本文研究了大黑汀水库表层沉积物碳氮磷污染负荷及分布特征,利用Peeper(pore water equilibriums)技术获取沉积物-水界面氮磷剖面特征,分析大黑汀水库间隙水氮磷分布的空间差异;采集沉积物无扰动柱样用静态培养法对其水土界面氮磷交换...本文研究了大黑汀水库表层沉积物碳氮磷污染负荷及分布特征,利用Peeper(pore water equilibriums)技术获取沉积物-水界面氮磷剖面特征,分析大黑汀水库间隙水氮磷分布的空间差异;采集沉积物无扰动柱样用静态培养法对其水土界面氮磷交换速率进行估算.结果表明:沉积物中TN、TP和TOC的含量分别在729～5894mg/kg、1312～2439mg/kg和0.5%～5.6%之间,沉积物中氨氮(NH_4^+-N)、硝酸盐氮(NO_3^--N)、亚硝酸盐氮(NO_2^--N)和活性磷(PO_4^(3-)-P)含量分别在0.6～202.9、34.4～168.3、0.1～0.3和16.1～75.2mg/kg之间,主要表现为下游含量高于上游,空间分布特征明显;沉积物C/N表明该水库有机质主要来源于水体内部,与人类网箱养殖活动有关.间隙水中NH_4^+-N和PO_4^(3-)-P浓度远高于上覆水,表明大黑汀水库间隙水具有向上覆水体扩散营养盐的潜力.在垂直方向上间隙水中NH_4^+-N浓度随深度的增加而变大,PO_4^(3-)-P浓度具有在0～4cm快速增加,之后表现出逐渐降低的趋势.静态释放结果表明,沉积物-水界面NH_4^+-N和PO_4^(3-)-P的交换通量分别为3.5～110.5mg/(m^2·d)和0.1～1.6mg/(m^2·d),NO_3^--N和NO_2^--N交换通量在-112.5～157.2mg/(m^2·d)和0.04～0.94mg/(m^2·d)之间.NH_4^+-N、NO_3^--N和PO_4^(3-)-P在下游表现出较高的释放速率.较高的沉积物内源负荷使得大黑汀水库沉积物具有较大的向上覆水释放营养盐的潜力,改善水库沉积物污染状况是治理大黑汀水库水体环境的必要之举.展开更多
Background With conventional imaging methods only the morphous of the visual nerve fiber bundles can be demonstrated, while the earlier period functional changes can not be demonstrated. We hypothesized that diffusion...Background With conventional imaging methods only the morphous of the visual nerve fiber bundles can be demonstrated, while the earlier period functional changes can not be demonstrated. We hypothesized that diffusion tensor imaging （DTI） would demonstrated the whole optic never fiber bundle and visual pathway and the earlier period functional changes. The purpose of the present study was to evaluate the application of DTI technique in the demonstration of the whole optic never fiber bundle and visual pathway, and the influence of orbital tumors on them. Methods GE 1.5T signa HD MR System, and the software package DTV2 were adopted. The total 45 subjects were enrolled, including 15 volunteers and 30 patients. All patients had ocular proptosis from minor to major. Seven patients had visual acuity decrescence. Results The nerve fiber bundles, e.g. optic chiasma, optic tract and optic radiation in posterior visual pathway were well demonstrated in all cases. Wherein, the intact whole visual pathway fiber bundles were clearly revealed in 10 volunteers and 17 patients, and optic nerve was not wholly revealed in the rest of the subjects. Shift of optic nerve caused by compression and partial deformation were seen in 7 patients with orbital tumor, in 6 of 7 patients, DTI displayed significant abscise and deformation of visual nerve. Chi-square test indicated significant correlation between visual acuity decrescence and DTI visual nerve non-display. Conclusions Visual nerve fiber bundles and the whole visual pathway were visualized in most of patients with DTI. It might be an effective method of providing imaging evidence for visual nerve fiber earlier period functional changes, and laid a foundation for the study in other cranial nerves. Chin Med J 2009; 122（2）： 178-182展开更多
文摘本文研究了大黑汀水库表层沉积物碳氮磷污染负荷及分布特征,利用Peeper(pore water equilibriums)技术获取沉积物-水界面氮磷剖面特征,分析大黑汀水库间隙水氮磷分布的空间差异;采集沉积物无扰动柱样用静态培养法对其水土界面氮磷交换速率进行估算.结果表明:沉积物中TN、TP和TOC的含量分别在729～5894mg/kg、1312～2439mg/kg和0.5%～5.6%之间,沉积物中氨氮(NH_4^+-N)、硝酸盐氮(NO_3^--N)、亚硝酸盐氮(NO_2^--N)和活性磷(PO_4^(3-)-P)含量分别在0.6～202.9、34.4～168.3、0.1～0.3和16.1～75.2mg/kg之间,主要表现为下游含量高于上游,空间分布特征明显;沉积物C/N表明该水库有机质主要来源于水体内部,与人类网箱养殖活动有关.间隙水中NH_4^+-N和PO_4^(3-)-P浓度远高于上覆水,表明大黑汀水库间隙水具有向上覆水体扩散营养盐的潜力.在垂直方向上间隙水中NH_4^+-N浓度随深度的增加而变大,PO_4^(3-)-P浓度具有在0～4cm快速增加,之后表现出逐渐降低的趋势.静态释放结果表明,沉积物-水界面NH_4^+-N和PO_4^(3-)-P的交换通量分别为3.5～110.5mg/(m^2·d)和0.1～1.6mg/(m^2·d),NO_3^--N和NO_2^--N交换通量在-112.5～157.2mg/(m^2·d)和0.04～0.94mg/(m^2·d)之间.NH_4^+-N、NO_3^--N和PO_4^(3-)-P在下游表现出较高的释放速率.较高的沉积物内源负荷使得大黑汀水库沉积物具有较大的向上覆水释放营养盐的潜力,改善水库沉积物污染状况是治理大黑汀水库水体环境的必要之举.
文摘Background With conventional imaging methods only the morphous of the visual nerve fiber bundles can be demonstrated, while the earlier period functional changes can not be demonstrated. We hypothesized that diffusion tensor imaging （DTI） would demonstrated the whole optic never fiber bundle and visual pathway and the earlier period functional changes. The purpose of the present study was to evaluate the application of DTI technique in the demonstration of the whole optic never fiber bundle and visual pathway, and the influence of orbital tumors on them. Methods GE 1.5T signa HD MR System, and the software package DTV2 were adopted. The total 45 subjects were enrolled, including 15 volunteers and 30 patients. All patients had ocular proptosis from minor to major. Seven patients had visual acuity decrescence. Results The nerve fiber bundles, e.g. optic chiasma, optic tract and optic radiation in posterior visual pathway were well demonstrated in all cases. Wherein, the intact whole visual pathway fiber bundles were clearly revealed in 10 volunteers and 17 patients, and optic nerve was not wholly revealed in the rest of the subjects. Shift of optic nerve caused by compression and partial deformation were seen in 7 patients with orbital tumor, in 6 of 7 patients, DTI displayed significant abscise and deformation of visual nerve. Chi-square test indicated significant correlation between visual acuity decrescence and DTI visual nerve non-display. Conclusions Visual nerve fiber bundles and the whole visual pathway were visualized in most of patients with DTI. It might be an effective method of providing imaging evidence for visual nerve fiber earlier period functional changes, and laid a foundation for the study in other cranial nerves. Chin Med J 2009; 122（2）： 178-182
