基于微生物生物完整性指数的地下水生态系统健康评价:以包钢稀土尾矿库周边地下水生态系统为例

生物完整性指数是水体生态系统健康评价的重要指标,已被广泛应用于湖泊河流等的生态系统健康评价中.但利用水体中分解者微生物群落构建IBI评价标准的报道很少,针对地下水生态系统的研究更是鲜见.本研究针对包钢稀土尾矿库周边地下水生态系统健康开展评价工作,基于地下水环境中微生物群落Illumina高通量测序信息,筛选关键环境因子,甄别敏感或耐受微生物分类属,确定候选生物参数,探索针对地下水的微生物完整性指数(microbiome index of biotic integrity,M-IBI)评价流程与标准构建方法.结果表明,总计12个地下水样点中,4个样点属于健康等级(Ⅰ级),占总样点的33.3%;2个样点属于亚健康等级(Ⅱ级),占总样点的16.7%;5个样点属于一般等级(Ⅲ级),占41.7%;1个样点属于较差等级(Ⅳ级),占8.3%;总体来看,靠近尾矿库的样点健康等级较低,而远离尾矿库参照点受到的干扰较小,健康等级较高,这可能与人类活动干扰影响程度密切相关.参照该地区地下水理化参数基础上的水质情况分析结果,发现应用M-IBI指数可较合理地评估包头稀土尾矿区周边地下水生态系统健康状况.结合生态系统健康内涵,本研究初步提出针对地下水生态系统健康的M-IBI指数评价体系构建流程.     

科学家研究发现:砍伐砂土植被或对气候威胁更大

正美国耶鲁大学等机构科学家的一项新研究发现,相比于其他土壤,砍伐砂土上生长的森林将更容易加剧全球气候变暖.土壤中的微生物能调节二氧化碳向外部的释放.砍伐森林会对土壤微生物的多样性造成破坏,这将降低土壤对二氧化碳的控制力,导致更多二氧化碳排放,并最终加剧全球气候变暖.研究人员对比了从美国11个地区采集的土壤后发现,不同质地土壤上的森林被砍伐后,土壤中微生物群落多样     

Reduction and characterization of bioaerosols in a wastewater treatment station via ventilation

Bioaerosols from wastewater treatment processes are a significant subgroup of atmospheric aerosols. In the present study,airborne microorganisms generated from a wastewater treatment station(WWTS) that uses an oxidation ditch process were diminished by ventilation.Conventional sampling and detection methods combined with cloning/sequencing techniques were applied to determine the groups,concentrations,size distributions,and species diversity of airborne microorganisms before and after ventilation. There were 3021 ± 537 CFU/m3 of airborne bacteria and 926 ± 132 CFU/m3 of airborne fungi present in the WWTS bioaerosol.Results showed that the ventilation reduced airborne microorganisms significantly compared to the air in the WWTS. Over 60% of airborne bacteria and airborne fungi could be reduced after4 hr of air exchange. The highest removal(92.1% for airborne bacteria and 89.1% for fungi) was achieved for 0.65–1.1 μm sized particles. The bioaerosol particles over 4.7 μm were also reduced effectively. Large particles tended to be lost by gravitational settling and small particles were generally carried away,which led to the relatively easy reduction of bioaerosol particles0.65–1.1 μm and over 4.7 μm in size. An obvious variation occurred in the structure of the bacterial communities when ventilation was applied to control the airborne microorganisms in enclosed spaces.     

Arbuscular mycorrhizal fungal phylogenetic groups differ in affecting host plants along heavy metal levels

Arbuscular mycorrhizal fungi（AMF） are important components of soil microbial communities,and play important role in plant growth. However, the effects of AMF phylogenetic groups（Glomeraceae and non-Glomeraceae） on host plant under various heavy metal levels are not clear. Here we conducted a meta-analysis to compare symbiotic relationship between AMF phylogenetic groups（Glomeraceae and non-Glomeraceae） and host plant functional groups（herbs vs. trees, and non-legumes vs. legumes） at three heavy metal levels. In the meta-analysis, we calculate the effect size（ln（RR）） by taking the natural logarithm of the response ratio of inoculated to non-inoculated shoot biomass from each study. We found that the effect size of Glomeraceae increased, but the effect size of non-Glomeraceae decreased under high level of heavy metal compared to low level. According to the effect size, both Glomeraceae and non-Glomeraceae promoted host plant growth, but had different effects under various heavy metal levels. Glomeraceae provided more benefit to host plants than non-Glomeraceae did under heavy metal condition, while non-Glomeraceae provided more benefit to host plants than Glomeraceae did under no heavy metal. AMF phylogenetic groups also differed in promoting plant functional groups under various heavy metal levels.Interacting with Glomeraceae, herbs and legumes grew better than trees and non-legumes did under high heavy metal level, while trees and legumes grew better than herbs and non-legumes did under medium heavy metal level. Interacting with non-Glomeraceae, herbs and legumes grew better than trees and non-legumes did under no heavy metal. We suggested that the combination of legume with Glomeraceae could be a useful way in the remediation of heavy metal polluted environment.     

Effect of a high strength chemical industry wastewater on microbial community dynamics and mesophilic methane generation

A high strength chemical industry wastewater was assessed for its impact on anaerobic microbial com- munity dynamics and consequently mesophilic methane generation. Cumulative methane production was 251 mL/g total chemical oxygen demand removed at standard temperature and pressure at the end of 30 days experimental period with a highest recorded methane percentage of 80.6% of total biogas volume. Volatile fatty acids （VFAs） analysis revealed that acetic acid was the major intermediate VFAs produced with propionic acid accumulating over the experimental period. Quantitative analysis of microbial communities in the test and control groups with quantitative real time polymerase chain reaction highlighted that in the test group, Eubacteria （96.3%） was dominant in comparison with methanogens （3.7%）. The latter were dominated by Methanomicrobiales and Methanobacteriales while in test groups increased over the experimental period, reaching a maximum on day 30. Denaturing gradient gel electrophoresis profile was performed, targeting the 16S rRNA gene of Eubacteria and Archaea, with the DNA samples extracted at 3 different time points from the test groups. A phylogenetic tree was constructed for the sequences using the neighborhood joining method. The analysis revealed that the presence of organisms resembling Syntrophomonadaceae could have contributed to increased production of acetic and propionic acid intermediates while decrease of organisms resembling Pelotomaculum sp. could have most likely contributed to accumulation of propionic acid. This study suggested that the degradation of organic components within the high strength industrial wastewater is closely linked with the activity of certain niche microbial communities within eubacteria and methanogens.     

Community structure and elevational diversity patterns of soil Acidobacteria

Acidobacteria is one of the most dominant and abundant phyla in soil,and was believed to have a wide range of metabolic and genetic functions. Relatively little is known about its community structure and elevational diversity patterns. We selected four elevation gradients from 1000 to 2800 m with typical vegetation types of the northern slope of Shennongjia Mountain in central China. The vegetation types were evergreen broadleaved forest,deciduous broadleaved forest,coniferous forest and sub-alpine shrubs. We analyzed the soil acidobacterial community composition,elevational patterns and the relationship between Acidobacteria subdivisions and soil enzyme activities by using the 16 S rRNA meta-sequencing technique and multivariate statistical analysis. The result found that 19 known subdivisions as well as an unclassified phylotype were presented in these forest sites,and Subdivision 6 has the highest number of detectable operational taxonomic units(OTUs). A significant single peak distribution pattern(P 0.05) between the OTU number and the elevation was observed. The Jaccard and Bray–Curtis index analysis showed that the soil Acidobacteria compositional similarity significantly decreased(P 0.01) with the increase in elevation distance. Mantel test analysis showed the most of the soil Acidobacteria subdivisions had the significant relationship(P 0.01) with different soil enzymes. Therefore,soil Acidobacteria may be involved in different ecosystem functions in global elemental cycles. Partial Mantel tests and CCA analysis showed that soil pH,soil temperature and plant diversity may be the key factors in shaping the soil Acidobacterial community structure.     

珠江口咸潮上溯对水生植物群落的影响研究

针对近二十多年来珠江口咸潮异常上溯可能引起的水生态环境变化,首次通过对磨刀门水道上、中、下游各河段及出海口现场踏勘和植物样方调查并参考有关文献资料,系统研究了咸潮上溯对珠江口主要入海河道水生植物群落分布的影响,结果表明:(1)磨刀门水道及出海口沿岸植被分布具有明显的差异:下游河段和出海口门处耐盐的红树、半红树植物明显占优,种类也多;中游河段咸、淡水植物均为优势种;而上游河段虽然优势种仍为淡水植物,但也出现了原本在下游和口门处常见的咸水植物。(2)河道水体盐度的变化已反映在植被分布变化上,主要表现为与正常情况下的河口植物种群分布相比,在河道中应完全是淡水植物分布的河段变为淡水植物、广适性植物和半咸水植物共同分布。(3)咸潮超常上溯是导致入海河道上、中游河段植物优势群落由喜淡水植物群落演替为广适性植物群落和半咸水(咸水)植物群落的根本原因。     

水温对浮游植物群落结构的影响实验研究

2012冬季,在香溪河中游建立水上水温实验系统,设置5个水温梯度(10、18、25、30、40℃),研究不同水温梯度下浮游植物群落结构变化。结果表明:浮游植物在设置水温梯度范围内均能大量增殖,但种类有所不同。10~30℃硅藻均有出现,绿藻在18~30℃下均能生长良好,蓝藻能在40℃的高水温下生长。25℃水体中藻类比增长率(μ)最大,为2.80。光照强度与叶绿素a浓度(Chl.a)响应关系较好。据此可知,水温影响浮游植物生长速率,且是导致香溪河库湾浮游植物群落演替的主要影响因素。光照是藻类生长和水华暴发的主导性因子。香溪河库湾冬季仍有暴发水华的可能,不能忽视冬季香溪河水体的观测。     

黄河口浮游生物群落结构特征及环境质量评价

通过2011年~2012年对黄河口水域浮游生物的周年调查,对该水域浮游生物种类组成、优势种、生物量、密度和生物多样性等进行了分析。结果表明:共检出浮游植物79种,其中绿藻门最多为34种,其次硅藻门20种,其它门类均低于10种;优势种共25种,主要为小球藻、小环藻和针杆藻等;细胞数与生物量随季节变化变动较大,均为8月5月2月11月。检出浮游动物4类46种,其中轮虫25种、原生动物9种、桡足类7种和枝角类5种;优势种主要为萼花臂尾轮虫、螺形龟甲轮虫和曲腿龟甲轮虫等;数量与生物量亦为8月5月2月11月。黄河口各站位浮游植物和浮游动物Shannon-Wiener指数均低于3,平均值分别为1.68和1.36,依据Shannon-Wiener指数评价标准,黄河口为中度污染。     

DGGE及T-RFLP分析光照下电位对细菌群落的影响

电位和光照能影响生物电化学系统中产电光合微生物的富集和生长,为了明确电位对细菌多样性的影响,采用变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)和末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)两种方法分析光照条件下电位对电极生物膜细菌群落多样性的影响,实验设置0、0.2、0.4、0.6 V(vs.Ag/AgCl)4个电位.结果表明,0.6 V(vs.Ag/AgCl)下电极生物膜细菌DGGE条带数量较其他处理明显降低,对条带的测序结果显示不同电位下电极生物膜细菌主要属于α-变形菌纲(α-Proteobacteria)、β-变形菌纲(β-Proteobacteria)和梭菌纲(Clostridia).而0.2 V(vs.Ag/AgCl)处理下末端限制性片段(terminal restriction fragment,T-RF)的数量最高,片段数量随电压进一步升高呈现降低趋势.虽然DGGE和T-RFLP两种方法分析结果有一定差异,但都能反映电位对电极生物膜细菌群落多样性影响显著,高电位降低了细菌多样性.