Stromatolites Discovered in Nihewan Formation and Their Paleoenvironment

Columnar stromatolites have been discovered in two beds of the upper part of the Nihewan Formation, a series of lacustrine deposits. The structure of the stromatolites is characterized by alternation of light, intergranular pore-rich laminae and dark, organic substance-rich laminae. Abundant filamentous algal remains have been discovered in stromatolite laminae, some of them are similar to the species present on the shore of the Caribbean Sea that are living in warmer climate than in the Nihewan area now. With the ESR and U-series age methods, it has been determined that the ages of the lower and upper stromatolite beds are about 130,000 and 93,000 a B. P. , respectively. Compared with many other geologic events taking place during the period in Northern China, we conclude that the two stromatolite beds were formed during the two warmer stages of the Last Interglacial.     

Valorization of Cladophora glomerata Biomass and Obtained Bioproducts into Biostimulants of Plant Growth and as Sorbents (Biosorbents) of Metal Ions

The aim of this study was to propose a complete approach for macroalgae biomass valorization into products useful for sustainable agriculture and environmental protection. In the first stage, the effects of macroalgal extracts and ZnO NPs (zinc oxide nanoparticles) on the germination and growth of radish were examined. Macroalgal extract was produced from freshwater macroalga, i.e., Cladophora glomerata by ultrasound assisted extraction (UAE). The extract was used to biosynthesize zinc oxide nanoparticles. In germination tests, extracts and solutions of ZnO NPs were applied on paper substrate before sowing. In the second stage, sorption properties of macroalga, post-extraction residue, and ZnO NPs to absorb Cr(III) ions were examined. In the germination tests, the highest values of hypocotyl length (the edible part of radish), i.e., 3.3 and 2.6 cm were obtained for 60 and 80% extract (among the tested concentrations 20, 40, 60, 80, and 100%) and 10 and 50 mg/L NPs, respectively. The highest sorption capacity of Cr(III) ions (344.8 mg/g) was obtained by both macroalga and post-extraction residue at a pH of 5 and initial Cr(III) ions concentration of 200 mg/L. This study proves that macroalgae and products based on them can be applied in both sustainable agriculture and wastewater treatment.     

含硅复合营养素对控制蓝藻水华作用的研究

向水体中添加不同浓度的含硅营养素以确定该营养素控制蓝藻水华的最优作用浓度,同时在不同温度及光照条件下按照最优作用浓度添加该营养素以确定该营养素的作用效果与环境变化的关系.结果表明,该营养素能抑制蓝藻水华,加入后蓝藻比例下降,硅藻和绿藻比例上升,水体中的氮含量增加,其最佳作用浓度为312.5μL/L,其作用效果在不同的光照和温度条件下均具有有效性.该研究为蓝藻水华的治理提供有效的实践基础.     

利用复杂网络理论研究三峡库区流域水华暴发

根据复杂网络(CNs)理论初步建立三峡流域的水华暴发动力学模型,利用水华暴发的三类因素建立起水华暴发CNs无边接连基本模型图,参考实际水域水华暴发因素设定各节点子节点范围,建立各节点的边连接,从而初步建立水华暴发的CNs模型.模型中代入2007年春季嘉陵江、长江和2002年乌江"黑潮"8月份乌江渡水库监测数据,计算得出两个区域水华暴发CNs模型的平均路径长度L和聚类系数C,发现发生水华的流域平均路径长度L越小流域水华暴发的可能性越大,且现场监测数据与CNs理论结果相符.同时,水华暴发流域的聚类系数比未暴发流域小,表明水华暴发前后聚类系数C是一个先增加后减少再增加的过程.因此水华暴发周期内(暴发前期、暴发时期、消退期),各因素间的相互作用是先增强后减弱再增强的过程.     

江津四面山藻类植物调查

江津四面山的藻类植物共162种(含变种),隶属于68属、33科、7门。文章分析了头道河、响水滩,洪海和大窝铺的藻类区系,对其种类成分、生态分布等作了初步探讨。结果表明,四面山的藻类区系中,以硅藻为多,占藻类总数的41.98％,其次为绿藻,占38.89％,蓝藻占15.43％,其它藻类占3.70％。分析藻类组成成分表明,微污水带种类多于乙型中污水带种类。另外,四面山藻类还有一个山区冷水种类明显的特征。     

二水草酸钙的热力学转化及海藻多糖的稳定作用

草酸钙结石的形成与尿液中草酸钙的存在形式密切相关，一水草酸钙(COM)促进尿石症形成，而二水草酸钙(COD)易随尿液排出体外。本文采用体外模拟方法，比较研究了COD晶体在水溶液、正常人尿液和结石患者尿液3个不同体系中的稳定性及海藻龙须菜多糖(SPS)对COD的稳定作用。在水溶液和患者尿液中，不但COD转化率高，而且得到的转化产物COM晶体聚集程度大；而在正常人尿液中，COD转化率低，转化产物聚集程度较小。COD在不同体系中转化的速度依次为：水溶液＞患者尿液＞正常人尿液。从海藻龙须菜中提取的硫酸多糖可以稳定COD的存在并减小COM的聚集，这有利于阻止草酸钙结石的形成，因此，海藻龙须菜多糖有可能用于防止草酸钙结石形成。     

Dynamical study of nutrient-phytoplankton model with toxicity: Effect of diffusion and time delay

A harmful algal bloom is one of the significant concerns of marine biodiversity. The control of such algal bloom is required for the conservation of marine ecology. The proposed work discusses a model for interacting nutrient phytoplankton systems with the effect of toxic chemicals released by phytoplankton and time delay in toxin liberation. Our main aim is to provide a great insight into the impact of toxins and time delay on the dynamics of nutrient-phytoplankton. We investigate the stability of system dynamics, and the condition for the existence of Turing instability is obtained. The role of time delay is also investigated for the proposed system. The numerical simulation shows that toxin release rate, the diffusion coefficient of nutrients, and time delay significantly impact system dynamics. We observe that increasing values of toxin release results in the system dynamics show stable and oscillatory behavior without diffusion. The spatial and spatio-temporal patterns show that the higher value of the rate of toxin release lead to periodic and standing waves. Finally, we observe that the time delay in toxin distribution term stabilizes and destabilizes the system dynamics.     

基于UNet深度学习算法的东海大型漂浮藻类遥感监测

基于语义分割神经网络UNet,利用GOCI(Geostationary Ocean Color Imager)卫星传感器数据,构建出能够有效提取大型漂浮藻类的深度学习模型,实现了对大型漂浮藻类信息端到端、像素到像素的分割识别.验证结果表明:所提出的深度学习模型对验证集中大型漂浮藻类的平均识别精度达到88.54％;通过与...     

衣藻增殖、悬浮与沉降过程对水-泥 界面磷素动态的影响

为阐明水华过程藻群动态对水-泥界面磷素变化的影响,采集太湖梅梁湾水样和泥样,以莱茵衣藻(Chlamydomonas reinhardtii)为对象,通过室内模拟实验(76 d),研究藻体增殖、悬浮与沉降过程水-泥界面不同形态磷素含量及碱性磷酸酶活性(APA)的变化。结果表明:衣藻快速增殖与悬浮导致水体pH与DO含量明显升高,总磷和无机磷浓度迅速降低,但底泥有机磷含量平均高出无藻处理1.5倍。此外,衣藻沉降期底泥水溶性磷含量明显降低,这是由于部分沉降在底泥表面的藻体继续存活并吸收利用了水溶性磷。上覆水APA在藻体大量沉降后平均高于增殖和悬浮期1～3倍。相比较而言,底泥APA在藻体快速增殖与悬浮期达到最高,此后,APA降低,但仍高于无藻处理2倍以上。因此,衣藻水华过程加速了水-泥界面磷素的释放,部分沉降至底泥表面的存活藻体吸收利用磷素进而增殖和再悬浮,这可能是富营养化水体水华反复和多次暴发的重要原因之一。     

基于HPLC的化学分类法对一些有害浮游植物的分类分析

采用基于HPLC和光合色素分析的化学分类方法对21种(株)常见的典型赤潮生物进行了分类分析,结果表明有些赤潮藻的不同属、属下不同种甚至同种的不同地理株系其光合色素组成和比例存在差异.根据T.pul-chellum、塔玛亚历山大藻的特征光合色素组成和比例差异,可为进一步鉴定和细分这些赤潮生物提供重要依据.根据光合色素组成和比例构建的聚类分析也能较好地反应这些赤潮生物间的相互关系.上述结果显示光合色素分析方法能作为重要的分类学依据,为一些浮游植物的分类提供更有价值的分类信息.