排序方式: 共有13条查询结果,搜索用时 15 毫秒
1.
Journal of Polymers and the Environment - To optimize the phase separation temperature of poly (N-isopropylacrylamide) two monomers have been used to fabricate a series of three functional and... 相似文献
2.
Journal of Polymers and the Environment - A new monomer has been synthesized on the basis of vanillin. This compound has the advantage of having a tertiary amine group, which makes it one of the... 相似文献
3.
Wang L Brenden T Seelbach P Cooper A Allan D Clark R Wiley M 《Environmental monitoring and assessment》2008,141(1-3):1-17
Identification of reference streams and human disturbance gradients are crucial steps in assessing the effects of human disturbances
on stream health. We describe a process for identifying reference stream reaches and assessing disturbance gradients using
readily available, geo-referenced stream and human disturbance databases. We demonstrate the utility of this process by applying
it to wadeable streams in Michigan, USA, and use it to identify which human disturbances have the greatest impact on streams.
Approximately 38% of cold-water and 16% of warm-water streams in Michigan were identified as being in least-disturbed condition.
Conversely, approximately 3% of cold-water and 4% of warm-water streams were moderately to severely disturbed by landscape
human disturbances. Anthropogenic disturbances that had the greatest impact on moderately to severely disturbed streams were
nutrient loading and percent urban land use within network watersheds. Our process for assessing stream health represents
a significant advantage over other routinely used methods. It uses inter-confluence stream reaches as an assessment unit,
permits the evaluation of stream health across large regions, and yields an overall disturbance index that is a weighted sum
of multiple disturbance factors. The robustness of our approach is linked to the scale of disturbances that affect a stream;
it will be less robust for identifying less degraded or reference streams with localized human disturbances. With improved
availability of high-resolution disturbance datasets, this approach will provide a more complete picture of reference stream
reaches and factors contributing to degradation of stream health. 相似文献
4.
5.
6.
Hashem Md. Abul Hasan Md. Anik Momen Md. Abdul Payel Sofia Hasan Mehedi Shaikh Md. Zillur Rahaman 《Environmental science and pollution research international》2022,29(21):31278-31292
Environmental Science and Pollution Research - The regular practice of using sodium chloride to preserve raw animal skin triggers increasing salinity and total dissolved solids (TDS) in the surface... 相似文献
7.
Anderson PD Houpis JL Helms JA Momen B 《Environmental pollution (Barking, Essex : 1987)》1997,97(3):253-263
Gas exchange and pigmentation responses of mature ponderosa pine (Pinus ponderosa Laws.) branches to ozone and acid rain exposure were investigated using three grafted clones growing in a managed seed orchard. Exposure of one-year-old foliage to twice ambient ozone (2 x AMB) resulted in significant decreases in net photosynthesis (Pn), stomatal conductance (gsw) and pigmentation relative to charcoal-filtered (CF) and ambient (AMB) ozone treatments. Ozone effects on gas exchange and pigmentation were most pronounced during late-season and differed significantly among clones. Environmental parameters (e.g. light, vapor pressure deficit, and temperature) accounted for more variation in Pn than did cumulative ozone exposure. Minimal differences in gsw and Pn among ozone treatments occurred during seasonal periods of high temperature and evaporative demand. Negative effects of 2 x AMB ozone on gsw and pigmentation were greatest for the clones having highest and lowest phenotypic vigor under ambient conditions; the clone of moderate phenotypic vigor under ambient conditions was least sensitive to ozone. Application of simulated acid rain of pH 3.0, pH 5.1 or no rain (NR) had little impact on gas exchange or pigmentation. 相似文献
8.
9.
Bahram Momen Larry W. Eichler Charles W. Boylen Jonathan P. Zehr 《Environmental management》1997,21(5):725-732
a (Chl a), silica (Si), and chloride (Cl) through the use of proper statistical techniques. Results indicate no statistically significant
changes in the concentrations of TP, Chl a, or Si in the spring or summer from 1981 to 1993. A significant temporal trend of increase in Cl concentration is, however,
detected. This is perhaps the strongest evidence that the development of the Lake George watershed has affected lakewater
chemistry. In spring, the concentrations of TP, Chl a, Si, and Cl, averaged over all 13 years, were higher in the south basin, but differences are not statistically significant
(i.e., P > 0.05). In summer, Si was slightly but significantly lower, and Cl was nonsignificantly higher in the south basin. Significant
interactions between temporal and spatial changes are detected based only on summer values of TP and Chl a, indicating differential trends of change for these two variables in the south and north basins during the last 13 years. 相似文献
10.
We investigated the additive and interactive effects of simulated acid rain and elevated ozone on C and N contents, and the C:N ratio of one-year-old and current-year foliage of field-grown mature trees and their half-sib seedlings of a stress tolerant genotype of ponderosa pine. Acid rain levels (pH 5.1 and 3.0) were applied weekly to foliage only (no soil acidification or N addition), from January to April, 1992. Plants were exposed to two ozone levels (ambient and twice-ambient) during the day from September 1991 to November 1992. The sequential application of acid rain and elevated ozone mimicked the natural conditions. Twice-ambient ozone significantly decreased foliar N content (by 12-14%) and increased the C:N ratio of both one-year-old and current-year foliage of seedlings. Although similar ozone effects were also observed on one-year-old foliage of mature trees, the only statistically significant effect was an increased C:N ratio when twice-ambient ozone combined with pH 3.0 rain (acid rain by ozone interaction). Enhancing the effect of twice-ambient ozone in increasing the C:N ratio of one-year-old foliage of mature trees in June was the only significant effect of acid rain. 相似文献