Model For Sediment Resuspension Research Articles

Physical and compositional characteristics of drinking water storage tank sediment

AbstractThirty‐one drinking water storage tank sediment samples were collected in 13 states, 17 distribution systems, and 29 tanks over the course of 4 years. Sediment samples were characterized for elemental composition and physical properties, which were found to be inconsistent both between samples of the same distribution system and across geographical regions. Differences between samples from the same tank also indicated spatial differences in sediment composition within storage tanks. Color was found to qualitatively trend toward darker or lighter depending on the concentration of a few elements (iron, aluminum, calcium, and magnesium). Particle shape varied between samples though uniformity increased as the particle size decreased. The average sediment particle density in this study (1.99 g/cm3) was lower than the density of a widely used sediment resuspension model silica sand (2.65 g/cm3), possibly resulting in underestimation of resuspension in models. This study suggests that sediment properties are highly site and storage tank specific, necessitating individual characterization to achieve greatest accuracy in storage tank suspension and draining model inputs.

Tracking of realistic nanoplastics in complicated matrices by iridium element labeling and inductively coupled plasma mass spectroscopy

Herein, we proposed a protocol to track realistic nanoplastics (NPs) by labeling them with an iridium-containing organic molecular agent (denoted as Ir) followed by inductively coupled plasma mass spectroscopy detection, as exemplified by polyethylene terephthalate (PET) NPs prepared from water bottles. The Ir showed satisfactory labeling stability in typical environmental and biological matrices. After 3d’s incubation, the leaching ratios were less than 3% in water, phosphate buffered saline, sea water, cell culture medium, artificial gastric juice, artificial intestinal fluid, sediment resuspension, and around 5% in fetal bovine serum. On this basis, in vivo distribution of PET NPs in mice was analyzed. The intravenously injected NPs widely distributed in liver, spleen, lung and kidney. Comparatively, NPs could hardly be detected in these organs after intragastric administration, suggesting that they could not penetrate the intestinal barriers. The temporal and spatial distribution of the NPs in an intertidal zone sediment resuspension model was also investigated. The NPs mostly deposited at the overlying deposit, implying the absorption-driven sinking behavior of NPs with natural organic matters. This work provided an effective way to quantitatively track realistic NPs, which could promote the understanding of the fate and effect of NPs in natural environments and organisms.

Effect of stem-generated turbulence on sediment resuspension within rigid vegetation canopies in waves

浅水湖泊沉积物再悬浮过程促进了沉积物内源性物质的释放，造成湖泊水体内源污染，加剧湖泊水质污染与生态恶化.开展刚性植被不同分布格局下的沉积物再悬浮水槽试验，能为浅水草型湖泊、滨海湿地等水环境治理与生态修复提供理论参考.本研究通过开展实验室波浪水槽试验，检验了3种直径12种密度的刚性模型植被对波浪扰动白洋淀沉积物再悬浮的影响，通过测定不同植被情景不同波浪条件下的瞬时速度和沉积物再悬浮浓度，详细阐述了植被产生的紊动能对沉积物再悬浮临界状态的影响，构建并验证了沉积物再悬浮植被紊流模型，预测了沉积物再悬浮的临界速度，为湿地生态恢复与保护提供参考.结果表明：1）植被的存在能有效增加近床面的紊动能；2）紊动能是控制沉积物再悬浮的关键性因素；3）沉积物再悬浮的临界波速与植被的固相体积分数相关.;Sediment resuspension in shallow lakes promotes the nutrients release, which leads to the internal pollution, degrading the water quality and lake ecology. This research aims to study the impact of rigid vegetation on wave-driven sediment resuspension through wave flume experiments. It could provide a theoretical reference for environmental management and ecological restoration of shallow lakes and coastal wetlands. Vegetation canopies were constructed by rigid cylinders considering three diameters and 12 vegetation densities. The near-bed instantaneous velocity was measured within vegetation canopies and under different wave conditions by a Nortek Vectrino at sampling rate of 200 Hz. Suspended sediment concentrations were measured using an optical backscatter with frequency of 20 Hz. The vegetation-generated turbulence was positively linear with the root mean square of wave velocity. This vegetated turbulence increased with an increasing ratio (A_w/S) of wave excursion (A_w) to stem spacing (S) when A_w/S>1, and was similar with bare bed case when A_w/S<1. The concentration of sediment resuspension increased with growing solid volume fraction. The critical state of resuspension was initiated when the suspended sediment concentration exceeded the background level. Higher solid volume fraction generated higher turbulence, which promoted a small critical wave velocity. A vegetation-generated turbulence model for sediment resuspension was proposed and validated using the measured turbulence in the model canopy. Therefore, we confirmed that the magnitude of stem-generated turbulence is a function of solid volume fraction. This model proved the key role of turbulent kinetic energy to control the initial sediment resuspension. Based on this, a threshold model of critical velocity for sediment resuspension was proposed and validated. It could predict the critical near-bed wave velocity for sediment resuspension within rigid vegetation canopy or sheath with diameters of 0.32 cm to 1.2 cm. The applicable particle size was limited to 85-280 μm.

Increase in silicon concentrations and release from suspended solids and bottom sediments in Lake Kasumigaura, Japan

Increasing trends of dissolved Si measured by a colorimetric method and ICP (DSicol and DSiICP, respectively) and total Si concentrations were detected at the center of Lake Kasumigaura during 1980–2006 (mean DSicol concentration in the 1980s and 2000s was 1.3 and 4.0 mg l−1, respectively). The observation of such trends is rare; therefore, the elucidation of the causes could be useful to understanding silicon dynamics in inland waters. Based on statistical analysis, we found that the increases in DSicol and lithogenic Si accounted for most of the total Si increase (44 and 45%, respectively) and that biogenic Si, consisting of diatom frustules, also increased with them. Increases in DSiICP concentration were not detected near the mouth of the inflowing rivers, suggesting that the increase was caused by in-lake processes. Because the increase in suspended solids (SS) caused by sediment resuspension had been observed in the lake for the same period, we assumed that the Si release from SS containing diatom frustules contributed to the increase. The results of the laboratory experiments in which surface sediments were stirred in lake waters showed that the change in DSicol concentration depended mainly on SS concentration, water temperature and the elapsed time of diatom frustules dissolution. An estimation of the released amount of Si from SS using the sediment resuspension model was (1.0–2.7) × 109 g year−1 in the 2000s, which was about 30–90% of the increase in the DSicol outflow of 3.0 × 109 g year−1 from the 1980s to the 2000s. We also determined the Si release rates from bottom sediments through laboratory experiments. The Si amount released from bottom sediments in the lake in the 2000s was estimated to be 4.3 × 109 g year−1, which was about 2–4 times higher than the estimated Si amount released from SS. These findings suggest that the sediment resuspension might be the cause of the latest DSi increase.

Modeling linkages between sediment resuspension and water quality in a shallow, eutrophic, wind-exposed lake

The interactions between bed sediments and the water column in shallow, eutrophic lakes have tremendous implications for the fate and transport of nutrients in those water bodies. This has resulted in the development of water quality models for lakes incorporating the processes of sediment resuspension. Reliable resuspension models are thus needed to accurately represent this phenomenon. In this paper, three different sediment-resuspension models are combined with a hydrodynamic and water quality model, dynamic lake model-water quality (DLM-WQ), and the resulting models are used to simulate nutrient distributions in the highly eutrophic Salton Sea, California, USA. One of the resuspension formulas is based upon sediment characteristics as well as the bed shear stress exerted by wind-induced waves and currents, while the other two are standard, power-law-type formulas for cohesive sediments with two different exponents. The outputs for water quality variables, such as temperature, chlorophyll a, dissolved oxygen and nutrients, obtained from the three resulting models and from an earlier DLM-WQ run with a simple empirical sediment-resuspension model are compared with measured data. The level of agreement between the simulations and the measured data is assessed by using both statistical and graphical model evaluation methods, including measures of residual errors, sample autocorrelations, t-tests, and box plots. Based on these assessments, DLM-WQ with an extended version of the García and Parker [García, M.H., Parker, G., 1993. Experiments on the entrainment of sediment into suspension by a dense bottom current. J. Geophys. Res.-Oceans 98, 4793–4807] relationship gave the best results for water quality in the Salton Sea, confirming that the use of formulas with more information on the sediment characteristics yields more accurate results. To the best of our knowledge, this is the first effort to combine water quality models for lakes and reservoirs with a sediment-resuspension model which was originally intended for open-channel flows. The simulations confirm that sediment resuspension is the most dominant process in the Salton Sea's nutrient cycling. The effect of proposed physical changes to the Salton Sea on water quality characteristics is also addressed.

Long term and high frequency monitoring of beam attenuation coefficient as a proxy for suspended particulate inorganic matter: use in the calibration of a sediment resuspension model

Long term and high frequency monitoring of beam attenuation coefficient as a proxy for suspended particulate inorganic matter: use in the calibration of a sediment resuspension model

Sediment Inclusions in Alaskan Coastal Sea Ice: Spatial Distribution, Interannual Variability, and Entrainment Requirements

We investigated the spatial characteristics of sedimentary inclusions and elucidated processes controlling their spatial and temporal variability in the fast ice cover of the shallow-marine environment of Elson Lagoon near Barrow, Alaska. This was accomplished by examining the frazil ice layer of sea-ice cores representing the 1998, 1999, and 2000 fall freeze-up periods and comparing the results with a sediment resuspension model. Sediments occur exclusively as aggregates of clay to fine-silt sized particles that were confined to brine inclusions in the frazil ice. The average cross-sectional area of these aggregates is positively correlated with sediment concentration of the frazil ice (R2 = 0.82, P < 0.01). The minimum distance between neighboring aggregates (nearest-neighbor distance) is negatively correlated with sediment concentration (R2 = 0.78, P < 0.01). However, little correlation exists between the number of aggregates and sediment concentration. Sediment concentrations ranged from 24 to 1470 mg L–1 and sediment loads ranged from 2 g m–2 to 384 g m–2, with 1998 and 2000 sediment loads being one to two orders of magnitude smaller than 1999 sediment loads. Similarly, the potential for bottom-sediment resuspension was greater in 1999 than in 1998 and 2000 by more than a factor of two. Resuspension potential is controlled spatially by the local bathymetry and interannually by wind velocity and fetch. At submeter scales, increases in bottom sediment resuspension result in greater sea-ice sediment concentrations, larger aggregates, and smaller nearest-neighbor distances.

Sediment Inclusions in Alaskan Coastal Sea Ice: Spatial Distribution, Interannual Variability, and Entrainment Requirements

We investigated the spatial characteristics of sedimentary inclusions and elucidated processes controlling their spatial and temporal variability in the fast ice cover of the shallow-marine environment of Elson Lagoon near Barrow, Alaska. This was accomplished by examining the frazil ice layer of sea-ice cores representing the 1998, 1999, and 2000 fall freeze-up periods and comparing the results with a sediment resuspension model. Sediments occur exclusively as aggregates of clay to fine-silt sized particles that were confined to brine inclusions in the frazil ice. The average cross-sectional area of these aggregates is positively correlated with sediment concentration of the frazil ice (R2 = 0.82, P < 0.01). The minimum distance between neighboring aggregates (nearest-neighbor distance) is negatively correlated with sediment concentration (R2 = 0.78, P < 0.01). However, little correlation exists between the number of aggregates and sediment concentration. Sediment concentrations ranged from 24 to 1470 mg L–1 and sediment loads ranged from 2 g m–2 to 384 g m–2, with 1998 and 2000 sediment loads being one to two orders of magnitude smaller than 1999 sediment loads. Similarly, the potential for bottom-sediment resuspension was greater in 1999 than in 1998 and 2000 by more than a factor of two. Resuspension potential is controlled spatially by the local bathymetry and interannually by wind velocity and fetch. At submeter scales, increases in bottom sediment resuspension result in greater sea-ice sediment concentrations, larger aggregates, and smaller nearest-neighbor distances.

An empirical model for sediment resuspension in shallow lakes

Suspended solids concentrations were measured at routine 2–3 week intervals and on additional windy days for at least one year in each of seven shallow (mean depth < 2 m) south Island, New Zealand lakes. Surface wave characteristics were estimated from water depths and local meteorological data using a shallow-water wave forecasting model for fetch-limited waves. Bottom shear stresses were computed from surface wave characteristics for the sampling stations and for a hypothetical lake-average station. The calculated shear stresses were, on average, much better predictors of suspended solids concentrations than alternative models using two different functions of wind speed, wave height2/depth or wavelength/depth. A combination of the sample station and lake average shear stresses provided slightly better predictions than the sample station values alone, suggesting that currents also contribute significantly to the concentration at a given point. Regressions of suspended solids on the combined functions had r 2 values ranging from 0.74–0.73 in the seven lakes. The slopes of these regressions were negatively related to the settling velocity of the lowest quartile of the sediment, and to macrophyte biomass, in multiple regression (r 2 = 0.94, p < 0.01).