里运河底泥CODCr和NH3-N释放对水质的影响实验

通过利用长江水体作为上覆水的里运河表层底泥的释放实验研究，分析了表层底泥中CODCr和NH3—N在静置和3种扰动条件下的释放规律，结果发现城区段底泥中CODCr和NH3—N的释放强度大于非常区段，底泥孔隙水与上覆水之间的浓度梯度增大促进了底泥中污染物质的更快更多地释放。同时得出了各个断面表层底泥中CODCr，和NH3-N的释放强度，在扰动条件下的释放强度远大于静置条件下的释放强度，底泥中污染物质的释放可能会在一定程度上影响里运河将来的调水水质。     

河道底泥污染物释放控制试验研究

采用自主研制的环形水槽试验装置，研究了水动力条件下河道底泥的污染物释放特性，开展了原位覆盖和原位固化对底泥污染物释放控制效果的研究。试验结果表明:河道水流速度直接影响底泥污染物的释放特性；底泥随流速逐渐增大分别呈现“未起动”、“少量动”和“普遍动”三种状态。流速小于起动流速时，底泥未起动，上覆水中污染物释放量、浊度与静水条件接近。流速大于起动流速时，底泥大幅起动，上覆水中污染物释放量大幅增加。原位覆盖和原位固化均能有效控制底泥污染物的释放。与未处理相比，原位覆盖后的污染物控制率能达到60％ ～90％，砂层的压重作用避免底泥大规模起动，进而导致上覆水中的污染物含量大幅降低。原位固化后的污染物控制率为97％，但固化会导致上覆水ｐＨ升高使水体呈碱性。     

环境因子对南四湖底泥磷释放的影响实验研究

通过室内模拟实验,分析了环境因子(温度、pH、扰动)对底泥内源磷释放的影响及原因.实验表明:温度升高和水的扰动有利于底泥磷的释放;中性条件磷的释放速率较慢,偏酸或偏碱条件都有利于底泥磷的释放.     

广州城市河涌氮、磷污染研究

对广州市区典型河涌氮、磷污染进行分析研究。结果表明:上覆水中氨氮质量浓度为6.21~22.40 mg/L,间隙水中氨氮质量浓度为19.9~152.0 mg/L。河涌上覆水以及间隙水中的氮污染主要是无机氮污染,且以氨氮为主,占总无机氮的90%以上。各河涌的氨氮和总氮值之间表现出很强相关性,但上覆水的氨氮和总氮值与间隙水的氨氮和总氮值之间,却不存在明显相关性。底泥间隙水与上覆水磷形态差异较大,间隙水中可溶性正磷酸盐与总磷具有较好的相关性,且有机磷质量浓度比上覆水要高;底泥中可溶性磷(Psol)、铝结合磷(PAl)质量浓度较低,铁结合磷(PFe)质量浓度较高。悬浮物中各形态磷质量浓度整体上均比底泥样品要高。     

底泥污染物释放水动力特性实验研究

在环境水动力学中,河口地区的河流底泥污染物释放扩散特性的研究越来越受到人们的重视.实际上,污染物在底泥和上覆水体之间的释放扩散,对上覆水体水质有很大影响.底泥污染物释放扩散受到底泥本身物理性质和上覆水体水动力特性的共同作用.本文对底泥污染物向上覆水体释放扩散规律进行了水槽实验,通过对水体中底泥释放污染物COD浓度的测量分析,初步得到了底泥污染物在动水条件下的释放机理.底泥污染物释放主要分为两种形式:一是底泥污染物泥水界面释放,二是底泥污染物起动悬浮释放.随后结合底泥污染物释放的水槽模拟实验,天然河道(苏州河)现场实测资料,对三者进行了分析比较.它们相互符合得较好,所反映的基本规律是一致的,表明了本文实验研究的合理性和可靠性.     

环境因子对鱼饵中磷释放影响的实验研究

通过室内模拟实验,分析了环境因子(上覆水、微生物活动、温度、pH、水动力条件)对鱼饵磷释放特征的影响及原因。结果表明:鱼饵在去离子水中总磷和正磷酸盐的平衡释放量约是潘家口水库水中的1.58倍和1.76倍;微生物作用有利于鱼饵中磷向水体释放,前者总磷和正磷酸盐的释放量约为后者的1.55倍和1.28倍;温度升高和水体扰动促进了鱼饵中磷的释放;酸性和碱性条件下鱼饵中磷的释放量高于中性条件下鱼饵中磷的释放量。各环境因子作用下,鱼饵中磷在前3h内的释放速率最大。     

泥沙颗粒和孔隙水在底泥再悬浮污染物释放中的作用

在环境水动力学中,河流底泥污染物释放是人们研究的主要问题之一。污染物进入到水体中后会有一部分聚集在水体底泥中,并在底泥的上层形成一条污染底泥层。底泥再悬浮时,污染物会通过再悬浮颗粒以及孔隙水重新释放到上覆水体中。此文中分别以氯化钠和磷代表典型非吸附性污染物和吸附性污染物,研究底泥污染物释放中底泥颗粒相和水相在不同的水力条件下所起到的作用。研究表明,在底泥静止状态和瞬间悬浮条件下,底泥污染物的释放主要来自于水相孔隙水,非吸附性污染物的释放主要集中在这两个状态下;而在连续悬浮条件下,再悬浮颗粒的解吸释放起着主要的作用,吸附性污染物的释放大部分发生在此阶段。另外,此文还研究了两种类型的泥沙即粘性细颗粒泥沙和非粘性粗颗粒泥沙在底泥连续悬浮时的释放量和释放时间的异同。研究表明,再悬浮粗颗粒泥沙的污染释放量要比再悬浮细颗粒小,但前者释放持续的时间要比后者长。     

富营养化湖塘底泥氮磷吸附—解吸模拟研究

当外源营养盐负荷得到控制后,水体底泥中氮、磷等营养物质的释放成为诱发水体富营养化的重要内因。通过室内实验模拟富营养化湖塘底泥中氮、磷的吸附与解吸过程,对比分析不同氮、磷浓度条件下,上覆水—底泥间氮、磷吸附与解吸过程中的特点,探讨了影响氮、磷吸附和解吸关键因素,揭示了底泥氮、磷吸附和解吸平衡质量浓度,为制定科学的底泥内源氮、磷的控制措施提供科学依据。     

研究生论文摘要

磷在浮萍修复富营养化水体系统中的分配行为研究研究生:缪静导师:汪群慧副导师:侯文华(哈尔滨工业大学市政与环境工程学院150090)由湖泊富营养化引起的蓝藻“水华”暴发是当今社会频繁发生的环境灾害之一。在大多数情况下,磷是最主要的限制因子,磷在水体系统中的循环,特别是沉积物(底泥)中磷的释放在一定程度上决定富营养化的进程。本文结合国内外研究最新动态,以浮萍科植物(青萍)为试验材料,采用实验室模拟的方法,研究不同植物种类、上覆水不同磷营养水平、上覆水不同氨氮浓度、上覆水不同pH、沉积物中微生物状况、培养温度(低温)6种环境…     

北运河(北京段)底泥磷含量及其对上覆水质的影响

采用SMT和Psenner分级提取法分别测定了北运河(北京段)底泥总磷和各结合态磷的含量,结果表明,春季北运河底泥TP平均含量为1 086.29mg/kg,含量偏高,属严重污染;各结合态磷平均含量顺序为Ca-P>Al-P>Fe-P>NH4Cl-P>Res-P>Org-P,相同结合态磷的含量在不同采样点存在明显差异。通过对各结合态磷与上覆水质的相关性分析发现,北运河(北京段)底泥TP含量主要受NH4Cl-P、Fe-P、Al-P和Res-P影响,其中Al-P的影响最大;NH4Cl-P、Fe-P、Al-P和Res-P均与上覆水含磷量显著相关,其中BAP(BAP≈NH4Cl-P+Fe-P+Al-P)平均含量达到TP的48.63%,且与上覆水含磷量极显著相关,说明底泥磷特别是BAP的转化释放是引起上覆水体富营养化的重要因素。     

Effects of benthic algae on release of soluble reactive phosphorus from sediments: a radioisotope tracing study

To evaluate the effect of benthic algae on soluble reactive phosphorus(SRP) release from sediments in shallow lakes, experiments on SRP release with and without benthic algae in sediment cores and an experiment on SRP uptake by benthic algae were conducted using the radioisotope(32P) tracing method. The dissolved oxygen(DO) concentration in sediment cores was also investigated. The results show that benthic algae effectively reduce the release of SRP from sediments to overlying water. The uptake of SRP by benthic algae, which is the direct way in which benthic algae affect the SRP release from sediments, is low in filtered water and increases with the SRP concentration. However, in the experiment, the increased uptake rate lasted for a short time(in one hour), and after that it returned to a low rate. Benthic algae make the DO concentration and the oxic layer thickness increased, which can indirectly reduce the SRP release from sediments. These findings indicate that benthic algae can reduce the SRP release from sediments in both direct and indirect ways. It seems that the indirect way also plays an important role in reducing the SRP release from sediments.     

底泥污染物的环境行为研究进展

综述了底泥主要污染物重金属、营养物质(氮、磷)和难降解有机物向上覆水体释放的机理和影响规律,并指出该研究领域尚需解决的技术难题:重视对能代表大水体实际情况实验装置的研制开发以及野外观测与室内实验的密切结合、加强沉积物—水体界面之间物质扩散交换过程的机理研究,建立污染物释放模型;加强底泥污染物释放的动力学研究。     

Hydrodynamic effects on contaminants release due to rususpension and diffusion from sediments

Hydrodynamic effects play a very important role in the contaminants release from sediments. Experiments were perfor-med to study contaminants releasing characteristics due to resuspension. The time-dep...     

Silica Regeneration Processes in Nearshore Southern Lake Michigan

The seasonal depletion of dissolved silica to levels that limit diatom production is particularly critical in Lake Michigan's nearshore zone where diatom biomass is greatest, and where silica regeneration from sediments is not well-understood. In our study, intact, medium-fine sand cores, collected from an 11 m deep site in nearshore Lake Michigan during July-August 1980, released soluble reactive silica (SRS) at a mean rate of 2,707 ± 122 (SE) μg Si cm^?2 yr^?1 when incubated in darkness and at 12° C. This measured SRS release was greater than a diffusive flux (270 ± 49 (90% C.I.) μg Si cm^?2 yr^?1) estimated from SRS pore water profiles and physical sediment properties. SRS release from individual cores was not correlated with abundance of most macroinvertebrates (chironomids, pisidiid clams, or oligochaetes). However, a significant (P < 0.05) and inverse relationship between SRS release and Pontoporeia hoyi densities implied that amphipods suppressed SRS release through mixing and burial of a surficial floe layer, where most dissolution of biogenic silica occurs. Moreover, SRS release rates measured from our coarse-grained nearshore sediments were comparable to rates reported for fine-grained offshore material and further implicate dissolution of surficial biogenic silica as the source of remineralized SRS. Because nearshore areas of Lake Michigan undergo strong seasonal variations in temperature and diatom production, and because significant riverine silica inputs exist, we cannot extrapolate our results on a lakewide, or season-long basis. The data, however, strongly imply that nearshore sediments are an important participant in the Lake Michigan silica cycle.     

Experiment study of the effects of hydrodynamic disturbance on the interaction between the cyanobacterial growth and the nutrients

The eutrophication of shallow lakes is sensitive to dynamic currents(i.e., disturbances) because of their shallow depths and high contents of nutrients in bed sediments. The relation between the sediment resuspension and the algae bloom is not well understood in the field scale because the interwoven influencing factors cannot be examined individually. By combining the laboratory experiment and the field observation, this paper proposes a sediment-water-algae concept to simulate the effects of hydrodynamic disturbances on the algae growth in the Taihu Lake located in east China. The sediments are sampled from the Taihu Lake while the Microcystis aeruginosa(M. aeruginosa) algae is cultured in the laboratory and then transplanted into the experiment cylinders. The temperature and the light intensity in the experiment are adjusted to be similar with the prevalent in situ conditions. The results indicate that the M. aeruginosa populations under the disturbance condition of the rotational speed ?300 rad/min in the experiment(corresponding to the bottom velocity flow ?0.059 m/s, the shear stress 2?0.069 N/m, or the wind speed ?4 m/s in the field) are higher than those under the disturbance condition of the rotational speed is 400 rad/min(corresponding to the bottom flow velocity 0.079 m/s, the shear stress 0.124 N/m2). It is suggested that a low to moderate disturbance prompts the release of the nitrogen as well as the phosphate nutrients from the bed sediments, amplifying the eutrophication of the Taihu Lake.     

Algal-Available Particulate Phosphorus in the Great Lakes Basin

For the purpose of comparing the relative availability of particulate phosphorus (P) from various sources to the Great Lakes, algal-available P was determined on suspended solids and bottom sediments from tributaries, wastewater suspended solids, lake bottom sediments, and eroding bluff solids from the region. Physicochemical and bioassay methods were used to estimate the rate and extent of available P release from particulates. Considering all types of particulates examined, ultimately available P ranged from nil to approximately 70 percent of total phosphorus (Total-P) content. During algal bioassays, changes in levels of base-extractable inorganic P (R-NaOH-P) in tributary suspended solids were nearly equivalent to the amounts of P used by algae during bioassays. For the tributary solids, ultimately available P averaged approximately 90 percent of R-NAOH-P. Consistent differences were found in amounts of available P among particles from different sources. Sources of particle-bound P ranked in order of decreasing availability were: wastewater solids, lake bottom sediments, tributary solids, and eroding bluff solids. Differences in available P release rates also existed among the different types of particles. Wastewater solids displayed the largest first-order release rates, eroding bluff samples and tributary-suspended solid samples that were high in apatite showed essentially no available P release, while other tributary suspended solids displayed intermediate release rates.     

原始损伤性片麻岩变形破坏中的能量特征分析

为探究不同初始损伤状态片麻岩在载荷作用下能量变化特征,取某隧道工程岩样进行单轴试验和三轴试验。对各试验岩样的应力-应变曲线特征进行分析,并对能量随应变的演化规律进行研究,结果表明:原地应力环境对试件性质影响较大;三轴试验条件下,岩石的能量演化规律可分为3个阶段,即稳定二次增长阶段、稳定破裂阶段及加速破裂阶段;损伤程度较高的片麻岩弹性能储存能力较弱,峰前扩容更明显,破裂位置更多;裂隙压密岩石弹性能储存比例高,脆性破坏更明显;卸围压过程中整体能量释放速率大于理论弹性能释放速率时,将造成卸荷损伤,使得岩石强度降低。该研究丰富了损伤性岩体的能量演化特征认识,并为片麻岩岩体工程建设提供了新的分析思路。     

Research and application of in-situ control technology for sediment rehabilitation in eutrophic water bodies

Phosphorus (P) is often the limiting nutrient for algal growth, and P in sediments can be released under suitable conditions. To control P release, in-situ control technology with lanthanum (La) modified bentonite clay (Phoslock(?)) was proposed and its effectiveness was tested and evaluated both in laboratory and field trials. The results of static and dynamic simulation experiments under different environmental conditions showed that with the application rate of Phoslock(?) at 0.5 kg/m(2), the orthophosphate (PO(4)-P) concentration of the overlying water decreased to a low level (≤0.02 mg/L) within 10 days. Even under anaerobic and high pH (pH = 9.0) conditions, the phosphate release suppression efficiency reached 98.3%, and the P-release rate was -8.20 mg/m(2) d (negative value indicates P adsorption by Phoslock(?)). The monitoring data of the field sediments rehabilitation project were consistent with the results achieved in laboratory experiments, thus showing that the application of Phoslock(?) could inhibit the internal P release effectively.     

Redox-related release of phosphorus from sediments in large and shallow Lake Peipsi: Evidence from sediment studies and long-term monitoring data

In large and shallow lakes, the role of the redox-related release of phosphorus (P) from sediments has remained in the shadow of sediment resuspension. In the current study, we concentrated on this knowledge gap regarding factors controlling lake water quality. We combined long-term monitoring data with the studies on sediment P mobility in August 2018 by measuring redox potential, pore water concentrations of soluble reactive phosphorus (SRP), dissolved iron (Fe), sediment P fractions, and by calculating diffusive P flux. Using lake water total P (TP) concentrations for 21 years (1997–2018), we quantified internal P load based on water column summer increase of TP (IL_{in situ}). Significant positive correlations were found between the diffusive P flux and the Fe-bound P concentration in the sediment for conditions of well-oxidized sediment surfaces. The analysis of long-term data showed that P mobilized in sediments is likely to be released via sediment disturbances. Sediment resuspension is favoured by decreased water level during late summer-early autumn. Additionally, the release of P from anoxic sediment surfaces is also possible, as was indicated by significant positive correlations of IL_{in situ} with the anoxic factor (a measure of extent of anoxia) and August water temperature. The potential P release from anoxic sediment surfaces contributed about 80% to IL_{in situ} in the northern basin, and about 280% in the more productive southern basin. Hence, the redox-related P release seems to sustain the high productivity of these large and shallow lake basins and is supported by sediment resuspension as a transport mechanism.     

Flushing flow recommendations for maintenance of salmonid spawning gravels in a steep,regulated stream

A study was conducted to develop flushing flow recommendations for maintaining the quantity of salmonid spawning gravels in the North Fork of the Feather River, a regulated stream in California, U.S.A. This required the development of a technique which would prescribe flows to remove sediments from the gravels without removing the gravels themselves, which are in finite supply in the river. Field studies involved the use of a ‘two-point-are’ procedure which allowed depth, velocity, and substrate measurements to be concentrated over spawning gravels at each site. Measurements were repeated at each site at three different flows ranging from 1.7 to 11.3 m³ s^?1. The local velocity and depth measurements were used to evaluate hydraulic conditions within areas containing spawning gravels. Four flow levels were derived which would provide varying degrees of sediment transport and flushing; (1) surficial flushing of gravels; (2) mobilization of gravels; (3) surficial flushing of cobbles; and (4) mobilization of cobbles. Results of the study indicated a flushing flow of 56.6 m³ s^?1 occurring as a planned release or natural flow for from 1–3 days would be sufficient to transport sediment from spawning gravels. This flow was intermediate to levels which maximize surficial gravel flushing and levels which maximize surficial cobble flushing.