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题名: 改性土壤技术调控富营养化水体营养盐限制的研究
作者: 王丽静
学位类别: 博士
答辩日期: 2016-11
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 潘纲
关键词: 营养盐限制,蓝藻藻华,绿藻藻华,改性当地土壤,全塘实验 ; Nutrient limitation, Cyanobacterial blooms, Chlorophytes blooms, Modofied local soils, Whole pond experiment
其他题名: Manipulating nutrient limitation of eutrophic waters using modified local soil technology
学位专业: 环境工程
中文摘要:       大量的人为营养盐输入水生态系统导致了有害藻华在世界范围内频繁暴发,对饮用水供给、食物链的完整性以及淡水生态系统的生态和经济可持续性造成了严重的威胁。发展有效的内源污染控制措施结合适当的营养盐管理策略对于富营养化湖泊的快速修复是至关重要的。本文考察了改性土壤技术分别对以蓝藻和绿藻为主导的富营养化水体的营养盐限制的调控效果及其生态修复效果;研究了以绿藻为优势种群的富营养化水体的营养盐限制情况;原位考察了不同营养状态水体中不同浮游植物对氮(N)和磷(P)营养盐添加的响应。主要结果如下:
(1)2013 年 10 月在太湖梅梁湾湖区“全塘体系”内实施改性土壤技术,原位营养盐添加生物测试实验结果表明技术实施后的短期内(2013.10 - 2014.03),相对于对照塘,处理塘内的浮游植物生长由 N 和 P 共同限制转化为单一 P 限制;长期内,尤其夏季藻华季节(2014.06),对照塘内浮游植物生长受 N和 P共同限制,N 是主要的限制性营养盐,而处理塘内 N 和 P 均成为浮游植物生长的限制性营养盐且 DIN 上限阈值由 0.8 提升至 1.5 mg L-1,SRP 的上限阈值由 0.1 提升至 0.3 mg L-1。短期高频和长期月度监测结果表明,在技术处理后的整个监测期内,浮游植物生物量(Chl-a)在技术处理后两小时内由 42 降低至 18 μg L-1 并在整个监测期内(15 个月)保持低于 20 μg L-1;夏季藻华季节(2014.06),蓝藻在对照塘内又重新捕获了优势地位,处理塘内,蓝藻、绿藻和硅藻等在水体中几乎平均分配,且浮游植物多样性指数由 1.22 增加到 3.37;另外,沉水植被在处理塘内成功修复,其优势种群由春夏季节的菹草逐渐演变为秋冬季节的伊乐藻。
      (2)通过综合营养状态指数法判断出位于中国北方的册田水库水体属重度富营养化;水体中优势浮游植物为以栅藻为主的绿藻;原位营养盐稀释和添加生物测试实验结果表明,册田水库下游水体中浮游植物生长受 N 和 P 共同限制,另外,为使水体中藻类浓度维持可接受的水平(< 20 μg L-1),TN 和 TP 浓度应分别控制在 1.5 mg L-1 和 0.13 mg L-1 之下。
      (3)在册田水库研究基地“全塘体系”内实施改性土壤技术,短期高频结合长期月度监测结果表明,技术处理后,水体中的大部分藻类及其部分营养盐通过改性当地土壤的絮凝作用迅速去除;技术处理 70 天后,以苦草、马来眼子菜和篦齿眼子菜为主的沉水植被大面积恢复,叶绿素浓度低于 10 μg L-1,实现了以藻类为主的富营养状态向以沉水植被为主的健康状态的过度;监测期终点(技术处理 150 天后),水体中 TN 和 TP 均由处理前的劣 V 类分别提升至 IV 类和 II 类水平,水体的营养状态由处理前的重度富营养降低至中营养状态,这主要与恢复的沉水植被吸收利用水体中的营养盐有关。
      (4)为了考察改性土壤技术对浮游植物生长营养盐限制的影响,分别在技术实施的不同阶段开展了原位营养盐添加生物测试实验。结果表明,改性土壤技术处理前,册田水库水体中的 N 和 P 营养盐浓度对浮游植物的生长已经饱和,因此,需同时减少系统中 N 和 P 营养盐以减轻下游水体的富营养化;改性土壤技术处理 10 天后,浮游植物生长受 P 限制,且 SRP 的上限阈值 0.1 mg L-1;改性土壤技术处理 70 天后,N 和 P 均成为浮游植物生长的限制性营养盐,且 DIN 和 SRP 的上限阈值分别为 0.5 mg L-1 和 0.1 mg L-1。
      (5)通过稀释册田水库原水模拟不同营养状态的水体,采用原位营养盐添加生物测试法判断不同营养营养状态水体中不同浮游植物对 N 和 P 添加的响应。结果表明,重度富营养状态下,主要藻类(绿藻、蓝藻和硅藻)的密度只有在共同添加 N 和 P 时表现出增加,其增加的绝对量从多到少依次为蓝藻 > 硅藻 > 绿藻,主要的响应种属分别为蓝藻门的颤藻和平裂藻、硅藻门的小环藻和针杆藻以及绿藻门的栅藻和蓝纤维藻;中度富营养状态下,上述三种藻类的密度在共同添加 N 和 P 时表现出与重度富营养化下相类似的增加趋势,但具体的响应种属不同。蓝藻的主要响应种属为颤藻和色球藻,硅藻门主要为针杆藻,绿藻门为小球藻;与重度和中度富营养状态相比,轻度富营养状态下,共同添加 N 和 P 对三种藻类密度均有明显的刺激作用,主要响应种属分别为绿藻门的栅藻和小球藻,蓝藻门的颤藻和色球藻,硅藻门的针杆藻;中和贫营养状态下,绿藻密度在 P 和 N+P 添加下显著增加,其响应的种属为栅藻和小球藻,蓝藻和硅藻在共同添加 N 和 P 时表现出增加,其主要响应种属分别为蓝藻门的色球藻和硅藻门的小环藻。
英文摘要:       Harmful algal blooms (HABs) caused by excessive anthrogenic nutrient inputs to aquatic ecosystems are expanding worldwide, which is a serious threat to drinking water supplies, integrity of food web and ecological and economic sustainability of some freshwater systems. To develop effective in-lake technologies together with appropriate nutrient management strategies are crucial for accelerating restoration of eutrophic lakes. This study investigated the mechanism of nutrient limitation manipulation and effects of eutrophication restoration of modified local soil technology (MLS) that used in cyanobacterial blooms lakes and chlorophytes dominant reservoir, respectively. In additon, we studied the nutrient limitation of chlorophytes dominant reservoir and investigated the specific responses of different phytoplankton to nitrogen (N) and phosphorus (P) enrichment in different trophic states by dilution bioassays and in-situ nutrient addition bioassays. The main results are listed as follows:
      (1) Modified local soils (MLS) were applied in two comparable whole water ponds that situated in Meiliang bay of Lake Taihu in October 2013. In situ nutrient addition bioassay experiments indicated that nutrient limitation of phytoplankton growth was shifted from N and P co-limitation to P limitation after MLS treatment from October 2013 to March 2014 compared to the control pond. In the long term, both N and P became the limiting nutrient in the cyanobacterial blooms season of June 2014, meanwhile, the upper limiting concentration of DIN was enhanced from 0.8 to 1.5 mg L-1 and SRP from 0.1 to 0.3 mg L-1 compared to the control pond. The results of high frequency monitoring together with monthly or quarterly monitoring showed that the Chl-a concentration was reduced from 42 to 18 μg L-1 and maintained below 20 μg L-1 within the whole monitoring period (15 months). The cyanobacterial-dominant state still remained in the control pond but chlorophytes, bacillariophytes and cyanophytes almost equal distributed in the treatment pond in the
cyanobacterial blooms season. The phytoplankton diversity index was increased from 1.22 to 3.37 in the treatment pond. Furermore, submerged vegetation restored largely in the treatment pond, and the dominant species changed from Potamogeton crispus in spring and early summer season to Elodea canadensis in fall-winer season.
      (2) The water quality of the Cetian reservoir that stuiated in the northern china belongs to hyper eutrophic state according to the method of comprehensive nutrient status index. The dominant algae species are chlorophytes. Dilution bioassays and in situ nutrient addition bioassay experiments indicated that the nutrient limitation of phytoplankton growth was N and P co-limitation, additionally, TN and TP concentration thresholds should be targeted at below 1.5 mg L-1 and 0.13 mg L-1, respectively, to limit intrinsic growth rates of chlorophytes dominant blooms.
      (3) MLS technology carried out in two comparable whole water ponds that located in the research base of Cetian reservoir. The high frequency monitoring in short term together with monthly monitoring showed that a large amount of algae cells and partly nutrients were removed from the water column in short term due to flocculation effects of MLS. About 70 days after MLS treatment, the major submerged vegetation species of Vallisneria natans, Potamogeton malaianus and Potamogeton pectinatus were restored in the treatment pond, and the algae dominant state was switched into the submerged aquatic vegetation dominant state. At the end of monitoring period (About 150 days after MLS treatment), TN and TP levels were enhanced from Grade V level of surface water before MLS treatment to IV and II level, respectively. Additionally, the trophic state was enhanced from hypereutrophic state to mesotrophic state, which mainly depended on the submerged vegetation restoration.
      (4) In order to estimate the changes of nutrient limitation of phytoplankton growth after MLS treatment, in situ nutrient addition bioassay experiments were carried out in different stages. Before MLS treatment, the N and P concentrations in the water column were almost staurated for phytoplankton growth, and hence, both N and P should be reduced to alleviate the eutrophication of the lower Cetian reservoir. Ten days after MLS treatment, P became the limiting nutrient for phytoplankton growth, and the upper threshold of SRP was 0.1 mg L-1. About 70 days after MLS treatment, both N and P became the limiting nutrients, and the upper thresholds of DIN and SRP were 0.5 and 0.1 mg L-1, respectively.
      (5) To simulate different trophic states of waters, we diluted the water of Cetian reservoir to a range of gradients. In situ nutrient addition bioassays were used to estimated the specific responses of different algae species to N and P enrichment in different trophic states of waters. In hyper eutrophic state waters, only combined N and P addition increased the density of cyanophytes, chlorophytes and bacillariophytes, and the absolute amount of increase as follows: cyanophytes > bacillariophytes > chlorophytes. The Oscillatoria sp. and Merimopedia sp. were the major response species in cyanophyes, Synedra sp. and Cyclotrlla sp. in bacillariophytes, Scenedesmus sp., Chlorella sp. and Ankistrodesmus sp. in chlorophytes. In middle eutrophic state waters, cyanophytes, chlorophytes and bacillariophytes showed similar responses to N + P additions, however, the specific species were different. For cyanophytes, Oscillatoria sp. and Chroococcus sp. were the major response species. For bacillariophytes, Synedra sp. were mainly response species. For chlorophytes, Chlorella sp. were the major response species. In light eutrophic state waters, the density of cyanophytes, chlorophytes and bacillariophytes showed more increase than those in the hyper and middle eutrophic state waters with N+P additions. The major responses species were Scenedesmus sp. and Chlorella sp. in chlorophytes, Oscillatoria sp. and Chroococcus sp. in cyanophytes and Synedra sp. in bacillariophytes. In mesotrophic and oligtrophic states waters, the dominance of Scenedesmus sp. and non-dominance of Chlorella sp. in chlorophytes showed increase significant with P and N+P additions. Chroococcus sp. in cyanophytes and Synedra sp. in bacillariophytes exhibited increase with N+P additions.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/36974
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王丽静. 改性土壤技术调控富营养化水体营养盐限制的研究[D]. 北京. 中国科学院研究生院. 2016.
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