Aspects and prospects of algal carbon capture and sequestration in ecosystems: a review

Long-term storage of carbon dioxide (CO₂) and other forms of carbon in non-atmospheric reservoirs is called carbon sequestration. Selective anthropogenic enrichment of the atmospheric carbon pool is causing dire environmental problems, thereby necessitating remediation by mitigation. Algae possess efficient carbon concentrating mechanisms and consequently high photosynthetic rates which make them suitable candidates for biosequestration of CO₂. Globally, nearly half of the atmospheric oxygen is generated by algal photosynthesis despite the fact that algae account for less than 1% of photosynthetic biomass. In water bodies, algae are responsible for creating the ‘biological pump’ that transports carbon from the upper sunlit waters to the depth below. A diverse array of photoautotrophs ranging from prokaryotic cyanobacteria to eukaryotic algae such as Chlorophytes, and even protists like euglenoids, contribute to this ‘biological pump’. It operates in a variety of aquatic ecosystems ranging from small freshwater ponds to the oceans where it has been most extensively studied. Two separate but intricately linked processes constitute this ‘biological pump’, viz. the ‘organic carbon pump’ and the ‘calcium carbonate pump’. The present review discusses the natural CO₂ sequestration processes carried out by algae and cyanobacteria in their native ecosystems.     

太湖蓝藻水华预警监测综合系统的构建

近年来随着浅水型湖泊的富营养化进程不断加快,蓝藻水华暴发现象也频繁出现,采用科学、全面的手段对太湖蓝藻暴发进行预警十分必要。根据太湖蓝藻预警监测中使用的现场巡视、卫星遥感、实验室分析、自动监测等监测技术手段,分别建立各自监测系统,结合各监测系统特点和相互关系,对太湖蓝藻水华预警监测综合系统的构建进行了探讨,以期能够更好地开展太湖蓝藻水华预警监测工作,为确保太湖地区饮用水安全,提高环保部门应对太湖蓝藻水华暴发的能力,为政府决策提供技术支持和保障。     

两座高原水库蓝藻群落结构与微囊藻毒素的分布对比研究

为了了解贵州高原水库蓝藻群落组成特征和微囊藻毒素分布,于2009年10月对贵州高原2座水库——万峰湖和百花湖采样调查。结果表明：万峰湖以蓝藻为主要优势藻,蓝藻中的拟柱孢藻（Cylindrospermopsis sp.）占绝对优势,浮游植物丰度在13.05×104～55.80×104 cells.L-1之间,蓝藻的丰度值占到了总量的82.55%,6个采样点中有3个（大坝、野鸭滩和革布）检出了微囊藻毒素MC-RR,且有1个点（革布）质量浓度超标,另外3个点（坝艾、坝达章和九里堡）未检出;百花湖以蓝藻、绿藻和硅藻共同构成优势藻,蓝藻中的假鱼腥藻（Pseudanabaena limnetica）是主要优势藻,浮游植物丰度在6.16×104～65.00×104 cells.L-1之间,蓝藻的丰度值在总体中所占比例为33.25%,3个采样点（大坝、岩脚寨和码头）均未检出微囊藻毒素。形成2个高原水库蓝藻群落结构和微囊藻毒素分布差异的原因可能是：2个水库中氮、磷营养盐水平不同引起浮游植物群落组成不同,进而导致了微囊藻毒素的分布出现差异。     

浮游植物半定量活检法在蓝藻预警监测中的应用

通过夏季太湖梅梁湾监测点位浮游植物的定性和定量研究,提出了半定量活检的蓝藻预警监测方法.半定量活检法不但能够及时、准确地确定蓝藻水华种类,而且通过与鲁哥氏液固定法的比对实验,在确定水华优势种和优势度方面也具有较好的可靠性.     

蓝藻好氧堆肥及其氮素损失控制的研究

选取锯木屑和药渣作为调理剂并分别添加酸化沸石、过磷酸钙和氢氧化镁与磷酸的混合液作为氮素固定剂或损失抑制剂,研究了蓝藻堆肥的效果.结果表明,V(蓝藻)∶V(锯木屑)∶V(药渣)=1∶1∶1时极易发酵.添加氮素固定剂在堆肥前期能促进发酵,特别是添加过磷酸钙的处理最高温度达66.8℃.固定剂的添加能促进物料的降解,尤其添加过磷酸钙的促进作用比较明显;各氮素固定剂在蓝藻堆肥过程中都起到了抑制氮素损失的作用,其中过磷酸钙和Mg(OH)2与H3PO4混合液对氮素的固定率达50%以上,且对氨氮的固定效果较好.堆肥结束后,添加过磷酸钙和Mg(OH)2与H3PO4混合液的两处理氨氮比堆肥起初分别增加23.52%和28.06%,P素分别增加了67.56%和36%.随着堆肥的进行,各处理堆肥物料中N、P、K含量均明显升高,C/N比显著下降,发芽指数增加到75%以上,而且添加氮素固定剂的处理效果更为明显.可见采用高温堆肥和氮素固定技术可有效实现蓝藻的资源化利用.     

蓝藻水华对太湖水柱反硝化作用的影响

反硝化作用是湖泊水体最主要的脱氮过程,对减轻湖泊的氮素污染和富营养化控制具有重要意义.蓝藻水华暴发和衰亡可能会通过改变水体氮素循环途径及微环境来促使反硝化作用直接在水柱中发生,加速氮的去除.为了验证这一假设,取太湖湖水添加不同生物量的蓝藻和连续10 d的NO_3~--N、PO_4~(3-)-P营养盐,进行蓝藻生长与降解对反硝化影响的模拟实验,测定蓝藻水华期水体藻类生物量和各形态氮浓度的动态变化,同时利用~(15)N同位素添加培养结合膜进样质谱仪(MIMS)实时定量测定反硝化速率.结果表明,蓝藻在生长期吸收氮素转变为颗粒氮,在衰亡期藻细胞通过降解矿化释放了大量的NH_4~+-N,继而转化为NO_3~--N,为反硝化作用提供底物,是大幅度促进水体反硝化作用的关键;反硝化速率(以N2计,下同)最高达到(1 614. 52±301. 57)μmol·(m~2·h)~(-1),是同时期最低蓝藻生物量组反硝化速率[(534. 45±242. 18)μmol·(m~2·h)~(-1)]的3倍,实验结束时添加初始蓝藻生物量倍数最高组的TN去除率达最高(40. 02%),是未添加蓝藻组TN去除率(17. 72%)的2. 26倍,说明蓝藻堆积会显著促进反硝化作用的强度,加速水体氮素的去除.蓝藻衰亡时反硝化速率的快慢受NH_4~+浓度的影响显著,表明附着在藻团的微生物的耦合硝化-反硝化作用是氮盐去除的主要途径.本研究结果表明,水华蓝藻生长期快速吸收氮素转变为颗粒氮,蓝藻死亡降解后通过耦合硝化-反硝化作用加速氮素去除,这可能是太湖夏季氮素浓度降低的原因之一.     

东苕溪蓝藻时空分布及其与环境因子关系研究

研究了东苕溪(太湖主要入湖河流)秋季和春季浮游植物的空间分布格局,监测了东苕溪18个采样点的浮游植物叶绿素a含量、细胞密度及种类组成等指标,分析了影响蓝藻时空分布差异的环境因子.结果表明:调查期间,共观察到浮游植物8门60属132种,其中,蓝藻门9属14种,蓝藻细胞密度占浮游植物细胞密度的平均比例为60.3%,蓝藻细胞密度自东苕溪下游至上游呈减小趋势,最高值出现在东苕溪下游距南太湖湖口3km以内.在秋季,东苕溪下游以铜绿微囊藻(Microcystis aeruginosa)为优势种,春季为水华鱼腥藻(Anabaena flos-aquae);丝状蓝藻(小席藻)是上游的优势代表种.东苕溪下游蓝藻的绝对优势与特殊的水动力条件、高浓度的营养盐有关.相关性分析表明,蓝藻细胞密度与水深(p<0.01)、总氮(p<0.01)和溶解性总碳(p<0.05)呈显著正相关.     

壳聚糖-纳米金属絮凝剂絮凝沉降水华蓝藻研究

研究了壳聚糖与纳米钛、纳米铁或妫水湖沉积物絮凝剂絮凝沉降水华蓝藻的效果。结果表明:在壳聚糖浓度为3 mg/L情况下,与妫水湖沉积物和纳米钛相比,纳米铁絮凝沉降蓝藻细胞的效果最好,在10 min内可以絮凝沉降79.5%以上的水华蓝藻细胞。进一步研究显示,在pH值为5~9的范围内,随着pH值的降低,絮凝沉降藻细胞的效率逐渐提高,pH值为5时10 min内可以絮凝去除89.6%以上的水华蓝藻细胞,具有重要的研究价值与应用价值。     

Current Status of Mathematical Models for Population Dynamics of Prymnesium parvum in a Texas Reservoir1

Grover, James P., Jason W. Baker, Daniel L. Roelke, and Bryan W. Brooks, 2010. Current Status of Mathematical Models for Population Dynamics of Prymnesium parvum in a Texas Reservoir. Journal of the American Water Resources Association (JAWRA) 46(1):92-107. DOI: 10.1111/j.1752-1688.2009.00393.x Abstract: Blooms of the harmful alga Prymnesium parvum have apparently increased in frequency in inland waters of the United States, especially in western Texas. A suite of mathematical models was developed based on a chemostat (or continuously stirred tank reactor) framework, and calibrated with data from Lake Granbury, Texas. Inputs included data on flows, salinity, irradiance, temperature, zooplankton grazing, and nutrients. Parameterization incorporated recent laboratory studies relating the specific growth rate of P. parvum to such factors. Models differed in the number of algal populations competing with P. parvum, and whether competition occurred only by consumption of shared nutrients, or additionally through production of an allelopathic chemical by one of the populations, parameterized as cyanobacteria. Uncalibrated models did not reproduce the observed seasonal dynamics of P. parvum in Lake Granbury, which displayed a maximum population in late February during a prolonged bloom in cooler weather, and reduced abundance in summer. Sensitivity analyses suggested two modifications leading to predictions that better resembled observations. The first modification greatly reduces the optimal temperature for growth of P. parvum, an approach that disagrees with laboratory experiments indicating a strong potential for growth at temperatures above 20°C. The second modification increases the growth rate of P. parvum at all temperatures, in models including cyanobacterial allelopathy. Despite these adjustments, calibrated models did not faithfully simulate all features of the seasonal dynamics of P. parvum.     

不同存放时间太湖蓝藻产沼气潜力

对不同存放时间蓝藻(新鲜蓝藻、存放3个月、6个月和9个月)进行厌氧消化处置,分析反应过程中沼气量、代谢产物和酶活等变化,获得各自的产沼气潜力。研究结果表明,存放6个月蓝藻组的产沼气率最大,为120.5 mL/g TS,是新鲜蓝藻组的1.29倍。Gompertz模型拟合表明,随着存放时间的延长,最大产沼气量(Pmax)先增大后减小,最大比产气率一直增加。存放3个月蓝藻组的VFA在第6天达到最大,为1 575.4 mg/L,而存放9个月蓝藻组的VFA在第2天达到最大,为1 116.5 mg/L。存放3个月蓝藻组的最大中性蛋白酶酶活为1 203.4μg/(g TS.h),比新鲜蓝藻组提高212.8μg/(gTS.h)。脱氢酶酶活随着蓝藻存放时间的增加呈现先增加后减小的趋势。