Estrutura crustal e mantélica da província Borborema através de funções do receptor e dispersão de ondas superficiais

The Borborema Province, located in northeastern Brazil, has a basement of Precambrian age and a tectonic framework structured at the Neoproterozoic (740-560 Ma). After separation between South America and Africa during the Mesozoic, a rift system was formed, giving rise to a number of marginal and inland basins in the Province. After continental breakup, episodes of volcanism and uplift characterized the evolution of the Province. Plateau uplift was initially related to magmatic underplating of mafic material at the base of the crust, perhaps related to the generation of young continental plugs (45-7 Ma) along the Macau-Queimadas Alignment (MQA), due to a small-scale convection at the continental edge. The goal of this study is to investigate the causes of intra-plate uplift and its relationship to MQA volcanism, by using broadband seismology and integrating our results with independent geophysical and geological studies in the Borborema Province. The investigation of the deep structure of the Province with broadband seismic data includes receiver functions and surface-wave dispersion tomography. Both the receiver functions and surface-wave dispersion tomography are methods that use teleseismic events and allow to develop estimates of crustal parameters such as crustal thickness, Vp/Vs ratio, and S-velocity structure. The seismograms used for the receiver function work were obtained from 52 stations in Northeast Brazil: 16 broadband stations from the RSISNE network (Rede Sismográfica do Nordeste do Brasil), and 21 short-period and 6 broadband stations from the INCT-ET network (Instituto Nacional de Ciência e Tecnologia – Estudos Tectônicos). These results add signifi- cantly to previous datasets collected at individual stations in the Province, which include station RCBR (GSN - Global Seismic Network), stations CAUB and AGBL (Brazilian Lithosphere Seismic Project IAG/USP), and 6 other broadband stations that were part of the Projeto Milênio - Estudos geofísicos e tectônicos na Província Borborema/CNPq. For the surface-wave vii tomography, seismograms recorde at 22 broadband stations were utilized: 16 broadband stations from the RSISNE network and 6 broadband stations from the Milênio project. The new constraints developed in this work include: (i) estimates of crustal thickness and bulk Vp/Vs ratio for each station using receiver functions; (ii) new measurements of surfassewave group velocity, which were integrated to existing measurementes from a continental-scale tomography for South America, and (iii) S-wave velocity models (1D) at various locations in the Borborema Province, developed through the simultaneous inversion of receiver functions and surface-wave dispersion velocities. The results display S-wave velocity structure down to the base of the crust that are consistent with the presence of a 5-7.5 km thick mafic layer. The mafic layer was observed only in the southern portion of the Plateau and absent in its northern portion. Another important observation is that our models divide the plateau into a region of thin crust (northern Plateau) and a region of thick crust (southern Plateau), confirming results from independent refraction surveys and receiver function analyses. Existing models of plateau uplift, nonetheless, cannot explain all the new observations. It is proposed that during the Brazilian orogeny a layer of preexisting mafic material was delaminated, as a whole or in part, from the original Brasiliano crust. Partial delamination would have happened in the southern portion of the plateau, where independent studies found evidence of a more resistant rheology. During Mesozoic rifting, thinning of the crust around the southern Plateau would have formed the marginal basins and the Sertaneja depression, which would have included the northern part of the Plateau. In the Cenozoic, uplift of the northern Plateau would have occurred, resulting in a northern Plateau without mafic material at the base of the crust and a southern Plateau with partially delaminated mafic layer.

Petrologia e geocronologia U-Pb do plúton granítico Serra da Rajada, porção central do domínio Rio Piranhas - Seridó, Província Borborema, NE do Brasil

The ediacaran plutonic activity related to the Brasilian/Pan-African orogeny is one of the most important geological features in the Borborema Province, represented along its extension by numerous batholiths, stocks, and dikes.The object of this study, the Serra Rajada Granitic Pluton (SRGP), located in the central portion of the Piranhas-Seridó River Domain is an example of this activity. This pluton has been the subject of cartographic, petrographic, geochronological and lithogeochemical studies and its rocks were characterized by two facies. First, the granitic facies were described as monzogranites consisting of K-feldspar, plagioclase (oligoclase - An23-24%), quartz and biotite (main mafic) and opaque minerals such as titanite, allanite, apatite, and zircon as accessories. Alteration minerals are chlorite, white mica and carbonate. Second, the dioritic facies consist of rocks formed by quartz diorite containing plagioclase (dominant mineral phase), quartz and K-feldspar. Biotite and amphibole are the dominant mafic minerals; and titanite, opaque minerals, allanite, zircon and apatite are the accessories. However, previous geological mapping work in the region also identified the presence of other lithostratigraphic units. These were described as gneisses and migmatites with undifferentiated amphibolite lenses related to the Caicó Complex (Paleoproterozoic) and metasedimentary rocks of the Seridó Group (Neoproterozoic) composed of paragneiss with calc-silicate lenses, muscovite quartzite and biotite schist (respectively, the Jucurutu formations, Equador and Seridó), the host rocks for the SRGP rocks. Leucomicrogranite and pegmatite dikes have also been identified, both related to the end of the Ediacaran magmatism and colluvial- eluvial and alluvial deposits related to Neogene and Quaternary, respectively. Lithogeochemical data on the SRGP granite facies, highlighted quite evolved rocks (SiO2 69% to 75%), rich in alkalis (Na2O+K2O ≥ 8.0%), depleted of MgO (≤ 0.45%), CaO (≤ 1.42%) and TiO2 (≤ 0.36%) and moderate levels of Fe2O3t (2.16 to 3.53%). They display transitional nature between metaluminous and peraluminous (predominance of the latter) with sub-alkaline/monzonitic (High K calcium-alkali) affinity. Harker diagrams show negative correlations for Fe2O3t, MgO, and CaO, indicating mafic and plagioclase fractionation. REE spectrum shows enrichment of LREE relative to heavy REE (LaN/YbN = 23.70 to 10.13), with negative anomaly in the Eu (Eu/Eu* = 0.70 to 0.23), suggesting fractionation or accumulation in the feldspars source (plagioclase). Data integration allows to correlate the SRGP rocks with those described as Calcium-Alkaline Suite of equigranular High K. The crystallization conditions of the SRGP rocks were determined from the integration of petrographic and lithogeochemical data. These data indicated intermediate to high conditions of ƒO2 (mineral paragenesis titanite + magnetite + quartz), parent magma saturated in H2O (early biotite crystallization), tardi-magmatic processes of fluids rich in ƒCO2, H2O and O2 causing part of the mineral assembly to change (plagioclase carbonation and saussuritization, biotite chloritization and opaques Sphenitization). Thermobarometrical conditions were estimated based on geochemical parameters (Zr and P2O5) and CIPW normative minerals, with results showing the liquidus minimum temperature of about800°C and the solidus temperature of approximately 700°C. The final/minimum crystallization pressure are suggested to be between 3 and 5 Kbar. The presence of zoned minerals (plagioclase and allanite) associated with lithogeochemical data in bi-log diagrams for Rb vs. Ba and Rb vs. Sr suggest the role of fractional crystallization as the dominant process in the magmatic evolution of SRGP. U-Pb Geochronological and Sm-Nd isotope studies indicated, respectively, the crystallization age of biotite monzogranite as 557 ± 13 Ma, with TDM model age of 2.36 Ga, and εNd value of -20.10 to the crystallization age, allowing to infer paleoproterozoic crustal source for the magma.

Petrologia e geocronologia U-Pb do plúton granítico Serra da Rajada, porção central do domínio Rio Piranhas - Seridó, Província Borborema, NE do Brasil

The ediacaran plutonic activity related to the Brasilian/Pan-African orogeny is one of the most important geological features in the Borborema Province, represented along its extension by numerous batholiths, stocks, and dikes.The object of this study, the Serra Rajada Granitic Pluton (SRGP), located in the central portion of the Piranhas-Seridó River Domain is an example of this activity. This pluton has been the subject of cartographic, petrographic, geochronological and lithogeochemical studies and its rocks were characterized by two facies. First, the granitic facies were described as monzogranites consisting of K-feldspar, plagioclase (oligoclase - An23-24%), quartz and biotite (main mafic) and opaque minerals such as titanite, allanite, apatite, and zircon as accessories. Alteration minerals are chlorite, white mica and carbonate. Second, the dioritic facies consist of rocks formed by quartz diorite containing plagioclase (dominant mineral phase), quartz and K-feldspar. Biotite and amphibole are the dominant mafic minerals; and titanite, opaque minerals, allanite, zircon and apatite are the accessories. However, previous geological mapping work in the region also identified the presence of other lithostratigraphic units. These were described as gneisses and migmatites with undifferentiated amphibolite lenses related to the Caicó Complex (Paleoproterozoic) and metasedimentary rocks of the Seridó Group (Neoproterozoic) composed of paragneiss with calc-silicate lenses, muscovite quartzite and biotite schist (respectively, the Jucurutu formations, Equador and Seridó), the host rocks for the SRGP rocks. Leucomicrogranite and pegmatite dikes have also been identified, both related to the end of the Ediacaran magmatism and colluvial- eluvial and alluvial deposits related to Neogene and Quaternary, respectively. Lithogeochemical data on the SRGP granite facies, highlighted quite evolved rocks (SiO2 69% to 75%), rich in alkalis (Na2O+K2O ≥ 8.0%), depleted of MgO (≤ 0.45%), CaO (≤ 1.42%) and TiO2 (≤ 0.36%) and moderate levels of Fe2O3t (2.16 to 3.53%). They display transitional nature between metaluminous and peraluminous (predominance of the latter) with sub-alkaline/monzonitic (High K calcium-alkali) affinity. Harker diagrams show negative correlations for Fe2O3t, MgO, and CaO, indicating mafic and plagioclase fractionation. REE spectrum shows enrichment of LREE relative to heavy REE (LaN/YbN = 23.70 to 10.13), with negative anomaly in the Eu (Eu/Eu* = 0.70 to 0.23), suggesting fractionation or accumulation in the feldspars source (plagioclase). Data integration allows to correlate the SRGP rocks with those described as Calcium-Alkaline Suite of equigranular High K. The crystallization conditions of the SRGP rocks were determined from the integration of petrographic and lithogeochemical data. These data indicated intermediate to high conditions of ƒO2 (mineral paragenesis titanite + magnetite + quartz), parent magma saturated in H2O (early biotite crystallization), tardi-magmatic processes of fluids rich in ƒCO2, H2O and O2 causing part of the mineral assembly to change (plagioclase carbonation and saussuritization, biotite chloritization and opaques Sphenitization). Thermobarometrical conditions were estimated based on geochemical parameters (Zr and P2O5) and CIPW normative minerals, with results showing the liquidus minimum temperature of about800°C and the solidus temperature of approximately 700°C. The final/minimum crystallization pressure are suggested to be between 3 and 5 Kbar. The presence of zoned minerals (plagioclase and allanite) associated with lithogeochemical data in bi-log diagrams for Rb vs. Ba and Rb vs. Sr suggest the role of fractional crystallization as the dominant process in the magmatic evolution of SRGP. U-Pb Geochronological and Sm-Nd isotope studies indicated, respectively, the crystallization age of biotite monzogranite as 557 ± 13 Ma, with TDM model age of 2.36 Ga, and εNd value of -20.10 to the crystallization age, allowing to infer paleoproterozoic crustal source for the magma.

Utilização de sismos regionais para a determinação de um modelo 1D de velocidades da onda P na Província Borborema - NE do Brasil

In this work it was performed a study to obtain parameters for an 1D regional velocity model for the Borborema Province, NE Brazil. It was used earthquakes occurred between 2001 and 2013 with magnitude greater than 2.9 mb either from epicentres determined from local seismic networks or by back azimuth determination, when possible. We chose seven events which occurred in the main seismic areas in the Borborema Province. The selected events were recorded in up to 74 seismic stations from the following networks: RSISNE, INCT-ET, João Câmara – RN, São Rafael – RN, Caruaru - PE, São Caetano - PE, Castanhão - CE, Santana do Acarau - CE, Taipu – RN e Sobral – CE, and the RCBR (IRIS/USGS—GSN). For the determination of the model parameters were inverted via a travel-time table and its fit. These model parameters were compared with other known model (global and regional) and have improved the epicentral determination. This final set of parameters model, we called MBB is laterally homogeneous with an upper crust at 11,45 km depth and total crustal thickness of 33,9 km. The P-wave velocity in the upper crust was estimated at 6.0 km/s and 6.64 km/s for it lower part. The P-wave velocity in the upper mantle we estimated at 8.21 km/s with an VP/VS ratio of approximately 1.74.

Utilização de sismos regionais para a determinação de um modelo 1D de velocidades da onda P na Província Borborema - NE do Brasil

In this work it was performed a study to obtain parameters for an 1D regional velocity model for the Borborema Province, NE Brazil. It was used earthquakes occurred between 2001 and 2013 with magnitude greater than 2.9 mb either from epicentres determined from local seismic networks or by back azimuth determination, when possible. We chose seven events which occurred in the main seismic areas in the Borborema Province. The selected events were recorded in up to 74 seismic stations from the following networks: RSISNE, INCT-ET, João Câmara – RN, São Rafael – RN, Caruaru - PE, São Caetano - PE, Castanhão - CE, Santana do Acarau - CE, Taipu – RN e Sobral – CE, and the RCBR (IRIS/USGS—GSN). For the determination of the model parameters were inverted via a travel-time table and its fit. These model parameters were compared with other known model (global and regional) and have improved the epicentral determination. This final set of parameters model, we called MBB is laterally homogeneous with an upper crust at 11,45 km depth and total crustal thickness of 33,9 km. The P-wave velocity in the upper crust was estimated at 6.0 km/s and 6.64 km/s for it lower part. The P-wave velocity in the upper mantle we estimated at 8.21 km/s with an VP/VS ratio of approximately 1.74.

Contribuição de uma seção gravimétrica transversal ao estudo da estruturação litosférica na porção setentrional da Província Borborema, NE do Brasil

Este trabalho apresenta um modelo gravimétrico 2,5D gerado a partir de 315 novas estações gravimétricas levantadas ao longo de uma seção transversal NW-SE com 750 km de extensão na porção setentrional da Província Borborema, NE do Brasil. A modelagem gravimétrica foi aplicada separadamente nas componentes regional e residual do campo gravitacional. A modelagem 2,5D das anomalias regionais revelou que a profundidade da interface crosta-manto varia de 28 a 32 km, considerando uma densidade média de 2,8 g/cm3 para a crosta continental e de 3,3 g/cm3 para o manto litosférico. As anomalias residuais de alta frequência foram interpretadas a partir do contraste de densidade da crosta superior, com uma espessura não superior a 10 km, e uma ampla associação litológica, com densidades variando de 2,55 a 2,9 g/cm3. A configuração geotectônica litosférica atual da Província Borborema é claramente resultado da ruptura dos continentes Sul-Americano e Africano no Mesozoico, na qual boa parte dos vestígios das estruturas tectônicas de grandes profundidades formadas durante a orogênese Brasiliana/Pan-Africana foi mascarada pelo último episódio tectônico responsável pela fragmentação do Gondwana Ocidental. _______________________________________________________________________________________ ABSTRACT

A bioregional classification of the continental shelf of northeastern North America for conservation analysis and planning based on representation

Understanding how well National Marine Sanctuaries and other marine protected areas represent the diversity of species present within and among the biogeographic regions where they occur is essential for assessing their conservation value and identifying gaps in the protection of biological diversity. One of the first steps in any such assessment should be the development of clearly defined and scientifically justified planning boundaries representing distinct oceanographic conditions and faunal assemblages. Here, we propose a set of boundaries for the continental shelf of northeastern North America defined by subdivisions of the Eastern Temperate Province, based on a review and synthesis (i.e. meta-analysis) of the scientific literature. According to this review, the Eastern Temperate Province is generally divided into the Acadian and Virginian Subprovinces. Broad agreement places the Scotian Shelf, Gulf of Maine, and Bay of Fundy within the Acadian Subprovince. The proper association of Georges Bank is less clear; some investigators consider it part of the Acadian and others part of the Virginian. Disparate perspectives emerge from the analysis of different groups of organisms. Further, while some studies suggest a distinction between the Southern New England shelf and the rest of the Mid-Atlantic Bight, others describe the region as a broad transition zone with no unique characteristics of its own. We suggest there exists sufficient evidence to consider the Scotian Shelf, Gulf of Maine, Georges Bank, Southern New England, and Southern Mid-Atlantic Bight as distinct biogeographic regions from a conservation planning perspective, and present a set of proposed mapped boundaries. (PDF contains 23 pages.)

Identification and characterization of a new class of human immunodeficiency virus type 1 recombinants comprised of two circulating recombinant forms, CRF07_BC and CRF08_BC, in China

We identified a new class of human immunodeficiency virus type 1 (HIV-1) recombinants (00CN-HH069 and 00CN-HH086) in which further recombination occurred between two established circulating recombinant forms (CRFs). These two isolates were found among 57 HIV-1 samples from a cohort of injecting drug users in eastern Yunnan Province of China. Informative-site analysis in conjunction with bootscanning plots and exploratory tree analysis revealed that these two strains were closely related mosaics comprised of CRF07_BC and CRF08_BC, which are found in China. The genotype screening based on gag-reverse transcriptase sequences if 57 samples from eastern Yunnan identified 47 CRF08_BC specimens (82.5%), 5 CRF07_BC specimens (8.8%), and 3 additional specimens with the novel recombinant structure. These new "second-generation" recombinants thus constitute a substantial proportion (5 of 57; 8.8%) of HIV-1 strains in this population and may belong to a new but yet-undefined class of CRF. This might be the first example of CRFs recombining with each other, leading to the evolution of second-generation inter-CRF recombinants.

辽东次生林土壤呼吸及主要组分分离与量化

土壤呼吸是森林生态系统碳循环的重要组成部分，对土壤呼吸的主要组分根系呼吸和土壤微生物呼吸进行分离并量化，对于了解土壤碳释放规律、估算生态系统土壤碳的年际通量以及预测气候变化条件下根系或土壤微生物对土壤碳释放格局的影响具有重要意义。本文采用挖壕法测定辽东山区蒙古栎林、杂木林和胡桃楸林的土壤表面CO2通量，并同步分析土壤水热因子及土壤有机质、N含量、根系生物量、土壤酶活性、土壤微生物生物量等。研究结果表明：（1）辽东山区次生林0-10cm土壤有机质含量为9.29-18.15%，全氮含量为0.43-0.90%，pH值为5.67-6.19；次生林生长季细根生物量平均为152.61- 447.79 g/m2，粗根生物量平均为255.42-507.42 g/m2，根系总量平均为540.93-955.22 g/m2；土壤酶活性季节变化明显，且具垂直分布特征，蒙古栎林的土壤转化酶、淀粉酶和脱氢酶活性最高，胡桃楸林最低，胡桃楸林过氧化氢酶活性相对最大；土壤微生物量碳、氮的季节变化呈明显的单峰曲线并与土壤温度相关，土壤微生物量碳氮之间具显著相关性（P<0.05）。（2）次生林土壤总呼吸、根呼吸和土壤微生物呼吸具明显的日、季变化规律，生长季根呼吸贡献相对较低，胡桃楸林根呼吸贡献率为34.0-34.8%，蒙古栎林为17.9-28.4%，杂木林为14.7-35.3%；土壤微生物呼吸贡献率为66.0-85.3%，高于根呼吸贡献率，说明辽东山区次生林土壤微生物呼吸决定土壤总呼吸的变化趋势。（3）土壤呼吸与地下5cm土壤温度呈指数函数关系，土壤总呼吸的Q10值为1.29-2.30，微生物呼吸的Q10值为1.28-2.09，根呼吸的Q10值为1.29-3.72；土壤总呼吸、微生物呼吸、根呼吸与土壤含水量均无明显相关关系；蒙古栎林根呼吸与细根生物量显著相关，杂木林根呼吸与粗根生物量及根系总生物量显著相关，胡桃楸林根呼吸与根系生物量总量显著相关（P<0.05）；微生物呼吸与淀粉酶、转化酶、脱氢酶、过氧化氢酶均无显著相关性（除胡桃楸林与过氧化氢酶显著相关）；微生物呼吸与土壤微生物量碳、氮均呈显著线性相关关系（P<0.05）。（4）蒙古栎林土壤总呼吸、根呼吸、土壤微生物呼吸年际碳释放量分别为572.78、147.78和425.59 g C m-2a-1，杂木林分别为403.12、108.92、297.51 g C m-2a-1，胡桃楸林分别为519.47、173.75、345.72 g C m-2a-1；生长季和非生长季通过根呼吸释放的碳量均小于分解土壤有机质的微生物呼吸释放的碳量，非生长季次生林土壤碳释放量为39.21-152.04 g C m-2a-1，占全年呼吸总量的10-29%，说明冬季土壤碳释放量不能忽略。

辽东山区次生林林窗环境因子动态

林窗是森林生态系统中的一种特殊结构，影响着整个森林生态系统的结构、物种组成、演替及生态系统功能。我国现有森林资源以次生林为主体，而林窗是森林演替的重要环节，因此通过次生林林窗特征及其内部环境因子动态研究，能够明确林窗在次生林演替中的重要作用。本论文以辽东山区次生林为对象，选取人工砍伐形成的三个不同大小的林窗，林窗按照面积大小分三个梯度来选取，从大到小分别为大林窗,中林窗和小林窗。通过野外调查、观测，较系统的研究了三个不同大小林窗的环境因子变化以及植物多样性与环境因子的相关关系。旨在明确林窗内各环境要素的变化规律及不同大小林窗间的差异，为东北山区的次生林管理经营与管理提供参考。 对林窗内环境因子（光量子通量密度、温度、空气湿度和土壤水分）、土壤氮素有效性以及植物多样性分析结果表明：（1）光量子通量密度日变化趋势均为单峰型，到达峰值的时间均在中午以前，且峰值出现的位置均在林窗中心偏北部。光量子通量密度在生长季开始时强度较大，而在生长旺季强度偏小；面积较大的林窗中心光量子通量密度没有显著差异，但林窗边缘与林内差异显著（P<0.05）。（2）空气温度日变化趋势为单峰型，非生长季面积小的林窗其温度高于面积大的林窗，生长季则面积大的林窗温度较高；林窗内南部的湿度高于林窗北部，而温度则为林窗北部高于林窗南部。（3）土壤水分在两个深度层次间无显著差异，但在雨季的土壤含水量明显高于其它月份；林窗内部不同位置，面积较大的林窗内部各点差异不显著，但面积小的林窗其中心与林窗内部各点差异显著（p<0.05）；土壤温度日变化与气温的变化一致，但其变幅较小，这可能与土壤和大气间的热量传递有关。（4）林窗内土壤硝态氮含量存在着明显的季节性，林内与林窗中心及林窗边缘差异显著，且面积较大的林窗硝态氮含量高于面积较小的林窗；面积较小林窗的氨态氮含量较高。矿化速率变化与硝态氮的变化一致。（5）各林窗内植物多样性在中林窗和小林窗边缘范围内都存在着物种多样性增加的趋势，而大林窗并未表现明显的物种多样性增加的趋势；环境因子与物种多样性指数在各林窗中均无显著的相关性。

辽东山区次生林生态系统主要林型土壤磷素特征

磷是植物生长发育所必需的营养元素之一，由于磷在土壤中的难溶性和难移动性，使得磷在陆地生态系统的循环越来越受到重视，尤其是在明确土壤磷素存在形态和分布特征的基础上，探讨土壤磷素与土地利用方式以及植被生长发育状况之间的关系，对于指导土地利用和恢复植被建设具有重要意义。本研究以辽东山区天然次生林主要林型胡桃楸林、杂木林（由蒙古栎、花曲柳和山杨等树种组成）和蒙古栎林为主要研究对象，系统研究了辽东山区天然次生林土壤磷素的分布特征，并比较研究了落叶松人工林取代天然次生林后土壤磷素的变化特征。主要结论如下： 1. 辽东山区天然次生林土壤磷素特征：（1）次生林0-30 cm土壤全磷含量的变化范围为326.5 mg kg-1-984.9 mg kg-1，土壤总有机磷含量、总无机磷含量、Olsen-P含量和土壤微生物量磷含量占全磷含量的比例变化范围分别为47%-76%、24%-53%、1.23%-1.40%和2.67%-3.45%，土壤全磷与土壤有机碳、全氮之间呈显著正相关，说明次生林土壤有机质含量是影响土壤磷素含量的主要因素之一；土壤Olsen-P和微生物量磷季节变化明显，均表现为夏季最高，且土壤Olsen-P和微生物量磷的季节变化规律不受植被类型的影响；另外，土壤Olsen-P、土壤微生物量磷的季节变化均与土壤含水量相关。（2）三个林型土壤酸性磷酸酶与土壤有机碳、全氮、全磷、Olsen-P和微生物量磷之间存在密切的相关性，酸性磷酸酶可以作为评价次生林土壤磷素状况的一个指标。（3）不同林型土壤各形态无机磷分布不同，胡桃楸林以Fe-P（铁结合的磷酸盐）和Ca-P（钙结合的磷酸盐）为主，杂木林和蒙古栎林以O-P（闭蓄态磷）为主；不同林型土壤各形态无机磷随季节的变化规律不同，与Olsen-P的关系也不同，胡桃楸林土壤Olsen-P与Al-P（铝结合的磷酸盐）之间具有显著的相关性，杂木林土壤Olsen-P与Fe-P和Ca-P之间相关性显著，蒙古栎林土壤Olsen-P与Ca-P之间显著相关，说明辽东山区不同林型土壤磷素的有效来源不同。（4）辽东山区有机磷各形态的分布特征为：中等活性有机磷 > 中等稳定性有机磷 > 高稳定性有机磷 > 活性有机磷；土壤活性有机磷的季节变化与Olsen-P变化一致，中等活性有机磷、中等稳定性有机磷和高等稳定性有机磷的含量随季节变化无此规律；胡桃楸林、蒙古栎林土壤Olsen-P与活性有机磷、中等稳定性有机磷和高等稳定性有机磷之间显著相关，杂木林土壤Olsen-P与活性有机磷、中等活性有机磷、中等稳定性有机磷和高等稳定性有机磷之间相关性显著，说明在本研究区土壤有机磷对磷素有效性的贡献较大。（5）三个林型内主要树种叶片磷含量均较高，且叶片N/P < 10，土壤磷素不是辽东山区次生林植被生长的限制性养分因子。 2. 落叶松人工林取代天然次生林后土壤磷素特征的变化：（1）和天然次生林相比，落叶松人工林土壤全磷、总有机磷、Olsen-P、土壤微生物量磷和磷酸酶活性均显著降低（P<0.05），土壤总无机磷含量无明显变化，这说明次生林转变为落叶松人工林后土壤磷素状况下降。（2）随着次生林转变为落叶松人工林和落叶松人工林连栽后，土壤无机磷各形态含量变化显著，土壤Fe-P和Ca-P含量逐渐降低，O-P含量升高，土壤Olsen-P与无机磷形态中的Fe-P和Ca-P之间显著正相关，表明了Fe-P和Ca-P是Olsen-P的主要无机磷来源。（3）落叶松人工林取代次生林后，土壤活性有机磷、中等活性有机磷、中等稳定性有机磷和高等稳定性有机磷含量均降低，土壤Olsen-P与活性有机磷显著正相关，活性有机磷是补充Olsen-P的直接有机磷源；土壤微生物量磷与各有机磷组分及 Olsen-P含量之间均呈显著正相关，这说明微生物量磷在有机磷转化中起着重要作用。

辽东山区与长白山植物物种多样性比较研究

辽东山区（龙岗山）为长白山余脉，原始林受干扰后形成的次生林是该区森林资源主体，长白山是以原始林为主。通过对两地区植物物种组成、林分结构、物种多样性等方面的比较，可以了解受干扰后处于不同演替阶段的森林物种多样性变化。同时，在一定程度上可以说明人类活动对植物物种多样性的影响。本研究通过地面样地调查的方法，分析长白山地区原始林、次生林和辽东山区次生林植物物种多样性差异，并引入干扰度的概念探讨形成这种差异的原因。通过遥感解译的方法分析两地乔木树种多样性空间分布格局的差异及其沿海拔梯度的变化情况。以期为次生林的恢复、经营，及长白植物区的植物保护提供参考。 主要结论：通过地面调查、比较可知1）Shannon-Wiener指数是物种丰富度和均匀度的综合反映，总体Shannon-Wiener多样性指数原始林大于次生林；乔木层和灌木层多样性：辽东山区（次生林）要大于长白山地区（原始林和次生林，下同），而草本层小于长白山地区。2）不同森林类型之间的比较结果表明：次生林的形成在一定程度上增加了物种丰富度，但受到物种散布方式等因素的影响，物种分布的均匀性较差。 引入干扰度的概念，分析干扰强度对两地物种多样性的影响，可知1）干扰对长白山次生林各层均有影响，且各层变化不一致；对辽东山区次生林的影响，基本表现为受中等水平干扰的林分具有较高的物种多样性和均匀度。2）人为干扰是十分复杂的，且各林型本身具有各自独特的特点，这就决定了干扰强度对不同林型的影响不同，且对同一林型不同层次的影响也不相同。随着干扰强度的增加，如长白山桦木林的总体物种多样性增加，乔木层先增加后降低，灌木层与乔木层相反，草本层变化较小；长白山杂木林的总体多样性、乔木层多样性、灌木层多样性均先增加后降低，草本层变化较小；针阔混交林总体、乔木层、草本层多样性各指数表现不一致，灌木层先增加后降低。 通过遥感影像的解译，分析长白山地区和辽东山区乔木树种多样性空间分布格局，结果表明1）两地乔木树种多样性指数多处于1.4-2.0之间，较高和较低多样性指数所占的比重较小；辽东山区乔木层树种多样性高于长白山地区，这与地面调查的结果相一致。2）长白山地区和辽东山区乔木树种多样性的海拔梯度变化不一致：随着海拔梯度的上升，辽东山区乔木层多样性下降；长白山地区乔木层多样性大致表现为先增加后减少，即单峰分布格局。

东南沿海火山碎屑岩40Ar/39Ar年代学研究

The Mesozoic pyroclastic rocks cover a vast coastal area in southeastern China, which is an important part of volcanic belt around Pacific Ocean. However, the previous dates for these rocks are confused and conflicted with each other, which have limited the further researches. It is difficult to date pyroclastic rocks, for almost all the dating methods, due to the multiple sources during their formation. Single crystal laser probe 40Ar/39Ar method is a powerful means to date pyroclastic rocks with complex sources. By distinguishing the xenocrysts and altered materials, Singe crystal total fusions of CO2 lasing on the sanidine separates could yield rational 40Ar/39Ar results and distinguish their sources. Timing on formations of the Moshishan Group, after avoiding the exotic and altered grains by lasing on the single sanidine separate, was reported in this study. 40Ar/39Ar incremental heating results of Cement part of the pyroclastic rocks show that the age spectrums are too complex to interpret for geological significance because of the alteration and 39Ar recoil. Incremental heating on K-feldspar separate from pyroclastic rocks give reliable data. Combining 40Ar/39Ar incremental heating ages and laser total fusion ages, we suggest the age was 125Ma-120Ma for Dashuang Fm, 120-119 Ma for Gaowu Fm, 119-114Ma for Xishantou Fm, 114-112Ma for Chawan Fm and 112-110Ma for Jiuliping Fm. The most intense period of volcanic activity in eastern Zhejiang Province was at about 120Ma. These new ages are much younger than the previous ones, suggesting that these thick volcanic formations had been formed in very short durations.

中国特有针叶树种对气候变化的敏感性研究

About 214 trees in 9 sampling sites, representing 5 endemic conifer species, were collected from the western Sichuan Province and eastern Qinghai Province, China. In this study, structure we try to investigate tree-ring sensitivity to climate in order to obtain primary information of reconstructing past climate from the trees in this region. All the 5 species present distinct ring boundaries ^ few ABS(absent rings) and available for cross-dating,which are all past the test by program COFECHA. Statistics for all the 8 tree-ring width residual chronologies present significant inter-correlation between series and high values of mean sensitivity. As well as the maximum latewood density of Picea crassifolia Kom and Pinus densata Mast. These results indicate usefulness of these chronologies for dendrochronological studies. Pearson correlation analyses were applied to provide a basic estimate of the causal relationships between tree-ring width and climate factors. We found some significant relationships between tree-ring width> maximum density and temperature as well as precipitation. Especially, there is high correlation between the maximum density of the Picea crassifolia Kom and the index of moisture, the ratio of precipitation and temperature, which can indicate well the climate; however the higher correlation can be see between the maximum density of Pinus densata Mast and the total temperature from June to September. Regardless of tree species, chronologies in our study region presented accordant variations of which may reveal strong common climate signal. Thus these chronologies are shown to be dependable for building tree-ring network in the nearly future. However, there are limitations in this study, only monthly mean of temperature and precipitation were available. Also, for this typical subtropical mountain system, meteorological stations are usually located in valley and biased to represent moisture conditions on the slopes. Thus the estimation of precipitation both in temporal and spatial domain was rather restricted. Further study, such as wood anatomy, physiology and densitometry, are needed for better understanding the environmental and climatic history in this area.

Optimising sorting and washing of home-grown maize to reduce fumonisin contamination under laboratory-controlled conditions

Subsistence farming communities with low socio-economic status reliant on a mono cereal maize diet are exposed to fumonisin levels that exceed the provisional maximum tolerable daily intake of 2 mu g kg(-1) body weight day(-1) recommended by the Joint FAO/WHO Expert Committee on Food Additives. In the rural Centane magisterial district, Eastern Cape Province, South Africa, it is customary during food preparation to sort visibly infected maize kernels from good maize kernels and to wash the good kernels prior to cooking. However, this customary practice seems not to sufficiently reduce the fumonisin levels. This is the first study to optimise the reduction of fumonisin mycotoxins in home-grown maize based on customary methods of a rural population, under laboratory-controlled conditions. Maize obtained from subsistence farmers was analysed for the major naturally occurring fumonisins (FB1, FB2 and FB3) by fluorescence HPLC. Large variations were observed in the unsorted and the experimental maize batches attributable to the non-homogeneous distribution of fumonisin contamination in maize kernels. Optimised hand-sorting of maize kernels by removing the visibly infected/damaged kernels (fumonisins, 53.7 +/- 15.0 mg kg(-1), 2.5% by weight) reduced the mean fumonisins from 2.32 +/- 1.16 mg kg(-1) to 0.68 +/- 0.42 mg kg(-1). Hand washing of the sorted good maize kernels for a period of 10 min at 25 degrees C resulted in optimal reduction with no additional improvement for wash periods up to 15 h. The laboratory optimised sorting reduced the fumonisins by 71 +/- 18% and an additional 13 +/- 12% with the 10 min wash. Based on these results and on local practices and practicalities the protocol that would be recommended to subsistence farmers consists of the removal of the infected/damaged kernels from the maize followed by a 10 min ambient temperature water wash. (C) 2010 Elsevier Ltd. All rights reserved.