Inhibition of sediment erosion and phosphorus release by remediation strategy of contaminated sediment backfilling.

The management of sediment-water interfaces, especially bed stability, is essential for controlling accumulated contaminants in the sediment. In this study, the relationship between sediment erosion and phosphorus (P) release under the remediation strategy of contaminated sediment backfilling (CSBT) was explored through a flume experiment, i.e. the dredged sediment was calcined into ceramsite after dewatering and detoxification and then backfilled to the dredged area for sediment capping, thus avoiding the introduction of foreign materials via in-situ remediation and the large-scale land occupation associated with ex-situ remediation. Acoustic Doppler velocimeter (ADV) and optical backscatter sensor (OBS) were used to measure the vertical distributions of flow velocity and sediment concentration in the overlying water, respectively, and diffusive gradients in thin films (DGT) was used to measure the P distribution in the sediment. The results revealed that improving bed stability from CSBT can considerably improve the robustness of sediment-water interface and reduce sediment erosion by more than 70%. The corresponding P release from the contaminated sediment could be inhibited with an inhibition efficiency as high as 80%. CSBT is a potent strategy for managing contaminated sediment. This study provides a theoretical reference for controlling sediment pollution, further supporting river and lake ecological management and environmental restoration.

Combining Ozonated Autohemotherapy with Pharmacological Therapy for Comorbid Insomnia and Myofascial Pain Syndrome: A Prospective Randomized Controlled Study.

Objective: To examine the efficacy and safety of ozonated autohemotherapy (O3-AHT) combined with pharmacological therapy for comorbid insomnia and myofascial pain syndrome (MPS). Materials and Methods: One hundred and eighteen patients were randomly divided into two groups: the control group (N = 50) and the O3-AHT group (N = 53). Patients in both groups were given the same pharmacological management for three weeks. Patients in the O3-AHT group were treated with ozonated autohemotherapy (the concentration of ozone was 20 µg/ml in the first week, 30 µg/ml in the second week, and 40 µg/ml in the third week) combined with pharmacological therapy. Primary (the insomnia severity index (ISI) and visual analogue scale (VAS)) and secondary outcomes (the Epworth sleepiness scale (ESS), polysomnography data, the anxiety and preoccupation about sleep questionnaire (APSQ), the beck depression index (BDI), and the multidimensional fatigue inventory (MFI)) were examined at pretreatment, posttreatment, 1 month, and 6 months. Results: Fifty patients in the control group and fifty-three patients in the O3-AHT group completed the study. In both groups, insomnia and pain symptoms were relieved significantly compared with pretreatment. Compared with the control group, the O3-AHT group had significantly improved sleep quality, pain, and negative mood at different time points. No adverse complications were observed in either group. Conclusion: Compared with pharmacological therapy alone, ozonated autohemotherapy combined with pharmacological therapy can ameliorate insomnia, reduce pain intensity, improve negative mood, and alleviate fatigue more effectively without serious adverse complications.

Phosphorus adsorption by sediment considering mineral composition and environmental factors.

Sediment, composed of a complex assemblage of minerals, controls the fate and behaviour of P in aqueous environments and affects trophic status. In this study, P adsorption was studied on minerals including quartz, hematite, potassium feldspar, montmorillonite, kaolin, and calcite (i.e., the main components of sediment) and sediment from the Guanting Reservoir. A general formula for P adsorption was proposed that considers mineral composition through the component additivity method, also incorporating the effects of environmental factors, including the aqueous P concentration (Ce), pH, sediment concentration (S), and ionic strength (IS). The P adsorption capacity gradually decreased with increasing particle size, and the contributions from kaolin and montmorillonite to P adsorption were significant despite representing only a small fraction of sediment (with a maximum amount of P adsorption of 0.92 and 0.36 mg/g, respectively). The content of quartz accounted for approximately 40-60% of sediment; however, its P adsorption capacity was only 0.13 mg/g. These minerals exhibited different adsorption characteristics due to their different surface morphologies and lattice structures. Multivariable regression analysis was used to show that the amount of P adsorption was strongly correlated with Ce, followed by S, IS, and pH.

Effects of hydrodynamic on the mobility of phosphorous induced by sediment resuspension in a seepage affected alluvial channel.

The phosphorus (P) mobility caused by sediment resuspension was investigated in a tilting flume, considering the important effect of upward seepage. The water level and velocity were observed during the experimental run, and water samples were collected for the measurement of sediment and P concentrations. A lower value of P and sediment concentrations occurred at the upstream end of the test section, and then a stable trend was gradually observed towards the downstream end due to the sediment resuspension and deposition within the test section. A lower P release was identified for the seepage run, accompanied with a lower sediment concentration in the overlying water. These phenomena were directly linked with the turbulent flow characteristics such as time-averaged velocity, Reynolds shear stresses, and turbulence intensity. Results show that the level of turbulence decreased with the upward seepage, indicating lower P and sediment concentrations. The turbulent length scale also decreased with the upward seepage, which led to a decrease in the energy and momentum transfer induced by the larger eddy size in the near-bed region, and eventually, a lower rate of sediment resuspension and P release with upward seepage. The results of the present study are useful for civil or hydraulic engineers since the knowledge of P transport with sediment will improve the management of contaminated sediment in seepage affected alluvial channel.

Effects of internal loading on phosphorus distribution in the Taihu Lake driven by wind waves and lake currents.

Wind-driven sediment resuspension exerts significant effects on the P behavior in shallow lake ecosystems. In this study, a comprehensive dynamic phosphorus (P) model that integrates hydrodynamic, wind wave and sediment transport is proposed to assess the importance of internal P cycling due to sediment resuspension on water column P levels. The primary contribution of the model is detailed modeling and rigorous coupling of sediment and P dynamics. The proposed model is applied to predict the P behavior in the shallow Taihu Lake, which is the third largest lake in China, and quantitatively estimate the effects of wind waves and lake currents on P release and distribution. Both the prevailing southeast winds in summer and northwest winds in winter are applied for the simulation, and different wind speeds of 5 m/s and 10 m/s are also considered. Results show that sediment resuspension and the resulting P release have a dominant effect on P levels in Taihu Lake, and likely similar shallow lakes. Wind-driven waves at higher wind speeds significantly enhance sediment resuspension and suspended sediment concentration (SSC). Total P concentration in the water column is also increased but not in proportion to the SSC. The different lake circulations resulting from the different prevailing wind directions also affect the distribution of suspended sediment and P around the lake ultimately influencing where eutrophication is likely to occur. The proposed model demonstrates that internal cycling in the lake is a dominant factor in the lake P and must be considered when trying to manage water quality in this and similar lakes. The model is used to demonstrate the potential effectiveness of remediation of an area where historical releases have led to P accumulation on overall lake quality.

Phosphorus adsorption on natural sediments with different pH incorporating surface morphology characterization.

Sediment samples from University Lake (U.L.) and Anacostia River (A.R.) were collected to study the phosphorus (P) adsorption with pH at 3.65, 4.75, and 5.65. The surface micro-morphology and pore structures of sediment particles were obtained using a scanning electron microscopy and gas adsorption method, respectively. Fourier analysis was then applied to approximate the surface morphology, which was incorporated into the Langmuir isotherm to directly derive the model parameters for P adsorption simulation. Meanwhile, an empirical function of pH was introduced to represent the pH effect on P adsorption. A stronger P adsorption was observed for the A.R. sediment due to the more clay minerals, smaller median diameter, and a greater percentage of large pores, and the increasing pH resulted in a decrease of adsorption equilibrium constant as well as the P adsorption capacity, which was well reproduced by the adsorption isotherms. This study would benefit the mechanism study of the interactions between sediment particles and pollutants, providing references for understanding the pollutants' transport in aqueous systems.

Mathematical model for interactions and transport of phosphorus and sediment in the Three Gorges Reservoir.

Phosphorus fate and transport in natural waters plays a crucial role in the ecology of rivers and reservoirs. In this paper, a coupled model of hydrodynamics, sediment transport, and phosphorus transport is established, in which the effects of sediment on phosphorus transport are considered in detail. Phosphorus adsorption is estimated using a mechanistic surface complexation model which is capable of simulating the adsorption characteristics under various aquatic chemistry conditions. The sediment dynamics are analyzed to evaluate the deposition and release of phosphorus at the bed surface. In addition, the aerobic layer and anaerobic layer of the sediments are distinguished to study the distribution of phosphorus between dissolved and particulate phases in the active sediment layer. The proposed model is applied to evaluate the effects of various operating rules on sediment and phosphorus retention in the Three Gorges Reservoir (TGR). Results show that the proposed model can reasonably reflect the phosphorus transport with sediment, and management scenarios that influence sediment retention will also influence the phosphorus balance in the TGR. However, modest operational changes which have only minor effects on sediment retention also have limited influence on the phosphorous balance.

Mobility of phosphorus induced by sediment resuspension in the Three Gorges Reservoir by flume experiment.

The mobility of phosphorus (P) induced by sediment resuspension have been examined in a circulated flume. During the flume run, the water level and velocity were monitored, and water samples were taken for measurement of sediment and P concentrations. Peak values of both the P and sediment concentrations existed at x=4m, and then decreased slightly along the flume due to deposition. A faster P release was observed for coarser sediment, while a more sustained P release for finer sediment. Combining with the measured data from Yangtze River and sorption experiment, the relation between the load of total P (LTP) and sediment load (Qs) was estimated, and the expressions of distribution coefficient Kd and the concentration of particulate P (PP) were obtained. This study established a bridge between the small-scale sorption experiment and the field observation of natural scale, providing references for the management of contaminated sediment in natural rivers.