乌江梯级水库碳氮耦合的生物地球化学循环

以乌江梯级水库及相关河段为研究对象, 对溶解CO₂和NO₃⁻ 含量的时空变化特征进行了研究. 溶解CO₂平均值为(113.6±105.7) μmol·L⁻¹, 变化为1.6934.6 μmol·L⁻¹; NO₃⁻ 平均值为(163.0±104.9) μmol·L⁻¹, 变化为0.4632.0 μmol·L⁻¹. 水库采样点溶解CO₂和 NO₃⁻ 的含量以及振幅均小于相应河流采样点. 由于来源及影响因素不同, 河流采样点CO₂和 NO₃⁻不存在显著性相关. 筑坝建库后, 水库浮游植物生物作用增强, 成为影响物质循环的重要因素. 光合作用和呼吸作用将C和N的生物地球化学循环耦合在一起, 致使水库CO₂和 NO₃⁻ 表现出显著性相关. 研究结果表明, 梯级水电开发显著改变了原始河流C和N的生物地球化学循环特征.     

The Southern Ocean biogeochemical divide

Modelling studies have demonstrated that the nutrient and carbon cycles in the Southern Ocean play a central role in setting the air-sea balance of CO(2) and global biological production. Box model studies first pointed out that an increase in nutrient utilization in the high latitudes results in a strong decrease in the atmospheric carbon dioxide partial pressure (pCO2). This early research led to two important ideas: high latitude regions are more important in determining atmospheric pCO2 than low latitudes, despite their much smaller area, and nutrient utilization and atmospheric pCO2 are tightly linked. Subsequent general circulation model simulations show that the Southern Ocean is the most important high latitude region in controlling pre-industrial atmospheric CO(2) because it serves as a lid to a larger volume of the deep ocean. Other studies point out the crucial role of the Southern Ocean in the uptake and storage of anthropogenic carbon dioxide and in controlling global biological production. Here we probe the system to determine whether certain regions of the Southern Ocean are more critical than others for air-sea CO(2) balance and the biological export production, by increasing surface nutrient drawdown in an ocean general circulation model. We demonstrate that atmospheric CO(2) and global biological export production are controlled by different regions of the Southern Ocean. The air-sea balance of carbon dioxide is controlled mainly by the biological pump and circulation in the Antarctic deep-water formation region, whereas global export production is controlled mainly by the biological pump and circulation in the Subantarctic intermediate and mode water formation region. The existence of this biogeochemical divide separating the Antarctic from the Subantarctic suggests that it may be possible for climate change or human intervention to modify one of these without greatly altering the other.     

Terminal Proterozoic reorganization of biogeochemical cycles

The Proterozoic aeon (2,500-540 million years ago) saw episodic increases in atmospheric oxygen content, the evolution of multicellular life and, at its close, an enormous radiation of animal diversity. These profound biological and environmental changes must have been linked, but the underlying mechanisms have been obscure. Here we show that hydrocarbons extracted from Proterozoic sediments in several locations worldwide are derived mainly from bacteria or other heterotrophs rather than from photosynthetic organisms. Biodegradation of algal products in sedimenting matter was therefore unusually complete, indicating that organic material was extensively reworked as it sank slowly through the water column. We propose that a significant proportion of this reworking will have been mediated by sulphate-reducing bacteria, forming sulphide. The production of sulphide and consumption of oxygen near the ocean surface will have inhibited transport of O2 to the deep ocean. We find that preservation of algal-lipid skeletons improves at the beginning of the Cambrian, reflecting the increase in transport by rapidly sinking faecal pellets. We suggest that this rapid removal of organic matter will have increased oxygenation of surface waters, leading to a descent of the O2-sulphide interface to the sea floor and to marked changes in the marine environment, ultimately contributing to the Cambrian radiation.     

红层泥岩击实作用下的破碎分布及破碎率指标的局限性

红层泥岩填料在西南地区的工程建设中使用较为广泛,其压实后颗粒的强度,渗透性与颗粒的破碎和实际分布情况息息相关。通过配置不同含水率,不同粗细比的泥岩试样,从红层泥岩击实后颗粒级配,破碎率等方面对颗粒破碎特征进行了对比研究。结果表明,含水率的增高以及粗颗粒含量的增多均会加剧岩土体的破碎效应。击实后试样的级配更加连续,且在含水率达到10%以后,水对颗粒级配的调节以及对粗颗粒破碎的影响较小。当P5初始值一定时,颗粒的破碎率随着含水率的增大而增大;当含水率一定时,破碎率与P5值呈正比例关系。破碎率在评价水作用影响下的破碎与实际较为符合,但用于评价其他因素对破碎的影响具有一定局限性。     

BTEX污染模拟含水层的生物地球化学作用

通过98 cm砂柱实验模拟BTEX污染含水层的过程,分析含水层中总有机碳、硫酸盐、铁、无机氮和可溶性碳酸盐含量的变化,揭示其厌氧生物地球化学作用.研究结果表明:以BTEX为电子供体,以环境中NO3-,Fe3+及SO42-为电子受体的微生物降解过程为主要作用,NO3-,Fe3+及SO42-电子受体的还原分别发生在距砂柱入水口70～89,55～70及34～55 cm处;有机氮矿化作用和CO2对碳酸盐的溶蚀作用发生在整个受污染区域;硫化亚铁沉淀生成主要发生在0～55 cm处,使该区域总铁量较55～70 cm处有所升高;可溶性碳酸盐含量变化由H+的溶解作用,0～70 cm处发生的碳酸亚铁沉淀生成及70～89 cm处CO2对碳酸盐的溶蚀作用共同决定;BTEX污染源附近污染晕中形成了高浓度有机碳的典型特征.     

Bioturbators enhance ecosystem function through complex biogeochemical interactions

Predicting the consequences of species loss is critically important, given present threats to biological diversity such as habitat destruction, overharvesting and climate change. Several empirical studies have reported decreased ecosystem performance (for example, primary productivity) coincident with decreased biodiversity, although the relative influence of biotic effects and confounding abiotic factors has been vigorously debated. Whereas several investigations focused on single trophic levels (for example, grassland plants), studies of whole systems have revealed multiple layers of feedbacks, hidden drivers and emergent properties, making the consequences of species loss more difficult to predict. Here we report functionally important organisms and considerable biocomplexity in a sedimentary seafloor habitat, one of Earth's most widespread ecosystems. Experimental field measurements demonstrate how the abundance of spatangoid urchins--infaunal (in seafloor sediment) grazers/deposit feeders--is positively related to primary production, as their activities change nutrient fluxes and improve conditions for production by microphytobenthos (sedimentatry microbes and unicellular algae). Declines of spatangoid urchins after trawling are well documented, and our research linking these bioturbators to important benthic-pelagic fluxes highlights potential ramifications for productivity in coastal oceans.     

饲料中总磷、无机磷和有机磷的含量测定

采用磷钼钒分光光度法研究了饲料中的总磷、无机磷、有机磷的含量。在酸性条件下,磷酸与钼酸铵[(NH4)2MoO4]和钒酸铵(NH4VO3)混合试剂形成黄色络合物,其最大吸收波长为374nm,摩尔吸光系数=e3.43×103 L·mol-1·cm-1,回收率为97.0%~101.5%,结果令人满意。     

Marine viruses and their biogeochemical and ecological effects.

Viruses are the most common biological agents in the sea, typically numbering ten billion per litre. They probably infect all organisms, can undergo rapid decay and replenishment, and influence many biogeochemical and ecological processes, including nutrient cycling, system respiration, particle size-distributions and sinking rates, bacterial and algal biodiversity and species distributions, algal bloom control, dimethyl sulphide formation and genetic transfer. Newly developed fluorescence and molecular techniques leave the field poised to make significant advances towards evaluating and quantifying such effects.     

高校图书馆破窗现象及其治理

破窗理论是管理学现代经典理论之一,其核心思想为,如若环境中的不良现象被放任存在,会诱使人们仿效,甚至变本加厉。本文就高校图书馆管理中破窗现象进行分析,并提出其治理方法及其优化方案。     

真空下用磷矿石无渣工艺制备磷

应用物质吉布斯自由能函数法讨论了不同压力下由磷矿石(其主要成分是磷酸钙)和碳反应生成碳化钙制备磷的反应条件。计算结果表明:在常压下反应起始温度为1891K,而当系统残余压力在90~9Pa间,反应进行的温度降低为1423K~1320K.同时用磷酸钙与还原剂碳在真空炉内实验,得到了磷单质,验证了理论研究的正确性,为下一步的研究提供了热力学理论依据和试验基础。     

无污泥外排除磷系统的磷平衡及除磷途径分析

在无剩余污泥外排的条件下,采用序批式生物膜反应器处理高浓度生活污水时磷得到了高效去除,传统聚磷菌除磷理论无法解释此现象.为此,文中通过对系统的磷平衡分析及污泥中聚合磷酸盐和结合态磷化氢含量的监测,探讨无剩余污泥外排下磷高效去除的途径.试验结果表明:反应器启动后在不外排污泥、连续曝气条件下连续运行38 d期间,出水总磷(...     

断圈定理的一个应用

利用断圈定理得到了（ｒ，ｓ，ｔ）－图的色多项式一次项系数的绝对值的计算公式。