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981.
苯并(a)芘及其代谢产物的连续降解研究 总被引:2,自引:1,他引:1
在以驯化过的芽孢杆菌(BA-07)降解BaP的过程中,鉴定出2个BaP的未开环代谢产物顺式-4,5-二氢-4,5-二醇-BaP(cis-BP4,5-dihydrodiol)和顺式-7,8-二氢-7,8-二醇-BaP(cis-BP7,8-dihydrodiol).由于该产物对微生物有一定毒性,所以难于进一步降解.为提高BaP降解的同时,降低cis-BP4,5-dihydrodiol和cis-BP7,8-dihydrodiol的累积,对2种降解方法(即单纯用BA07降解和运用高锰酸钾与BA-07耦合的方法降解)进行了比较,并且优化了连续降解的参数.结果表明,①对BaP及其代谢产物的连续降解,化学氧化与微生物耦合(高锰酸钾与BA-07)的降解效果明显好于单纯利用微生物(细菌BA-07)的降解;②在同一时间取样,cis-BP4,5-dihydrodiol的残留率均高于cis-BP7,8-dihydrodiol;③当BaP的浓度为40μg/mL,培养基的最佳pH为7.0,以琥珀酸钠为共代谢底物,可以显著提高BaP降解率,降低cis-BP 4,5-dihydrodiol和cis-BP7,8-dihydrodiol的累积.同时提出了化学氧化与微生物协同的方法可以有效促进环境中持久有机污染物的连续降解. 相似文献
982.
Mackay D Foster KL Patwa Z Webster E 《Environmental science and pollution research international》2006,13(1):2-8
- DOI: http://dx.doi.org/10.1065/espr2006.01.002
Background Davide Calamari and his colleagues were among the first to appreciate that vegetation could play a key role in determining
the fate and effects of organic contaminants. They conducted pioneering experiments to investigate the uptake of contaminants
by plants from the atmosphere and they sought to model the observed phenomena. In the nearly two decades since there has been
a marked increase in understanding of these phenomena as a result of both experimental and modelling studies.
- Goal. In this study we briefly review our current understanding of chemical partitioning between foliage and air. A model
in both fugacity and concentration format is described, based on that of Tolls and McLachlan (1994), in which the leaf is
treated as consisting of two layers, a waxy cuticle with an underlying 'reservoir' layer, the cuticle being surrounded by
an air boundary layer and containing stomata that provide direct access from the air to the 'reservoir'. The model quantifies
the dynamic penetration of a defined chemical into a defined leaf as a function of time.
Main Features The model is applied for illustrative purposes to a hypothetical but typical leaf for a set of illustrative chemicals to
demonstrate the effect of changes in physical-chemical properties and leaf characteristics.
Discussion The results are compared qualitatively with a variety of field and laboratory studies of foliage uptake and clearance of
chemicals.
Conclusion It is concluded that the model yields results that are generally consistent with observations. It is suggested that with
appropriate parameterisation and validation, the model can contribute to an improved understanding of the process of foliage
uptake from the atmosphere and to the development of an improved predictive capability. 相似文献
983.
984.
The influence of ionic composition on the water chemistry and thereby on aquatic flora was investigated. Two major wetlands
of North India were taken for the study. Quality parameters of the lakes showed the enrichment of the water especially in
the month of September with higher values of P and BOD in almost all of the lakes viz., LSJ, LCH, LSN, and LHT as <5.0, 9.0,
1.0, 1.7 and <7.3, 6.0, 6.3, and 4.0, respectively. Statistically correlated values of the ions in the water quality showed
an effect of one on another. An attempt has also been made to investigate if ionic constituent is one of the major causes
affecting the aquatic floral diversity. 相似文献
985.
危险废物稳定化/固化技术的现状与发展 总被引:1,自引:0,他引:1
本文对危险废物稳定化/固化处理技术的历史、现状以及今后的发展方向进行了较为系统的论述,对该技术在处理危险废物时所存在的问题进行了探讨,认为今后药剂稳定化技术在废物处置预处理领域将会占据重要的地位。 相似文献
986.
Seasonal Variations and Chemical Forms of Heavy Metals in Soils and Dusts from the Satellite Cities of Seoul, Korea 总被引:10,自引:0,他引:10
This research investigated heavy metal pollution of soils and dusts in two representative satellite cities of Seoul, Korea and studied the seasonal variations in metal concentrations through the rainy season and the chemical forms of metals using a sequential extraction analysis. The metal dispersion pattern was illustrated to match with urban structure. Soil and dust samples were collected from the cities of Uijeongbu and Koyang, which are the northern and northwestern satellite cities of Seoul (the capital), before and after rainy season. Concentrations of Cu, Pb and Zn were higher than those of the world averages for soils, and their levels decreased after rain, particularly in highly contaminated samples. Relatively high pH values were found in roadside soils, but no seasonal variation was found after the rainy season. The three metals (Cu, Pb and Zn) in soils and dusts were associated with various chemical fractions of soils and dusts as distinguished by the sequential extraction scheme, and a strong similarity of metal association between soils and dusts was found, which indicates that airborne dust may be a principle source of soil contamination. Copper is uniformly distributed, and Pb is largely associated with the reducible phase. There is an appreciable proportion of total Zn in the exchangeable/water-acid soluble fraction. After the rainy season, the most soluble fractions in soils and dusts were leached away. In terms of mobility and bioavailability of metals in soils and dusts, the order Zn >> Cu > Pb is suggested. Geographical variations of total metals corresponded well with urbanised areas of cities, especially the industrial complex and major motorways. 相似文献
987.
通过对浙江省安吉县的调查发现,在自然生态环境相似的两个自然村中,以农业为基础产业的禹山坞村稻田及其环境中水栖无脊椎动物、畦畔和沟渠植物的种类和数量多于以工业为主导产业的北村,稻田杂草和秋季稻田天敌的种类和数量少于北村。研究分析表明,稻田及其环境的生物种类和数量与农业生态环境质量的优劣及化肥、农药、除草剂的施用量密切相关。 相似文献
988.
Many “natural” areas are exposed to military or recreational off-road vehicles. The interactive effects of different types
of vehicular disturbance on vegetation have rarely been examined, and it has been proposed that some vegetation types are
less susceptible to vehicular disturbance than others. At Fort Riley, Kansas, we experimentally tested how different plant
community types changed after disturbance from an M1A1 Abrams tank driven at different speeds and turning angles during different
seasons. The greatest vegetation change was observed because of driving in the spring in wet soils and the interaction of
turning while driving fast (vegetation change was measured with Bray-Curtis dissimilarity). We found that less vegetation
change occurred in communities with high amounts of native prairie vegetation than in communities with high amounts of introduced
C3 grasses, which is the first experimental evidence we are aware of that suggests plant communities dominated by introduced
C3 grasses changed more because of vehicular disturbance than communities dominated by native prairie grasses. We also found
that vegetation changed linearly with vehicular disturbance intensity, suggesting that at least initially there was no catastrophic
shift in vegetation beyond a certain disturbance intensity threshold. Overall, the intensity of vehicular disturbance appeared
to play the greatest role in vegetation change, but the plant community type also played a strong role and this should be
considered in land use planning. The reasons for greater vegetation change in introduced C3 grass dominated areas deserve further study. 相似文献
989.
990.
盐碱池塘底栖动物的初步研究 总被引:9,自引:0,他引:9
研究了不同放养模式的高青盐碱池塘底栖动物的种类组成、生物量及其季节变动。结果表明,盐碱池塘底栖动物群落结构简单,主要优势种是羽摇蚊幼虫和奥特开水丝蚓,底栖动物密度和生物量无鱼对照池比养鱼池高得多,平均密度(nar/m^-2)和生物量(ρA/g m^-2)分别为1103(40-2085)m^-2和4.61(0.15-12.91)g m^-2,养地池底栖动物nar/m^-2和ρA/g m^-2分别为54-161m^-1和0.14-0.54g m^-2。底栖动物密度和生物量在春夏之交有一高峰,对盐碱池塘底栖动物种、量特点及其与鱼类捕食和一些生态因子的关系进行了讨论。 相似文献