Mapping Invasive Aquatic Vegetation in the Sacramento-San Joaquin Delta using Hyperspectral Imagery

The ecological and economic impacts associated with invasive species are of critical concern to land managers. The ability to map the extent and severity of invasions would be a valuable contribution to management decisions relating to control and monitoring efforts. We investigated the use of hyperspectral imagery for mapping invasive aquatic plant species in the Sacramento-San Joaquin Delta in the Central Valley of California, at two spatial scales. Sixty-four flightlines of HyMap hyperspectral imagery were acquired over the study region covering an area of 2,139 km² and field work was conducted to acquire GPS locations of target invasive species. We used spectral mixture analysis to classify two target invasive species; Brazilian waterweed (Egeria densa), a submerged invasive, and water hyacinth (Eichhornia crassipes), a floating emergent invasive. At the relatively fine spatial scale for five sites within the Delta (average size 51 ha) average classification accuracies were 93% for Brazilian waterweed and 73% for water hyacinth. However, at the coarser, Delta-wide scale (177,000 ha) these accuracy results were 29% for Brazilian waterweed and 65% for water hyacinth. The difference in accuracy is likely accounted for by the broad range in water turbidity and tide heights encountered across the Delta. These findings illustrate that hyperspectral imagery is a promising tool for discriminating target invasive species within the Sacramento-San Joaquin Delta waterways although more work is needed to develop classification tools that function under changing environmental conditions.     

Mechanism of NO reduction with non-thermal plasma

Non-thermal plasma has been proved to be an effective and competitive technology for removing NO in flue gas since 1970. In this paper, the NO reduction mechanism of the non-thermal plasma reaction in NO/N2/O2 system was investigated using the method of spectral analysis and quantum chemistry. By the establishment of NO reduction and gas discharge plasma emission spectrum measuring system, the NO reduction results, gas discharge emission spectra of NO/N2/O2 and pure N2 were obtained, and then the model of molecular orbit of N2 either in ground state or its excited state was worked out using the method of molecular orbit Ab initio in SelfConsistent Field(SCF). It was found that NO reduction in NO/N2 gas discharge plasma was achieved mainly through a series of fast elementary reactions and the N(E6) at excited state was the base for NO reduction.     

西安市冬季PM2.5中WSOC的光谱特性和来源解析

利用紫外-可见吸收光谱法、三维荧光-平行因子分析法(EEMs-PARAFAC)和后向轨迹模型等,分析西安市冬季PM_(2.5)中水溶性有机物(WSOC)的光谱特性和来源.结果表明,西安市PM_(2.5)中WSOC的浓度为4.66～14.75μg·m~(-3). WSOC的E_2/E_3、E_3/E_4、S_(275-295)、 SUVA_(254)、 AAE和MAE_(365)的值分别为2.85～4.32、 2.21～3.56、 0.009 9～0.012 7 nm~(-1)、 2.35～3.89 m~2·g~(-1)、 2.66～4.60和1.51～2.60 m~2·g~(-1).南郊(西安建筑科技大学)采样点PM_(2.5)中WSOC的E_2/E_3值、E_3/E_4值、S_(275-295)和AAE值均较高于北郊(城市运动公园)采样点的,而SUVA_(254)和MAE_(365)值较低. EEMs-PARAFAC模型鉴别出WSOC中主要含有4个荧光组分,C1和C2分别归属为类富里酸和类蛋白,C3和C4均归属为类腐殖质,各荧光组分的荧光强度及其总和与PM_(2.5)、 OC、 WSOC浓度和A_(254)值呈显著正相关(P0.01). WSOC的FI、 BIX和HIX值分别为1.75～2.12、 1.14～1.46和1.18～2.06.监测期间气团传输轨迹以本地西南向短距离传输为主,其轨迹占比超过50%;新疆、内蒙古和甘肃等地区冬季污染物排放对西安也有较明显的贡献.西安市南北郊PM_(2.5)的碳组分含量存在差异较小,南郊(西安建筑科技大学)采样点PM_(2.5)中WSOC的相对分子质量、腐殖化程度和光吸收能力比北郊(城市运动公园)的低,而光吸收强度的波长依耐性相对较强. WSOC主要为生物来源或由生物来源和陆源共同组成,且以自生源为主,陕西省区域输送对冬季PM_(2.5)和WSOC的来源贡献最为显著.     

地表水中甲醛的光谱吸收曲线-线性拟合斜率-乙酰丙酮分光光度法检测

光谱吸收曲线-线性拟合斜率-分光光度法(SAC-LFS-S)用于检测地表水中甲醛尚存准确度不足问题,通过筛选合适的参比波长段,使SAC-LFS-S法准确度进一步提高。以试剂空白和浊度梯度地表水样品的检测结果及方法检出限为主要筛选对象,得到425～435、420～435、420～440、415～440、415～445、410～445、415～450、410～450、455～495、410～455、405～455、450～500 nm等共12个合适的测定波长段;再选择试剂空白结果较低、批间重复性较好的450～500 nm测定波长段,筛选参比波长段(455～465、480～495、450～490 nm共3个)。结果表明:优化后SAC-LFS-S法线性范围为0. 100～3. 00 mg/L,方法检出限为0. 025～0. 033 mg/L;优化前、后方法测得部分地表水样品结果分别为有检出和未检出,回收率为73. 4%～108. 8%,后者与无亮黄色化合物产生的实验现象更吻合。经参比波长段校正的SAC-LFS-S法具有更高的准确度,非常适用于地表水中甲醛的直接测定。     

基于实测光谱的海河悬浮物浓度反演研究

悬浮物浓度是评价水质优劣的重要指标之一。以天津滨海新区海河为研究区域,进行光谱数据测量和水体样本采集,并在实验室进行水质参数提取,得到归一化光谱反射率和光谱一阶微分数据。然后对光谱测量数据和悬浮物浓度实测值进行相关性分析,发现896 nm归一化光谱反射率和光谱反射率比值(R_(896)/R_(546))与悬浮物浓度相关性较好。最后,分别建立单波段、波段比值和一阶微分函数拟合模型,进行对比分析。结果表明,基于R_(896)/R_(546)的二次多项式模型拟合效果最好,方差齐性检验(F)值也是最高的,可用于该地区水体的悬浮物浓度反演和预测。     

汤逊湖水体叶绿素浓度遥感估测研究

内陆水体叶绿素浓度遥感监测的各种经验模型在模型的方法和参数上都有一定的时空限制。为了实现武汉汤逊湖叶绿素浓度的遥感监测,利用同步实测的光谱数据和水质数据进行了该湖泊叶绿素浓度的遥感定量反演研究。首先分析了汤逊湖水体的反射率光谱曲线;其次通过相关分析的方法,发现了汤逊湖水体反射率在单波段法、一阶微分法和比值法建模中的最优波段或组合,并进行了一元线性建模;最后对3种模型的反演精度进行了比较分析。结果表明,对于汤逊湖叶绿素浓度遥感反演,一阶微分法和比值法优于单波段法,一阶微分法的最优波段在446.9 nm附近,比值法的最优波段组合为R861.1/R865.7,二者回归R2都在0.86以上。本项研究可为汤逊湖叶绿素浓度的遥感估测提供了参考。     

石油石化企业泄漏检测技术现状及前景

石油石化站场设备繁多,挥发性介质泄漏易造成安全事故。目前站场点式、线式等固定式检测设备存在泄漏检测反应滞后、泄漏点定位困难等缺点,便携式检测设备人工巡检工作量大。文章对可调谐二极管激光吸收光谱技术、红外热成像技术、红外多光谱技术和红外高光谱技术进行了分析,提出红外成像检测技术在泄漏检测方面优势明显,具有视频成像、反应迅速、定位准确、连续监控等优点,有望在石油石化行业普及。     

Remote sensing water observation for supporting Lake Victoria weed management

This paper aims to assess the suitability of remote sensing for enhancing the management of water body resources and for providing an inexpensive way to gather, on a wide area, weed infestation extent and optical parameter linked to the water body status. Remotely sensed satellite images and ancillary ground true data were used to produce land cover maps, trough classification techniques, and water compounds maps, applying radiative transfer models. The study proposed within the framework of the cooperation between Italian Foreign Affair Ministry (through the University of Rome) and Kenyan Authorities has been carried out on the Kenyan part of the Lake Victoria. This lake is one of the largest freshwater bodies of the world where, over the last few years environmental challenges and human impact have perturbed the ecological balance affecting the biodiversity. The objective of this research study is to define the thematic products, retrievable from satellite images, like weed abundance maps and water compound concentrations. These products, if provided with an appropriate time frequency, are useful to identify the preconditions for the occurrence of hazard events like abnormal macrophyte proliferation and to develop an up-to-date decision support system devoted to an apprised territory, environment and resource management.     

Determination of soil content in chlordecone (organochlorine pesticide) using near infrared reflectance spectroscopy (NIRS)

Chlordecone is a toxic organochlorine insecticide that was used in banana plantations until 1993 in the French West Indies. This study aimed at assessing the potential of near infrared reflectance spectroscopy (NIRS) for determining chlordecone content in Andosols, Nitisols and Ferralsols from Martinique. Using partial least square regression, chlordecone content conventionally determined through gas chromatography–mass spectrometry could be correctly predicted by NIRS (Q² = 0.75, R² = 0.82 for the total set), especially for samples with chlordecone content <12 mg kg⁻¹ or when the sample set was rather homogeneous (Q² = 0.91, R² = 0.82 for the Andosols). Conventional measures and NIRS predictions were poorly correlated for chlordecone content >12 mg kg⁻¹, nevertheless ca. 80% samples were correctly predicted when the set was divided into three or four classes of chlordecone content. Thus NIRS could be considered a time- and cost-effective method for characterising soil contamination by chlordecone.     

铊在黄铁矿中的相态分布及碳酸盐在其释放过程中的作用

采用分级提取-电感耦合等离子体质谱法,对黄铁矿中铊的相态分布进行了考察.结果表明,黄铁矿中的铊主要以存在于硅酸盐相中和以酸可交换的形式存在于矿物结构中的铊为主,这部分铊分别占到58.3%和25.1%;以可氧化态形式结合在黄铁矿(FeS2)中的铊次之,占11.2%;以易还原态形式存在于铁氧化物相中的铊最少,为5.4%.自然条件下铊的释放主要是酸可交换态铊和可氧化态铊的释放迁移过程.漫反射红外光谱表征发现,黄铁矿在表面氧化过程中其表面羟基增多,表明存在表面溶解及表面酸化现象.进一步的释放机理探讨认为,铊在黄铁矿表面存在一种"溶解-吸附沉淀"平衡,这一平衡由碳酸盐中和作用和黄铁矿表面氧化共同控制,并决定了铊的释放迁移.