基础上,利用输出系数模型,结合RS和GIS技术,对长江上游的非点源污染负荷进行了空间模拟和负荷估算.模拟结果表明,在不考虑流域损失的前提下,由于土地利用造成的非点源污染负荷TN总量从20世纪70年代的123万t下降至2000年的116万t,基本呈逐年减少的趋势,由土地利用造成的TP的变化趋势与TN基本相同,从70年代的3.7万t下降到2000年的3.5万t左右.就省份、土地利用类型和水系而言,四川省、种植用地和草地以及金沙江水系和嘉陵江水系对长江上游的非点源污染贡献较大.在非点源污染负荷强度上,重庆市和嘉陵江水系单位面积负荷最高,是今后应重点治理的地区.结果表明,该模型可以对长江上游这样的超大尺度空间的非点源污染进行较好的空间模拟.     

污染物零排放的化石燃料燃烧系统

介绍了熔融盐循环热载体无烟燃烧技术(nonflame combustion technology usingthermal cyclic carrier of molten salt,简称NFCT).利用沉淀法制备了Fe2O3粉末,并通过机械法加工成氧载体.XRD分析表明所制备的Fe2O3粉末为单一的α-Fe2O3相在固定床反应器中表征了氧载体得失晶格氧的过程,随循环次数的增多,氧载体被CH4还原的速率会有所增加,氧载体在CH4和空气气氛中得失晶格氧是可逆过程,反应后,氧载体内部形成了蜂窝状结构.氧载体的转化度最大为82%,占氧载体总质量18%的晶格氧可以用来氧化CH4.在熔融盐反应器中用CH4作为燃料和所制备的氧载体进行了燃料燃烧和氧载体复原的实验研究在燃料燃烧反应的开始阶段,CH4大部分被氧化成了CO2,CO2的体积分数最高可以达到85%,随着反应时间的增加,氧载体的氧化能力下降,不完全氧化产物CO和未反应的CH4的体积分数逐渐升高,3000s时,CO2的体积分数只有50%在氧载体恢复晶格氧的过程中,在1500s以前,空气中的O2都被氧载体所吸收,1500s以后,该过程排出气体中的O2体积分数开始上升,至2000s气体成分与空气的成分相同.在实验中没有检测出NOx的生成.     

改良型Carrousel氧化沟工艺生物脱氮除磷效果研究

为了提高改良型Carrousel氧化沟工艺污水处理厂的脱氮除磷效果,结合某污水处理厂3年的运行实践,讨论了该工艺的处理效果,生物脱氮除磷原理及影响出水效果的因素.分析表明将DO控制在0.3～0.7 mg/L范围内,能够使出水中的TN浓度低于20 mg/L;在氧化沟中发生的同步硝化反硝化反应(SND)对总氮的去除的贡献占总系统脱氮的66%;该系统剩余污泥的含磷率为3.0%,生物细胞中平均含磷量可达细胞干重的4.2%;总磷去除率与污泥龄具有很好的线性关系,加大污泥排放量可以提高除磷效果.     

厌氧-好氧生物滤池处理城市污水试验

研究了生物滤池处理城市污水的性能特点,结果表明:厌氧-好氧生物滤池去除城市污水中的CODCr、SS和NH4+-N等具有较好的效果,当进水CODCr、SS和NH4+-N分别为23、112mg/L和56mg/L时,水力停留时间8h,曝气强度在0·5~0·6L/(m2·s)时,CODCr、SS和NH4+-N的去除率分别在90%、80%和75%以上。     

用生物填料塔处理三甲胺废气

为解决废气中有机胺类物质的恶臭污染问题,采用自制生物填料塔处理三甲胺废气,考察了生物填料塔运行的主要影响因素及对三甲胺废气的净化效果。实验结果表明,在进气中三甲胺质量浓度为80.00mg/m3、气体流量为0.3m3/h(停留时间不小于30s)、循环液喷淋密度为0.5m3/(m2.h)的条件下,三甲胺去除率达99.9%,净化后气体能达到国家二级排放标准;生物填料塔对三甲胺的总去除量与容积负荷呈直线关系,相关系数达0.9949,表明三甲胺废气的生物净化效果显著。