The dynamics of bacterial community in a polyculture aquaculture system of Penaeus chinensis,Rhopilema esculenta and Sinonovacula constricta

Polyculture with Chinese shrimp Penaeus chinensis, jellyfish Rhopilema esculenta and razor clam Sinonovacula constricta (S.J.R) is a common aquaculture system in Dandong, China. Investigation on the composition and function of microbial communities and their relationship with environmental factors in aquaculture systems have crucial implications. Therefore, the sequencing of 16S rRNA gene was applied to profile the bacterial community composition of water and sediment in S.J.R polyculture system in the present study. Proteobacteria was the dominant phylum in S.J.R polyculture ponds following with Actinobacteria and Bacteroidetes in water; in contrast, more diverse phyla were detected in sediments. Water temperature, pH and dissolved oxygen were determined the bacterial community composition in the S.J.R polyculture systems. Specially, Planktomarina, PS1 clade, Candidatus Aquiluna and Fibrobacteres, which can resist the phytoplankton blooms or degrade the cellulose, were more abundant in water at the early stage of cultivation in the S.J.R polyculture system. Moreover, the functions of bacterial communities in water were mainly associated with cell communication mediated, while the functions related to basal metabolism were enriched in sediments. The findings of this study allowed us to better understand the bacterial community in the S.J.R polyculture system and accumulated data for the improvement of cultural management.     

以鲥为瘟:古代长江鲥鱼的污名化

鲥鱼在明清一些著作中被称为瘟鱼。历来关于瘟鱼的解释主要围绕鲥鱼本身来阐发,但这些观点不能很好地解释鲥鱼为何会在江西、两湖以及四川一带被称作瘟鱼,而在盛产鲥鱼的江东却没有这种指称。明人的“瘟鱼”观点源自唐人孟诜“发疳、痼”的说法,李时珍所说的蜀地瘟鱼并不是鲥鱼。一些清人认为瘟鱼并非来自鲥鱼本身。《见闻录》中记载了一个鲥鱼被虚构成瘟鱼的故事,揭示出瘟鱼是后人将瘟疫附会到鲥鱼身上的结果。显然,鲥鱼在特定地点被称为瘟鱼,是鲥鱼与地方文化结合的产物。     

江西退化红壤人工重建森林土壤微生物碳源代谢功能研究

应用MicroResp方法研究4种重建森林土壤微生物对不同类型碳源的代谢特征,自然恢复地为对照处理。结果表明,不同培养时间(6 h和继续培养18 h)和不同土壤深度(0~10和10~20 cm),土壤微生物对单一碳源的利用能力差异显著。4种重建森林土壤微生物对碳源利用能力有显著差异,表现为:自然恢复地阔叶混交林阔叶纯林针阔混交林针叶纯林。多样性指数和均匀度指数表明4种重建森林土壤微生物群落多样性的变化趋势为:自然恢复地阔叶混交林阔叶纯林针阔混交林针叶纯林,除自然恢复地外,土壤微生物的多样性和均匀度在4种不同重建森林类型之间差异不显著。主成分分析结果表明,所选15种碳源能够阐述4种不同重建森林土壤微生物功能多样性的差异,森林土壤微生物的敏感碳源主要为糖类。     

松子壳热解重质油的催化改性

以红松松子壳为原料,采用连续热解装置研究了热解反应温度和时间对生物油得率的影响规律,在反应温度为450℃、反应时间为6 min时,生物油得率可达到40.74%,热值可达到22.66 MJ/kg。采用气相色谱质谱联用仪对生物油成分进行了分析,其成分以酚类为主,质量分数约为33.5%;选用HZSM-5及NiO/HZSM-5分子筛催化剂对热解重质油部分分别进行催化改性试验,结果表明:经NiO/HZSM-5分子筛催化剂催化后其中高沸点有机物质量分数降低约13个百分点;其黏度由原来的约3 290 mPa·s大幅度地降低至450 mPa·s,热值则由原来的约26.16 MJ/kg增加到30.33 MJ/kg,增加了16%,同时提高了重质油的燃烧性和稳定性;负载物氧化镍(NiO)的添加提高了HZSM-5催化剂的抗积碳能力。该研究也为后续生物油改性提供了参考。     

基于土地功能的农村居民点内部用地结构分类

科学合理的农村居民点内部用地功能结构分类是提升农村土地利用效率、实现用地结构优化配置的重要前提。该文在梳理农村居民点用地分类现状的基础上,从土地利用的功能角度出发,构建了涵盖农村居民点用地生产功能、生活功能、生态功能和潜在功能的分类体系,其中包含4个一级类、10个二级类和37个三级类;并以该分类方法为基础,通过实地调查典型农村居民点内部用地结构现状,从微观视角揭示内部用地结构。基于新的分类体系,大兴庄村用地类型可分为28种,农村居民点内部生产用地、生活用地和生态用地的比例分别为34.73%、53.53%和4.06%,可挖潜面积比例为占农村居民点总面积的13.09%。研究结果为中国农村居民点用地分类体系构建提供了基本思路和工作框架。     

湖区小麦-玉米轮作模式下不同施肥措施调控氮磷养分流失研究

针对我国南水北调东线过水区南四湖富营养化问题,利用沿湖流域典型种植模式——小麦-玉米轮作体系,选择材料易获取的几种施肥措施,采用田间原位安装淋溶水采集器和地表水径流池收集水样,室内分析不同处理防控氮磷养分流失的效果。结果表明:各施肥措施在作物不同茬口均能降低氮磷养分的随水流失,不同模式防控养分流失效果有差异;氮径流损失中,硝态氮占主要比例,玉米季和小麦季分别为82.7%~86.4%和94.2%~96.5%,而淋溶途径中硝态氮比例略有下降;径流为氮损失的主要途径,玉米茬口氮损失比例占轮作周年的67.0%~71.4%;磷径流损失中可溶性磷和颗粒磷比例相当,而淋溶磷以可溶性磷为主;淋溶途径损失的磷养分比例稍高,仍以玉米茬口总磷损失为主,占54.4%~63.1%;防控氮磷流失结合周年作物产量,玉米上使用减量控释氮肥或优化施肥配合秸秆还田、小麦上优化施肥或使用减量控释氮肥是相对理想的养分运筹搭配模式。     

几种胡敏酸还原容量的表征与比较

还原容量(RC)是衡量胡敏酸(HA)还原特性的重要指标。采用饱和H2振荡法和土壤溶液法对HA分别进行化学和微生物预处理,分别以硝酸铁(Fe(NO3)3)、柠檬酸铁(FeCit)作电子受体,测定了三种HA(上海巨枫SH,天津光复TJ,缙云山JY)的本底还原容量(NRC),化学还原容量(CRC),微生物还原容量(MRC)。对不同电子受体条件下、不同初始状态和不同种类的胡敏酸的RC进行比较。结果表明：三种HA中,以缙云山土壤提取的胡敏酸RC值最高,还原容量最大,分别为20.21?0.26mmolc mol-1C (NRC)、26.02?1.12mmolc mol-1C (CRC)和29.29?1.56mmolc mol-1C (MRC)。两种电子受体中,采用Fe(NO3)3得到的RC明显高于在FeCit条件下。另外,溶液态HA的RC明显高于固态。由此证明胡敏酸还原容量是一个相对量;其容量大小不仅和自身结构、性质有关,也受到HA初始形态和不同电子受体的影响。对比三个还原容量指标发现CRC和MRC显著大于NRC,而CRC和MRC之间无明确大小关系,因此用CRC来表征HA被微生物还原后的还原容量(MRC)还需作进一步验证。     

Kinetics of a bioactive compound (caffeine) mobility at the vicinity of the mechanical glass transition temperature induced by gelling polysaccharide

An investigation of the diffusional mobility of a bioactive compound (caffeine) within the high-solid (80.0% w/w) matrices of glucose syrup and κ-carrageenan plus glucose syrup exhibiting distinct mechanical glass transition properties is reported. The experimental temperature range was from 20 to -60 °C, and the techniques of modulated differential scanning calorimetry, small deformation dynamic oscillation in shear, and UV spectrometry were employed. Calorimetric and mechanical measurements were complementary in recording the relaxation dynamics of high-solid matrices upon controlled heating. Predictions of the reaction rate theory and the combined WLF/free volume framework were further utilized to pinpoint the glass transition temperature (T(g)) of the two matrices in the softening dispersion. Independent of composition, calorimetry yielded similar T(g) predictions for both matrices at this level of solids. Mechanical experimentation, however, was able to detect the effect of adding gelling polysaccharide to glucose syrup as an accelerated pattern of vitrification leading to a higher value of T(g). Kinetic rates of caffeine diffusion within the experimental temperature range were taken with UV spectroscopy. These demonstrated the pronounced effect of the gelling κ-carrageenan/glucose syrup mixture to retard diffusion of the bioactive compound near the mechanical T(g). Modeling of the diffusional mobility of caffeine produced activation energy and fractional free-volume estimates, which were distinct from those of the carbohydrate matrix within the glass transition region. This result emphasizes the importance of molecular interactions between macromolecular matrix and small bioactive compound in glass-related relaxation phenomena.     

多场次降雨对崩岗崩积体细沟侵蚀的影响

崩积体是崩岗的重要组成部分,因土质疏松,极易被侵蚀。细沟侵蚀特征是探讨崩积体侵蚀机制的重要内容。采用人工模拟降雨试验,研究多场次降雨条件（1.00、1.67、2.33 mm/min分别降3次雨）对崩积体30°坡面（5m×1 m）细沟侵蚀产沙过程及发育形态特征的影响。结果表明：1）1.00 mm/min降雨强度条件下,3次降雨的后期产沙过程趋于一致,而1.67和2.33 mm/min降雨强度条件下,前2次降雨后期产沙过程趋于一致,但第3次降雨后期产沙率急剧增大;2）各降雨强度条件下,沟头溯源作用、细沟平均宽度及深度随着降雨场次的增加而增加;3）不同降雨强度条件下的细沟特征存在差异,1.00和1.67 mm/min降雨强度时,随着降雨场次的增加,坡面的细沟数及细沟密度增加,宽深比减小,但在2.33 mm/min降雨强度条件下的结果恰好相反;4）各降雨强度条件下细沟侵蚀量及其增加幅度均增大,细沟侵蚀愈剧烈。     

乌梁素海和岱海上覆水中碳的形态分布及其制约机制

以乌梁素海和岱海2个不同类型湖泊上覆水中TIC、DIC、TOC、DOC的地球化学特征为基础,分析和探讨了2个湖泊上覆水的水化学特征和TIC、DIC、TOC、DOC的空间分布格局及其制约机制。结果表明,乌梁素海和岱海湖泊的水化学特征均属蒸发-浓缩类型,湖泊水体离子组分特征受控于流域的蒸发-浓缩作用及蒸发盐岩的风化作用;岱海TIC、DIC、TOC、DOC的含量范围分别为（0.93-1.16）×10^4、（0.78-0.90）×10^4、（0.07-0.63）×10^4、（0.07-0.48）×10^4 μmol·L^-1,乌梁素海TIC、DIC、TOC、DOC的含量范围分别为（0.18-1.00）×10^4、（0.03-0.81）×10^4、（0.10-0.51）×10^4、（0.04-0.32）×10^4 μmol·L^-1,2个湖泊上覆水中TIC和DIC含量的差异性是湖泊富营养化类型、自然地理区划、水文地质背景及水量收支方式等因素综合作用的结果;岱海上覆水中DIC、TIC、DOC、TOC受N、P、Si等3种营养盐的共同影响,乌梁素海上覆水中DIC、TIC、DOC、TOC主要受N的影响。