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111.
为了解南湖浮游植物功能群特征及其与环境因子的关系,于2017年3月到2018年2月对浮游植物群落结构进行研究.结果表明,南湖共记录浮游植物7门58属98种.浮游植物密度和生物量的年平均值分别为44.1×105 cells/L和0.41mg/L.南湖浮游植物群落可划分为23个功能群,其中功能群C、D、E、F、G、H1、J、K、Lo、M、MP、P、TC、W1、X1、X2、Y为优势功能群.优势功能群的季节演替为春季(C、F、X1、X2)→夏季(J、K、Lo、TC)→秋季(Lo、M、TC)→冬季(E、J、P、X2).TLI指数、Shannon指数和Margalef指数均表明,南湖水体处于中营养水平.冗余分析表明,水温、TN浓度和浮游甲壳动物是影响南湖浮游植物功能群的主要因子. 相似文献
112.
根据2007年7-9月新疆艾比湖湿地25种主要植被在47个调查样地的存在.缺失数据,应用非度量多维标度(NMDS)方法研究了干旱区典型湖泊湿地内植物群落生态种组的划分,并与系统聚类分析结果做了比较分析。研究显示:艾比湖湿地的主要植物种划分为5个生态种组,各生态种组内的植物种之间具有相似的生境和生态位;NMDS是基于高维数据非线性迭代的降维排序方法,与传统的生态种组分析方法相比较,NMDS充分抽取了植被在样地内非线性集聚分布的信息,因而其种组划分结论更符合实际调查结果,也更为可靠、有效。研究结果从生态种组的视角为艾比湖湿地生态恢复和保护植物多样性提供更具有实践价值的参考依据。 相似文献
113.
考察了不同有机改性硅对微囊藻毒素LR(mLR)和LA(mLA)的等温吸附行为。结果表明,有机改性硅可有效吸附去除水体中<0.1×10-6(质量分数)的微囊藻毒素,并且吸附去除效果随表面改性官能团中碳原子数量的增加而增加;相同条件下,有机改性硅在微囊藻毒素异构体之间存在着一定的吸附选择性。 相似文献
114.
在固定床吸附实验台上对低温等离子改性前后的复合钙基吸附剂进行脱汞实验,深入探究SO2和O2对具有较高孔隙率和比表面积的复合钙基吸附剂脱汞性能的影响.并通过多种表征手段和方法分析复合钙基吸附剂对Hg0的吸附机理.实验结果表明,由于等离子改性提高了吸附剂表面的含氧官能团的相对含量,经等离子改性的复合钙基吸附剂的脱汞效率有明显提高.在N2+0.07% SO2+6% O2气氛下,吸附剂脱汞效率相比于无氧气氛由23.7%增至91.2%,吸附剂脱汞效率明显提高.此时吸附剂表面的羟基、酯基官能团作为主要反应活性位点,而羰基官能团的作用不明显.O2的存在促使活性炭表面由碳原子不饱和键形成的活性位增加,促进了Hg0的吸附,同时生成多种汞化合物.随着SO2浓度升至0.15%,改性复合钙基吸附剂表面活性位再次出现不足,此时SO2抢夺Hg0的吸附位点,脱汞效率降至23.3%. 相似文献
115.
An undisturbed natural reserve area iocated in a tropical montane rain forest at about 1800 m altitude in Sri Lanka served as a study site to investigate and assess the natural background concentration levels of As, Cd, Co, Cu, Ni, Pb and Zn in plants representing different taxonomic groups (divisions) in the plant kingdom. The plants selected were: the lichen,Usnea barbata (old man's beard);Pogonatum sp. (a moss);Lycopodium selago (epiphytic lycopod);Polypodium lanceolatum (epiphytic fern);Bulbophyllum elliae (epiphytic orchid) andActinodaphne ambigua (dicotyledonous large tree). Degree of homogeneity with respect to Cd, Cu, Pb and Zn in homogenised materials of all samples were within acceptable limits, whereasPogonatum sp. showed the highest degree of homogeneity for Pb. In addition to confirming extremely low levels of heavy metals in all plant species, the survey also found that generally the primitive plants,Usnea andPogonatum appear to have a greater tendency to accumulate As, Cd, Co and Pb; in particular,U. barbata appears to be an efficient accumulator for those heavy metals, suggesting its potential use in environmental studies.Actinodaphne ambigua was found to have a specific accumulating ability for nickel. Surface cleaning of theA. ambigua leaves resulted in a substantial decrease in the foliar contents of Cd, Ni, Pb and Zn. Variations in heavy metal contents observed in different plant genera are discussed in terms of their habits and place of growth in the forest. It is anticipated that the background levels presented in this paper from a remote, unpolluted tropical ecosystem will provide useful reference data for comparative environmental studies. 相似文献
116.
Climate is a group‐level phenomenon that should be measured and studied at the group level. The group level has theoretical and methodological advantages over the individual level. In this paper, I theoretically review the assumptions in measuring climate at the individual and group levels and demonstrate that the group‐level assumptions are more adequate for climate research because of their influences in exposure to events, interpretation of events, and preservation of perceptions. Methodologically, I discuss advantages in group‐level climate measurement accuracy that are based on multiple evaluators of climate and I suggest group aggregation is an organizational form of “wisdom of the crowds.” Finally, I point to three topics that remain to be investigated to understand climate at the group level better. The first is use of variability measures to compensate for information that is lost in aggregation. The second is challenging the assumption that formal organizational structure defines the group boundaries. I suggest that other levels of analysis apply to group‐level climate measurement and demonstrate the use of informal, more natural groups as an additional level. Third, I point to recently developed statistical procedures that can aid the study of climate perception emergence over time. 相似文献
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119.
Introduction: The objective of this study was to analyze which factors (including factors pertaining to the individual, the household, and the local area) increase the risk of fall injuries for the three age groups with the highest risk for fall injuries in Sweden. Method: The study combined longitudinal data covering the period 1999–2013 from several different official registries from Statistics Sweden as well as from the Swedish health care system and fitted the models to data using mixed model regressions. Results: Three age groups had a markedly heightened risk for fall injuries: 1–3-year olds, 12–14 year olds, and the elderly (65+). The home was the most common location for fall injuries, as about 40% of all fall injuries occur in the home. Only for the elderly strong predictors for fall injuries were found, and these were: age, single household, and special housing. Conclusions: There is preventive potential in the special residences for the elderly and disabled. People living in these special residences make up a strongly selected group that needs extra safe environments. Our findings indicate that their needs are currently not meet. Practical applications: Design of special residences for the elderly and disabled should aim at reducing the consequences of falling. 相似文献
120.