Sources and transformations of nitrogen in the South China Sea: insights from nitrogen isotopes

To elucidate the sources and transformations of nitrogen in the South China Sea (SCS), the nitrogen isotopic composition of nitrate (\({\updelta }^{ 1 5} {\text{N}}_{{{\text{NO}}_{ 3} }}\)) was measured in seawater samples from the water column of this marginal sea and the adjacent western North Pacific Ocean (WNP). Comparison of the isotopic signatures from these two locations suggests that the main source of nitrogen into the SCS was nitrate that entered from the WNP through the Luzon Strait. Values of \({\updelta }^{ 1 5} {\text{N}}_{{{\text{NO}}_{ 3} }}\) were generally lower in the SCS than in the WNP, and the \({\updelta }^{ 1 5} {\text{N}}_{{{\text{NO}}_{ 3} }}\) maximum observed in the SCS intermediate water was lower than the corresponding WNP maximum. This pattern is attributed to mixing within the SCS in combination with the outflow of SCS intermediate water to the WNP. A mass balance model indicates that atmospherically derived N (a combined input of new nitrogen from marine N₂ fixation and atmospheric deposition) supplied approximately 6% of the particulate nitrogen exported from the euphotic zone to the deep SCS. This supply of isotopically light nitrogen cannot, however, explain the low and downward-decreasing δ¹⁵N that has been previously observed in sinking particles of the deep SCS. We propose that an alternative explanation might be a downward-increasing ratio of isotopically light NH₄ ⁺-N to organic N due to the degradation of organic N within the sinking particles (i.e., relative enrichment of the NH₄ ⁺) and also particle incorporation of excreted ammonium from zooplankton.     

花鲈三种甲状腺激素受体(TRs)基因克隆及表达分析

甲状腺激素受体(TR)介导甲状腺激素发挥生理作用,调控机体生长、发育及代谢。本文采用RACE技术克隆花鲈(Lateolabrax maculatus)甲状腺激素受体TRαA、TRαB和TRβ的cDNA全长序列,并进行表达分析。结果表明,花鲈TRαAcDNA全长序列1851bp,编码416个氨基酸;TRαBcDNA全长序列2370bp,编码409个氨基酸;TRβcDNA全长序列3343bp,编码395个氨基酸。与TRαB和TRβ相比,各组织中TRαA表达量明显较低。TRαA主要在肝脏、脑、心脏中表达。TRαB在垂体中表达量最高,其次是脑、肾脏、心脏、肝脏等。TRβ在脑中表达量最高,垂体表达量次之。TRαB和TRβ在垂体和脑中普遍表达较高。花鲈TRαB与TRβ可能共同参与TH对TSH的负反馈调控过程。TRαB可能在TH对心脏的调控作用中发挥重要作用。     

北京市城近郊区工程排水对地质环境和建筑物影响分析

近些年来, 北京市城近郊区工程排水工程日益增多, 工程排水会产生以下不良后果： （１） 浪费水资源; （２） 导致地面沉降和对周围的高大建筑物稳定性产生影响; （３） 使周围地区地下水水位局部下降,形成小范围的水位降落漏斗, 导致地下水水质下降。因此, 有必要进行这方面的调查和研究工作     

新疆博斯腾湖水体颗粒和溶解有机碳的季节变化及其来源初探

在博斯腾湖选取了13个点位,于2012年5、8、10月测定表层和底层水体中的颗粒有机碳、溶解有机碳、颗粒有机氮和叶绿素a含量.结果显示颗粒和溶解有机碳在表层水体中的浓度与底层相近.博斯腾湖水体中颗粒有机碳的季节变化十分明显,其平均浓度从春季(0.64 mg/L)到夏季(0.71 mg/L)变化不大,但在秋季变化十分显著(浓度达1.58 mg/L).其中西北湖区和湖心区颗粒有机碳的季节变化最明显,东部湖区颗粒有机碳的季节变化相对较小.博斯腾湖水体的颗粒有机碳在春、秋两季主要来自外源输入,在夏季受水体中浮游生物的影响较大.博斯腾湖水体中溶解有机碳也具有一定的季节变化,夏季浓度(平均为9.3 mg/L)略低于春、秋两季(平均为10.3 mg/L).溶解有机碳在河口区的季节变化最强,其夏季浓度明显偏低,主要是由于开都河河水的稀释作用.总体上,博斯腾湖水体中溶解有机碳浓度的变化主要受外部因素的影响.     

热带水库敞水区轮虫种类组成与数量结构—基于海南7座典型水库的分析

海南省是我国典型的热带区域,目前对该地区浮游动物的研究和报道极少.为了解该地区轮虫的群落组成,于2006年12月和2007年5月对分布于海南省7座典型的水库敞水区进行了采样调查.共采集到轮虫32种,多为营浮游性生活的广温性和嗜温性种类.在不同时期,水库具体优势种类及其相对优势度有一定差别,主要优势种个体较小且有被甲.在丰水期,剪形臂尾轮虫和镰状臂尾轮虫为主要优势种,在枯水期则以柬隐三肢轮虫为主要优势种.海南省7座水库的平均丰度和生物量分别为66.8ind./L和21.6μg/L,均远低于亚热带和温带地区.总体上,海南省水库敞水区轮虫呈现出种类少、个体小、丰度低的特点.尽管两次采样期间的轮虫优势种的相对丰度存在一定变化,但轮虫的种类组成结构相对一致,反映出该地区水库轮虫的群落结构具有较高稳定性.     

Relative model score: a scoring rule for evaluating ensemble simulations with application to microbial soil respiration modeling

This paper defines a new scoring rule, namely relative model score (RMS), for evaluating ensemble simulations of environmental models. RMS implicitly incorporates the measures of ensemble mean accuracy, prediction interval precision, and prediction interval reliability for evaluating the overall model predictive performance. RMS is numerically evaluated from the probability density functions of ensemble simulations given by individual models or several models via model averaging. We demonstrate the advantages of using RMS through an example of soil respiration modeling. The example considers two alternative models with different fidelity, and for each model Bayesian inverse modeling is conducted using two different likelihood functions. This gives four single-model ensembles of model simulations. For each likelihood function, Bayesian model averaging is applied to the ensemble simulations of the two models, resulting in two multi-model prediction ensembles. Predictive performance for these ensembles is evaluated using various scoring rules. Results show that RMS outperforms the commonly used scoring rules of log-score, pseudo Bayes factor based on Bayesian model evidence (BME), and continuous ranked probability score (CRPS). RMS avoids the problem of rounding error specific to log-score. Being applicable to any likelihood functions, RMS has broader applicability than BME that is only applicable to the same likelihood function of multiple models. By directly considering the relative score of candidate models at each cross-validation datum, RMS results in more plausible model ranking than CRPS. Therefore, RMS is considered as a robust scoring rule for evaluating predictive performance of single-model and multi-model prediction ensembles.     

地震数据处理系统Earthworm在福建地震预警系统项目中的应用

本文介绍了USGS（美国地质勘探局）开发的Earthworm系统在福建地震预警系统项目中的应用。该系统为开源软件,由C语言编写,由不同模块组建而成,每个模块实现不同的功能,主要包括数据接收模块、P波拾取模块、地震定位报告产出模块、地震事件图件绘制模块、地震波存储容器等。同时,用户可以根据自己的需求编写相应的功能模块。文章对该系统的应用进行了介绍,内容包括Earthworm系统的组织架构、业务流程、软件模块的主要功能搭建与配置及软件模块之间的逻辑关系等,目的在于介绍该系统的架构方法与使用心得,促进该系统在地震行业内得到应用与推广。     

沉积物-水界面污染物迁移扩散的研究进展

污染物在沉积物-水界面的迁移扩散对研究其环境生物地球化学循环过程和评估水生态系统质量具有重要意义.本文回顾了关于沉积物-水界面的基本研究历程,重点介绍沉积物-水界面的垂向结构以及扩散边界层（DBL）的作用,展示污染物在沉积物-水界面的多维度分布（一维垂向、二维平面和三维立体）及其在沉积物-水界面的扩散过程,详细总结影响污染物在沉积物-水界面迁移扩散的环境因素（包括温度、溶解氧或氧化还原条件、pH值、离子强度或盐度、沉积物组成、共存污染物、溶解性有机质、水动力条件、生物扰动、微生物以及其他因素）,讨论当前关于沉积物-水界面污染物扩散通量估算几种方法的优缺点,最后,对沉积物-水界面污染物扩散研究在未来发展需要关注的几个方面进行了展望.