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431.
432.
本文对陇海铁路宝天段路基的地质地理及气象因素进行了综合分析。认为气象因素是路基灾害的主要原因,是触发机制,尤其是路基选址不当所产生的路基气象综合效应更加重了灾害程度.文章认为,设计铁路时,不但要注意气象条件的研究,同时要模拟研究路基与气象条件相互作用所产生的气象效应. 相似文献
433.
Use of man-made impoundment in mitigating acid mine drainage in the North Branch Potomac River 总被引:1,自引:0,他引:1
The US Department of the Army, Baltimore District Corps of Engineers, oversees a long-term monitoring study to assess and
evaluate effects of the Jennings-Randolph reservoir on biota in the North Branch Potomac River. The reservoir was intended,
in part, to mitigate effects of acid mine drainage originating in upstream and headwater areas. The present study assessed
recovery of benthos and fish in this system, six years after completion of the reservoir. Higher pH and lower iron and sulfate
concentrations were observed upstream of the reservoir compared to preimpoundment conditions, suggesting better overall water
quality in the upper North Branch. Water quality improved slightly directly downstream of the reservoir. However, the reservoir
itself was poorly colonized by macrophytes and benthic organisms, and plankton composition suggested either metal toxicity
and/or nutrient limitation. One large tributary to the North Branch and the reservoir (Stony River) was shown to have high
(and possibly toxic) levels of manganese, iron, zinc, and aluminum due to subsurface coal mine drainage. Macroinvertebrate
diversity and number of taxa were higher in sites downstream of the reservoir in the present study. Compared with previous
years, the present study suggested relatively rapid recovery in the lower North Branch due to colonization from two major
unimpacted tributaries in this system: Savage River and South Branch Potomac. Abundance of certain mayfly species across sites
provided the most clear evidence of longitudinal gradients in water quality parameters and geomorphology. Fish data were consistent
with macroinvertebrate results, but site-to-site variation in species composition was greater. Data collected between 1982
and 1987 suggested that certain fish species have unsuccessfully attempted to colonize sites directly downstream of the reservoir
despite the more neutral pH water there. Our results show that recovery of biota in the North Branch Potomac was attributed
to decreased acid inputs from mining operations and dilution from the Savage River, which contributed better water quality.
Continued improvement of North Branch Potomac biota may not be expected unless additional mitigation attempts, either within
the reservoir or upstream, are undertaken. 相似文献
434.
EffectsofsimulatedacidrainontheinjuryandphysiologicalresponsesofcropsZhangFuzhu,YangXiaofeng,ZhangJingyang(ResearchCenterforE... 相似文献
435.
佛山市区酸雨时空分布特征及其成因分析 总被引:1,自引:0,他引:1
从致酸源、地理环境、工业状况、气候条件等因素分析了佛山市酸雨的成因,提出一些控制酸雨污染的建议。 相似文献
436.
The effects of simulated acid rain with pH values of 6.63 (control, 4.5, 3.0, and 2.0 on saplings of Pinus massoniana and Cunninghamia lanceolate, were studied. The results showed that the pH of C.lanceolate, leaf sap and soil decreased as the acidity of rainfall increased. The acid rain with very low pH had significant effects on the photosynthetic rates per plant, but not on that of the per unit weight of dry leaves. The respiration rates of the two species were stimulated. Root and leaf boimass, but not stem biomass, were also reduced tremendously during a seven months period. 相似文献
437.
438.
Shen Ji Zhao Qianxue Zhang Xiaoshan Zhang Baozhu Zhao Dianwu Fan Zenghu Cheng Panjiang 《环境科学学报(英文版)》1991,3(1):41-58
-The concentrations of gas phase SO2, O3 and chemical composition of sequential rainwater samples were measured on 6/11/88 to 6/28/88 at some sites of Guiyang area. S (IV) was present in great excess of H2O2 in rainwater samples collected at residential sites of the city corresponding to high level of gas phase SO2. Considerable H2O2 in rainwater samples was observed in background air at suburbs. The evidence that clean rainwater samples were collected at 20km away from the city in 6/18/88 precipitation event revealed that the major process of acidification of the rain in the high polluted areas was below-cloud scavenging of trace gases. From a simulation calculation it was found that the rate of oxidation of S(IV) by O3 and by Mn2+, Fe3+ catalytic in high pH rainwater is significant, but for low pH the major SO42- is produced by the reaction of S (IV) with H2O2. 相似文献
439.
雨水中微量过氧化氢的间接原子吸收测定 总被引:6,自引:0,他引:6
通过过氧化氢与重铬酸钾的定量反应,用原子吸收测铬的方法达到测定过氧化氢的目的。试验表明,该法用于雨水中微量过氧化氢的测定,试验令人满意,且操作方便。 相似文献
440.
Several factors, namely, coal-dominated primary energy mix, extensive economic development mode, inefficient energy utilization, end the imperfect environmental regulations, result in the serious urban sulfur dioxide pollution end large-scale sulfatetype acid precipitation in China. In 1995, China's sulfur dioxide emissions reached 23.70 Mt, and the areas affected by acid rain accounted for 40% of the territory. Chinese government accords considerable importance to the sulfur dioxide end acid rain contamination. New sets of environmental friendly policies have been promulgated. But enforcement of laws and regulations on SO2 emissions need to be further improved and broadened, especially those respond to market conditions. This paper focuses particular attention on the analysis of strategy, policies, and national actions which had or should be taken against sulfur dioxide emissions nationwide to achieve the environmental targets, on the basis of which gives the technical options in future. 相似文献