Amazon floodplain hydrology and implications for aquatic conservation

1. The amplitude, duration, frequency, and predictability of runoff and inundation of aquatic habitats are key hydrological characteristics linked to aquatic ecosystem functioning and biodiversity, but they are seldom integrated into analyses of Amazon floodplain ecology. Remote sensing approaches, measurements and modelling of floodplain hydrology provide a basis for this integration.
2. Effective legislation to protect floodplains and other wetlands depends on operational definitions that require application of hydrological data.
3. Extent and changes of flooded areas are linked to fish diversity and to presence and growth of flooded forests and floating plants.
4. Dam construction reduces river system connectivity and modifies the flood pulse, with major negative implications for floodplain ecosystems adapted to and dependent on a natural flood regime.
5. Trends and variability in climate plus deforestation are altering the Amazon's hydrological cycle, causing changes in discharge and flooded area with concomitant ecological impacts.

     

大庆城郊湿地沉积物重金属污染评价

通过对大庆城郊湿地北二十里泡沉积物重金属含量的分析测定,结果表明主要重金属在各点位含量均超过清洁对照点,将全区域土壤重金属元素背景值作标准,北二十里泡湿地沉积物中Hg、Zn、Cu、Cd、Pb等元素超标较多。内梅罗综合污染指数评价表明,北二十里泡底泥沉积物重金属内梅罗综合污染指数范围是2.7￣28.79,平均值为6.14,综合评价等级为Ⅲ级,属于中度污染。     

泉州湾海岸带湿地生态特征及保护利用研究

初步探讨了泉州湾湿地的资源特点,分析了面临的主要环境问题,并针对泉州湾湿地自然资源、生态环境特征和区域发展要求,提出泉州湾海岸湿地恢复和保护对策。     

磷钾钙配比对芦苇末基质栽培甜椒幼苗生长及生理代谢的影响

以甜椒品种‘中椒5号’为试材,以芦苇末和蛭石(体积比3∶1)混合基质为栽培基质,运用正交试验设计法,研究了营养液中不同磷、钾、钙水平对甜椒幼苗生长及体内营养元素含量等的影响。结果表明,芦苇末混合基质栽培甜椒时,提高营养液中磷和钙水平,甜椒幼苗的株高、生物积累量、根系活力、叶绿素含量和净光合速率(Pn)显著提高,过氧化物酶(POD)活性和丙二醛(MDA)含量降低,幼苗体内营养元素含量较高;而提高营养液中的钾水平对甜椒幼苗没有明显的影响。总之,营养液中磷和钙处于较高水平、钾处于较低水平时,芦苇末混合基质栽培的甜椒幼苗生长势良好;用芦苇末基质栽培甜椒时应具有较高的磷和钙营养管理水平,浇灌营养液中磷、钾、钙浓度的最佳配比组合为:1.66、3、3 mmol.L-1。     

Methane emissions from different vegetation zones in a Qinghai-Tibetan Plateau wetland

We measured methane (CH₄) emissions in the Luanhaizi wetland, a typical alpine wetland on the Qinghai-Tibetan Plateau, China, during the plant growth season (early July to mid-September) in 2002. Our aim was to quantify the spatial and temporal variation of CH₄ flux and to elucidate key factors in this variation. Static chamber measurements of CH₄ flux were made in four vegetation zones along a gradient of water depth. There were three emergent-plant zones (Hippuris-dominated; Scirpus-dominated; and Carex-dominated) and one submerged-plant zone (Potamogeton-dominated). The smallest CH₄ flux (seasonal mean=33.1 mg CH₄ m⁻² d⁻¹) was observed in the Potamogeton-dominated zone, which occupied about 74% of the total area of the wetland. The greatest CH₄ flux (seasonal mean=214 mg CH₄ m⁻² d⁻¹) was observed in the Hippuris-dominated zone, in the second-deepest water area. CH₄ flux from three zones (excluding the Carex-dominated zone) showed a marked diurnal change and decreased dramatically under dark conditions. Light intensity had a major influence on the temporal variation in CH₄ flux, at least in three of the zones. Methane fluxes from all zones increased during the growing season with increasing aboveground biomass. CH₄ flux from the Scirpus-dominated zone was significantly lower than in the other emergent-plant zones despite the large biomass, because the root and rhizome intake ports for CH₄ transport in the dominant species were distributed in shallower and more oxidative soil than occupied in the other zones. Spatial and temporal variation in CH₄ flux from the alpine wetland was determined by the vegetation zone. Among the dominant species in each zone, there were variations in the density and biomass of shoots, gas-transport system, and root-rhizome architecture. The CH₄ flux from a typical alpine wetland on the Qinghai-Tibetan Plateau was as high as those of other boreal and alpine wetlands.     

湿地生态系统对污水中重金属的修复作用

湿地污水处理技术的研究是国内外众多学者关注的热点之一。综合国内外在污水湿地处理技术方面的研究成果,对湿地生态系统及其各组成要素对重金属污染的修复作用及其作用机理进行了讨论,针对目前利用湿地生态系统进行重金属污染废水修复过程中应注意的几个问题进行了探讨,并对今后研究发展方向进行了评述。     

Seasonal changes in periphyton nitrogen fixation in a protected tropical wetland

Cyanobacteria are important for global nitrogen cycle and often form complex associations referred to as cyanobacterial mats or periphyton that are common in tropical, limestone-based wetlands. The objective of this study was to monitor the nitrogen fixation rate using the acetylene reduction assay of these cyanobacterial mats in a tropical, unfertilized, and protected wetland. To account for temporal and spatial variation of nitrogenase activity, we were interested in seasons in a hydrological cycle (dry, rains, and end of rains), sites with different vascular vegetation, and rates of nitrogenase activity in a 24-h cycle. The annual average of nitrogenase activity was 22 nmol C₂H₄ cm⁻² h⁻¹, with a range of <6 to 35 nmol C₂H₄ cm⁻² h⁻¹, and the annual nitrogen fixation rate of our study site (9.0 g N m⁻² year⁻¹) is higher than similar estimates from other freshwater wetlands. There was a clear temporal pattern in nitrogenase activity with a maximum rate occurring during the rainy season (August) and a maximum nitrogenase activity occurring between 0600 and 1200 hours. We found spatial differences in nitrogenase activity among the four sites that could be attributed to variations in species composition within the periphyton.     

塘渠-湿地复合系统治理农业面源污染研究

The effects of agricultural non-point source pollution control by pond-wetland combined system in Shenxi river basin of Anji county were studied based on nearly one-years experiment. The removal rate of total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD) of the pond-wetland combined system was also studied with different inlet wastewater concentration and time. The results showed that the removal effect of TN, TP, and COD in pond-wetland combined system was fairly good. The removal rate of TN, TP, and COD in the system could respectively reach 96%, 98%, 82% when the TN, TP, and COD of inlet wastewater reach the highest point 33.3, 0.99, and 121.6 mg·L^-1. Generally, the removal effect of the system was better in plant growth season and higher concentration of inlet wastewater period.     

我国湿地保护法制建设的简要回顾与展望

回顾了我国湿地保护立法的2个阶段,总结了我国湿地保护法制建设的主要成就,分析了存在的主要问题。对出台一部国家级的湿地保护综合性立法、加大湿地保护综合协调和组织机构建设进行了展望。     

北京湿地现状调查与分析

通过对北京市湿地资源普查结果和湿地动态变化的分析,对水资源、湿地植物资源、湿地动物资源、湿地生态旅游资源、湿地土地资源的合理利用提出了建议。