高速公路沿线暗浜填土的勘察和评价

目前,线路勘探中对浜填土检测不够重视或缺乏有效的方法,使浜填土的处理缺乏针对性,造成不必要的浪费或工程隐患。该文探讨了在线路勘探中暗浜的勘查技术及相应评价与整治方法。

QUANTITATIVE STUDY OF SOIL EROSION AND ELEMENT RUN-OFF IN THE SONGHUA LAKE VALLEY

Under the condition of different precipitation intensities, different gradients, different land-use types and different vegetation coverage, the soil erosion and transference of element (or pollutant) are studied by simulating and analyzing the surface run-off of experimental plots in the catchment area of Songhua Lake, with an area of about 43 370.8km2. And the influencing factors that produce the spatial difference are analyzed and assessed. It is put forward that the irrational land utilization is the reason of soil erosion and pollutant run-off. The gradient of farmland, the growing season of vegetation and the vegetation coverage are chiefly restricting factors that lead to the soil erosion and pollutant run-off. This study can provide the fundamental data for comprehensive planning and harnessing of the non-point source pollution in the valley.

Effect of sulfate erosion on strength and leaching characteristic of stabilized heavy metal contaminated red clay

Solidification/stabilization(S/S)technology has been widely used for remediation of the heavy metal contaminated soils.The heavy metal ions will be leached from the stabilized contaminated soil under sulfate erosion conditions,which gives rise tosecondary contamination to the areas around the mine sites.The commonly used Portland cement,fly ash and quicklime were takenas binder raw materials with various mix proportions.And then,the sulphuric acid and nitric acid method was used to investigate theleaching characteristic of stabilized heavy metal contaminated soils.The effects of binder types and binder contents,sulfateconcentrations(1.5,3.0and6.0g/L)and erosion time(0,7,14and28d)on leached concentrations of heavy metal ions fromcontaminated soils were studied.Moreover,a parameter named immobilization percentage(IP)was introduced to evaluate theinfluence of erosion time and sulfate concentration on immobilization effectiveness for heavy metal ions.The results showed that,theleached heavy metal concentrations increased with sulfate concentration and erosion time.Comparatively speaking,the compositebinders that had calcium oxide in it exhibited the worst solidification effectiveness and the lowest immobilization percentage,withthe largest leached heavy metal concentration.

SPATIAL ANALYSIS OF SOIL EROSION AND NON-POINT SOURCE POLLUTION BASED ON GIS IN ERLONG LAKE WATERSHED, JILIN PROVINCE

Data collection, factor composition, nappe analysis and integrative simulation of natural geographical factors in Erlong Lake watershed have been carried out based on GIS. The risk areas where non-point source pollution may occur were compartmentalized and assessed, and the total soil erosion and the runoffs of N and P with rainfall in this valley were worked out by experiment and GIS mapping. The study indicated that the main type of soil erosion was moderate (erosion modulus is 1000-2500t/(km(2).a)) at present, and the intense erosion areas are located in dry land with variable slope east of the lake and the middle-south parts of steep slope mountainous region (erosion modulus is more than 5000t/(km(2).a)). Though the area is small, it should be paid attention to. The trend of non-point source pollution (NSP) of nitrogen and phosphorus loss was corresponded with the soil erosion. Spatial distribution and the reasons of the distribution difference have been presented and it was emphasized that the human activities among the influence factors was the most important. It surely offers a scientific basis to control and prevent non-point source pollution in the watershed.

An Integrated Quantitative Method to Simultaneously Monitor Soil Erosion and Non-Point Source Pollution in an Intensive Agricultural Area

In China, some areas with intensive agricultural use are facing serious environmental problems caused by non-point source pollution(NPSP) as a consequence of soil erosion(SE). Until now, simultaneous monitoring of NPSP and SE is difficult due to the intertwined effects of crop type, topography and management in these areas. In this study, we developed a new integrated method to simultaneously monitor SE and NPSP in an intensive agricultural area(about 6 000 km2) of Nanjing in eastern China, based on meteorological data,a geographic information system database and soil and water samples, and identified the main factors contributing to NPSP and SE by calculating the NPSP and SE loads in different sub-areas. The levels of soil total nitrogen(TN), total phosphorus(TP), available nitrogen(AN) and available phosphorus(AP) could be used to assess and predict the extent of NPSP and SE status in the study area.The most SE and NPSP loads occurred between April to August. The most seriously affected area in terms of SE and NPSP was the Jiangning District, implying that the effective management of SE and NPSP in this area should be considered as a priority. The sub-regions with higher vegetation coverage contributed to less SE and NPSP, confirming the conclusions of previous studies, namely that vegetation is an effective factor controlling SE and NPSP. Our quantitative method has both high precision and reliability for the simultaneous monitoring of SE and NPSP occurring in intensive agricultural areas.

Viral infection of tobacco plants improves performance of Bemisia tabaci but more so for an invasive than for an indigenous biotype of the whitefly

The ecological effects of plant-virus-vector interactions on invasion of alien plant viral vectors have been rarely investigated. We examined the transmission of Tomato yellow leaf cur/China virus （TYLCCNV） by the invasive Q biotype and the indigenous ZHJ2 biotype of the whitefly Bemisia tabaci, a plant viral vector, as well as the influence of TYLCCNV-infection of plants on the performance of the two whitefly biotypes. Both whitefly biotypes were able to acquire viruses from infected plants and retained them in their bodies, but were unable to transmit them to either tobacco or tomato plants. However, when the Q biotype fed on tobacco plants infected with TYLCCNV, its fecundity and longevity were increased by 7- and 1-fold, respectively, compared to those of the Q biotype fed on uninfected tobacco plants. When the ZHJ2 biotype fed on virus-infected plants, its fecundity and longevity were increased by only 2- and 0.5-fold, respectively. These data show that the Q biotype acquired higher beneficial effects from TYLCCNV-infection of tobacco plants than the ZHJ2 biotype. Thus, the Q biotype whitefly may have advantages in its invasion and displacement of the indigenous ZHJ2 biotype.