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841.
采用GDX-502大孔树脂和GC-MS等仪器对城市河流,湖库中的痕量有机污染物进行测试分析,共检出58种有机污染物,其中含有多种美国EPA公布的重点污染物。因而为痕量有机污染物的研究建立了灵敏度高,分辨率好的测试方法。 相似文献
842.
W. C. Schutte R. S. Cole K. R. Long C. W. Frank 《Environmental monitoring and assessment》1982,1(3):257-261
Twenty seven UFFI homes in Colorado and Wisconsin were sampled for formaldehyde levels. The formaldehyde concentrations found in these homes averaged 0.059 ppm. Two homes were monitored for an extended period to determine the impact of ambient climatic conditions. 相似文献
843.
本文就扬子板块东南缘湖南段上元古代三套同期异相沉积层—泥市群、板溪群及高涧群的构造变形特征分别作了简要概述。指出它们的主体构造变形是显生宙以来构造叠加变形的综合反映,其中,板溪群与高涧群的构造变形型式迥然有别,“雪峰隆起”的南北两侧不仅在组成上而且结构上均具显著的不对称性。 相似文献
844.
A forest tree growth-response to atmospheric deposition is expected to arise indirectly through soil chemical changes and would probably be observable only in the long term. We examined this hypothesis by evaluating the relationship between periodic height growth of mature northern red oak (Quercus rubra L.) trees and soil, physiography and atmospheric sulfate deposition along a 170-km west-to-east gradient of decreasing sulfate deposition in north central Pennsylvania, USA. Height increments for three common 20-year periods beginning in 1929, 1949 and 1969 were estimated from exponential-monomolecular growth functions fitted to stem analysis data for each of 45 trees in 13 ecologically analogous stands along the deposition gradient. Canonical analysis was used to identify a statistically manageable subset of the original 48 independent soil, site and tree (age, crown width) variables strongly associated with height growth. Predictive models relating total (60-year) and the three 20-year height increments to the reduced variable set plus estimated average sulfate and nitrate deposition were derived by best subsets multiple regression. An inherent spatial gradient of decreasing height growth from western to eastern sites was apparent in even the earliest (1929-1948) increment. This inferred non-deposition-related spatial growth trend was accounted for in the 1949-1968 growth increment by introduction of the earliest (1929-1948) growth increment as a significant covariate in the regression model. The inherent growth largely disappeared by the 1969-1988 period as a probable consequence of converging growth rates reported to occur in oaks after age 60 years regardless of site quality. The 1969-1988 growth increment was not as strongly correlated with site factors as was growth in preceding periods, nor was early growth or sulfate deposition significantly related to this height increment. Growth effects from sulfate deposition, if any, would most likely occur within the recent (1969-1988) increment coincident with the period of naturally decreasing growth rate, when site differences and possibly environmental factors would have less influence on growth. Our results give no indication that wet sulfate inputs are affecting northern red oak height growth across the atmospheric deposition gradient. 相似文献
845.
通过对重庆市生活垃圾的取样分析,得出重庆市城区、郊区城镇生活垃圾中污染物含量,从而计算出重庆现有的生活垃圾污染负荷。同时,对重庆市到2000年生活垃圾污染负荷进行了预测,为重庆市水污染控制规划提供了必须的生活垃圾污染负荷数据。 相似文献
846.
吸附胶体浮选法处理电解钴废水的研究 总被引:6,自引:0,他引:6
采用吸附胶体浮选法处理电解钴废水。用十二烷基磺酸钠(SLS)作浮选剂,用FeCl3和Al2(SO4)3作混凝剂,浮选后废水可达到国家工业废水排放标准(3mg/L)。为实际废水的处理提供了可靠的依据。 相似文献
847.
针对维生素B1生产废水成分复杂、难于生化降解、水质不稳定、固体悬浮颗粒含量高的特点,采用混凝-氧化-微电解-过滤的方法进行处理。当混凝剂三氯化铁的投加量为150mg/L,氧化剂次氯酸钠使用量为40mL/L,微电解反应器内pH为3~5,反应时间为50min,混合滤料滤柱停留时间为35min时,出水TOC、COD、色度等指标均达到了GB8978-1996所规定的二类水质的要求。 相似文献
848.
Chin Long Chiang 《Environment international》1978,1(6):315-319
The concept of the life table originated in longevity studies of man, where it was always presented as a subject peculiar to public health, demography, and actuarial science. As a result, its development has not received sufficient attention in the field of statistics. Actually, the problems of mortality studies are similar to those of reliability theory and life testing, and they may be described in terms familiar to the statistically oriented mind. From a statistical point of view, human life is a random experiment and its outcome, survival or death, ss subject to chance. The life table systematically records the outcomes of many such experiments for a large number of individuals over a period of time. Thus, the quantities in the table are random variables subject to established statistical analysis. The purpose of this presentation is to discuss the life table from a statistical viewpoint. 相似文献
849.
850.