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991.
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994.
Pesticide toxicity using protozoans as test organisms 总被引:2,自引:0,他引:2
Summary A toxicity test using protozoa as test organisms was devised for pesticides. Two different methods were used, the most probable number method and the absorbance method (based on measurement of protozoa growth through absorbance). The ciliates Colpoda cucullus and Blepharisma undulans and the flagellate Oikomonas termo were isolated from different biological starter cultures and tested with the herbicides Chlorex, MCPA, dichlorprop and Matrigon, the fungicide Benlate, and the insecticide Sumicidin. The protozoans showed quite different sensitivities to the pesticides, using 9-h lethal concentrations (LC50 and LC10) as criteria. The 9-h LC50 (concentration at which 50% of the protozeon population has died after 9 h of incubation) ranged from 0.7 ppm for Benlate to 40000 ppm for Chlorex. The usual soil application rates of Chlorex, MCPA, and Benlate were toxic to some of the organisms. 相似文献
995.
Using the soil gas radon as an indicator for ground contamination by non-aqueous phase-liquids 总被引:1,自引:0,他引:1
Michael Schubert Klaus Freyer Hans-Christian Treutler Holger Weiß 《Journal of Soils and Sediments》2001,1(4):217-222
1 The Problem One of the major problems facing risk assessment at polluted industrial sites and military bases is subsurface contamination
by non-aqueous phase-liquids (NAPLs), since tracing the extent of a NAPL plume using conventional methods (drive point profiling)
is usually associated with difficulties. In an effort to trace subsurface contamination as precisely as possible, monitoring
points are placed in the area that might be affected by contaminants, and groundwater and soil samples are taken to the laboratory
for analysis. However, the final number of monitoring points is hardly ever sufficient for distinctive contamination mapping,
and this may ultimately result in an unsuitable remediation action being taken.
2 Objectives To obtain a more detailed image of a subsurface NAPL plume and, hence, to facilitate remediation measures that are best suited
for the site in question, a denser network of monitoring points is desirable. The aim of the investigation described in this
paper was therefore to develop a new detection method for subsurface NAPL contamination, which is based on an easily accessibleindicator for NAPLs rather than on the analysis of soil and groundwater samples taken at the site. Based on the good solubility of
radon in NAPLs, the idea was put forward that subsurface NAPL contamination should have an influence on the natural radon
concentration of the soil gas. Provided this effect is significant, it would be possible to carry out a straightforward radon
survey on an appropriate sampling grid covering the suspected site and thus enabling the NAPL contamination to be detected
by the localization of anomalous low radon concentrations in the soil. The overall aim of the investigation was to assess
the general suitability of the soil-gas radon concentration as an indirect tracer for NAPL contamination in the ground.
3 Methods The partitioning coefficient KNAPL/air is one of the most influential parameters governing the decrease of the radon concentration in the soil gas in the presence
of a subsurface NAPL contamination. Since NAPL mixtures such as gasoline, diesel fuel and paraffin are among the most important
NAPLs regarding remediation activities, laboratory experiments were performed to determine the radon-partitioning coefficient
for these three NAPL mixtures.
Field experiments were carried out as well. The aim of the field experiments was to test the use of the soil-gas radon concentration
as a tracer for NAPL contamination on-site. For the field experiments, each site was covered with a suitable grid of soil
gas sampling points. Finally, the lateral radon distribution pattern achieved on each of the sites was compared to the respective
findings of the earlier research performed by conventional means.
4 Results and Discussion The results of the laboratory experiments clearly show a very strong affinity of radon to the NAPL mixtures examined. The
partitioning coefficients achieved correspond to those published for pure NAPLs (Clever 1979) and are thus in the expected
range. The results of the field experiments showed that the minimum radon concentrations detected match the respective NAPL
plumes traced previously.
5 Conclusions Both the results of the lab experiments and the on-site findings demonstrate that the soil-gas radon concentration can be
used as an indicator for subsurface NAPL contamination. The investigation showed that NAPL-contaminated soil volumes give
rise to anomalous low soil-gas radon concentrations in the close vicinity of the contamination. The reason for this decrease
in the soil-gas radon concentration is the good solubility of radon in NAPLs, which enables the NAPLs to accumulate and ‘trap’
part of the radon available in the soil pores.
6 Recommendations and Outlook Further research is required into contamination with rather volatile NAPLs such as BTEX. Further research is also needed to
examine whether it is possible to not only localize a NAPL plume, but also to obtain some quantitative information about the
subsurface NAPL contamination. The authors also believe that additional investigations should be carried out to study the
ability of the method to not just localize a NAPL contamination, but also to monitor on-site, clean-up measures. 相似文献
996.
城市化开发场平工程沉沙池设计的原理与方法 总被引:1,自引:0,他引:1
对城市化开发场平工程沉沙池设计中的流量标准,容积条件涉及的侵蚀强度、泥沙沉积水动力学条件进行了分析和探讨,并结合深圳市花岗岩风化物赤红壤典型泥沙颗粒级配条件,提出了沉沙池设计计算的基本方法。 相似文献
997.
998.
畜禽粪便堆肥养分释放及其合理施用 总被引:8,自引:0,他引:8
本文采用室内培养法和田间埋设玻璃滤纸包法研究了粉状畜禽粪便堆肥和颗粒堆肥的养分释放。结果表明,粉状堆肥经颗粒化处理后,养分释放速度变缓,适合在生长期较长的农作物上施用。在一个生长季中牛粪、猪粪和鸡粪颗粒堆肥N素释放率分别为30~35%,35%~45%和45~55%,但其中60~80%的N素释放主要集中在施用后的前二个月内。 相似文献
999.
1000.
基于掌上电脑的农田信息快速采集与处理系统的研究 总被引:4,自引:9,他引:4
为了解决精细农业中空间信息及属性信息的快速获取与分析处理问题,提出并实现了基于掌上电脑的农田信息快速采集与实时处理系统。分析了具体实现系统功能的若干关键技术,如地理信息系统(GIS)、空间索引、Windows CE数据库技术、采样控制等因硬件环境的不同而产生的问题及相应的解决方案,又针对农场环境下的特殊性,提出并实现了一个面向对象的农场模型,以便于更好的描述农场环境及更方便的确定采样方案。作为一种实时系统,该系统可结合全球定位系统(GPS)和各种传感器,快速地测量和分析农田信息。应用该系统对两种GPS(Ag132与MAP330)进行了精度比较试验,快速而方便地证实了Ag132有更好的精确性与稳定性,更适于农业生产要求。试验的过程与结果也间接表明了该系统具有较好的实用性,为精细农业田间信息快速采集和处理设备的研制与开发奠定了基础。 相似文献