Transformation of Carbon and Nitrogen by Earthworms in the Decomposition Processes of Broad-leaved Litters

Earthworms are the important constituents in the decayed food web and the main ecological conditioners in the process of decomposition and nutrient mineralization. The transformation of organic carbon (C) and total nitrogen (N) in the broad-leaved litters ingested by earthworms was researched by means of a laboratory experiment. Experimental samples were collected from broad-leaved Korea Pine mixed forest in Liangshui National Natural Reserve (47°10′50″N, 128°53′20″E) in the northeastern Xiao Hinggan Mountains of Northeast China. The contents of organic C and total N in earthworms, leaf litters and earthworm faeces were analyzed. Results show that the organic C content was in the fol- lowing order: leaf litters>faeces>earthworms, while total N content was contrary to that of the organic C. The organic C contents in the different leaf litters were in the following order: Tilia amurensis>Betula costata>Acer mono, whereas the total N contents in the different leaf litters were: Betula costata>Tilia amurensis>Acer mono. The contents of organic C and total N in the faeces from the different leaf litters were almost consistent with the contents of the leaf litters. After the leaf litters were ingested by earthworms, the organic C, which was transformed to increase earthworms' weights, ac- counted for 3.90%-13.31% of the total ingestion by earthworms, while that in the earthworm faeces accounted for 6.14%-13.70%. The transformed organic C through the other metabolism (e.g., respiration) of earthworms accounted for 75.04%-89.92%. The ingested organic C by earthworms was mostly used for metabolic activities. The N ingested by earthworms was less than organic C. It is estimated that 37.08% of total N was transformed to increase the earthworm's weight, 19.97% into earthworm faeces and 47.86% for the consumption of the earthworm's activities. The earthworms not only increased the content of organic C and total N in the soil, but also decreased the values of C/N in the soil and leaf litters. Earthworms play a major role in the leaf litters' decomposition and transformation.     

西北太平洋九州-帕劳海脊北部KPR12岩芯40万年来有机碳来源、埋藏特征及其环境响应

西北太平洋海陆相互作用强烈,受黑潮和亚洲大陆风尘输入影响显著,是研究海洋沉积物中有机碳埋藏与陆源输入、海洋初级生产力和海洋环境演化关系的理想靶区。本研究基于采自九州-帕劳海脊北部的重力活塞647 cm长的KPR12岩芯,分析了总有机碳（TOC）、总氮（TN）、有机碳稳定碳同位素组成（δ¹³C_TOC）、蛋白石（Opal）以及粒度等指标,初步探讨了近40万年来轨道尺度沉积有机碳的来源、埋藏特征及其影响机制。岩芯的TOC含量平均值为0.214%,呈冰期较高、间冰期较低的旋回特征。岩芯沉积物粒度的不同端元反映了研究区风尘输入大致呈冰期较高的趋势。岩芯的δ¹³C_TOC（-25.24‰~-21.04‰,平均值为-22.59‰）显示有机质以海源为主（约62%）,海源有机碳含量趋势与TOC的变化一致。研究区不同时期陆源物质的输入受风尘输送和黑潮的综合控制,黑潮增强可能对该区间冰期陆源有机碳贡献的升高有一定影响。岩芯中TOC与Opal含量的相关性分析表明,海洋初级生产力可能不是控制该岩芯有机碳含量变化的主要原因。冰期-间冰期旋回中的深层水通风条件、黑潮和北太平洋中层水的发育以及陆源细颗粒物质输入可能共同影响着本区沉积有机碳的降解与埋藏保存。

     

烟台市牟平区尺坎金矿床地质特征

尺坎金矿床地处胶东东部著名的牟平-乳山金成矿带中,区内金矿主要受区域性牟平-海阳断裂上盘的NNE向断裂控制,沿走向、倾向均具膨胀狭缩现象,中生代燕山早期的岩浆侵入活动为成矿提供了热源,古元古代荆山群变质岩系是金矿的原始矿源层。矿床成因为中温热液充填交代型。     

Recycling of crustal materials and implications for lithospheric thinning:Evidence from Mesozoic volcanic rocks in the Hailar–Tamtsag Basin,NE China

Late Mesozoic Nb-rich basaltic andesites and high-Mg adakitic volcanic rocks from the Hailar-Tamtsag Basin,northeast China,provide important insights into the recycling processes of crustal materials and their role in late Mesozoic lithospheric thinning.The Late Jurassic Nb-rich basaltic andesites(154 ± 4 Ma) are enriched in large-ion lithophile and light rare earth elements,slightly depleted in high-field-strength elements,and have high TiO_2,P_2 O_5,and Nb contents,and(Nb/Th)PM and Nb/U ratios,which together with the relatively depleted Sr-Nd-Hf isotopic compositions indicate a derivation from a mantle wedge metasomatized by hydrous melts from subducted oceanic crust.The Early Cretaceous high-Mg adakitic volcanic rocks(129-117 Ma) are characterized by low Y and heavy rare earth element contents,and high Sr contents and Sr/Y ratios,similar to those of rocks derived from partial melting of an eclogitic source.They also have high Rb/Sr, K_2 O/Na_2 O,and Mg#values,and high MgO, Cr, and Ni contents.These geochemical features sugge st that the adakitic lavas were derived from partial melting of delaminated lower continental crust,followed by interaction of the resulting melts with mantle material during their ascent Our data,along with available geological,paleomagnetic,and geophysical evidence,lead us to propose that recycling of Paleo-Pacific oceanic crustal materials into the upper mantle due to flat-slab subduction and rollback of the Paleo-Pacific Plate during the late Mesozoic likely provided the precondition for lithospheric thinning in northeast China,with consequent lithospheric delamination causing recycling of continental crustal materials and further lithospheric thinning.     

鲁寺村地下水位抬升灾害成因分析

通过对鲁寺村受灾区水文地质条件、抽水试验、水质、环境及工程地质条件的分析,确定了地下水位抬升灾害产生的原因。沿河小煤窑的无序开采是这种地质灾害产生的根源,而地质及环境因素是灾害产生的必要条件。分析成果为灾害治理工程提供了理论依据,同时也在治理工程过程中得到了验证。     

潜源划分进展及我国海域和邻近海域区划潜源划分问题研究

对于陆域地区,我国已进行5次全国范围大面积地震区划研究工作,获得了丰富研究成果。但对于海域地区地震区划的研究较薄弱,较少涉及海域潜源划分模型。随着经济发展,涉及海域地区的经济活动日益频繁,对海域地区潜源划分研究及进一步地震区划研究工作的需求越来越强烈。为此,详细介绍代表性国家在潜源划分方面采取的原则和方法,总结我国海域地区地震地质背景及相应的研究现状,并在此基础上提出我国海域地区潜源划分可考虑的原则和基本思路,为后续我国海域地区区划研究提供方案。     

Piecewise prediction model for watershed‐scale erosion and sediment yield of individual rainfall events on the Loess Plateau,China

Establishing a universal watershed‐scale erosion and sediment yield prediction model represents a frontier field in erosion and soil/water conservation. The research presented here was conducted on the Chabagou watershed, which is located in the first sub‐region of the hill‐gully area of the Loess Plateau, China. A back‐propagation artificial neural model for watershed‐scale erosion and sediment yield was established, with the accuracy of the model, then compared with that of multiple linear regression. The sensitivity degree of various factors to erosion and sediment yield was quantitatively analysed using the default factor test. On the basis of the sensitive factors and the fractal information dimension, the piecewise prediction model for erosion and sediment yield of individual rainfall events was established and further verified. The results revealed the back‐propagation artificial neural network model to perform better than the multiple linear regression model in terms of predicting the erosion modulus, with the former able to effectively characterize dynamic changes in sediment yield under comprehensive factor conditions. The sensitivity of runoff erosion power and runoff depth to the erosion and sediment yield associated with individual rainfall events was found to be related to the complexity of surface topography. The characteristics of such a hydrological response are thus closely related to topography. When the fractal information dimension is greater than the topographic threshold, the accuracy of prediction using runoff erosion power is higher than that of using runoff depth. In contrast, when the fractal information dimension is smaller than the topographic threshold, the accuracy of prediction using runoff depth is higher than that of using runoff erosion power. The developed piecewise prediction model for watershed‐scale erosion and sediment yield of individual rainfall events, which introduces runoff erosion power and runoff depth using the fractal information dimension as a boundary, can be considered feasible and reliable and has a high prediction accuracy. Copyright © 2013 John Wiley & Sons, Ltd.     

Submarine groundwater discharge revealed by aerial thermal infrared imagery: a case study on Jeju Island,Korea

Submarine groundwater discharge (SGD) is a global phenomenon that carries large volumes of groundwater and dissolved chemical species such as nutrient, metals, and organic compounds to coastal zones. We report the influence of SGD on the coastal waters of Jeju Island, Korea, using high‐resolution aerial thermal infrared (TIR) mapping techniques and field investigations. An aircraft‐based system was implemented using a cost‐effective TIR camera for aerial TIR mapping. Ground‐based calibrations and system integration with GPS/IMU (global positioning system/inertial measurement unit) were performed for the aerial systems. The aerial surveys showed distinct low‐temperature signatures of SGD along the coasts of Jeju Island, revealing large groundwater inputs from the coastal aquifers to the ocean. Multiple aerial surveys over a range of seasons and tidal stages revealed that SGD rates dynamically affect the sea surface temperature (SST) of the coastal zone. The in‐situ measurements supported that SGD has a substantial influence on the coastal water chemistry as well as SST. Our observations highlight the extent to which aerial‐based TIR mapping can serve as a powerful tool for studying SGD and other coastal processes. Copyright © 2016 John Wiley & Sons, Ltd.