泸州老窖古酿酒作坊夏季空气真菌分布特征

通过定点取样研究了泸州老窖古酿酒作坊群中3个代表性作坊及其周围环境夏季空气真菌的群落结构和分布特征.结果表明:(1)泸州老窖3个古作坊空气真菌平均浓度为(3.52×103±0.27×103)CFU/m3,变幅在0.94×103～7.01×103CFU/m3之间;3个作坊内外环境真菌浓度不一,营沟头作坊内平均值高于作坊外(P0.05),什字头作坊和新街子作坊内则低于作坊外(P0.05).(2)作坊内的真菌种类略低于作坊外.在古酿酒作坊内共检测出真菌14个类属,优势种群为曲霉属(Aspergillus)、酵母菌(Yeasts)、青霉属(Penicillum)和无孢菌(Nonsporing),芽枝霉属(Cladosporium)和短梗霉属(Aureobasidiu)分别在营沟头和什字头作坊占有优势;作坊外检测出真菌16个类属,优势种群为青霉属、无孢菌、芽枝霉属、曲霉属和短梗霉属。其中青霉属和无孢菌在3个作坊内外环境均无显著差异.(3)古酿酒作坊内、外环境的空气真菌表现出明显的交流现象.在作坊内,青霉属、芽枝霉属、链格霉属(Alternaria)等杂菌占有一定比例;而在作坊外,曲霉属、根霉属(Rhizopus)、酵母菌等酿酒功能菌浓度处于相对较高水平.     

喀斯特石漠化区植被恢复不同阶段土壤真菌群落组成分析

为阐明西南喀斯特石漠化区植被恢复过程土壤真菌群落组成及优势关键类群,采集乔林、灌木林、灌草和草本群落4种不同植被恢复阶段不同小生境中(石面、石沟、石缝)的表层土壤,提取其DNA,利用IlluminaHiSeq平台对真菌ITS区扩增进行高通量测序后注释鉴定,开展植被恢复不同阶段真菌群落组成结构分析。结果表明,36个土壤样品中共获得2 437 541条有效序列,每个样品获得35 911条有效序列,OTU数目为5 437,包含5个门、626个属。乔林、灌木林阶段土壤真菌群落组成相近,由未分类真菌、Geminibasidium、被孢霉属Mortierella、蜡壳耳属Sebacina、青霉属Penicillium、子囊菌门Ascomycota未定属等组成,其中木霉属Trichoderma(LDA=4.11)、青霉属(LDA=4.35)、小蔓毛壳科Herpotrichiellaceae(LDA=4.00)、革菌科Thelephoraceae(LDA=4.10)、未分类真菌(LDA=4.86)为该类型的关键优势真菌类群。灌草过渡阶段与草本群落阶段各成一种类型,灌草过渡阶段包括蜡壳耳属、Geminibasidium、被孢霉属等,其中,蜡壳耳属(LDA=5.30)、Geminibasidium(LDA=4.77)、煤炱目Capnodiales(LDA=4.15)、格孢菌目Pleosporales未定属(LDA=4.28)为该类型的关键优势真菌类群。草本群落阶段由未分类真菌、镰刀菌属Fusarium、子囊菌门、被孢霉属、Archaeorhizomyces等组成,镰刀菌属(LDA=4.78)、Archeaorhizomyces(LDA=4.48)、支顶孢属(LDA=4.22)、肉座菌科(LDA=4.54)、子囊菌门未定属(LDA=4.63)为该类型的关键优势真菌类群。     

长期秸秆还田与施肥对潮土酶活性和真菌群落的影响

秸秆还田对土壤肥力的提升有重要作用,然而其对于土壤真菌群落的影响及其主导因子尚不清楚。以国家土壤肥力和肥料效益长期监测站为平台,探究秸秆还田配施化肥与单施化肥条件下黄淮海平原潮土区土壤养分含量、酶活性的变化,运用Illumina高通量测序技术对土壤真菌群落结构进行调查,分析了不同施肥处理下真菌群落结构变化的主要影响因素。结果表明,两种施肥条件下土壤全氮(TN)、硝态氮(NO_3~--N)以及速效磷(AP)均显著提高;同时秸秆还田配施化肥处理显著提高了土壤有机碳(SOC)含量,增加了45.21%。土壤过氧化物酶(POD)和纤维素酶(CL)活性在秸秆还田配施化肥条件下与对照相比分别显著增加了80.89%和60.16%。秸秆还田处理下土壤真菌群落多样性显著提高,群落组成结果显示,秸秆还田配施化肥条件下弯孢菌属(Curvularia)、篮状菌属(Talaromyces)、赤霉菌属(Gibberella)、镰刀菌属(Fusarium)、被孢霉属(Mortierella)、毛壳属(Cheatomium)以及枝顶孢属(Acremonium)真菌的相对丰度显著提高。Spearman分析发现枝顶孢属(Acremonium)、镰刀菌属(Fusarium)、曲霉属(Aspergillus)、青霉属(Penicillium)、篮状菌属(Talaromyces)和弯孢菌属(Curvularia)真菌丰度与土壤β-葡萄糖苷酶(β-GC)活性呈显著正相关。蒙特分析显示,POD、β-GC是促进秸秆还田条件下真菌群落结构分异的主要影响因子。研究结果揭示了长期秸秆还田配施化肥条件下,真菌群落结构的变异及其影响因子,对预测黄淮海平原潮土区秸秆还田条件下农田真菌群落的演替规律具有重要意义。     

四川彭州大蒜根腐病发病土壤细菌与真菌群落结构

为了解土壤微生物群落与大蒜根腐病之间的关系,采集四川省彭州市不同地点大蒜正常生长和发病土壤样品,采用Illumina MiSeq测序技术分析土壤细菌与真菌的群落结构变化.结果显示,供试土壤的优势细菌主要为变形菌门和绿弯菌门,优势真菌主要为子囊菌门和担子菌门;与正常土壤相比,发病土壤细菌多样性减少,真菌多样性和丰富度增加,其中硝化螺菌属、Nitrosomonadaceae-uncultured、芽孢杆菌属和鞘氨醇单胞菌属等有益细菌及青霉属、木霉属和热霉属等有益真菌丰度降低,匐柄霉属和镰刀菌属等病原真菌丰度增加.Spearman分析结果显示,匐柄霉属和镰刀菌属等病原真菌的相对丰度与土壤pH呈负相关,与土壤速效钾含量呈正相关.本研究表明彭州大蒜根腐病发病与土壤微生物群落结构改变、土壤微生态失衡有关,结果对探明病害的发生机理具有现实意义,可为有效防治大蒜根腐病提供理论依据.(图2表5参36)     

室外空气细菌群落特征研究进展

着重论述了空气细菌的来源、粒子特征、群落特征、浓度的时空变化及其群落结构的影响因素.国内外研究结果表明:空气细菌主要来源于自然界的土壤、动植物、人类和水体,另外一些非自然的人类活动也是其重要来源;空气细菌的粒径主要在 0. 3~15. 0μm间变化,海岸边细菌气溶胶的粒径相对较小,而其他地方 84%或更多的细菌粒子的粒径≥2. 1μm;空气中革兰氏阳性细菌占绝大多数,无论在森林、海岸、城市还是乡村,芽孢杆菌 (Bacillus)都是优势菌属;一年中空气细菌浓度夏季最高,冬季最低,一天中则可以明显的划分为 5个阶段: (ⅰ )午夜细菌浓度最低, (ⅱ )日出时细菌浓度达到高峰, (ⅲ)正午细菌浓度积累逐渐上升, (ⅳ)下午后期细菌浓度降低, (ⅴ )晚上到午夜细菌浓度较低;人类活动频繁,动植物较多的地方空气细菌浓度较高.此外,空气细菌不仅与各种环境因素有关,还受到各种污染因子的影响. 表 2参 53     

垃圾填埋场空气微生物污染及评价

用撞击法采集某垃圾填埋场不同区域空气微生物样品,通过微生物浓度评价不同区域污染状况,并对优势菌落PCR产物经同源性比对分析了空气微生物的优势菌群。结果表明,填埋场的主要污染区域为裸露的填埋区和垃圾运输路段,达到轻微污染程度,其它区域均达到较清洁以上程度。风沙、扬尘大的春季微生物总浓度明显高于夏季。填埋场的空气微生物污染主要为细菌的超标,污染区域空气中的细菌总量比清洁区高13.5倍,空气微生物总浓度相差10.7倍,而霉菌的数量变化相对较小。垃圾填埋场空气中优势细菌以芽孢杆菌属（Bacillus）、节杆菌属（Arthrobacter）和微球菌属（Micrococcus）为主,其中以枯草芽孢杆菌（Bacillus subtilis）,短小芽孢杆菌（Bacillus pumilus）和黄金节杆菌（Arthrobacter aurescens）出现的频率较高;优势真菌菌群为青霉属（Penicillium）、曲霉属（Aspergillus）、链格孢属（Alternaria）等。     

室内空气颗粒物中HCHs和DDTs的含量

采用中流量TSP采样器在北京大学住宅小区和教学楼同步采集了室内和室外的大气颗粒物样本 ,分析了其中的HCHs和DDTs残留量 .结果表明 :室内外大气颗粒物中∑HCH的含量分别为 0 1 39ng·m- 3和 0 1 63ng·m- 3,∑DDT含量为 0 40 1ng·m- 3和 0 42 4ng·m- 3.室内外的浓度差别不大 .但由于室内空气颗粒物含量显著低于室外 ,其颗粒物中HCHs和DDTs的质量浓度显著高于室外 ,这可能与室内颗粒物的粒径较小有关 .考虑到室内外空气颗粒物中有机氯异构分布的相似性 ,居住区室内空气颗粒物中的HCHs和DDTs主要来自室外 .而实验室内空气在一定程度上受HCHs内部源污染 .     

贺兰山东坡不同植被类型的土壤真菌多样性及其群落结构

为了解植被对土壤真菌群落结构及其优势菌群影响,利用高通量测序技术,研究了贺兰山东坡山地荒漠草地、浅山灌丛、亚高山针叶林和亚高山草甸4种植被类型土壤真菌多样性及其群落结构。结果表明,（1）贺兰山东坡不同植被类型土壤真菌α多样性由高到低依次为浅山灌丛、山地荒漠草地、亚高山草甸、亚高山针叶林;且亚高山针叶林显著低于其他植被类型。（2）相对丰度1%的真菌共检测到子囊菌门（Ascomycota）、担子菌门（Basidiomycota）、被孢霉门（Mortierellomycota）、球囊菌门（Glomeromycota）、壶菌门（Chytridiomycota）5个门类,其中子囊菌门和担子菌门为主要优势菌群,平均丰度占比分别为46.7%和29.6%;担子菌门在亚高山针叶林中丰度显著高于其他菌门,子囊菌门在山地荒漠草地、浅山灌丛和亚高山草甸植被类型中显著高于其他菌门。（3）从土壤真菌群落组成与环境因子相关性分析可知,植物多样性、pH、年均温、土壤有机质、年均降雨量、土壤含水率及海拔都会显著影响到真菌群落组成;从真菌α多样性指数与植物多样性指数和海拔Pearson相关性分析可知,植物多样性是影响真菌...     

青藏高原高寒草甸土壤真菌多样性与植物群落功能性状和土壤理化特性的关系

为探究高寒草甸土壤真菌多样性与植物群落功能性状(community-weighted mean, CWM; functional diversity,FD)及土壤理化特性的关系,选取3个试验点,每个试验点选择4种生境(沟底平地、阴坡、阳坡和山顶),采用高通量测序技术分析各生境土壤真菌多样性特点;利用广义线性混合模型,比较土壤真菌优势类群(门和属水平)及土壤理化特性在不同试验点和生境之间的差异;采用多元分析和偏回归检验土壤真菌多样性与群落水平功能性状(CWM)和性状多样性(FD)及土壤理化特性的关系.结果表明:(1)高寒草甸土壤真菌在门水平上的优势类群为接合菌门、子囊菌门、担子菌门和球囊菌门,在属水平上的优势类群为被孢霉属、隐球菌属、丝盖伞属、蜡壳菌属和蜡伞属.接合菌门、球囊菌门及被孢霉属在不同生境的分布存在显著差异,在山顶接合菌门和被孢霉属的相对丰度显著高于其他3种生境(沟底平地、阴坡和阳坡),在沟底球囊菌门的相对丰度显著高于其他3种生境(阴坡、阳坡和山顶).(2)土壤理化特性能够解释土壤真菌丰富度变化的21%.土壤真菌丰富度随土壤pH、全氮和速效氮的增加而增加,随土壤有机碳、有机质和碳氮比的增加而降低.(3)植物群落水平功能性状能够解释20%的土壤真菌丰富度变化.土壤真菌丰富度与植物群落水平的植株高度呈显著负相关.(4)植物群落性状多样性能够解释土壤真菌丰富度变化的33%.土壤真菌丰富度随植物群落叶片氮和磷含量多样性的增加而增加,随植株高度和叶片干物质含量的增加而减小;土壤真菌Shannon指数与土壤理化特性及植物群落功能性状均无显著相关性.因此,植物群落功能性状和土壤理化特性可共同解释高寒草甸土壤真菌丰富度的变化,植物群落性状多样性与土壤真菌群落协同变化,可促进高寒草甸生态系统稳定性维持.(图3表2参51)     

5种植物根际真菌群落结构与多样性

根际真菌在植物生长和健康方面具有非常重要的作用,然而由于分离和培养技术的限制,对根际真菌群落、多样性及功能仍缺乏认识.为明确不同植物根际真菌群落的结构与差异,揭示其潜在的生态功能,采用Illumina MiSeq技术对马蔺、葡萄、大豆、玉米等5种植物根际真菌ITS rRNA基因的ITS2区进行高通量测序,并利用FUNGuild对其功能进行预测分析.结果显示,5种植物根际中80%以上的真菌序列划分到17-45个OTUs中,优势菌门为子囊菌门,优势菌纲为座囊菌纲和粪壳菌纲等;这5种植物根际真菌群落各自聚群,其香农指数(Shannon)和丰富度(Chao1)从大到小依次为木瓜、马蔺、葡萄、大豆、玉米;在获得的1 290个OTUs中,49.76%的OTUs归属于8个功能类群,其中腐生菌约占总OTUs数的25.89%,是主要功能类群,其次是病原菌/腐生/共生过渡型、植物病原体等,葡萄、木瓜和马蔺根际中腐生菌显著高于大豆和玉米.本研究表明木瓜、马蔺和常见植物根际真菌的群落结构和多样性不同,一年生作物的根际真菌多样性小于多年生植物,进而也表明根际真菌群落及其生态功能受到植物的生活周期或类型的影响.(图4表1参30)     

Lead and cadmium in urban allotment and garden soils and vegetables in the United Kingdom

In order to assess the intake of lead and cadmium by consumers of home grown vegetables in urban areas, replicated experimental plots of uniform size, comprising summer and winter crops, were established in 94 gardens and allotments in nine towns and cities in England.The geometric mean lead and cadmium concentrations for the soils (n = 94) were 217 g g^–1 (ranging from 27 to 1,676 g g^–1) and 0.53 g g^–1 (<0.2–5.9 g g^–1), respectively. Compared with agricultural soils, the garden and allotment soils contained elevated levels of lead but not cadmium.Lead concentrations in the vegetables ranged from <0.25 g g^–1 to 16.7 g g^–1 dry weight and cadmium concentrations ranged from <0.025 g g^–1 to 10.4 g g^–1 dry weight. Lead concentrations were higher than reported background levels, although <1% exceeded the statutory limit for saleable food in the UK (1 g g^–1 fresh weight). Cadmium concentrations were generally similar to background levels.     

Nanosensors and nanobiosensors in food and agriculture

The food and agriculture sector controls the economic growth of a developing country. The food industries have practices of growing crops, raising livestock and sea foods, food processing and packaging, regulating production and distribution with quality and safety. The process control and monitoring quality are crucial steps. Here we review nanosensors and nanobiosensors as alternative of classical quantification methods. Nanoscale dimensions of metal nanoparticles, metal nanoclusters, metal oxide nanoparticles, metal and carbon quantum dots, graphene, carbon nanotubes, and nanocomposites expand the sensitivity by signal amplification and integrate several novel transduction principles such as enhanced electrochemical, optical, Raman, enhanced catalytic activity, and superparamagnetic properties into the nanosensors. The electrochemical nanosensors, optical nanosensors, electronic nose and electronic tongue, nanobarcode technology, and wireless nanosensors have revolutionized the sensing in food and agriculture sectors with multiplex and real-time sensing capabilities. Despite previous success stories of the remunerative health sector, the approaches are transferred subsequently to food and agriculture sector; with potential application in detection of food contaminants such as preservatives, antibiotics, heavy metal ions, toxins, microbial load, and pathogens along with the rapid monitoring of temperature, traceability, humidity, gas, and aroma of the food stuff.     

南京市蔬菜中滴滴涕和六六六的残留及摄食暴露分析

为研究有机氯农药在食物中的残留及人群的摄食暴露,在2015年5月采集了南京市居民普遍食用的10种蔬菜,利用气相色谱-质谱联用仪(GC-MS)进行检测。研究表明滴滴涕(DDTs)和六六六(HCHs)在蔬菜中均有检出,∑DDTs的残留量为1.78~5.29 ng·g~(-1),∑HCHs的残留量为0.21~4.77 ng·g~(-1),其中∑10OCPs(有机氯农药)含量最高的蔬菜是藕(10.07 ng·g~(-1)),含量最低的是青菜(2.32 ng·g~(-1))。通过来源分析发现,蔬菜中DDTs可能有新的输入,而HCHs则主要源于历史残留。通过对不同人群的每日摄取量(EDI)进行摄食暴露分析发现,儿童的摄食暴露量要高于同性别其他年龄段人群,在儿童和未成年阶段,男性的暴露量普遍高于女性,而在成年和老年阶段,男性的暴露量低于女性。平均而言,各年龄段人群对γ-HCH和DDTs的日均口摄暴露量(EDI)值远低于联合国粮农组织和世界卫生组织(FAO/WHO)所规定的ADI值,表明在目前蔬菜消费量下,南京市居民通过摄入蔬菜引起的健康风险水平较低。     

Changes in chemical forms of lead in temperate and semiarid soils in sterile and unsterile conditions

Sequential extraction has been used as a suitable method for fractionation of chemical forms of trace elements and study of their plant availability. Surface soils were sampled from Guilan and Hamadan provinces in north and northwest of Iran with temperate and semiarid climates. The chemical forms of Pb in the Pb(NO₃)₂-treated (400 μg Pb g⁻¹) soils have been studied in solid state incubation (FC) at 27°C in sterile and unsterile conditions. After 20 min and 3600 h a sequential extraction scheme was also used to fractionate Pb of incubated samples into soluble-exchangeable (Sol-Exch), carbonates associated (ACar), organic matter associated (AOM), Mn oxide associated (AMnOx), Fe oxide associated (AFeOx), and residual (Res) forms. Temperate soil samples had higher clay content, cation exchange capacity (CEC), dichromate oxidable organic carbon (OC), total Kjeldahl-nitrogen (TN), biological activity, amorphous and crystalline Fe and Al, but semiarid soil samples had higher sand content, pH, equivalent calcium carbonate (ECC), available P and K. Soil lead fractionation revealed that in both groups of soils Pb largely changed to exchangeable, carbonates associated and organic associated forms after 20 min. The chemical forms of Pb differed widely among soils after 3600-h incubation. The conversion rate of Pb from more available forms to less available forms was higher in temperate soils with higher Fe–Mn oxides and OM contents compared to semiarid soils. In temperate soils after 3600-h incubation, greater content of Pb was observed in Res (68%), AOM (14%), ACar (7%), and AMnOx (5%) fractions. However, in semiarid soils greater content of Pb was observed in Res (61%), ACar (16%), Sol-Exch (8%), and AOM (8%) fractions. The sum of AMnOx and AFeOx chemical forms for Pb in semiarid soils compared to temperate soils was lower. It was only 7% against 9% in temperate soils. Soil microorganisms in unsterile soils had significant effect on AOM, AFeOx and Res fractions of Pb. They not only increased AOM and AFeOx fractions of Pb in soils but also decreased Res fraction of Pb significantly.     

Occurrence and removal of N-nitrosodimethylamine and its precursors in wastewater treatment plants in and around Shanghai

Six wastewater treatment plants （WWTPs） were investigated to evaluate the occurrence and removal of N-nitrosodimethylamine （NDMA）, NDMA formation potential （FP） and four specific NDMA precursors, dimethylamine （DMA）, trimethylamine （TMA）, dimethyl- formamide （DMFA） and dimethylaminobenzene （DMAB）. DMA and tertiary amines with DMA functional group commonly existed in municipal wastewater. Chemically enhanced primary process （CEPP） had no effect on removal of either NDMA or NDMA FP. In WWTPs with secondary treatment processes, considerable variability was observed in the removal of NDMA （19%-85%） and NDMA FP （16%-76%）, moreover, there was no definite relationship between the removal of NDMA and NDMA FP. DMA was well removed in all the six surveyed WWTPs; its removal efficiency was greater than 97%. For the removal of tertiary amines, biologic treatment processes with nitrification and denitrification had better removal efficiency than conventional activated sludge process. The best removal efficiencies for TMA, DMFA and DMAB were 95%, 68% and 72%, respectively. CEPP could remove 73% of TMA, 23% of DMFA and 36% of DMAB. After UV disinfection, only 17% of NDMA was removed due to low dosage of UV was applied in WWTP. Although chlorination could reduce NDMA precursors, NDMA concentration was actually increased after chlorination.     

Recent advances in pharmaceuticals and personal care products in the surface water and sediments in China

Pharmaceuticals and personal care products (PPCPs) have been regarded as an emerging problem in the surface water environment in the past few decades. In China, although related studies were initiated several years ago, an increasing number of studies on this topic have been conducted in recent years. These studies have expanded knowledge of their occurrence, behavior and associated risk in the surface water environment in China. This review compiles the most recent literature related to the studies of PPCPs in the surface water environment in China. It includes PPCP occurrence in surface water and sediments, their geographical distribution, and outcomes of the associated risk assessment. It shows that antibiotics have received much more attention in both surface water and sediments than other PPCPs. Compared to other countries; most antibiotics in the collected sediments in China showed higher contamination levels. Many more study areas have been covered in recent years; however, attention has been given to only specific areas. Environmental risk assessment based on risk quotients indicated that sulfamethoxazole presents the most significant environmental risk to relevant aquatic organisms; followed by ofloxacin, ciprofloxacin, enrofloxacin, 17α-ethynylestradiol, ibuprofen and diclofenac. Despite limited research on the environmental risk assessment of PPCPs in sediments, higher risks posed by PPCPs in the sediments rather than surface water were identified highlighting the need for further risk assessment of PPCPs in sediment samples.

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H and O isotopic differences in typhon and urban-induced heavy rain in Tokyo

Stable isotope ratios of hydrogen and oxygen of water are useful tracers of the hydrological cycle. For example, isotopes monitor the evapotranspiration in vegetated areas, local snow ice processes and stream water flow processes. δ¹⁸O and δD in rainwater reflect the processes of evaporation, condensation and precipitation. Heavy rains thus modify the stable isotope ratio of ground water, stream water and transpiration water vapor. However, the controlling factors of δ¹⁸O and δD are not clear. Here we analyzed the inorganic ion concentration and stable isotope ratio in 38 normal rainwater and 15 heavy rainwater samples were collected in Shinjuku, Tokyo, Japan, during four years from October 2012 to December 2015. Results show a decrease in δ¹⁸O and δD values with the total rainfall amount, thus highlighting the amount effect. δ¹⁸O and δD volume-weighted mean values in typhoon heavy rain were higher than the values estimated from amount effect, whereas δ¹⁸O and δD volume-weighted mean values in urban-induced heavy rain were lower. Typhoon heavy rain has high Na⁺ ratio and stable isotope ratios, while urban-induced heavy rain has low Na⁺ ratio and stable isotope ratio.     

Spatial and temporal pattern in seagrass community composition and productivity in south Florida

We document the distribution and abundance of seagrasses, as well as the intra-annual temporal patterns in the abundance of seagrasses and the productivity of the nearshore dominant seagrass (Thalassia testudinum) in the south Florida region. At least one species of seagrass was present at 80.8% of 874 randomly chosen mapping sites, delimiting 12,800 km² of seagrass beds in the 17,000-km² survey area. Halophila decipiens had the greatest range in the study area; it was found to occur over 7,500 km². The range of T. testudinum was almost as extensive (6,400 km²), followed by Syringodium filiforme (4,400 km²), Halodule wrightii (3,000 km²) and Halophila engelmanni (50 km²). The seasonal maxima of standing crop was about 32% higher than the yearly mean. The productivity of T. testudinum was both temporally and spatially variable. Yearly mean areal productivity averaged 0.70 g m⁻²day⁻¹, with a range of 0.05–3.29 g m⁻² day⁻¹. Specific productivity ranged between 3.2 and 34.2 mg g⁻¹ day⁻¹, with a mean of 18.3 mg g⁻¹ day⁻¹. Annual peaks in specific productivity occurred in August, and minima in February. Integrating the standing crop for the study area gives an estimate of 1.4 × 1011 g T. testudinum and 3.6 × 10¹⁰ g S. filiforme, which translate to a yearly production of 9.4 × 10¹¹ g T. testudinum leaves and 2.4 × 10¹¹ g S. filiforme leaves. We assessed the efficacy of rapid visual surveys for estimating abundance of seagrasses in south Florida by comparing these results to measures of leaf biomass for T. testudinum and S. filiforme. Our rapid visual surveys proved useful for quantifying seagrass abundance, and the data presented in this paper serve as a benchmark against which future change in the system can be quantified. Received: 30 January 2000 / Accepted: 24 July 2000     

中部城市秋冬季PM2.5水溶性离子的化学特征及来源

PM2.5是影响空气质量、引发灰霾污染发生的关键污染物.本研究以南昌为主要采样对象,分析了南昌市2017-1018年秋、冬季PM2.5和水溶性无机离子(WSIIs)的化学组成及其来源,并同时期采样和对比分析了中部城市(武汉和长沙)秋冬季(10月和1月)PM2.5及WSIIs化学特征及其来源.结果 表明,南昌市采样期间W...     

Gut pigment accumulation and destruction by arctic copepods in vitro and in situ

The results presented here were obtained at six locations during three cruises in 1985 (off the coast of Labrador), 1986 (at the eastern end of Viscount Melbourne Sound) and 1988 (off the coast of Labrador). In situ chlorophyll maximum concentrations were >7 gl^-1 at depths of between 0 and 30 m in all sampling areas. In feeding experiments copepods attained higher gut pigment concentrations the longer they had been previously starved and higher concentrations when fed in the dark than when fed in the light. Community ingestion rates calculated from changes in particulate chlorophyll were higher than estimates derived from gut pigment data except when copepods had been starved for 24 h. Differences between estimates by the two methods suggested pigment destruction. In feeding experiments pigment: biogenic silica ratios in food and faecal pellets suggested that the length of starvation period affected the degree of pigment destruction differently at different stations and that feeding in the light greatly increased pigment destruction. A comparison of pigment: silica ratios in the water column, and in faecal pellets collected from copepods which had fed there, suggested that pigment destruction may occur in situ sometimes and that the degree to which it occurs may be affected by feeding history, light, diel feeding behaviour and species composition.