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41.
多光谱数据定量反演土壤营养元素含量可行性分析 总被引:3,自引:0,他引:3
运用室内光谱模拟多光谱数据,采用回归分析方法建立土壤营养元素含量预测模型,并进行验证.首先,根据光谱响应函数将实验室光谱数据重采样至多光谱传感器(TM和 ASTER)波段;然后,分别利用多元逐步回归(SMLR)和偏最小二乘回归(PLSR)方法,建立建模土壤样本实测光谱以及模拟光谱(TM和ASTER)与土壤营养元素含量间的经验模型;最后,利用检验土壤样本进行模型精度验证.与实测光谱模型相比,模拟光谱模型对土壤营养元素含量的预测精度受光谱分辨率的影响并不大.模拟光谱模型对N、P、K元素含量预测精度最高分别为0.89、0.79和 0.67.土壤N、P、K元素含量SMLR模型的入选波段分别位于2 000~2 300 nm、1 650~1 800 nm和600~800 nm波长附近范围内; 土壤N、P、K元素含量PLSR模型的系数表明,近红外(NIR)波段对总氮和总磷元素含量比可见光(VIS)波段敏感,而VIS对K元素含量预测的贡献更大.利用多光谱数据进行土壤营养元素含量的估测具有理论上的可行性;由于不同元素对不同光谱波段的响应不同,在选择多光谱遥感数据时要充分考虑传感器的波段特征. 相似文献
42.
对主要在北京行驶的总里程在34×104~59×104km的6辆轻型出租车用三效催化剂,利用X射线荧光光谱仪(XRF)分析了其表面元素的种类、含量,以及污染物元素含量与行驶里程的关系.结果表明,在催化剂表面检测到的元素种类近30种,含量较高的元素种类基本相同.前后级催化剂上检测到的共同污染物元素有P、Ca、Zn和Mn等,主要来自于机油和汽油,34×104km行驶里程后,P在催化剂的累积速度已非常缓慢,Ca、Zn和Mn在催化剂表面的沉积经过56×104km后仍有增加的趋势.在后级催化剂上还检测到了明显的S含量,说明S更容易在后级催化剂上沉积.经过40×104km行驶里程后,S在催化剂表面的沉积量基本达到平衡状态.累积规律说明经过40×104km行驶里程后,容易使催化剂中毒的P和S对催化剂活性影响已较小,而Ca、Zn和Mn的持续累积,将会继续降低催化剂的活性. 相似文献
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45.
Chih Ming M Ya Wen Lee Gui Bing Hong Te Li Su Je Lueng Shie Chang Tang Chang 《环境科学学报(英文版)》2011,23(4):687-692
TiO2 nanoparticles, doped with di erent Pt contents, were prepared by a modified photodeposition method using Degussa P-25 TiO2,
H2PtCl6 6H2O and methanol as the solvents. The physicochemical properties of Pt/TiO2 were investigated by the nitrogen adsorption
and desorption isotherm measurement technique, X-ray di raction analysis and photoluminescence spectra, respectively. Reaction rates
from photocatalytic removal of dichloromethane over Degussa P-25 TiO2 and Pt/TiO2 were evaluated. The average diameter and BET
surface area of the TiO2 catalyst particles were 300 nm and 50 m2/g, respectively. The degradation e ciency was 99.0%, 82.7%, 55.2%,
and 57.9% with TiO2 at inlet concentrations of 50, 100, 200, and 300 ppm, respectively. And the degradation e ciency was 99.3%,
79.7%, 76.5%, and 73.4% with a 0.005 wt.% Pt/TiO2 at inlet concentrations of 50, 100, 200, and 300 ppm, respectively. In addition, we
found that the photoluminescence emission peak intensities decreased with increases in the doping amount of Pt, which indicates that
the irradiative recombination was weakened. Furthermore, the results showed that the UV/0.005 wt.% Pt/TiO2 process was capable of
e ciently decomposing gaseous DCM in air. 相似文献
46.
Removal of phosphate by Fe-coordinated amino-functionalized 3D mesoporous
silicates hybrid materials
Phosphate removal from aqueous waste streams is an important approach to control the eutrophication downstream bodies of water.
A Fe(III) coordinated amino-functionalized silicate adsorbent for phosphate adsorption was synthesized by a post-grafting and metal
cation incorporation process. The surface structure of the adsorbent was characterized by X-ray di raction, N2 adsoropion/desoprotion
technique, and Fourier transform infrared spectroscopy. The experimental results showed that the adsorption equilibrium data were well
fitted to the Langmuir equation. The maximum adsorption capacity of the modified silicate material was 51.8 mg/g. The kinetic data
from the adsorption of phosphate were fitted to pseudo second-order model. The phosphate adsorption was highly pH dependent and
the relatively high removal of phosphate fell within the pH range 3.0–6.0. The coexistence of other anions in solutions has an adverse
e ect on phosphate adsorption; a decrease in adsorption capacity followed the order of exogenous anions: F?? > SO2?? 4 > NO??3 > Cl??. In
addition, the adsorbed phosphate could be desorbed by NaOH solutions. This silicate adsorbent with a large adsorption capacity and
relatively high selectivity could be utilized for the removal of phosphate from aqueous waste streams or in aquatic environment. 相似文献
47.
Potential particulate pollution derived from UV-induced degradation of
odorous dimethyl sulfide 总被引:1,自引:0,他引:1
UV-induced degradation of odorous dimethyl sulfide (DMS) was carried out in a static White cell chamber with UV irradiation. The
combination of in situ Fourier transform infrared (FT-IR) spectrometer, gas chromatograph-mass spectrometer (GC-MS), wide-range
particle spectrometer (WPS) technique, filter sampling and ion chromatographic (IC) analysis was used to monitor the gaseous and
potential particulate products. During 240 min of UV irradiation, the degradation e ciency of DMS attained 20.9%, and partially
oxidized sulfur-containing gaseous products, such as sulfur dioxide (SO2), carbonyl sulfide (OCS), dimethyl sulfoxide (DMSO),
dimethyl sulfone (DMSO2) and dimethyl disulfide (DMDS) were identified by in situ FT-IR and GC-MS analysis, respectively.
Accompanying with the oxidation of DMS, suspended particles were directly detected to be formed by WPS techniques. These
particles were measured mainly in the size range of accumulation mode, and increased their count median diameter throughout
the whole removal process. IC analysis of the filter samples revealed that methanesulfonic acid (MSA), sulfuric acid (H2SO4) and
other unidentified chemicals accounted for the major non-refractory compositions of these particles. Based on products analysis and
possible intermediates formed, the degradation pathways of DMS were proposed as the combination of the O(1D)- and the OH- initiated
oxidation mechanisms. A plausible formation mechanism of the suspended particles was also analyzed. It is concluded that UV-induced
degradation of odorous DMS is potentially a source of particulate pollutants in the atmosphere. 相似文献
48.
The adsorption behaviors of heavy metals onto novel low-cost adsorbent, red loess, were investigated. Red loess was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectra. The results indicated that red loess mainly consisted of silicate, ferric and aluminum oxides. Solution pH, adsorbent dosage, initial metal concentration, contact time and temperature significantly influenced the efficiency of heavy metals removal. The adsorption reached equilibrium at 4 hr, and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model. The adsorption of Cu(II) and Zn(II) onto red loess was endothermic, while the adsorption of Pb(II) was exothermic. The maximum adsorption capacities of red loess for Pb(II), Cu(II) and Zn(II) were estimated to be 113.6, 34.2 and 17.5 mg/g, respectively at 25°C and pH 6. The maximum removal efficiencies were 100% for Pb(II) at pH 7, 100% for Cu(II) at pH 8, and 80% for Zn(II) at pH 8. The used adsorbents were readily regenerated using dilute HC1 solution, indicating that red loess has a high reusability. All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution. 相似文献
49.
50.
采用超滤膜法将2-丁烯醛生产废水中的有机物分为相对分子质量不同的7个级分,并应用溶解性有机碳(dissolved organic carbon,DOC)、紫外吸收光谱(ultraviolet spectrum,UV)、傅里叶变换红外光谱(fourier transform infrared spectrometer,FT-IR)和气相色谱/质谱联用仪(gas chromatography with mass spectrometry,GC-MS)技术对不同相对分子质量区间的有机物所占比例及物质结构进行了研究.结果表明,废水中相对分子质量1×103的有机物所占比例最高,达到88.57%;采用GCMS对废水中相对分子质量1×103的级分进行分析,定性出27种化合物,包含醛、酮、酯、醇、酚、酸、烷烃类及其他苯系物等,其峰面积占有机物峰面积总和的比例分别为6.9%、5.3%、35.4%、13.2%、4.6%、0.4%、1.7%、16.8%,总和为84%.UV和FT-IR分析结果均显示不同相对分子质量区间的光谱吸收特征没有明显差别,级分中存在含有不饱和双键、羟基、羰基化合物及芳香族化合物,与GC-MS检测结果相吻合.研究结果为废水处理工艺的开发与优化提供了重要的指导作用. 相似文献