Using Rock‐Eval 6 pyrolysis for tracking fossil organic carbon in modern environments: implications for the roles of erosion and weathering

This work relates to the debate on the fossil organic carbon (FOC) input in modern environments and its possible implication for the carbon cycle, and suggests the use of Rock‐Eval 6 pyrolysis as a relevant tool for tracking FOC in such environments. Considering that such a delivery is mainly due to supergene processes affecting the continental surface, we studied organic matter in different reservoirs such as bedrocks, alterites, soils and rivers in two experimental catchments at Draix (Alpes de Haute Provence, France). Samples were subjected to geochemical (Rock‐Eval 6 pyrolysis) investigations and artificial bacterial degradations. After comparing the geochemical fingerprint of samples, geochemical markers of FOC were defined and tracked in the different reservoirs. Our results confirm the contribution of FOC in modern soils and rivers and display the various influences of weathering and erosional processes on the fate of FOC during its exchange between these pools. In addition, the contrasting behaviour of these markers upon the supergene processes has also highlighted the refractory or labile characters of the fossil organic matter (FOM). Bedrock to river fluxes, controlled by gully erosion, are characterized by a qualitative and quantitative preservation of FOM. Bedrock to alterite fluxes, governed by chemical weathering, are characterized by FOC mineralization without qualitative changes in deeper alterites. Alterite to soils fluxes, controlled by (bio)chemical weathering, are characterized by strong FOC mineralization and qualitative changes of FOM. Thus weathering and erosional processes induce different FOM evolution and affect the fate of FOC towards the global carbon cycle. In this study, gully erosion would involve maintenance of an ancient sink for the global carbon cycle, while (bio)chemical processes provide a source of CO₂. Finally, this study suggests that Rock‐Eval 6 pyrolysis can be considered as a relevant tool for tracking FOC in modern environments. Copyright © 2006 John Wiley & Sons, Ltd.     

江西柘林水库春季浮游藻类、叶绿素a与环境因子的分布、关系及意义

江西柘林水库是长江中游的大型峡谷型旅游性水库,库容79.2×10~8m~3,长115 km.2015年4月在56 km的中心库区走航和定点测量了水库表层水体浮游藻类、叶绿素a(Chl.a)浓度与溶解无机氮(DIN)浓度、溶解无机磷(DIP)浓度、溶解硅(DSi)浓度、水温、浊度和溶解氧浓度等环境因子的分布特征.结果表明:1)水库属于中营养水体,表层主要浮游藻类(细胞丰度1000 cells/L)有34种,平均生物量为0.41 mg/L.主要优势藻类(优势度≥0.02)为硅藻和蓝藻,藻类组成与DIN浓度、DIP浓度、DSi浓度和水温等环境因子关系密切,4种因子对藻类结构的解释水平达60%以上.2)水库水体Chl.a浓度具有显著的次表层叶绿素最大值(SCM)现象,SCM层深度为3~8 m,厚度为2~7 m,SCM层占整个水体的25.2%~74.1%.SCM层的藻类对营养盐吸收消耗致使DIN、DIP和DSi浓度下降,同时藻类的产氧使溶解氧浓度增加.3)水库对DSi具有显著的生物过滤器效应,中、上层约有11%~12%的DSi被生物吸收利用,从上游至下游,累积约有21%的DSi被藻类吸收沉降于库底.4)人类氮、磷排放对水库生态和水质有严重影响,毗邻县城区域水体的Chl.a和DIP浓度分别是自然河段的2.9倍和3倍左右.     

Development of microsatellite loci for two Agabus diving beetle species from the pooled DNA and testing their utility in mountain lake populations

Diving beetles (Dytiscidae) are the most speciose water beetle group, occurring on all continents except Antarctica. They inhabit various lotic and lentic habitats and play an important role in ecosystem functioning. In this study, we developed functional polymorphic microsatellites for two widely distributed species from one of the most diversified dytiscid genus Agabus: Agabus bipustulatus (Linnaeus, 1767) and Agabus cf. guttatus from the Agabus guttatus group sensu Foster and Bilton (1997). For microsatellites development, pooled DNA and NGS pyrosequencing were used. Microsatellites are still very useful genetic markers for studying recent population changes, but for dytiscids, highly diversified and ecologically important group of freshwater invertebrates, only 8 microsatellite loci are available for one North American species. To test utility of the developed markers, we used several populations of alpine lakes, situated in the Tatra Mountains (Western Carpathians). From the 60 tested markers, 13 loci for Agabus bipustulatus and 8 loci for A. cf. guttatus showed polymorphism. The number of alleles per locus varied from 2 to 10 and no significant linkage disequilibrium was observed. Observed/expected heterozygosity varied from 0/0.077 to 1/0.834 within populations of A. cf. guttatus and from 0/0.056 to 1/0.837 within populations of A. bipustulatus. The significant deviation from HWE was probably caused by presence of null alleles or undetected biological processes. Bayesian cluster analysis revealed differences in the cluster proportions, confirming applicability of the developed markers for future studies of population structure of both Agabus species.     

卤虫休眠卵的若干生物学特性研究进展

结合作者的研究工作对卤虫休眠卵的耐性、形态结构、胚胎发育及细胞(核)数目、以及卤虫休眠卵的生化适应性等方面的国内外研究成果及现状进行了综述,并提出应该在现有的研究基础上对Clegg的假设、卤虫卵内hsp70的分子结构特征、卤虫卵的卵壳结构及卤虫卵亚壳层的功能等方面进行深入研究,为卤虫休眠卵的基础生物学研究积累资料.     

三疣梭子蟹乳化病血液生化指标诊断技术的研究

对患乳化病的三疣梭子蟹进行了血液生化指标检测．结果表明：与健康三疣梭子蟹相比，病蟹肌酐、总胆固醇、Na^＋、Cl^-、Mg^2＋、Ca^2＋等含量明显上升，而血糖、总蛋白、白蛋白、谷丙转氨酶、谷草转氨酶、乳酸脱氢酶、碱性磷酸酶等含量却显著下降．通过感染试验的追踪检测，并与对照组相比，感染后24h含量发生明显变化的血液生化指标为血糖、总胆固醇、总蛋白、谷草转氨酶和Mg^2＋，此5种指标可作为三疣梭子蟹乳化病早期诊断的参考指标．     

眼斑拟石首鱼的生化组成及预测模式

测定了养殖眼斑拟石首鱼肌肉及鱼体中的蛋白质、脂类、灰分和水分等生化组成。分析了肌肉蛋白质中17种常见氨基酸的含量。建立了以鱼体体重、体长、含水量与蛋白含量、脂肪含量、灰份、比能值的回归关系的预测模型。回归结果表明，眼斑拟石首鱼的鱼体组分与鱼体重、含水量间呈显著线性相关，而与全长则呈乘幂函数，基本呈立方关系，比能值与体重无相关性，其相关系数蛋白质＞水份＞灰分＞脂肪＞比能值。     

Study of effects of environmental factors on biochemical compositions of four species of marine single-celled algae

INTRODUCTIONThecontentsandtheirvariationofcellularbiochemicalcomponentsinnormallygrowingmarinealgaereflectthedifferenceinecologicalenvironments,reportedbymanyresearchers(MomsandSkea,1978;SmithandMoms,1980;LiandHarrison,1982;SmithandGeider,1985;Yangetal.,1991,1992).Lightintensity,temperatureandnutrientsaremostimPOrtantenvironmentalfactorsintheocean.ThispaperemphasizestheeffectsofenvironmentalfactorsonthecompositionofPhaendactylumtricornutum,Dunaliellaspp.,SkeletonemacostatumandIsOChr…