我国淡水水域光合产物的气候生产力探讨

根据太阳辐射在水体中的有效分布、生长季水温和浮游植物光合生态特性等因子,模拟计算了我国大陆东部淡水水域的光合生产力、气候生产力及其季节变化的地理规律。从中得知,这些水域初级产物的年气候生产力主要呈纬向分布,由南向北递减,各地范围在 1.6-24.4gC/m²·a之间,长江以南是>15.0gC/m²·a的高值区,长城以北和四川盆地为<10.0gC/m²·a的低值区,因此,在气候生产力高值区有可能充分利用气候资源优势,开发低成本的自然淡水水域渔业;而在低生产力区,受自然资源的局限其自然捕鱼量需适量控制,因地制宜。     

典型湖泊水华特征及相关影响因素分析

通过2011-2015年对太湖、巢湖和滇池水华高发季节的连续监测,以藻类密度和水华面积为判据评价了3个湖体的水华情况及变化趋势,探讨了水华发生的主要影响因素。结果表明：太湖水华程度以"轻度水华"为主,巢湖水华程度以"轻微水华"为主,滇池水华程度以"中度水华"为主;太湖、巢湖和滇池水华规模均以"零星性水华"为主;太湖和巢湖藻类密度与水温、pH、溶解氧、总氮、总磷和高锰酸盐指数均呈显著正相关,与透明度呈显著负相关,与氨氮无显著相关性;滇池藻类密度与水温、总磷和高锰酸盐指数均呈显著正相关,与透明度和氨氮呈显著负相关,与pH、溶解氧和总氮无显著相关性。     

海河流域水生态功能一级二级分区

水生态功能分区是实现流域水环境"分区、分级、分期和分类"管理的基础.通过分析海河流域的陆地和水生态系统特点,确定了一级二级分区的指标体系,一级分区指标包括地貌类型、径流深、年降水量、年蒸发量,反映水资源供给功能的空间格局特征,共划分了6个一级水生态功能区;二级分区利用植被类型和土壤类型的空间异质性,反映流域生态水文过程及水质净化功能的空间格局特征,共划分了16个二级水生态功能区.最后,通过野外调查各个分区的水生态系统结构和生境差异性(水量、水质、河流生境、水生动植物等),对一级和二级分区结果进行了评价.分区结果能够为海河流域的水质目标管理和区域生态环境建设提供支持,分区方法和指标体系也可以为国内其它类似流域的水生态功能分区提供参考.     

Sustainable Development in Small Island Developing States

This paper explores the status of sustainable development in small island developing states (SIDS), through the presentation of a case study on the Maldives, which is a typical small island developing state in the Central Indian Ocean. At the outset, a brief history of sustainable development as related to SIDS on the international agenda is outlined, starting from Rio to Barbados to Johannesburg. SIDS are expected to face many challenges and constraints in pursuing sustainable development due to their ecological fragility and economic vulnerability. It is the position of this paper that issues related to environmental vulnerability are of the greatest concern. A healthy environment is the basis of all life-support systems, including that of human well-being and socio-economic development. Priority environmental problems are: climate change and sea-level rise, threats to biodiversity, threats to freshwater resources, degradation of coastal environments, pollution, energy and tourism. Among these, climate change and its associated impacts are expected to pose the greatest threat to the environment and therefore to sustainable development. For small islands dependent on fragile marine ecosystems, in particular on coral reefs, for their livelihoods and living space, adverse effects of climate change such as increased frequency of extreme weather events and sea-level rise will exacerbate the challenges they already face. It is concluded that the paper path from Rio to Barbados to Johannesburg has made significant progress. However, much remains to be done at the practical level, particularly by the developed countries in terms of new and additional efforts at financial and technical assistance, to make sustainable development a reality for SIDS.     

基于光合色素的化学分类法在淡水藻类研究中的应用

采用反相高效液相色谱技术(RP HPLC)系统研究了我国主要淡水藻类--蓝藻、绿藻、硅藻、甲藻、金藻、裸藻和隐藻等的光合色素,在8种纯培养藻类中共确定类胡萝卜素、叶绿素及其衍生物19种。分离到的主要标志性色素按洗脱时间分别为脱植基叶绿素a、19′ 丁酰氧岩藻黄素、叶绿素c、脱镁叶绿素a、多甲藻素、甲基脱植基叶绿素a、岩藻黄素、新黄质、紫黄质、蓝藻叶黄素、硅甲藻黄素、硅藻黄质、叶黄素、玉米黄素、叶绿素b异构体、叶绿素b、叶绿素a异构体、叶绿素a和β 胡萝卜素;其中在纯培养的铜绿微囊藻中首次鉴定到19′ 丁酰氧岩藻黄素;通过官桥基地的实际监测,证实了该技术应用的可行性,为基于HPLC分析技术的浮游植物化学分类法提供了理论依据。     

长江中游水生生物多样性保护面临的威胁和压力

长江中游地区作为世界上最大的淡水生态区之一,生物多样性保护具有非常特殊的地位和作用。分析了长江中游地区生物多样性保护面临的主要威胁与压力,认为生境破碎萎缩、资源不合理开发利用、水环境污染、外来物种入侵等是生物多样性面临的主要威胁,而传统方式下的经济增长、土地利用粗放、人口增长与贫困、政策与管理等方面存在的问题将是生物多样性保护面临的主要压力。     

模拟盐水入侵及Fe(III)浓度增强对河口感潮淡水沼泽湿地土壤反硝化速率及理化特征的影响

以闽江河口塔礁洲感潮淡水野慈姑(Sagittaria trifolia Linn.)湿地为研究对象,于2016年2、4、7和9月每月均在连续2个小潮日内向研究样地施加人造海水和Fe(OH)_3溶液,研究短期的盐水入侵及Fe(III)浓度增强对河口感潮淡水湿地土壤反硝化速率及理化特征的影响.结果表明,短期的盐水入侵、Fe(III)浓度增强对河口感潮淡水沼泽湿地土壤反硝化速率的影响不显著,然而,盐水和Fe(III)共同施加会显著提高湿地土壤反硝化速率,与对照(CK)相比,盐水和Fe(III)共同施加可使土壤反硝化速率提高270.9%.盐水入侵、盐水和Fe(III)共同施加均可显著提高湿地土壤、间隙水的电导率及Cl~-、SO_4~(2-)的含量;Fe(III)浓度增强可显著降低土壤和间隙水pH值,同时显著提高土壤三价铁含量.     

Deriving freshwater quality criteria of sulphocyanic sodium for the protection of aquatic life in China

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船用钢板材料在淡水环境中初期腐蚀行为

目的研究船用钢板材料在长江淡水环境中的初期腐蚀行为。方法运用形貌分析、腐蚀质量损失、XRD、开路电位、极化曲线等方法研究Q235B和CCSA两种船用钢板材料在室外长江淡水环境中不同暴露方式(水面大气、半浸、全浸)及不同浸泡时间(0.5,1 a)腐蚀行为;室内长江淡水环境不同暴露方式(半浸、全浸)浸泡768 h内的腐蚀行为;室内长江淡水环境全浸泡下在不同时间(0~14 d)的电化学腐蚀行为。结果两种船用钢板材料在武汉长江淡水中腐蚀严重,半浸泡环境下腐蚀速率最大,达到100μm/a,水面区大气腐蚀速率最小,腐蚀速率为30μm/a左右,全浸区腐蚀速率为80μm/a左右,1 a和0.5 a的腐蚀速率相近,CCSA耐蚀性优于Q235B。室内长江淡水浸泡环境下两种船用钢板材料腐蚀电位随时间而降低,2d后趋于稳定;半浸泡环境下腐蚀速率大于全浸区;极化曲线说明浸泡2 d后,腐蚀速率降低且趋于稳定。结论 CCSA耐蚀性优于Q235B,半浸泡环境下腐蚀最严重,其次为全浸区,水面大气环境腐蚀最小。     

Lignoid chemical defenses in the freshwater macrophyte Saururus cernuus

Summary. Chemical defense against herbivores has rarely been investigated for freshwater plants, possibly due to the common misconception that herbivory on aquatic macrophytes is low and would not select for chemical defenses. In previous work, the freshwater angiosperm Saururus cernuus was shown to be a low preference food for omnivorous crayfish despite its high nutrient value and relatively soft texture. We used feeding by the crayfish Procambarus clarkii to guide fractionation of the deterrent lipid-soluble extract of this plant, leading to the identification of seven deterrent lignoid metabolites, (–)-licarin A, (+)-saucernetin, (–)-dihydroguaiaretic acid, (–)-sauriols A and B, (–)-saucerneol, and (–)-saucerneol methyl ether. Lignans have been implicated in terrestrial plant chemical defenses as insect growth inhibitors, insect toxins, nematocides, antibacterial, and antifungal agents. However, these activities have rarely been demonstrated using ecologically relevant methodologies in terrestrial systems, and never before in freshwater systems. The widespread nature of lignans amongst very distantly related plants, along with their rich diversity of molecular structure, suggests that they could play a large role in mediating plant-herbivore interactions. In addition to the lignoid compounds we identified, there were other compounds present in low concentration or unstable compounds that were deterrent, that did not appear to be lignans, but that we were unable to identify. This plant thus appears to be defended by a complex mixture of natural products. Received 6 June 2000; revised 23 August 2000; accepted 2 September 2000