Biometric Based Carbon Flux Measurements and Net Ecosystem Production (NEP) in a Temperate Deciduous Broad-Leaved Forest Beneath a Flux Tower

Biometric based carbon flux measurements were conducted over 5 years (1999–2003) in a temperate deciduous broad-leaved forest of the AsiaFlux network to estimate net ecosystem production (NEP). Biometric based NEP, as measured by the balance between net primary production (including NPP of canopy trees and of forest floor dwarf bamboo) and heterotrophic respiration (RH), clarified the contribution of various biological processes to the ecosystem carbon budget, and also showed where and how the forest is storing C. The mean NPP of the trees was 5.4 ± 1.07 t C ha⁻¹ y⁻¹, including biomass increment (0.3 ± 0.82 t C ha⁻¹ y⁻¹), tree mortality (1.0 ± 0.61 t C ha⁻¹ y⁻¹), aboveground detritus production (2.3 ± 0.39 t C ha⁻¹ y⁻¹) and belowground fine root production (1.8 ± 0.31 t C ha⁻¹ y⁻¹). Annual biomass increment was rather small because of high tree mortality during the 5 years. Total NPP at the site was 6.5 ± 1.07 t C ha⁻¹ y⁻¹, including the NPP of the forest floor community (1.1 ± 0.06 t C ha⁻¹ y⁻¹). The soil surface CO₂ efflux (RS) was averaged across the 5 years of record using open-flow chambers. The mean estimated annual RS amounted to 7.1 ± 0.44 t C ha⁻¹, and the decomposition of soil organic matter (SOM) was estimated at 3.9 ± 0.24 t C ha⁻¹. RH was estimated at 4.4 ± 0.32 t C ha⁻¹ y⁻¹, which included decomposition of coarse woody debris. Biometric NEP in the forest was estimated at 2.1 ± 1.15 t C ha⁻¹ y⁻¹, which agreed well with the eddy-covariance based net ecosystem exchange (NEE). The contribution of woody increment (Δbiomass + mortality) of the canopy trees to NEP was rather small, and thus the SOM pool played an important role in carbon storage in the temperate forest. These results suggested that the dense forest floor of dwarf bamboo might have a critical role in soil carbon sequestration in temperate East Asian deciduous forests.     

除草剂精喹禾灵用于硅藻过量产生二十碳五烯酸

硅藻Nitzschia laevis是EPA很好的替代来源。除了对硅藻进行高密度培养外,EPA的产量还能利用除草剂来提高。本文研究了除草剂精喹禾灵对硅藻的生长和产EPA的影响。DMSO作为除草剂的溶剂,会对硅藻的生长造成抑制,DMSO在培养基中的添加量最好不要超过0.2%。除草剂能对硅藻的细胞形态造成损害,随着除草剂浓度的增加,硅藻的产量减低了,但脂质和EPA的含量提高了。当除草剂浓度为0.1mmol/L时,EPA的含量从3.00%增加到3.58%,提高了19.3%,EPA占总脂肪酸的含量也由25.15%提高到了32.88%。实验表明,除草剂精喹禾灵能促进硅藻EPA的积累,因而在筛选过量产生EPA微藻方面有重要用途。     

异养微生物在金属生物淋滤技术中的应用

生物淋滤技术主要应用于低品位矿石金属选矿、煤气脱硫、废弃物中金属回收和污染介质中金属离子毒性的去除等方面。作为生物淋滤技术中的主体微生物之一,异养微生物可通过其产生的酸性代谢物还原、酸化及络合,提取或者溶解非硫化矿、固体废弃物、污水污泥及土壤中的金属,有助于解决目前的资源短缺问题,还可对污染环境治理提供技术支持,具有重要的理论意义和实践价值。应用于异养微生物淋滤技术中的常见微生物包括细菌(以假单胞菌为主)和真菌(以曲霉菌和青霉菌应用最为广泛)。淋滤过程涉及酸解、络合、还原及碱化等。目前,异养微生物淋滤技术主要应用于生物冶金、固体废弃物处理、污水处理和污染土壤修复等。本文分析了异养微生物金属淋滤过程中的问题,并提出了未来研究的发展方向。     

微生物制剂对斑节对虾亲虾池异养细菌的影响

研究了施用10 mg·kg-1光合细菌以及1、2和3 mg·kg-1芽孢杆菌制剂对斑节对虾亲虾培育池水体异养细菌和弧菌数量的影响.结果表明:在试验初期,试验组和对照组水体总异养细菌和弧菌数量都明显上升;试验后期,试验池水体异养细菌和弧菌数量均明显下降,明显低于对照池;施用10 mg·kg-1光合细菌能显著抑制亲虾池水体异养细菌的生长(P＜0.01);施用3 mg·kg-1芽孢杆菌对亲虾池水体弧菌数量的抑制效果最好(P＜0.01).     

Distribution Pattern of Photosynthetic Picoplankton and Heterotrophic Bacteria in the Northern South China Sea

The environmental regulation of plcoplankton distribution in the northern South China Sea was examined In winter and summer of 2004. The average abundance of Synechococcus, Prochlorococcus, and heterotrophlc bacteria was lower In winter （30, 21, and 780×10^3 cells/cm^3, respectively） than In summer （53, 85, and 1 090×10^3 cells/cm^3, respectively）, but the seasonal pattern was opposite for plcoeukaryotlc phytoplankton （4 500 and 3 200 cells/cm^3 In winter and summer, respectively）. Synechococcus, picoeukaryotes, and bacteria were most abundant in the nutrient-rich coastal zone and continental shelf, but Prochlorococcus was most abundant In the continental slope and open ocean. The vertical distribution of each photosynthetic group and heterotrophlc bacteria changed between the two seasons. Synechococcus populations with apparently different phycoerythrobilin content occurred at many stations In the summer. In addition, two different populations of Prochlorococcus were found： （i） small, weakly fluorescing cells in the surface layer; and （ii） larger, strongly fluorescent cells In the deep layer. The distribution pattern of photosynthetic plcoplankton and heterotrophlc bacteria depends on environmental effects and their ecophyslologlcal differences. The distribution of Synechococcus appeared to be related to nutrient availability, whereas the distribution of Prochlorococcus appeared to be limited by temperature. Synechococcus was the only plcophytoplankton with a consistent strong relationship with bacteria.     

Isolation and characterization of surfactant degrading bacteria in a marine environment

Abstract Sea water and sediment samples taken near the coasts of Hyeres bay (France) were used for anionic surfactant titrations with surface and bottom waters and the finest part of sediments. The capacity for surfactant degradation by the 'in situ' microflora was evaluated. By using a selective plating technique 26 strains able to utilize anionic surfactant were isolated from the selected bacterial communities. Their ability to degrade anionic surfactant was verified according to the biodegradation standard method. Isolated strains were characterized by morphological and physiological properties using API 20 NE micro-method. All tested strains were Gram negative, strictly aerobic, rod or helical shaped. Their weak utilization of phenolic substrates suggests that they degrade preferentially the alkyl chain of the surfactant molecule. Biodegradation was more efficient with bacterial communities rather than with any isolated strains. Such observations indicate that complete mineralization involves several other so far non-isolated strains which complete the degradation initiated by the isolated strains.     

Nitrogen transformations in a small mountain stream

Ammonium, urea, and nitrate were added to Bear Brook, a second and third order stream in the Hubbard Brook Experimental Forest, New Hampshire. Removal of ammonium and urea during downstream transport coincided with the release of nitrate. Nitrate removal did not occur when it was added alone or with dissolved organic carbon. Laboratory experiments showed that coarse particulate organic material (detritus) and bryophytes taken from the streambed were active in the removal of ammonium from enriched stream water, and in the release of nitrate upon the addition of ammonium.The patterns of removal and release observed in these experiments suggest a biologically mediated, oxidation process. Budgetary calculations show that the in-stream transformation of nitrogen inputs during summer and autumn could represent 12 to 25 percent of the nitrogen exported as nitrate during winter and spring from heterotrophic streams like Bear Brook. This type of internal cycling affects the timing and form of nitrogen export from small streams draining forested watersheds in the northeastern United States.     

Alternative formation of anthraquinones and lipoquinones in heterotrophic and photoautotrophic cell suspension cultures of Morinda lucida Benth.

Photoheterotrophic and photoautotrophic cell suspension cultures were raised from a callus tissue derived from a Morinda lucida Benth. plant (Rubiaceae). The cultures were characterized with regard to fresh weight, dry weight, cell number, pH, chlorophyll and quinoid natural products. The amount of lipoquinones (phylloquinone, -tocopherol, plastoquinone, ubiquinone) isolated from the photoautotrophic cultures matched the amount detected in an intact leaf. Anthraquinone glycosides which are found in the roots of Morinda plants were not present in the photoautotrophic culture. The photoheterotrophic culture contained only trace amounts of these pigments. Abundant anthraquinone synthesis was observed when photoautotrophic and photoheterotrophic suspension cultures were transferred into darkness, provided sucrose was present in the medium. Induction of synthesis of anthraquinone pigments coincided with a rapid disappearance of lipoquinones from the culture. Thus, in the suspension culture, photoautotrophy correlates with lipoquinone synthesis and heterotrophy correlates with anthraquinone synthesis. This reflects the situation in the intact plants where lipoquinones are chloroplast-associated whereas anthraquinones occur in the roots.Abbreviation HPLC high-performance liquid chromatography     

THE BOTTOM-ICE MICROALGAL COMMUNITY FROM ANNUAL ICE IN THE INSHORE WATERS OF EAST ANTARCTICA1

The structure, productivity and heterotrophic potential of an extensive microalgal community growing on the underside of sea ice near the Australian Antarctic Station of Casey, are described. Underwater observations made near the Australian Antarctic stations of Davis and Mawson are also reported. This community develops during September, is largely suspended from the bottom surface of annual sea ice and often extends into the underlying water column as conspicuous strands up to 15 cm long. The algal community structure in the strands is dominated by an unidentified tube diatom belonging to the Amphipleura/Berkeleya group and chains of a species of Entomoneis cf. Amphiprora paludosa var. hyperborea (Grunow) Cleve. Unlike previously described bottom ice environments, a brash ice layer under the hard sea ice is absent. Living cells, predominantly Nitzschia frigida Grunow, also occur in microbrine channels in the bottom 3 cm of the ice. Maximal primary production rates of 81 μg C · L^-1· h^-1 occurred during November, then began declining near the end of December. Minimal rates (2.8 μg C · L^-1· h^-1) were reached in mid-January and coincided with changes in the physical structure of the sea ice and in the stability of the water column. An abundant epibacterial community associated with the microalgal strands assimilated ³H-labelled amino acids suggesting significant heterotrophic recycling of dissolved organic matter. Turnover times of assimilated amino acids in the bottom ice community averaged 55 h during November while negligible turnover of these substrates occurred in the water column 1.5 m below the ice. These bottom ice communities have higher primary productivity than typical brash ice communities; they are also accessible to marine herbivores and so may be more important to the Antarctic marine food chain than previously supposed.     

Cryopreservation ofTetraselmis suecica cultured under different nutrients regimes

The commercially important member of the PrasinophyceaeTetraselmis suecica CCAP 66/4, which is widely used in the aquaculture industry, can be cryopreserved with levels of post-thaw viability in excess of 65%. The nutritional mode which the alga uses appears to be of secondary importance to the cryoprotectant and cooling protocol used, to maximise survival. Glycerol was the least cytotoxic and most protective of the cryoprotectants employed and a cooling rate of 5 °C min^-1 to -30 °C with a 10-minute equilibration, followed by plunging into liquid nitrogen was found to give the highest levels of post-thaw viability.