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81.
彭里 《中国生态农业学报》2006,14(2):19-22
简述了近年来国内外畜禽养殖环境污染现状及其危害、畜禽粪便环境污染治理研究进展。 相似文献
82.
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
83.
The 1997-1998 El-Niño Southern Oscillation was the most severe on record and dramatically impacted corals worldwide. However, the effect of this event on the associated community of reef organisms has received much less attention. The composition of the bryozoan assemblage from the coral reefs of Northern Bahia, Brazil were monitored annually from 1995 to 2000, allowing the investigation of the effects of this large-scale stressor on an important, diverse, yet understudied component of the coral reef system. Bryozoan samples (35 replicates/reef) were collected during April/May from four shallow bank reefs (10-40 m depth) located a few kilometres off the coast, together with measurements of the associated environmental parameters. Currently 157 species have been recorded from the study area, but significant reductions in density and diversity were apparent between pre- and post El-Niño Southern Oscillation (ENSO) years, multivariate analysis denoting significant changes in assemblage composition. A total of 61 species were unrecorded following the 1997-1998 ENSO event (22 species from 1997; 25 further species from 1998 and 14 more from 1999). These included several species endemic to Brazil, suggesting that the 1997-1998 ENSO has had a marked influence on the reef bryozoan community, resulting in the local extinction of several species. Bryozoan mortalities were probably initiated by elevated temperatures, but continued disappearance of species for 2 years after ENSO suggests other indirect factors are also influential. These results demonstrate that ENSO events can have severe long-term impacts on the biodiversity of coral reefs, with important conservation consequences. 相似文献
84.
重庆市主城区街道地表物中重金属的污染特征 总被引:31,自引:0,他引:31
分析了重庆市主城区街道地表物的基本性质及As、Cd、Cr、Cu、Hg,Ni、Pb,Zn等元索的全置、模拟酸雨(pH4.5)的浸出量。结果表明:各功能区中街道地表物的自然组成均以中等粒径的为主;就元素而言,粒径越细对重金属的贡献率越高;就功能区而言.细粒径与中等粒径的颗粒对重金属贡献率较为接近。街道地表物呈碱性,有潜在的有机物污染。重庆市主城区街道地表物重金属元素含量有较大的差异,受人为活动干扰严重的重金属种类为Cr、Cd、Hg、Cu。内梅罗指数评价结果显示除Ni外,其他元素均有不同程度的污染,各功能区均受到重金属的严重污染。重庆市主城区街道地表物中的重金属只与其中的磷素含量显著正相关。 相似文献
85.
J.E. Barrett R.A. Virginia J. Aislabie J.G. Bockheim W.B. Lyons J.N. Nkem H. Steltzer M.D. Wallenstein 《Soil biology & biochemistry》2006,38(10):3019-3034
Terrestrial environments of Victoria Land, Antarctica are ideal systems to test hypotheses about the sensitivity of ecosystem processes to climate variability, and the relationships between soil biodiversity and ecosystem functioning because of their high sensitivity to climate change and their limited diversity. This region is also considered among the most pristine of ecosystems, and therefore may serve as an indicator for detecting the response of other ecosystems to global environmental change. Rates and controls over key ecosystem processes remain poorly documented over much of Victoria Land, but it is generally held that the distribution and functioning of soil communities are most limited by the availability of liquid water and organic carbon. Here we review examples of ecosystem processes from several sites in North and South Victoria Land and develop a regional synthesis accounting for variation in the availability of soil resources (i.e. liquid water, organic matter, inorganic nutrients). Variation in soil microclimate, organic matter, moisture and salinity encountered over gradients of coastal to interior sites, latitude, and soil chronosequences are the primary controls over the structure of soil communities and their functioning. Imbalanced stoichiometric nutrient ratios frequently encountered in Victoria Land ecosystems also contribute to limited distribution of soil biota, and where they occur these elemental imbalances indicate lower biological activity and little biotic control over bulk element ratios in soils. Priorities and future directions of Victoria Land soil and ecosystem research are also discussed. 相似文献
86.
Exotic plant invasions threaten ecological communities world-wide. Some species are limited by a lack of suitable pollinators, but the introduction of exotic pollinators can facilitate rapid spread. In Tasmania, where many non-native plants are naturalised, exotic honeybees (Apis mellifera) and bumblebees (Bombus terrestris) have become established. We determined how these species affect the pollination of Lupinus arboreus, an invasive, nitrogen-fixing shrub, which is rarely visited by native pollinators. The proportion of flowers setting seed and the number of ovules fertilised per flower were positively related to the visitation rates of both exotic bee species. There was no effect of bee visitation rates on the proportion of seeds aborted prior to maturity, possibly due to post-fertilisation environmental constraints. We conclude that the spread of B. terrestris may not alter the fecundity of L. arboreus because of the pollination service provided by A. mellifera, and discuss potential interactions between these two bee species. 相似文献
87.
微生物肥料效应及其应用展望 总被引:24,自引:2,他引:24
简述了微生物肥料种类、特点及其生理生态效应,指出应加强微生物肥料基础与应用研究,并展望微生物肥料发展前景。 相似文献
88.
东北苏打盐碱地生态渔业模式研究 总被引:1,自引:0,他引:1
试验结果表明 ,东北苏打盐碱地实施鱼 稻 苇 蒲生态渔业模式效益显著 ,平均单产水稻为 6 0 2 4 .2kg/hm2 、芦苇 8336 .2kg/hm2 和蒲草 7387.6kg/hm2 ;平均鱼产量稻田养鱼为 912 .1kg/hm2 、蒲塘养鱼 35 37kg/hm2 和苇塘养鱼2 76 6kg/hm2 ;平均净收入 5 6 6 7.1元 /hm2 ,产投比为 2 .0 74。 1个生长期节水 1.9万m3 /hm2 ,节约化肥 2 90kg/hm2 ,降低土壤盐分 5 0 7kg/hm2 。 相似文献
89.
Veerle Vanacker Gerard Govers Jean Poesen Jozef Deckers Gerd Dercon George Loaiza 《CATENA》2003,51(3-4):329-347
Aerial photographs taken in 1976 and 1989 and a field survey in 1999 showed that land use in a 900-ha catchment in the southern part of the Ecuadorian Andes is highly dynamic. Over 23 years, ca. 83 ha of arable land was abandoned and ca. 70 ha was taken into agricultural production. Changes in land use were not spatially homogeneous. Parcels on unstable geologic formations and close to village centres were preferably set-aside. Land taken into cultivation was preferably located on gently sloping areas close to newly built sites and arterial roads. The area with bush vegetation increased by regeneration of natural vegetation on fields set-aside in the late 1970s and early 1980s. There was a complex interaction between water erosion and environmental change in the study area. Land taken into production was levelled for furrow irrigation: this led to a net reduction in the area susceptible to water erosion. However, one quarter of the area affected only by sheet and rill erosion 23 years ago has since become incised by deep gullies. This increase in gully density was related to inadequate construction and management of irrigation infrastructure, rather than to change in vegetation cover and/or soil erodibility caused by agricultural practices. This factor is often overlooked in studies of the effects of environmental change on geomorphologic processes. 相似文献
90.
The aim of this study is to compare the density and vertical distribution of ghost crab Ocypode quadrata burrows at three beaches with different degrees of anthropic impact. In order to achieve this, 12 1 m2 quadrants were laid out at random daily on each beach, over a 100 m wide strip stretching from the dunes to the waterline, in order to estimate the density of the burrows. The results showed that the density of O. quadrata burrows was lower at beaches with higher anthropic impact - Tramandaí and Harmonia. Jardim do Éden beach, which suffers little impact, had the highest density of burrows. Vertical distribution of the burrows at Tramandaí beach was restricted by the presence of a strip which cars drive along. The burrows along this beach tended to be distributed over a strip where there are kiosks which offer protection from the traffic. At Jardim do Éden and Harmonia beaches, vertical distribution of the burrows was affected only by the dynamics of the rise and ebb of the waterline, caused by two storm events. The results showed that the density of ghost crab O. quadrata burrows is a tool of quick and easy use in diagnosing anthropic impact in coastal areas. 相似文献