Vegetation Change in Great Lakes Coastal Wetlands: Deviation from the Historical Cycle

Water-level change is integral to the structure and function of Great Lakes coastal wetlands, and many studies document predictable relationships between vegetation and water level. However, anthropogenic stressors, such as invasive species, land-use change, and water-level stabilization, interact to shift the historical cycle (of native vegetation migration up- and down-slope) toward dominance by invasive Typha species. Knowing from earlier studies that water-level stabilization alters the historical vegetation cycle, we asked if similar shifts can occur where water levels are not stabilized. Using historical aerial photographs of three coastal wetlands (in Lake Michigan's Green Bay, Wisconsin), we determined that habitat dominated by Typha species has expanded to eliminate wet meadow habitat. Between 1974 and 1992, linear regressions showed strong, significant relationships of both meadow area (R² ≥ 0.894; p < 0.02) and marsh area (R² ≥ 0.784; p < 0.05) to water level in all three wetlands. In 2000, meadow area was below that predicted by the historical pattern due to the landward advance of marsh habitat during a year of decreasing water levels. In the same period, land use in the wetland watersheds converted from agriculture to urban. Urbanization and the replacement of native Typha latifolia by the invasive hybrid Typha xglauca may have overwhelmed the beneficial impact of water-level fluctuation. The documentation of vegetation shifts, as herein, is an essential step in the process of preserving and restoring ecological integrity.     

基于体外模型研究广叶绣球菌多糖的酵解特性

目的:通过人体新鲜粪便酵解模型研究广叶绣球菌多糖在体外的酵解特性,以便为其体内的消化特性研究提供理论支持.方法:制备广叶绣球菌多糖和人体粪便菌群混合液,在无氧环境下发酵0、1、2、6、12、24、48h后,检测酵解液中的OD600值、pH值,总糖、还原糖、短链脂肪酸(乙酸、丙酸、丁酸)含量,乳酸杆菌、双歧杆菌和大肠杆菌...     

茭白废弃生物质苯酚液化及其产物树脂化制备胶黏剂

采用正交试验,考察了苯酚用量、催化剂用量、反应时间及反应温度对茭白废弃生物质液化效果的影响,并研究了该液化产物制备胶黏剂的影响因素。结果表明：茭白废弃生物质液化过程中,苯酚用量的影响最大,反应温度和反应时间次之,而催化剂用量的影响相对较弱,优化参数是苯酚用量为1：5,催化剂用量为7％,反应时间为90 min,反应温度为140℃,在此优化条件下,液化率为95．83％。胶黏剂制备过程中,茭白液化物与甲醛的质量比为1：1．8,高温缩聚反应温度为92℃较为合适。     

Characterization of Gum Ghatti (Anogeissus latifolia): A Structural and Rheological Approach

ABSTRACT:  Gatifolia, a commercial gum ghatti ( Anogeissus latifolia ) product was studied for its structural, thermal, and rheological characteristics. This study may prove helpful for the use of gum ghatti in a diverse range of food applications. The molecular weight ( M _W) and  R_g  (radius of gyration) for gum ghatti were calculated to be approximately 8.94 × 10⁷ g/mol and 140 nm, respectively, using high-performance size exclusion chromatography (HPSEC) system combined with multi-angle laser light scattering (MALLS). Gum ghatti solutions exhibited pseudoplastic behavior (as determined by flow experiments), which became more prevalent with increasing concentrations. Gum ghatti also displayed time-dependent shear-thickening behavior and showed negative hysteresis during up–down flow measurements. Under the measurement conditions at the range of frequencies and temperatures studied, the gum did not behave as a typical viscoelastic gel.     

苦丁茶冬青与大叶冬青苦丁茶提取物体外抗氧化活性的比较研究

比较苦丁茶冬青苦丁茶和大叶冬青苦丁茶提取液中多酚、黄酮的含量及体外抗氧化能力,结果表明：多酚含量高的苦丁茶冬青苦丁茶比黄酮含量高的大叶冬青苦丁茶具有较高的体外抗氧化能力;对5 种体外抗氧化活性评价方法之间的相关性进行分析,表明各抗氧化方法间相关性良好(R2 ＞ 0.8478),尤以DPPH 自由基法与ABTS＋·法的相关性最高(R2=0.9967)。     

Survivorship and growth of Typha latifolia L. across a NaCl gradient: a greenhouse study

Oil sands surface mining operations in northeastern Alberta have created a substantial area of land needing to be reclaimed. Historically, these lands were a mosaic of uplands and boreal wetlands, particularly peatlands. While protocols for upland reclamation are well-defined, protocols for peatland reclamation are still in development. Two major concerns for peatland reclamations are (1) the ability of wetland plants to tolerate the increased sodicity present after surface mining and (2) the potential for the invasion of aggressive wetland plants, such as Typha latifolia, that could crowd out peatland plants and hinder the development of a peat layer. This study addresses these concerns by quantifying the response of T. latifolia seedlings to a sodium gradient. In the lowest two concentrations (0 and 300 mg L^?1), there was about 100% survival rate as compared to about 56% at sodium concentration of 2400 mg L^?1. At 300 mg L^?1, T. latifolia leaf health began to decrease, and at 600 mg L^?1, the health, plant height and the biomass aboveground decreased substantially. Our findings suggest that T. latifolia populations might be kept in check by keeping sodium concentrations within a range between 300 and 600 mg L^?1.     

大叶冬青叶中总黄酮测定方法和提取工艺研究

采用氯化铝法、硝酸铝- 亚硝酸钠法分别测定大叶冬青叶中的总黄酮含量。实验结果表明两种方法的测定结果相差很大,通过显色机理的分析,确立了氯化铝法为大叶冬青叶总黄酮含量测定的适宜方法,方法的回收率90.7%～109.5%,平均回收率为97.8%,相对标准偏差2.2%。通过正交试验研究了大叶冬青叶中总黄酮提取工艺,结果表明其适宜工艺条件为液料比12:1(V/m)、乙醇浓度60%、提取时间2h、提取次数2 次,此条件下总黄酮得率为0.68%。     

大孔树脂纯化宽叶缬草中缬草素工艺优化

以宽叶缬草中的缬草素提取物为原料,对选取的 5 种大孔吸附树脂进行静态吸附试验,确定 D101 树脂为最优吸附树脂。通过 D101 树脂吸附缬草素的上样量试验与动态洗脱试验,确定上样溶液中缬草素质量浓度为10.0mg/mL,上样体积为 20.0mL,洗脱体积为 4BV。采用三元二次通用组合试验,考察上样流速、洗脱流速和洗脱液甲醇体积分数对柱层析纯化缬草素效果的影响,建立大孔树脂柱层析纯化缬草素的数学模型,经回归与方差分析,对模型进行局部寻优得出最佳工艺条件为：上样流速 2.5BV/h、洗脱流速 1.7BV/h,甲醇体积分数 75%,纯化后缬草素理论得率为72.40%,验证值为(72.12 ± 0.1)%。     

宽叶香蒲人工湿地对铅/锌矿废水净化效能的研究

研究以宽叶香蒲（Typha latifolia)为优势种的人工湿地系统对广东省韶关市凡口铅／锌矿采矿废水净化性能。研究结果表明：宽叶香蒲人工湿地生态系统能有效地净化铅／锌矿废水。经系统处理后,COD、固体悬浮物、Pb、Zn、Cu、和Cd的去除率分别为92．19％、99．62％、93．98％、97．02％、96．87％和96．39％,水质得到明显改善。主要污染物TSS、Pb、Zn、Cu和Cd等均达到工业标准,并接近农灌标准。     

Flooding tolerance of Sagittaria latifolia and Sagittaria rigida under controlled laboratory conditions

Pool‐scale growing‐season water‐level reductions (drawdowns) have been implemented on the Upper Mississippi River in an effort to improve fish and wildlife habitat. Aquatic vegetation is a key habitat component, with perennial emergent species, such as Sagittaria latifolia and Sagittaria rigida, especially important. River managers have assumed the need for continuous drawdown during the growing season with limited reflooding and used this guidance in assessing the potential for an ecologically successful drawdown. However, information on the effects of growing‐season flooding episodes on survival and growth of Sagittaria is limited. To assess the flooding tolerance of S. latifolia and S. rigida, we evaluated multiple levels of timing, duration, and depth on survival and productivity of plants. Plants were produced from S. latifolia and S. rigida seeds and S. latifolia tubers; all were reared under moist‐soil or shallow‐flooded rearing conditions. Mortality of plants was low (2%) among plants from large tubers, low (7%) among seedlings (and largely associated with early flooding treatments), and modest (11%) among plants from small tubers (with no clear effects of inundation). Flooding treatments generally had a positive effect on biomass production from seedlings, particularly when treatments occurred early, were relatively shallow, and were short in duration. There were no clear effects of depth, duration, or timing components of flooding treatments on plant biomass arising from tubers. This experiment indicates that S. latifolia and S. rigida are relatively tolerant of flooding events during the growing season and may actually benefit from some level of inundation.