辽河三角洲湿地表层沉积物的风化特征及其对生物作用的指示意义

摘要

通过对辽河三角洲273个上三角洲平原湿地表层沉积物及100个浅海湿地表层沉积物的粒度和常量元素的系统测试, 且对其中的128个表层沉积物样进行了球囊霉素蛋白 (GRSP) 的提取与分析, 揭示了研究区GRSP、粒度、常量元素分布和风化特征及其控制机制, 研究表明:上三角洲平原湿地表层沉积物以砂质粉砂和粉砂为主, 而浅海湿地表层沉积物由于受潮汐及波浪的淘洗作用影响, 颗粒较粗以粉砂质砂和砂质粉砂为主;研究区常量元素以Si O2和Al2O3含量最高, 其它元素平均含量均小于5％, 且除了Ca O外, 其它常量元素与沉积物粒度呈显著相关 (p<0.01) ;值得注意的是, 本研究发现有植被覆盖的上三角洲平原湿地地区的风化指数 (CIA=58.50) 显著地高于浅海湿地沉积物的风化指数 (CIA=50.17, p<0.05) 以及近基岩山区的风化指数 (CIA=52, p<0.05) , Na/K值与CIA指数分析表明该区从近基岩山区、浅海湿地至有植被覆盖的上三角洲平原湿地依次呈未受化学风化、初等化学风化和中等化学风化过渡特征, 且CIA值与GRSP含量呈显著相关 (r=0.47, p<0.01) , 由此揭示了生物作用在地质体风化过程的重要意义.%Objectives: In order to reveal the relationship among the particle size, major elements, glomalin-related soil protein ( GRSP) distributions, and to explore weathering characteristics and the control mechanism in Liaohe river Delta.Methods: 373 surface sediments across the upper delta plain wetlands ( UDPW) and shallow-sea wetlands ( SSW) were collected from study area. The particle size were tested by Master sizer 2000 laser particle size analyzer, and major elements of surface sediments were tested by Axios PW4400 X-ray fluorescence spectrometer, GRSP analyses used Coomassie plus ( Bradford) assay method.Results: The averaged mean grain size ( Mz) of sediment in the SSW was 5.22 ± 0.14 Ф, significantly larger than that in the UDPW. Six types were identified for the SSW and river channel, less concentrated than UDPW, where presenting mainly sandy silt and silt, and indicating less sorting degree.The contents of SiO2 and Al2O3 were the highest in the study area, and the average contents of other elements were generally less than 5％. With the exception of CaO, other constant elements were significant correlated with sediment particle size ( p < 0. 01) ;Notably, the mean value of chemical index of alteration ( CIA = 58.50) of the vegetated UDPW were significantly higher than that of the SSW ( CIA = 50.17, p<0.05) and the flooding area, where is near bedrock mountains ( CIA= 52.00, p<0.05) .Moreover, the CIA values were significant correlated with GRSP content ( r = 0.47, p<0.01) .Conclusions: The surface sediments of the UDPW are mainly sand silt and silt, while, the surface sediments of the SSW are mainly silty sand and sandy silt due to the influence of tide and wave actions.The contents of CaO、Na2O and K2O in the UDPW were higher than SSW.There were the high correlations between chemical element and grain size.The Na/K ratio and CIA index analyses showed that the sediments in the LHD wetlands were experienced three weathering stages, namely, unweathering, primary and moderate weathering. Moreover, the correlations between CIA values and GRSP content revealed that the important significant role of biological processes in the mineral weathering, and presumably the AMF have made an significant contribution to the nutrient retains in this region.