植物大气污染响应高光谱监测实例研究

选择某钢铁企业绿化树种桂花当年生叶片作为供试样本,测试叶片光谱反射率之后分别测试叶液pH值、叶片含硫量、叶绿素含量、叶片含水量,研究生长在S02 污染环境下桂花叶片光谱的变化以及相应的部分生理生化指标的变化.研究表明,污染较严重生产区采集的叶片光谱反射率和红边斜率均较生活区低.叶片含硫量随大气SO2 浓度的增减而相应地变化,叶片叶绿素含量、叶液pH值、叶片含水量的变化规律与叶片含硫量和大气SO2浓度的变化规律相反.     

The stable isotope signature of methane emitted from plant material under UV irradiation

Recent experiments have shown that dry and fresh leaves, other plant matter, as well as several structural plant components, emit methane upon irradiation with UV light. Here we present the source isotope signatures of the methane emitted from a range of dry natural plant leaves and structural compounds. UV-induced methane from organic matter is strongly depleted in both ¹³C and D compared to the bulk biomass. The isotopic content of plant methoxyl groups, which have been identified as important precursors of aerobic methane formation in plants, falls roughly halfway between the bulk and CH₄ isotopic composition. C3 and C4/CAM plants show the well-established isotope difference in bulk ¹³C content. Our results show that they also emit CH₄ with different δ¹³C value. Furthermore, δ¹³C of methoxyl groups in the plant material, and ester methoxyl groups only, show a similar difference between C3 and C4/CAM plants. The correlation between the δ¹³C of emitted CH₄ and methoxyl groups implies that methoxyl groups are not the only source substrate of CH₄.Interestingly, δD values of the emitted CH₄ are also found to be different for C3 and C4 plants, although there is no significant difference in the bulk material. Bulk δD analyses may be compromised by a large reservoir of exchangeable hydrogen, but no significant δD difference is found either for the methoxyl groups, which do not contain exchangeable hydrogen. The δD difference in CH₄ between C3 and C4 plants indicates that at least two different reservoirs are involved in CH₄ emission. One of them is the OCH₃ group, the other one must be significantly depleted, and contribute more to the emissions of C3 plants compared to C4 plants. In qualitative agreement with this hypothesis, CH₄ emission rates are higher for C3 plants than for C4 plants.     

Investigation of various physicochemical and environmental parameter influence on pesticide sorption to ditch bed substratum by means of experimental design

Diffuse pollution by pesticide applied in rural catchments may contribute to alter water quality. Besides actions relative to the way the substances are introduced into the environment, it is also possible to limit the contamination by interfering on their transfer pathways from fields to the main river network. Especially, interface areas such as buffer strips or small ditches may play a major part in pesticide diffuse pollution decrease. In ditches a great variety of materials may act as sorbents for organic contaminants: grass, leaves, wood debris or sediments. In this study, laboratory experiments were designed to determine sorption characteristics for three herbicides with different physicochemical properties on sediment and leaves in decay commonly found in agricultural ditches. Sorption capacities were assessed for the herbicides isoproturon, diuron and diflufenican.

Experimental design was carried out to investigate the effects of five parameters on herbicide sorption on sediment and dead leaves. These parameters have been chosen according to parallel field experiment needs. Thus, the influence of initial sorbent moisture, herbicide form, i.e. active substance or commercial formulation, water quality (tap or natural ditch water), bromide ions (used as conservative tracers) and solid/liquid ratio have been tested. Within the parameters investigated, pesticide formulation and solid/liquid ratio were the most important parameters affecting pesticide sorption on both ditch materials.     

原子吸收光度法测定树叶中的重金属

用浓硝酸与高氯酸消解树叶,Ｃｕ、Ｚｎ、Ｍｎ含量较高,可直接用火焰原子吸收法测定,含量较低的Ｐｄ、Ｃｄ,Ｃｒ则用石墨炉法测定。Ｐｂ及Ｃｄ含量甚微,受基体及共存元素干扰严重用标准加入法可消除干扰,结果令人满意。     

桑叶中多菌灵的残留量分析方法

本文报道了用高效液相色谱仪测定桑叶中多菌灵残留量的分析方法。样品用酸性甲醇振荡提取，二氯甲烷萃取纯化，样品浓度为10、5、0．5ppm时，方法回收率范围、标准差、变异系数分别为88．14～98．94％、1．01～2．58、1．05～2．82％；添加平均回收率为86．98～95．58％，标准差和变异系数为0．96～3．47、1．00～3．99％。     

Functional traits of poplar leaves and fine roots responses to ozone pollution under soil nitrogen addition

Concurrent ground-level ozone（O₃） pollution and anthropogenic nitrogen（N） deposition can markedly influence dynamics and productivity in forests.Most studies evaluating the functional traits responses of rapid-turnover organs to O₃ have specifically examined leaves,despite fine roots are another major source of soil carbon and nutrient input in forest ecosystems.How elevated O₃ levels impact fine root biomass and biochemistry remains to be resolved.This study was...     

Characteristics of Anaerobic Fermentation with Different Parts of Corn Stalks at Low Concentrations

In order to obtain the characteristics of anaerobic fermentation with different parts of corn stalks at low concentrations, air-dried corn stalks stem bark (SB), stem pith (SP), leaves (L), and corn stalks (CS) were, respectively, mixed with cow dung to perform fermentation at the temperature of 35 ^oC and carbon-to-nitrogen ratio (C/N) of 25. Mixed with cow dung compost, the fermentation broths were adjusted to a neutral pH value. Along with the enhancing of the total solid (TS) content of SB, SP, L, and CS fermentation broths, both of the daily biogas yields and methane contents increased under the same fermentation condition, except for Sample TS 6% of L. The optimal TS content of SB, SP, L, and CS broth is 8%, 5%, 10%, and 8%, separately. In 35 days, the highest methane yield of SB, SP, L, and CS broth was 125.0 mL/(volatile solid) VS g, 115.3 mL/VS g, 109.7 mL/VS g, and 80.0 mL/VS g, respectively, and the potential of methane transformation production of broth ranks as: SB> L> SP> CS. Daily methane producing rate of SB, SP, and L broth are faster than that of CS. It is necessary to separate the corn stalks into different parts to ferment because the optimal fermentation concentrations for the different parts are different. Additionally, the Gompertz equation was also adopted to simulate the anaerobic digestion process of different materials. The Gompertz equation fitting parameters show that the biodegradation (from easy to difficult) was: L < SP < SB < CS.     

Contribution to biomonitoring of some trace metals by deciduous tree leaves in urban areas

Leaves of the deciduous tree species, horse chestnut (Aesculus hippocastanum L.) and Turkish hazel (Corylus colurna L.) were used as accumulative biomonitors of trace metal pollution in the urban area of Belgrade. Using differential pulse anodic stripping voltametry, trace metal concentrations (Pb, Cu, Zn, Cd) were determined at the single leaf level (ten leaves per species, per month), during two successive years with markedly different atmospheric level of trace metals. Increased trace metal concentrations in the leaves of A. hippocastanum reflected elevated atmospheric trace metal pollution, whereas C. colurna L. did not respond accordingly. The contents of Pb and Zn in soil over the same period also followed this trend. Anatomical analyses, in young as well as in old leaves of both species, indicated typical foliar injuries of plants exposed to stressful air conditions. Water relations that correspond to leaf age may have contributed to the considerable trace metal accumulation in leaves.     

Biomonitoring of Environmental Pollution Using Dielectric Properties of Tree Leaves

In the present work, dielectric measurements were performed in plane-tree leaves collected from a polluted urban site and a natural unpolluted one, in order to investigate the sensitivity of dielectric relaxation spectroscopy to the detection of heavy metals pollution. Although heavy metal concentrations at the urban site are not found considerable higher than those at the natural site, the two samples exhibit different features in the recorded dielectric spectra. Evaluation of experimental data suggests that the dielectric modulus (M*(ω)) representation is the most suitable for accenting the different dielectric relaxation processes of each sample. The imaginary part of dielectric modulus M″(ω) was fitted using a three-term Havriliak–Negami relaxation function, with fitting parameters, which depend on the concentrations of heavy metals. The lower frequency relaxation process is attributed to the ionic conductivity of the samples, while the two others are due to different charge transport mechanisms of α-response. The investigation of plane-tree leaves in terms of their dielectric properties can be considered as a promising biomonitoring for environmental pollution.