Effects of hydrodynamics processes on phosphorus fluxes from sediment in large,shallow Taihu Lake

The turnover of phosphorus （P） in lake sediments, a major cause of eutrophication and subsequent deterioration of water quality, is in need of deep understanding. In this study, effects of resuspension on P release were studied in cylindrical microcosms with Yshape apparatus. The results indicated that there was a positive correlation between flux of suspended substance across sediment-water interface （Fss） and the wind speed, and an increasing Fss during each wind process followed by a steady state. The maximal Fss under fight, moderate, and strong wind conditions were 299.9±41.1,573.4±61.7, and 2093.8±215.7 g/m^2, respectively. However, flux of P across sediment-water interface （Fp） did not follow a similar pattern as Fss responding to wind intensity, which increased and reached the maximum in initial 120 rain for fight wind, then decreased gradually, with maximal flux of 9.4±1.9 mg/m^2. A rapid increase of Fp at the first 30 rain was observed under moderate wind, with maximal flux of 11.2±0.6 mg/m^2. Surprisingly, strong wind caused less Fp than under light and moderate wind conditions with maximal flux of 3.5±0.9 mg/m^2. Fss in water column declined obviously during the sedimentation process after winds, but Fp varied with wind regime. No obvious difference was detected on Fp after 8 h sedimentation process, compared with the initial value, which means little redundant P left in the water column after winds.

Lincang Superlarge Germanium Deposit in Yunnan Province,China: Sedimentation,Diagenesis,Hydrothermal Process and Mineralization

The mineralization is related closely to sedimentation, diagenesis and hydrothermal processes. In this paper, investigations are carried out on coal occurrence, maceral composition, inorganic minerals, trace elements and huminite reflectance. It is concluded that the source of Lincang superlarge deposit is mainly the muscovite granite in the west edge of the basin. During sedimentation, Ge (germanium) was leached out and entered the basin. Ge was adsorbed by lower organism and humic substances in water. Lincang lignite underwent three thermal processes: peatification, early diagenesis and hydrothermal transformation. During peatification, Ge was adsorbed or complexed by humic colloids. During early diagenesis, the Ge associated with humic acids was hard to mobilize or transport. Most of Ge entered the structure of huminite while a small amount of Ge was associated with residual humic acids as complex or humate. During hydrothermal transformation, the heated natural water or deep fluid from basement encountered the coal layer within tectonic weak zone. SO 2- 4 was reduced by coal organic matter. Pyrite and calcite formed. Hydrothermal process did not contribute significantly to mineralization.

Effects of Suspended Culture of the Seaweed Laminaria japonica Aresch on the Flow Structure and Sedimentation Processes

The culture of suspended kelp, such as Laminaria japonica Aresch, has arisen in nearshore areas for approximately 30 years since the 1980 s. This long-term activity has significant impact on the regional hydrodynamic and sedimentary environments. In this study the impact was investigated, based on synchronized multi-station data from continuous observations made within and around the culture area. In total, three current velocity profiles were identified inside and on the landward side of the culture area. Based on the current velocity profiles we calculated the boundary layer parameters, the fluxes of erosion/deposition, and the rate of sediment transport in different times at each observation site. Comparison between culture and non-culture periods showed that the presence of suspended kelp caused the reduction in the average flow velocity by approximately 49.5%, the bottom friction velocity by 24.8%, the seabed roughness length by 62.7%, and the shear stress and the flux of resuspended sediment by approximately 50%. From analyses in combination with the corresponding vertical variation of the suspended sediment distribution, it is revealed that the lifted sediments by resuspension is mixed with the upper suspended material, which will modify the regional distribution of suspended sediment. These changes in flow structure and sediment movement will accelerate seabed siltation, which corresponds to the changes in seabed erosion/deposition. However, under the influences of the seasonal changes in kelp growth the magnitude of change with the seabed siltation was not obvious inside the culture area, but a fundamental change was apparent around the culture area.

Validation of GLASOD Map for Sediment Sources and Erosion Processes Identification in the Nyumba Ya Mungu Reservoir Catchment

The main objective of this paper is to report on the preliminary validation results of the Global Assessment of Soil Degradation (GLASOD) as a tool for mapping sediment sources in Tanzania. This study was carried out in a well studied catchment, the Nyumba Ya Mungu (NYM) reservoir catchment located in the upstream of Pangani River Sub-basin. Previous studies in the same catchment used quantitative approach that entailed comprehensive sediment sampling programme and numerical modelling to identify sediment sources and erosion processes. Although previous researchers’ findings were satisfactory, the methods used were demanding in terms of resources (time, funding, and personnel) and impractical to a large ungauged catchment. The quest to validate GLASOD map is evident as it was qualitatively developed through collating expert judgments of many soil scientists to produce a world map of human-induced soil degradation at a scale 1:10,000,000. In the current study sediment sources mapped from qualitative method (GLASOD) plus supplement field visit observations and quantitative approaches are compared and discussed in detail. Preliminary results suggest that the paired information on sediment sources, field based data versus GLASOD, for upper catchments or upland locations are more strongly correlated than lower reaches. The results of this study have further emphasized the fact that GLASOD map is satisfactory to depict large regional differences in soil degradation but it is not capable of explaining local degradation. Besides, GLASOD map does not capture erosion processes dynamics compared to comprehensive sediment sampling programme. Notwithstanding, GLASOD map might be a useful tool for sediment sources and erosion processes identification scoping studies in the study area. Based on this study, it is therefore recommended to complement the GLASOD map with field based data for detailed study initiatives.

Pollution of bed sediments and its changing process of Nansihu Lake

In order to research the changing process of the pollution from the formation of Nansihu Lake, this study determined the isotope age and depositional rate and analyzed the organic geo-chemical quotas and heavy metal quotas of two sedimentary profiles of Weishan and Dushan lakes. Research results showed that from the formation of Nansihu Lake, the change of the pollution could be divided into four phrases. At the early phrase of the formation, the organic matters of the lake mainly derived from the exotic matters and had a close relation to the effect on the water and sands from the Huanghe (Yellow) River. At the middle and late phrases of the development, the endogenous matters of the lake became the main and stable source of the organic matters. The overflow of the Huanghe River, the excavation of the Grand Canal and the cut of trees caused the changes of the historic pollution. In recent 20 years, the modern industrial pollution from the organic matters and heavy metals has an increasingly heavy tendency.

从水动力学角度看三角洲前缘的沉积特征

三角洲前缘发育过程的深入剖析对沉积环境判断具有重要意义,有必要从水动力学角度深入探讨其形成特点与产生的机制。为此,从水动力学、水槽实验及水下地貌观察等多个角度,研究了河道水体的流速垂向分布、三角洲前缘沉积体发育的特点。研究发现,河流流速随深度增加单调降低的现象未被足够重视;中下游河床顺流向地形起伏增大,发育垂直于流向的水下沙波,而垂直于流向的河道断面地形起伏会越来越平缓;河流入海过程中,在水下一般以一条主流河道入海,水下不会出现分叉河道,且原先起伏的河床也会逐步填平补齐,由尖锐的V形或W型转变为U形。得出:三角洲前缘大多呈席状、扇状,而非顺流向带冲刷面的条带状;三角洲前缘亚相不发育水下分流河道、水下分流间湾等微相,在现代三角洲前缘亚相中找不到这些微相,且无水槽实验支持;提出了河道、三角洲沉积的水深—流速共同作用模式。

川西北晚三叠世卡尼期浅水碳酸盐生产工厂构成及其转换过程定量化研究

【目的】准确识别碳酸盐工厂类型并阐明其发育控制因素,定量化评价工厂发育过程的环境条件,厘清其在沉积体系转换过程中的古生态学和沉积学信号是探究碳酸盐岩沉积体系演化的关键。【方法】以川西北绵竹市汉旺镇观音崖剖面的马鞍塘组为例,通过系统的碳酸盐岩微相分析,结合粒径统计分析方法对20391个颗粒定量分析,在此基础上对该时期热带浅水碳酸盐生产工厂的构成、特征、转变过程、驱动因素等进行了详细阐述。【结果】研究区热带浅水碳酸盐生产工厂可进一步划分为似球粒、鲕粒、生屑及生物礁等多个细分特异化工厂类型,指示多样化的碳酸盐生产路径。通过分析研究区热带浅水工厂的构成,沉积环境、水动力条件和营养水平等因素,发现各个细分工厂类型有着非常强烈的“生境”特点,工厂类型的转变更多地受区域海平面变化控制。【结论】频繁的海平面变化导致营养水平、水动力条件和碳酸盐矿物饱和度等因素快速变化,进而驱动了具体细分工厂的转变。而众多细分工厂在沉积序列上的快速变化指示了它们在横向上的共生关系。因此,较短时间尺度下细分工厂类型的转变主要与区域海平面控制的横向生产工厂类型的迁移有关,与极端事件和沉积体系的转变可能无关。

微生物碳酸盐生产工厂的构成、特征及沉积学意义——以河南云梦山剖面为例

【目的】“碳酸盐(生产)工厂”研究强调生物群落对碳酸盐生产过程以及规模的调控和特异性影响,在深入认识碳酸盐岩成因和形成机制方面具有重要价值,是碳酸盐沉积学领域关注热点和重要方向。虽然该概念的正式提出已有二十多年历史,但如何从工厂角度解读地质历史时期,特别是深时特异性、大规模碳酸盐岩的发育过程和影响因素方面仍缺乏系统性认识。【方法】以河南云梦山剖面寒武系崮山组为例,利用多尺度、网格定量化评价方法对微生物碳酸盐生产工厂的样式、内部结构、建造过程等方面进行了详细阐述。【结果】研究区微生物碳酸盐生产工厂以底栖微生物群落为主要建造者,形成样式包括叠层石、凝块石、树枝石、均一石以及微生物诱导沉积构造(MISS)。伴生的颗粒类型包括鲕粒、球粒、生屑、竹叶状内碎屑和微生物岩角砾,主要分布于工厂建造格架间。微生物碳酸盐生产工厂发育具期次性,单期工厂发育规模较小(海底至水面高度不足1 m)但空间延伸广,包括半球状、穹窿状、板状等宏观形态;其内部结构包括少量单独的建造样式,以及广泛发育的垂向复合形式。【结论】通过分析影响工厂发育的各类因素,局限潮坪环境下较高的营养水平对微生物碳酸盐生产工厂的繁盛可能起到了主要作用,而古丈期总体海侵背景造成适宜微生物碳酸盐生产工厂发育的环境消失,导致工厂最终关闭。相关工作的开展提供了一个与现代澳大利亚Hamelin Pool微生物碳酸盐生产工厂非常相似的古代实例,对认识寒武纪碳酸盐生产工厂类型、特征和演化规律方面具有较好的参考价值。

考虑泥沙因子的四川省山洪风险评价研究

近年来,山洪灾害频发高发,为进一步提高山洪灾害预警防控水平,提出将泥沙因子纳入山洪风险评价中。以四川省为例,从洪水危险性、脆弱性和防灾能力3个方面选取12个山洪风险指标,运用层次分析法构建山洪风险评估指标体系,分别建立了不考虑泥沙因子和考虑泥沙因子的山洪灾害风险评估模型。结果表明:泥沙因子对山洪危险性和风险性有较大影响。不考虑泥沙因子的模型将低估山洪高风险、较高风险区域和中等风险区面积,而高估低风险、较低风险区域面积。研究成果可为山洪风险评价与灾害预防提供参考。

水库拦沙对黄河下游河床演变的影响

为充分认识水库拦沙对其下游河道河床演变及防洪的影响,基于三门峡水库和小浪底水库拦沙期水沙及断面观测资料,研究了黄河下游河槽冲淤、洪水冲刷效率、河槽几何特征、排洪能力等规律。结果表明:水库拦沙期,黄河下游沿程河槽均发生了不均衡冲刷;河床粗化明显,粗化后床沙中值粒径最大值为冲刷前的2.1~2.5倍;高村以上河段同水位过洪能力增加明显,冲刷后较大的河槽容积可为小浪底水库排沙提供暂时的滞沙;河床粗化后细泥沙和中泥沙补给能力不足,河槽冲刷效率随冲刷历时的增加衰减明显。由于水库多年调节水沙过程及下游相对完善的河道整治工程约束,小浪底水库拦沙期黄河下游河槽冲刷重心下移,河床粗化程度增加,冲刷效率明显降低。研究成果可为水库水沙调控技术指标的选取提供科学依据。

鄱阳湖水沙与氮磷输移过程及滞留效应研究

为了开展鄱阳湖水沙、氮磷输移过程及滞留变化的研究,收集了鄱阳湖“五河”七口水文站1958-2021年的径流量和悬沙浓度数据、1965-2020年鄱阳湖湖口入江水道地形数据、2003-2021年水质监测数据以及1973-2018年湖区围垦遥感解译等数据,采用统计、对比、双累计曲线及质量守恒法等方法,分析了鄱阳湖“五河”入湖沙量变化趋势、鄱阳湖入江水道地形变化以及鄱阳湖TN、TP滞留变化过程.结果表明:①从20世纪90年代起“五河”入湖总沙量呈显著下降趋势.②鄱阳湖出口河段河床于2000-2010年期间在深度10.0~12.0m中滩河床发生了强烈下切和横向展宽,2010-2020年下切显著减缓,中滩河床还存在横向展宽的可能.③出入湖TN、TP通量与出入湖泥沙通量成正比.④鄱阳湖2003-2021年逐年TN、TP滞留率显著降低.研究显示:鄱阳湖“五河”流域各大中型梯级水库的建设使得鄱阳湖湖区多年来沙量显著降低,鄱阳湖流域水土保持及闸坝体系在2000年后水土流失韧性增强;但湖区采砂挖沙和航道整治等使得鄱阳湖出口河段河床显著下切;采砂挖沙活动导致鄱阳湖湖盆沉积物受到扰动,使得沉积物中的氮磷被释放出来,增加了出湖TN、TP通量,在一定程度上降低了鄱阳湖TN、TP滞留率.

黄河下游游荡性河段心滩形态特征与水沙过程响应关系

黄河下游游荡性河段素以调整速度快与幅度大著称,河道心滩复杂多变,探究心滩形态特征与水沙过程之间的响应关系对于解析下游游荡性河段的河床演变机制具有重要的意义。围绕黄河下游铁谢至高村游荡性河段的心滩面积与数量等形态特征指标,结合下游水沙及冲淤特性,采用遥感影像和数值模拟相结合的研究方法厘清游荡性河段水沙过程与心滩面积及数量之间的响应关系,揭示水沙变化对心滩形态特征的影响机制。结果表明:自小浪底水库运用以来,下游河道发生剧烈冲刷,游荡性河段累计冲刷量15.37亿m^(3),占下游累计冲刷量的68%;在小浪底水库运用以前,游荡性河段的心滩面积与数量年际变化剧烈,存在着明显的增长与降低变化过程,而小浪底水库运用以后,该河段的心滩面积与数量呈现先减小后增大再减小的变化趋势;随着4 a滑动汛期平均流量和4 a滑动汛期平均来沙系数的增加,游荡性河段的心滩面积及数量分别呈现出减小和增大的变化趋势。数值模拟方法不仅可以较好地再现心滩发育及演变过程,还可以定性地表征特定水动力学因素对心滩形态特征塑造的影响,为阐明游荡性河段的心滩演变理论提供了一种新的研究方法。研究成果不仅有助于阐明河流平面形态的调整过程,还可为今后河道整治工程的布局提供理论支撑。

基于地震沉积学和沉积物理模拟的河流决口扇沉积演化过程分析以渤海K油田明化镇组下段为例

为厘清渤海海域K油田明化镇组下段砂体分布特征,为下一步的目标优选提供参考依据,基于优选的地层属性地震切片和测井响应特征,分析了明化镇组下段沉积演化过程,设计了沉积物理模拟对比实验。结果表明:①平均负振幅属性最能反映该地区沉积特征且该属性特征与测井曲线特征结合最好,确立5种地震属性相分别对应于强水动力下的决口扇沉积、弱水动力下的决口扇沉积、曲流河沉积、分支河道沉积、洪漫沉积;②渤海K油田主要发育河流决口扇沉积,分为前期的洪漫沉积与决口扇沉积、中期的扇上下切河道沉积及分支河道沉积、末期的曲流河道沉积3个部分,平面差异分布较为明显;③沉积模拟实验共分为洼地填充期、扇体改造期、支流发育期、汇聚摆动期,与渤海K油田明化镇组下段沉积演化有较好的对应,很好地验证并再现了河流决口体系演化过程。以上认识明确了明下段在K油田地区的沉积演化特征,有利于该地区的勘探评价,物理模拟验证也提供了一种新的研究思路。

黄河上游宁蒙河段平滩流量变化与水沙过程的响应关系

平滩流量是表征河道排洪输沙能力的重要指标,开展宁蒙河段平滩流量变化机理的研究对于治理黄河意义重大,本文采用实测资料分析的方法,研究了黄河上游宁蒙河段平滩流量变化特征及其与汛期水沙过程的定量关系。研究结果表明:黄河上游宁蒙河段沿程六站平滩流量由1960年代中期的3600~5800 m^(3)/s减小到目前的1900~4000 m^(3)/s。2000年前宁蒙河段三湖河口平滩流量与汛期水沙过程关系点群与2000年后两者关系点群存在明显分区,说明2000年后宁蒙河段河床演变机理发生了变化,遵循不同规律。建立的宁蒙河段三湖河口平滩流量与汛期水沙过程的定量关系式表明,宁蒙河段平滩流量随着汛期平均水量的减小(增大)而减小(增大),随着汛期平均来沙系数的减小(增大)而增大(减小),随着汛期水流过程参数的增大(减小)而增大(减小)。

物化预处理-生化组合工艺处理草甘膦生产废水工程实例

对不同工艺废水采用物化方法分质预处理后,利用厌氧-缺氧-CAST组合工艺处理综合废水,设计处理量为470 m^(3)/d。运行实践表明:中和反应-混凝沉淀对总磷的去除率可以达到46%,整个工艺处理出水COD稳定低于500 mg/L,总磷稳定低于8 mg/L,出水水质达到接管要求。

涪江流域日输沙率的时间尺度变化效应

[目的]解析日输沙率与关键环境因子之间的尺度依赖关系,探索有效的预测方法,以应对由于泥沙输运机制的复杂性和水文过程的非线性所带来的预测挑战。[方法]采用集合经验模态分解与自适应噪声(CEEMDAN)方法,分析了西南地区涪江流域4个水文站点控制区域2013—2018年的日输沙率与5个潜在影响变量(流量、降水量、平均气温、潜在蒸散发量和NDVI)间多时间尺度变异特征,识别不同时间尺度下日输沙率与相关变量相互作用关系,在此基础上,对日输沙率作出预测。[结果]CEEMDAN方法成功将日输沙率及其潜在影响变量分解为10-11本征模态函数(IMF)和残差项,揭示出日输沙率在3~730天不同时间尺度上的显著变化。分解后的日输沙率与流量、降水量在各个时间尺度上均显示出显著的相关性增强,而气温、潜在蒸散发量和NDVI主要与长时间尺度的日输沙率显著相关。通过逐步多元线性回归预测日输沙率,模型的预测性能显著,R2值在所有站点均超过0.55。[结论]CEEMDAN方法能够有效揭示输沙率及其影响变量之间的尺度依赖性,为理解河流输沙动态提供了新的视角。

基于泥沙异重流稳定性与衰减过程的床面淤积特性研究

泥沙异重流在稳定分层和不断衰减的过程中,伴随着床面淤积特征的变化。通过水槽试验观测异重流“稳定-衰减”过程,结合异重分层流运动理论模型,探究该过程对床面淤积特征的影响。研究结果表明,增加异重流层密度或厚度,形成稳定分层形态的时间明显缩短,同时延长了分层形态的维持时间;计算得到的临界雷诺数与扰动波数虚部相应增加,分层形态稳定性得以增强。异重流的稳定行进对于减小床面淤积具有重要作用,试验中临界雷诺数增加568~820,平均淤积厚度降低了42%~46%。因此,提高异重流稳定性并延缓衰减速率,有助于提高输沙率,可以达到减淤的目的。

人工湿地中沉积物溶解性有机质与Cd结合机制——以株洲市某人工湿地为例

为探究人工湿地不同季节的溶解性有机质(DOM)组分变化以及与Cd之间的相互作用及差异,本研究利用紫外光谱、荧光光谱、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等多种光谱表征技术,并结合平行因子分析(PARAFAC)和二维相关光谱(2D-COS)分析对春秋两季湿地沉积物中DOM进行深入探讨。研究发现,湿地沉积物DOM主要来源于微生物活动、植物凋落物和根系分泌物,亲水性强且芳香性较低。春季与秋季的DOM含量分别为434 mg·kg^(-1)和700 mg·kg^(-1),其中春季主要由两种类蛋白和两种腐殖质组成,而秋季则为一种类蛋白和三种腐殖质。各组分与Cd的淬灭过程主要是静态淬灭,其中春季的蛋白质残基表现出最为明显的淬灭效果,存在两类以上结合位点,而秋季的类蛋白和类富里酸为单齿络合物。类蛋白和类富里酸与Cd的结合比其他组分更为强烈且稳定,并且类蛋白质组分与Cd优先结合。结合过程中,Cd主要与DOM的酰胺、酚羟基、羧基官能团相互作用,其中酰胺的结合速率最快,其次是酚羟基和羧基。

水处理中高密度沉淀池工艺的应用研究

针对当前很多企业的传统废水处理工艺已无法满足现代化废水处理要求和排放标准的情况,高密度沉淀池工艺自动化程度较高,且能有效处理废水悬浮物以及钙镁离子,在工业废水处理、生活废水处理等方面得到广泛应用。本次研究以某化工企业为研究对象,对高密度沉淀池工艺的应用进行研究,并分析应用效果,以期能够促进废水处理行业的发展。

基于数字图像处理技术的粒径筛分方法综述

非固结颗粒的粒度分布在河床或海床稳定性分析、沉积物输移以及沿海扩散等方面发挥着重要作用。随着图像处理技术的发展涌现出了许多数字图像筛分方法。本文依据数据处理结果的维度将数字图像筛分方法分为二维数字图像粒径筛分方法和三维数字图像粒径筛分方法。首先,根据二维数字图像粒径筛分方法所依赖的核心算法将其进行了分类并总结了每种方法的适用性和不足。其次,分析了三维数字图像粒径筛分方法并总结了其存在的不足。最后,依据各个方法优缺点提出了“几何”粒度筛分方法和“人工智能”粒度筛分方法相融合的新构想,即前者为后者提供标记训练集,经过训练后后者可以快速适应新环境的数字筛分任务。