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百花湖水体氮的空间分布研究 总被引:1,自引:1,他引:1
初步探讨了百花湖水体中氮的空间分布特征,并分析了氮及溶解氧(DO)的相关性。对8个站位的表层、4m、8m及12m水体中总氮、氨氮、硝酸盐氮、亚硝酸盐氮及溶解氧进行了测定。结果表明,百花湖水体中总氮的平均含量为1.18mg/L,氨氮的平均含量为0.144mg/L,硝酸盐氮的平均含量为0.20mg/L,亚硝酸盐氮的平均含量为0.018mg/L。百花湖入湖口附近的1号采样点总氮、氨氮和硝酸盐氮的平均浓度都较其它采样点高。分析表明百花湖中DO浓度与硝酸盐氮和亚硝酸盐氮呈负相关,相关系数分别为-0.629、-0.724。 相似文献
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The bioavailability of five divalent cationic heavy metals(Pb,Cd,Cu,Zn and Ni) in 10 superficial sediment samples from Baihua Lake was assessed based on the molar ratio of simultaneously extracted metals(SEMs) to acid volatile sulfide(AVS).Atomic absorption spectrometry(AAS) and X-ray powder diffraction(XRD) were used to determine the heavy metal concentrations and examine the mineralogy of the crystalline phases,respectively.The AVS loadings in sediments from Baihua Lake ranged from 64.30 to 350.08 μmol/g(dry weight).The corresponding SEM levels for the sampling sites varied from 1.770 to 14.660 μmol/g.The molar ratio of SEMs to AVS ranged from 0.014 to 0.084 with a mean value of 0.034.The XRD analysis also confirmed the presence of some metal sulfides in sediments from Baihua Lake.The SEMs/AVS ratios for all sampling sites were significantly lower than 1.0,indicating that AVS in the sediments was sufficient to bind the five heavy metals;thus,these heavy metals are currently not significantly bioavailable to benthic organisms.Comparing the SEMs results to published guideline values for metal toxicity to benthic organisms in sediments,however,suggests that Zn and Ni pose a risk at some sampling locations in Baihua Lake. 相似文献
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地铁列车运行会给上部建筑带来振动噪声问题,因此,有必要对地铁列车运行引起的地层和建筑物振动响应及其减振措施进行研究。以杭州市未来科技城第三初级中学的新建项目为背景,首先利用ABAQUS软件分别建立普通整体道床和钢弹簧浮置板2种轨道结构下的车辆-轨道耦合动力模型,通过瞬态动力分析确定相应的列车移动荷载;然后利用MIDAS GTS NX软件建立隧道-土体-桩-建筑物三维有限元模型,以车辆-轨道耦合模型动力分析得到的列车荷载作为动力激励,对隧道-土体-桩-建筑物模型进行动力分析,预测地铁运行引发的土层和建筑物振动响应,对钢弹簧浮置板轨道结构的减振效果进行评估。结果表明:地铁运行引起的土层和建筑物振动以竖向为主;建筑物的优势频率出现在20、38和55 Hz附近;不同建筑物的振动加速度幅值随着与振源距离的加大而逐渐减弱;通过与普通整体道床轨道相比,钢弹簧浮置板轨道对建筑物减振有着显著的效果,其z振级最大值在25.3~42.3 dB之间,低于规范规定,为安全范围。 相似文献
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