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1.
Influence of wave on sediment resuspension and nutrients release from sediments, collected from Lake Taihu and Lake Chaohu, was studied in flume experiments. Under strong-wave conditions, concentrations of suspended solids (SS), total phosphorus (TP) and dissolved total phosphorus (DTP) in overlying water were increased significantly following the sediments re-suspension. During the experiments on sediments of Lake Taihu and Lake Chaohu, TP concentrations increased 6 times and 3 times, and DTP concentration increased 100% and 70% more than it in presuspension, respectively. Concentration of soluble reactive phosphorus (SRP) of experiment on sediment of Lake Taihu increased 25%. During the massive sediment suspension, the dissolved phosphorus in pore water and much of the phosphorus adsorbed by the sediment particles were released into overlying water. The phenomena in this wave flume experiment are quite similar to the situation observed in situ of Lake Taihu. The critical wave stresses of sediment re-suspension are nearly equal. The change of concentrations of SS, TP, and SRP was the same as that in situ situation. This study showed that concentrations of TP and SRP in lake water could be increased significantly by wave disturbance. Phosphorus release was significantly enhanced by wave disturbance at the beginning of massive sediment re-suspension, but decreased later.  相似文献   

2.
Influence of wave on sediment resuspension and nutrients release from sediments, collected from Lake Taihu and Lake Chaohu, was studied in flume experiments. Under strong-wave conditions, concentrations of suspended solids (SS), total phosphorus (TP) and dissolved total phosphorus (DTP) in overlying water were increased significantly following the sediments re-suspension. During the experiments on sediments of Lake Taihu and Lake Chaohu, TP concentrations increased 6 times and 3 times, and DTP concentration increased 100% and 70% more than it in presuspension, respectively. Concentration of soluble reactive phosphorus (SRP) of experiment on sediment of Lake Taihu increased 25%. During the massive sediment suspension, the dissolved phosphorus in pore water and much of the phosphorus adsorbed by the sediment particles were released into overlying water. The phenomena in this wave flume experiment are quite similar to the situation observed in situ of Lake Taihu. The critical wave stresses of sediment re-suspension are nearly equal. The change of concentrations of SS, TP, and SRP was the same as that in situ situation. This study showed that concentrations of TP and SRP in lake water could be increased significantly by wave disturbance. Phosphorus release was significantly enhanced by wave disturbance at the beginning of massive sediment re-suspension, but decreased later.  相似文献   

3.
Estimation of internal nutrient release in large shallow Lake Taihu,China   总被引：1，自引：0，他引：1  
Based on field investigation of wave, sediment suspension and the changes in nutrient concentration of the water column in Lake Taihu, China, we proposed two release models to quantify nutrient release under static and dynamic conditions, respectively. Under static conditions, nutrient release from sediments to the overlying water mainly depends on chemical diffusion induced by concentration gradient, in which the nutrient release is controlled by the temperature, dissolved oxygen concentration in the sediment-water interface, oxidation-reduction potential and the concentration difference between porewater and overlying water. Under dynamic condition (or disturbed condition), both dissolved and particulate nutrients in sediments are released into the water column because of wind-induced sediment suspension. The amount of nutrient release under dynamic conditions is larger than that under the static condition. The release of dissolved nutrients, however, does not increase because the wind induced turbulence made oxidation of metallic elements such as Fe (ferric iron), Mn which are capable of precipitating soluble reactive phosphate (SRP). Under dynamic conditions, therefore, the release of total phosphorus (TP) increases dramatically but the release of SRP is close to those under static conditions. In sediments of Lake Taihu, high Fe content leads to a high ratio of Fe to P contents in sediments (Fe:P ratio). Under dynamic conditions, therefore, nutrient release is controlled by the intensity of disturbance, sediment consolidation and nutrient content in sediments. As for dissolved nutrients, especially SRP, the release is also controlled by the intensity of dynamic re-oxidation, Fe content in sediments and nutrient concentration gradient between porewater and overlying water. Based on these two release modes, the release flux in Lake Taihu has been estimated. In the static condition (i.e. laboratory experimental condition), total release of NH4 +-N for whole lake is ca. 10,000 ton/a, and PO4 3?-P is ca. 900 ton/a. In the dynamic condition, nutrient release following sediment suspension was estimated according to three different intensities of wind forcing which were defined as “calm” (wind speed is less than 2 m/s), “gentle” (wind speed is greater than 2 m/s and less than 6 m/s) and “gust” (wind speed is greater than 6 m/s). The release rate in the condition of “calm” was estimated in terms of the nutrient release in the laboratory experimental static condition; whereas the release rate in conditions of “gentle” and “gust” was estimated in terms of measurement during sediment resuspension conducted in flume experiments. With the observation of wind velocity and frequency in 2001, each type of wind forcing took the frequency of 12%, 82% and 6% for “calm”, “gentle” and “gust”, respectively. The yearly release of nitrogen was 81,000 ton and phosphorus was 21,000 ton, which is about 2–6 folds of annual external loading, respectively.  相似文献   

4.
The internal source, especially resuspension process of the sediments in lakes and its environ- mental effect has been paid shining attention in the West as well as in China[1—6] although the influence of external source is important to water environment[7]. S鴑dergaard et al. compared the releases of soluble reactive phosphorus (SRP) in the surface sediments of Lake Arres before and after disturbance and they found that disturbing can increase the release by 20—30 times[3]. Robarts and ot…  相似文献   

5.

Based on field investigation of wave, sediment suspension and the changes in nutrient concentration of the water column in Lake Taihu, China, we proposed two release models to quantify nutrient release under static and dynamic conditions, respectively. Under static conditions, nutrient release from sediments to the overlying water mainly depends on chemical diffusion induced by concentration gradient, in which the nutrient release is controlled by the temperature, dissolved oxygen concentration in the sediment-water interface, oxidation-reduction potential and the concentration difference between porewater and overlying water. Under dynamic condition (or disturbed condition), both dissolved and particulate nutrients in sediments are released into the water column because of wind-induced sediment suspension. The amount of nutrient release under dynamic conditions is larger than that under the static condition. The release of dissolved nutrients, however, does not increase because the wind induced turbulence made oxidation of metallic elements such as Fe (ferric iron), Mn which are capable of precipitating soluble reactive phosphate (SRP). Under dynamic conditions, therefore, the release of total phosphorus (TP) increases dramatically but the release of SRP is close to those under static conditions. In sediments of Lake Taihu, high Fe content leads to a high ratio of Fe to P contents in sediments (Fe:P ratio). Under dynamic conditions, therefore, nutrient release is controlled by the intensity of disturbance, sediment consolidation and nutrient content in sediments. As for dissolved nutrients, especially SRP, the release is also controlled by the intensity of dynamic re-oxidation, Fe content in sediments and nutrient concentration gradient between porewater and overlying water. Based on these two release modes, the release flux in Lake Taihu has been estimated. In the static condition (i.e. laboratory experimental condition), total release of NH4 +-N for whole lake is ca. 10,000 ton/a, and PO4 3−-P is ca. 900 ton/a. In the dynamic condition, nutrient release following sediment suspension was estimated according to three different intensities of wind forcing which were defined as “calm” (wind speed is less than 2 m/s), “gentle” (wind speed is greater than 2 m/s and less than 6 m/s) and “gust” (wind speed is greater than 6 m/s). The release rate in the condition of “calm” was estimated in terms of the nutrient release in the laboratory experimental static condition; whereas the release rate in conditions of “gentle” and “gust” was estimated in terms of measurement during sediment resuspension conducted in flume experiments. With the observation of wind velocity and frequency in 2001, each type of wind forcing took the frequency of 12%, 82% and 6% for “calm”, “gentle” and “gust”, respectively. The yearly release of nitrogen was 81,000 ton and phosphorus was 21,000 ton, which is about 2–6 folds of annual external loading, respectively.

  相似文献   

6.
选取典型表面流人工湿地——盐龙湖人工湿地为研究对象,通过对沉积物理化性质分析,湿地系统水动力模拟,风场与悬浮物(SS)再悬浮浓度关系的拟合及全年再悬浮对湿地净化效果的影响估算,探索表面流湿地沉积物在动力条件下的再悬浮特征及此过程中营养物质的再悬浮量.结果显示:0.3～0.5 m水深沉积物的理论起动流速在18.54～22.62cm/s之间,模拟得到湿地运行过程中水体流速最大值为1.62 cm/s,会远小于理论起动流速值,因此湿地内部流动产生的底部扰动难以形成湿地底泥的大规模再悬浮现象.但湿地内部仍存在一定的底泥再悬浮效应,风场扰动是主要影响因素,风场作用受植物影响显著,萌发期(3-4月)和收割期(11月-次年2月)再悬浮贡献量大于生长期(5-8月)与成熟期(9-10月),并且当风速4 m/s时再悬浮浓度明显增加.再悬浮浓度与运行水深也有关,0.3 m水深SS再悬浮浓度分别高出0.4 m和0.5 m水深12.48%和18.67%;高锰酸盐指数(CODMn)分别高出12.61%和19.52%;总氮(TN)分别高出248.12%和341.94%;总磷(TP)分别高出35.53%和43.48%.全年SS、CODMn、TN和TP再悬浮量分别达到2.8、0.47、0.15和0.011 kg/m2.  相似文献   

7.
太湖底泥悬浮中营养盐释放的波浪水槽试验   总被引：37，自引：9，他引：37       下载免费PDF全文
波浪水槽中研究了小波掀沙(波高8.77cm,波周期0.8s)和大波掀沙(波高12.31cm和13.29cm,波周期1.0s)对太湖沉积物悬浮及N、P营养盐释放的作用规律.结果显示:小波掀沙时,底泥并未发生大量悬浮,SS浓度最高时仅13.6mg/L;大波掀沙时,底泥大规模悬浮,SS浓度最高达达245.2mg/L水体悬浮物、营养盐浓度变化滞后波高变化1h以上.当波高改变1h后,水体悬浮物、N、P营养盐浓度才改变到相应的平衡浓度.除总磷浓度显著提高外,小波掀沙对水体N、P浓度的影响很小,大波掀沙则显著提高了水体总氮、总溶解氮、总磷、总溶解磷、氨氮(NH4 -N)、溶解性活性磷(SRP),其中NH4 -N、SRP最大增幅达30％和20％.小波和大波掀沙过程中,水体溶解氧浓度均持续增加,掀沙2h后增高2mg/L,溶解性有机碳持续下降,2h后下降33％-51％.试验结果表明,掀沙过程中水体充氧及颗粒物的絮凝、吸附作用可能是限制NH4 -N、SRP浓度增高的重要因素之一.  相似文献   

8.
Between 1999 and 2002, a former open-cast mine was filled with river water forming the recent Lake Goitsche. During filling initially acid water was neutralised. Phosphorus (P) imported from Mulde River was nearly completely removed from the water column by co-precipitation with iron (Fe) and aluminium (Al) and deposited in the sediment.During extremely high waters of the Mulde River in 2002, a dike breach facilitated a second high import of P into Lake Goitsche with suspended and dissolved matter. The analysis of total phosphorus (TP), however, showed that P again had been eliminated from the water body a few months after the flood event. Sediment investigations before filling with river water, during filling, and after the flood event were used to analyse the process of P immobilisation in a lake with acid mine drainage history.The ratios of Fe to soluble reactive P (SRP) of sediment pore water were up to three orders of magnitudes higher than in natural lakes and can serve as an indicator for potential internal P loading from sediments. The SRP concentrations at the oxic/anoxic boundary were near or below the limit of quantification (< 0.2 μmol/L). Fe and manganese (Mn) redox cycling were responsible for hindering P dissolution from sediment to lake water.Finally it can be stated, that the risk of eutrophication for such a lake seems to be low.  相似文献   

9.
为探讨水丝蚓(Tubificid worms)扰动对磷在湖泊沉积物-水界面间迁移的影响,选取太湖梅梁湾与大浦口两富营养化湖区为研究对象,通过室内培养实验,利用Rhizon间隙水采样器等技术,研究了水丝蚓扰动对太湖沉积物-水界面理化性质及溶解活性磷(SRP)在界面通量的影响.结果表明水丝蚓扰动能够增大表层沉积物含水率、氧化还原电位,减小间隙水中Fe2+浓度.水丝蚓没有显著改变梅梁湾间隙水中SRP浓度,同时促进了梅梁湾沉积物中SRP向上覆水的释放;但水丝蚓显著减小了大浦口间隙水中SRP浓度,并抑制了大浦口沉积物中SRP向上覆水的释放.水丝蚓扰动对磷在沉积物-水界面间迁移的不同影响可能是由沉积物中Fe2+含量差异较大造成的.  相似文献   

10.
东巢湖沉积物水界面氮、磷、氧迁移特征及意义   总被引：2，自引：0，他引：2  
以东巢湖近城市湖湾沉积物为研究对象,在沉积物氮、磷营养盐分析的基础上,采用沉积物柱状芯样静态释放模拟法定量评估研究区域沉积物—水界面氨氮、溶解性活性磷酸盐营养盐释放潜力,利用微电极非损伤测定技术获得沉积物—水微界面溶解氧(DO)剖面分布及微界面DO消耗和扩散特征.结果表明:东巢湖近城市湖湾沉积物氮、磷污染物蓄积量较高,受TN、TP污染程度较重.沉积物内源氨氮、磷酸盐释放明显,平均释放速率分别达到32.44 mg/(m~2·d)和1.25mg/(m~2·d),区域内沉积物已成为水柱中氮、磷营养盐的污染源.研究区域上覆水体处于好氧状态,沉积物—水微界面平均DO穿透深度(OPD)达到5.3 mm,平均DO扩散通量为4.56 mmol/(m~2·d),表现出良好的DO扩散能力.沉积物内源氨氮和磷酸盐释放能力与表层沉积物TN/TP物质含量及沉积物—水微界面DO穿透深度有关,在沉积物氮、磷污染较重的情况下,DO穿透深度越低越有利于氮、磷污染物从沉积物向上覆水体释放.  相似文献   

11.
2010-2017年太湖总磷浓度变化趋势分析及成因探讨   总被引：4，自引：0，他引：4  
近年来，太湖流域各省市政府加大治理力度，流域水体水质取得明显好转，氨氮浓度和总氮浓度呈大幅度下降趋势，然而太湖水体总磷浓度呈上升趋势.为探讨太湖总磷浓度升高的原因，采用太湖流域管理局2010年以来的水质水量实测数据、遥感监测数据等，分别从太湖入湖河流污染负荷量、水生植被和蓝藻与总磷浓度的关系3个方面进行相关性分析.结果表明，入湖河流总磷浓度高于太湖水体总磷浓度，且磷不易出湖，逐年总磷净入湖量持续累积与太湖总磷浓度有明显的正相关性，入湖污染负荷量大是太湖总磷浓度居高不下的根本原因；水生植被可吸收湖泊沉积物中的营养盐，并抑制底泥再悬浮从而降低内源性营养盐的释放，东太湖水生植被的大量减少，一方面减少了沉水植物对磷元素的吸收，另一方面增加了风浪对底泥的扰动再悬浮，造成磷元素释放，是造成湖水总磷浓度升高的重要因素；近年来太湖蓝藻密度呈上升趋势，受其影响，总磷浓度也有上升，蓝藻水华加快湖体磷循环，藻类密度增加也是太湖总磷浓度升高的影响因素之一.  相似文献   

12.
菹草、伊乐藻对沉积物磷形态及其上覆水水质的影响   总被引：3，自引：1，他引：2  
采集武昌南湖湖水、沉积物进行沉水植物的盆栽试验,试验设置沉积物未施磷处理和施100mg/kg磷处理,分别对应沉积物低内源磷和高内源磷状态,同时种植菹草、伊乐藻,以研究沉积物中磷形态及上覆水水质的变化特点.研究从2007年9月15日开始,历时160d.结果表明,高内源磷沉积物处理后,上覆水中水溶性总磷含量在沉水植物的作用下明显降低;种植沉水植物可使水体总磷、总氮、叶绿素a含量显著降低,且伊乐藻对总磷的净化效果优于菹草;沉水植物对高内源磷沉积物的上覆水中叶绿素a的控制比对低内源磷条件下的效果更好;无论沉积物是否输入磷,在盆栽条件下,上覆水中叶绿素a随时间的变化均能较好地用一级动力学模型来描述;上覆水TDP、TP与沉积物中Ca_(10)-P之间有极显著正相关;种植菹草或伊乐藻的沉积物中Ca_(10)-P与上覆水中TDP和TP的相关系数分别为0.990(P≤0.01)和0.977(P≤0.05).  相似文献   

13.
Lake metabolism scales with lake morphometry and catchment conditions   总被引：1，自引：0，他引：1  
We used a comparative data set for 25 lakes in Denmark sampled during summer to explore the influence of lake morphometry, catchment conditions, light availability and nutrient input on lake metabolism. We found that (1) gross primary production (GPP) and community respiration (R) decline with lake area, water depth and drainage ratio, and increase with algal biomass (Chl), dissolved organic carbon (DOC) and total phosphorus (TP); (2) all lakes, especially small with less incident light, and forest lakes with high DOC, have negative net ecosystem production (NEP < 0); (3) daily variability of GPP decreases with lake area and water depth as a consequence of lower input of nutrients and organic matter per unit water volume; (4) the influence of benthic processes on free water metabolic measures declines with increasing lake size; and (5) with increasing lake size, lake metabolism decreases significantly per unit water volume, while depth integrated areal rates remain more constant due to a combination of increased light and nutrient limitation. Overall, these meta-parameters have as many significant but usually weaker relationships to whole-lake and benthic metabolism as have TP, Chl and DOC that are directly linked to photosynthesis and respiration. Combining water depth and Chl to predict GPP, and water depth and DOC to predict R, lead to stronger multiple regression models accounting for 57–63% of the variability of metabolism among the 25 lakes. It is therefore important to consider differences in lake morphometry and catchment conditions when comparing metabolic responses of lakes to human impacts.  相似文献   

14.
Large lakes enclosures were used to examine the influence of nutrient (P, N) enrichment and planktivorous fish (1 + yellow perch) predation on hypolimnetic oxygen depletion. Results were compared to similar data for lakes with high (Lake St. George) and low (Haynes Lake) abundances of planktivorous fish. In both the unfertilized and fertilized enclosures, fish predation on large cladocerans increased the biomasses of pico- and nanoplankton (0.2–20 µm), phytoplankton (chlorophyll a) and total phosphorus (TP), reduced sedimentation, water clarity, and hypolimnetic oxygen concentrations (AHO). Fertilized enclosures without fish had highest TP and sedimentation rates, but the AHO were low. The high planktivore lake had higher pico- and nanoplankton, higher chlorophyll a, reduced water clarity, and lower AHO than the low planktivore lake. Areal hypolimnetic oxygen depletion (AHOD) rates were strongly related with Secchi depth and plankton size-distribution (r 2 = 0.77, and 0.79, respectively), but not as strongly with TP, chlorophyll a, and sedimentation rates (r 2 = 0.25, 0.53, and 0.02, respectively). Such observations are useful in forming a generalized hypothesis that lakes with low planktivory and high water clarity have lower oxygen depletion because 1) plankton that are settling are larger and spend less time in the hypolimnetic water column before reaching the sediment, and therefore undergo less decomposition, and 2) the euphotic depth extends into the hypolimnion and production of oxygen can take place.  相似文献   

15.
基于2019年夏季(8月)对岱海水样的实测数据分析,通过运用克里金插值、相关性分析、多元线性逐步回归、主成分分析方法,探究了叶绿素a(Chl.a)的空间分布特征及其与水环境因子的相关关系,并讨论了相应的防治措施。研究显示:Chl.a空间分布呈现由岸边向湖心递减的趋势,总氮(TN)、总磷(TP)、氨氮(NH3-N)、硝态氮(NO-3-N)、正磷酸盐(PO3-4-P)空间分布特征与Chl.a空间分布特征相近,采样期内岱海湖局部区域水质状况已达到富营养状态;Chl.a与浊度(Turbidity)、TP、TN、悬浮物(SS)、pH、NO-3-N、NH3-N、PO3-4-P、蓝绿藻丰度(CYANO)呈极显著正相关,与溶解氧(DO)呈显著负相关,与电导率(Cond.)呈正相关、与氮磷比(TN/TP)呈负相关;各湖区Chl.a与环境因子相关关系不同,全湖逐步线性回归方程为YChl.a=-21.42+8.658XpH-0.865XDO+0.779XNH3-N+0.699XTurbidity+0.502XCYANO;岱海不同湖区因子对Chl.a浓度的影响存在差异,各湖区Chl.a与环境因子相关关系不同,通过岱海与我国其他湖泊Chl.a与环境因子的相关性关系对比分析,湖泊地理属性差异及营养物质输入浓度是影响Chl.a变化的重要因素;本研究岱海的TN/TP平均值为12.23,说明夏季岱海湖Chl.a变化为氮磷共同限制。  相似文献   

16.
Two adjacent bays in a large oligotrophic lake (Georgian Bay, Lake Huron) were compared to determine how the inputs from relatively pristine, but moderately humic, tributaries may influence phytoplankton, nutrients and system metabolism. Dissolved organic carbon (DOC) concentrations decreased from 4 to 5 gC m?3 at inner sites to 2 gC m?3 or less at outer sites. The concentration gradient from inner to outer was greater in the bay with a major tributary, and optical properties (intensity and slope of light absorption spectrum) showed there was a loss of material with allochthonous characteristics along the gradient. Chlorophyll a (Chl a) and total phosphorus (TP) were also higher at inner (2–4 mg Chl a m?3 and 8–12 mgP m?3, respectively) than outer sites (≤1 mg Chl a m?3 and 4–5 mgP m?3). Chl a and TP, as well as particulate nutrient ratios (C:P, C:N, N:P), indicated significant eutrophication at inner sites, especially in the bay with the tributary, and there was a strong positive Chl a-phosphorus relationship. The stable oxygen isotope ratio (18O:16O) of dissolved oxygen indicated greater influence of biological oxygen fluxes at inner sites (where ratios were 2–3 ppt below atmospheric equilibrium) than at outer sites (where ratios were within 0.5 ppt of equilibrium). Community photosynthesis:respiration ratios inferred from 18O:16O varied positively with Chl a and inorganic nutrients, but negatively with DOC. Altered loading of allochthonous organic matter can be expected under changing climate and development scenarios and will have significant influence on optical properties and system metabolism through changes in DOC in this coastal system. The effects will nonetheless be strongly modulated by any accompanying change in inorganic nutrients.  相似文献   

17.
Estimation of internal nutrient release in large shallow Lake Taihu, China   总被引：17，自引：2，他引：17  
Based on field investigation of wave, sediment suspension and the changes in nutrient concentration of the water column in Lake Taihu, China, we proposed two release models to quantify nutrient release under static and dynamic conditions, respectively. Under static conditions, nutrient release from sediments to the overlying water mainly depends on chemical diffusion induced by concentration gradient, in which the nutrient release is controlled by the temperature, dissolved oxygen concentration in the sediment-water interface, oxidation-reduction potential and the concentration difference between porewater and overlying water. Under dynamic condition (or disturbed condition), both dissolved and particulate nutrients in sediments are released into the water column because of wind-induced sediment suspension. The amount of nutrient release under dynamic conditions is larger than that under the static condition. The release of dissolved nutrients, however, does not increase because the wind induced turbulence made oxidation of metallic elements such as Fe (ferric iron), Mn which are capable of precipitating soluble reactive phosphate (SRP). Under dynamic conditions, therefore, the release of total phosphorus (TP) increases dramatically but the release of SRP is close to those under static conditions. In sediments of Lake Taihu, high Fe content leads to a high ratio of Fe to P contents in sediments (Fe:P ratio). Under dynamic conditions, therefore, nutrient release is controlled by the intensity of disturbance, sediment consolidation and nutrient content in sediments. As for dissolved nutrients, especially SRP, the release is also controlled by the intensity of dynamic re-oxidation, Fe content in sediments and nutrient concentration gradient between porewater and overlying water. Based on these two release modes, the release flux in Lake Taihu has been estimated. In the static condition (i.e. laboratory experimental condition), total release of NH4 -N for whole lake is ca. 10,000 ton/a, and PO43--P is ca. 900 ton/a. In the dynamic condition, nutrient release following sediment suspension was estimated according to three different intensities of wind forcing which were defined as "calm" (wind speed is less than 2 m/s), "gentle" (wind speed is greater than 2 m/s and less than 6 m/s) and "gust" (wind speed is greater than 6 m/s). The release rate in the condition of "calm" was estimated in terms of the nutrient release in the laboratory experimental static condition; whereas the release rate in conditions of "gentle" and "gust" was estimated in terms of measurement during sediment resuspension conducted in flume experiments. With the observation of wind velocity and frequency in 2001, each type of wind forcing took the frequency of 12%, 82% and 6% for "calm", "gentle" and "gust", respectively. The yearly release of nitrogen was 81,000 ton and phos- phorus was 21,000 ton, which is about 2-6 folds of annual external loading, respectively.  相似文献   

18.
太湖不同湖区底泥悬浮沉降规律研究及内源释放量估算   总被引：5，自引：1，他引：4  
胡开明  王水  逄勇 《湖泊科学》2014,26(2):191-199
太湖是一个大型浅水湖泊,湖湾、沿岸及湖心等区域受地形影响,湖流结构及水土界面水力要素均有显著差异.针对目前对不同湖区底泥再悬浮规律差异性研究的缺失,本研究选取了3个具有代表性的点采集太湖底泥,采用矩形水槽开展底泥再悬浮模拟实验,并结合太湖二维水量水质模型及太湖全年实测数据,建立了不同湖区底泥再悬浮通量与风速之间的定量关系;通过室内静沉降实验,得到了静沉降通量与风速的相关关系;最后将底泥再悬浮实验结果参数化应用于太湖二维水量水质模型中,并对底泥悬浮沉降过程进行分解和概化,估算太湖全年内源释放量.结果表明:太湖每日的内源释放量受风速影响显著,和风速变化趋势较为接近,太湖全年进入水体的净底泥量有47.81×104t,夏季最大,冬季次之;就营养物质释放量而言,COD约为2.06×104t、总氮约为1149.05 t、总磷约为564.35 t,其中秋季营养物质释放量最小,夏季最大.  相似文献   

19.
Periodical algal blooms result in deposition and release of phosphorus (P) from the sediment into the water. Therefore, during seasonal changes when algal particles begin to settle to the bottom, understanding the behavior and distribution characteristics of the P in sediment is the most important key to manage the water quality of the Saemangeum Reservoir. In this study, the variation of water quality and sediment composition including chlorophyll-a (Chl-a) and P was investigated to determine the interaction between water and sediment. The study focused primarily on algal particle sedimentation that affects the P release and mineralization of sediment. The Chl-a concentration in water showed a sharp decline in October when the algae began to die in the fall, and afterward the concentration of chemical oxygen demand (COD) and total P (TP) in the sediment increased due to the sedimentation of decaying algal particles in November. During the same period of time, the readily bio-available P (RAP) in the sediment showed a drastic increase in the upper region where the Chl-a concentration of water was high. In sequence, the high RAP zone shifted from the upper region to the lower region in the early winter. The RAP shift was considered to be derived from the physical flow of the overlying water from which the decomposing algae settled on the surface of the sediment. The Saemangeum Reservoir was constructed recently; therefore, all the types of inorganic P fractions except soluble reactive phosphorus (SRP) that exist on the bottom surface of the lake and the marsh's sediment layer were not sufficient to significantly influence the overlying water. On the other hand, the released P from the algae was distinct and sensitive to the seasonal change. In conclusion, the algal particle sedimentation was important to control eutrophication rather than P release from the mineralized inorganic P of the sediment surface layer in the Seamangeum Reservoir.  相似文献   

20.
In 2007/08, a study was undertaken on the sediment dynamics in shallow Lake Markermeer (the Netherlands). Firstly, sediment characteristics were determined at 49 sites in the lake. Parameters such as median grain size and loss on ignition showed a spatial as well as water depth related pattern, indicating wind-induced sediment transport. Highly significant correlations were found between all sediment parameters. Lake Markermeer sediment dynamics were investigated in a sediment trap field survey at two permanent stations in the lake. Sediment yields, virtually all coming from sediment resuspension, were significantly correlated with average wind speeds, though periods of extreme winds also played a role. Sediment resuspension rates for Lake Markermeer were high, viz. on average ca. 1,000 g m−2 day−1. The highly dynamic nature of Lake Markermeer sediments must be due to the overall shallowness of the lake, together with its large surface area (dynamic ratio = [√(area)]/[average depth] = 7.5); wind-induced waves and currents will impact most of the lake’s sediment bed. Indeed, near-bed currents can easily reach values >10 cm/s. Measurements of the thickness of the settled “mud” layer, as well as 137Cs dating, showed that long-term deposition only takes place in the deeper SE area of the lake. Finally, lake sediment dynamics were investigated in preliminary laboratory experiments in a small “micro-flume”, applying increasing water currents onto five Lake Markermeer sediments. Sediment resuspension started off at 0.5–0.7 cm/s and showed a strongly exponential behaviour with respect to these currents.  相似文献   

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