Using dendrogeomorphology and Cs and Pb radiochronology to estimate recent changes in sedimentation rates in Kushiro Mire,Northern Japan,resulting from land use change and river channelization

The purpose of this study is to describe the history of sediment deposition that has been occurring for several decades along the margins of the Kushiro Mire, into which the Kuchoro River drains. The dendrogeomorphic technique was used to examine an even-aged forest and adventitious roots to assess short-term (20 years) deposition rates and the frequency of heavy rainfall events. For medium- (40 years) and long-term (100 years) deposition rates, radiochronological analyses using ¹³⁷Cs and ²¹⁰Pb were also conducted. Several instances of high deposition rates caused by flooding events during the last 20 years were identified from the analysis of adventitious roots. The average sedimentation rate from 1963 to the present, estimated from the ¹³⁷Cs study, is over 1.3 cm/year. Using the ²¹⁰Pb dating method, based on a CFCS model which considered the organic matter content appropriate to wetland sediment, three deposition rates in the last 60 years were estimated: 2.0 cm/year from 1981 to 2000, 8.9 cm/year from 1975 to 1981, and 0.14 cm/year from 1939 to 1975. The analysis of environmental radionuclides indicated that the greatest sedimentation rates occurred in the years 1975 to 1981, when the Kuchoro River was extensively channelized and flood and/or precipitation events occurred. This suggests that land-use development and channelization introduced a large amount of sediment into the marginal areas of wetland through the drainage system and this was deposited on top of the peat soil.     

地基基础不均匀沉降原因分析

作者依据工程实例,详细分析了地基基础发生不均匀沉降的种种原因,为工程设计人员更好地搞好地基设计方案,起到了一定的借鉴作用。     

农用柴油机械杂质沉淀净化的试验研究

笔者按我国农村燃油净化现况与需求进行了柴油沉淀净化试验。用非线性回归法,在试验条件下得出了机械杂质沉淀规律的数学模型,并提出了机械杂质理论沉降量的计算方法。据此,导出理论净化效率,同时分析了实际的与理论的净化规律。     

盆地型喀斯特流域土壤侵蚀模数的沉积量测量法

 为研究盆地型喀斯特石漠化地区的土壤侵蚀模数,运用沉积量测量法计算乌蒙山脉的麻窝山岩溶盆地中沉积区内土壤的沉积量,推算出流域内的土壤侵蚀模数,从而反演其石漠化进程,并探讨人类活动对喀斯特石漠化地区土壤侵蚀模数的影响。结果表明:麻窝山岩溶盆地流域的土壤侵蚀模数较高,为2900.55t/(km2.a),能客观地反映喀斯特石漠化山区土壤的侵蚀状况;沉积量测量法计算的土壤侵蚀模数比较接近现实,且其计算方法简单,数据可靠,容易操作,因此,该方法可作为无资料数据和测站时盆地型喀斯特流域计算土壤侵蚀模数的首选模型。     

南京某食品厂废水处理工艺设计

食品厂废水的成分一般较为复杂,通常包含大量可生物降解的有机物和较高浓度的动植物油。针对食品厂废水的特点,对南京某食品厂的废水处理工程进行了设计与实现,废水处理工艺采用了"混凝沉淀+水解-好氧"工艺,经处理后出水可以达到《污水综合排放标准》(GB8978-1996)中表4一级标准。     

东北寒冷地区高等级公路软土地基沉降计算与分析

东北地区的软土地基沉降除了具有变形大、不均匀沉降大、沉降稳定历时较长的特点外。受地质和气候因素影响也较大，这极大地影响了道路的长期稳定和安全使用。这里结合塑料板排水法在东北寒区高等级公路软土地基处理中的应用研究课题，利用哈尔滨绕城高速公路软土地基沉降观测资料，分析了影响沉降的主要原因，利用二种计算方法对软土地基进行沉降计算井做了讨论分析，得出较为符合工程实际的结论。     

武汉月湖沉积物中硅藻的垂直分布与水质变化

采用活塞取样器采集了月湖湖中央2处钻孔沉积物,分析了其中硅藻种类与密度的垂直变化,同时采用210Pb/137Cs推测沉积物的沉积速率.并进行了总有机质、生物硅含量分析,以了解月湖各个不同年代的水质变化.结果表明,2个柱状沉积物中硅藻的优势属为:小环藻属、直链藻属、舟形藻属、Cyclostephanos属.Z-1钻孔优势种为:梅尼小环藻、颗粒直链藻、Navicula porifera、Cyclostephanos tholifomis.Z-2钻孔中优势种为:梅尼小环藻、颗粒直链藻、舟形藻、Cyclostephanos invisitatus.就硅藻密度而言,总趋势是上层最多,平均7.14×105～58.65×105 ind·g-1,中层其次,平均0.08×105～13.98×105 ind·g-1,下层最少,平均0.24×105～0.64×105 ind·g-1.硅藻种类数变化虽然没有明显规律,但种类最少的样品出现在中层,210Pb/137Cs测年数据表明中层为19世纪90年代-20世纪70年代.相关分析表明:Z-1孔生物硅与沉积硅藻密度显著正相关(r=0.933,P=0.021<0.05),总有机质含量与种类数显著负相关(r=-0.972,P=-0.005<0.05);Z-2孔生物硅与沉积硅藻密度显著正相关(r=0.985,P=0.002<0.05),沉积硅藻密度与种类数显著负相关(r=-0.933,P=0.021<0.05).研究结果表明,月湖沉积物中硅藻种类与密度的垂直变化可以反映月湖的富营养演化历程:19世纪60年代-19世纪80年代,月湖水质较好;19世纪90年代-20世纪10年代,月湖开始由贫营养状态向中营养状态转变,为水体富营养化开始发生时间;20世纪20年代-20世纪40年代,月湖水体营养等级持续增加,已富营养化;20世纪50年代-20世纪70年代,周边人口数量急剧上升与污水的直接排放导致月湖水质持续恶化;20世纪80年代至月湖截污前这段时期使月湖最终沦为劣五类水体的湖泊.     

Effects of Hatching Time Interval on Growth Performance,Survival Rate,Sedimentation Behavior,and Exogenous Feeding Onset of Great Sturgeon (Huso huso Linnaeus, 1758)

We examined the influence of different hatching times on growth and survival of beluga, Huso huso, over a 28-day period. Larvae from a single pair of beluga, Huso huso, were divided according to hatching time into four groups: early, mid (between 6–9 h after the first group), late (23–26 h after the first group), and a mixture of first to last hatched larvae. At hatching time, there was no statistical difference (P > 0.05) in size and length among the four groups. Prior to the onset of exogenous feeding, groups A and D exhibited slightly earlier onset of aggregation behavior and began exogenous feeding 18 h sooner than the other groups (P < 0.05). Mortality after the onset of the endogenous feeding phase was not significantly different among groups (A: 8.15% ± 0.47%; B: 8.55% ± 0.41%; C: 6.63% ± 0.53% and C: 8.23% ± 0.43%) (P > 0.05). Results showed that hatching time has no effect on the growth and overall mortality of larval beluga.     

Evidence of mutual benefits of nest association among freshwater cyprinids and implications for conservation

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