scholarly journals Sediment Phosphate Release Flux Under Hydraulic Disturbances in the Shallow Lake of Chaohu, China

2021 ◽  
Author(s):  
Wenguang LUO ◽  
Yao Yue ◽  
Jing Lu ◽  
Lina Pang ◽  
Senlin Zhu
Keyword(s):  
Shallow Lakes ◽  
Release Rate ◽  
Surface Sediment ◽  
Shallow Lake ◽  
Chaohu Lake ◽  
Small Motion ◽  
Phosphate Release ◽  
Wide Range ◽  
Sediment Phosphate ◽  
Motion Mode

Abstract Quantifying the effect of hydraulic disturbances on sediment phosphate release is a key issue in the water quality assessment of lakes, especially for the shallow lakes which are susceptible to winds and waves. Here, we sampled the original sediment columns from 12 positions in the eastern, central, and western areas of the Chaohu Lake, a representative shallow lake in China, and observed phosphate release under three levels of hydraulic disturbances in the laboratory. When the disturbance was weak and the surface sediment of bottom mud moved individually (the Individual Motion Mode), sediment phosphate release rate was insignificant (0.24 mg/m2/d). When the disturbance was medium and only a small percentage (<16%) of surface sediment started to move (the Small Motion Mode), phosphate release rate sharply increased to 4.81 mg/m2/d. When the disturbance was further strengthened and most (≥16%) of the surface sediment moved (the General Motion Mode), phosphate release rate was more than doubled (10.23 mg/m2/d). With the increase of hydraulic disturbance intensity, the variation range of phosphate release also became wider. Spatial distribution showed that the release rate varies the most in the western area, followed by the eastern and the central areas. By extrapolating the experimental results to the real scale, we found the phosphate release fluxes would probably fall within a wide range between 203.43 kg/d to 7311.01kg/d under different levels of hydrodynamic disturbances with considerably affects phosphate release from shallow lakes. This study also has implications for the pollutant management in other shallow lakes.

Iron:phosphorus ratio in surface sediment as an indicator of phosphate release from aerobic sediments in shallow lakes

Hydrobiologia ◽  
1992 ◽  
Vol 235-236 (1) ◽  
pp. 731-743 ◽  
Author(s):  
H. S. Jensen ◽  
P. Kristensen ◽  
E. Jeppesen ◽  
A. Skytthe
Keyword(s):  
Shallow Lakes ◽  
Surface Sediment ◽  
Phosphate Release

Non-steady variations of SOD and phosphate release rate due to changes in the quality of the overlying water

2000 ◽  
Vol 42 (3-4) ◽  
pp. 265-272 ◽  
Author(s):  
T. Inoue ◽  
Y. Nakamura ◽  
Y. Adachi
Keyword(s):  
Release Rate ◽  
Oxygen Demand ◽  
Phosphate Concentration ◽  
Sediment Oxygen Demand ◽  
Biochemical Reactions ◽  
Overlying Water ◽  
Phosphate Release ◽  
Do Concentration ◽  
The Difference

A dynamic model, which predicts non-steady variations in the sediment oxygen demand (SOD) and phosphate release rate, has been designed. This theoretical model consists of three diffusion equations with biochemical reactions for dissolved oxygen (DO), phosphate and ferrous iron. According to this model, step changes in the DO concentration and flow velocity produce drastic changes in the SOD and phosphate release rate within 10 minutes. The vigorous response of the SOD and phosphate release rate is caused by the difference in the time scale of diffusion in the water boundary layer and that of the biochemical reactions in the sediment. Secondly, a negative phosphate transfer from water to sediment can even occur under aerobic conditions. This is caused by the decrease in phosphate concentration in the aerobic layer due to adsorption.

Phosphate release from waste stabilisation pond sludge: significance and fate of polyphosphate

2011 ◽  
Vol 63 (8) ◽  
pp. 1689-1694 ◽  
Author(s):  
N. Powell ◽  
A. Shilton ◽  
S. Pratt ◽  
Y. Chisti
Keyword(s):  
Release Rate ◽  
Phosphorus Removal ◽  
Algal Bloom ◽  
Chemical Precipitation ◽  
Phosphorus Release ◽  
Common View ◽  
Phosphate Release ◽  
Initial Release ◽  
Polyphosphate Accumulation ◽  
The Common

Net phosphorus removal from waste stabilisation pond (WSP) systems is governed by the rate of phosphorus incorporation into the sludge layer and the rate of phosphorus release from this sludge back to the overlying wastewater. Luxury uptake of phosphorus by microalgae has been shown to occur under WSP conditions in the laboratory; however, the significance of this mechanism and the fate of polyphosphate contained in the settled solids have not previously been investigated. In this work the analysis of sludge samples from three WSP showed that up to 71% of the total phosphorus in the sludge was in the form of polyphosphate. This indicates that polyphosphate accumulation could potentially be an important mechanism for phosphorus sequestration in WSP and challenges the common view that chemical precipitation is the predominant phosphorus removal mechanism in these systems. The release of phosphate from WSP sludge samples was monitored in the laboratory. The samples from two different pond systems had release rates in the order of 4.3 μgP/gTSS.d. However, the third sample which was collected during an algal bloom had a release rate of 12.4 μgP/gTSS.d. Phosphate release from fresh microalgal sludge grown under laboratory conditions was also studied and was shown to have a release rate of 160 μgP/gTSS.d. Analysis of polyphosphate during the experiments on laboratory grown microalgal sludge showed that polyphosphate was indeed degraded resulting in phosphate release. Interestingly, after the initial release phase phosphorus was assimilated by the biomass and some polyphosphate was reformed. It is likely that this is due to bacterial growth in the sludge.

scholarly journals A STUDY ON A NOVEL FORMULATION APPROACH TO DELIVER DOXYCYCLINE THROUGH BUCCAL ROUTE

2019 ◽  
Author(s):  
Tanzeena Afroz ◽  
Md. Jasim Uddin ◽  
Md. Shahidul Islam
Keyword(s):  
Drug Delivery ◽  
Release Rate ◽  
Oral Drug Delivery ◽  
Rapid Onset ◽  
Oral Drug ◽  
Onset Of Action ◽  
Drug Degradation ◽  
Wide Range ◽  
Buccal Films

Recent developments in drug delivery technologies have a great impact on the limitations of traditional oral drug delivery for both the pediatric and geriatric patients. Administration of drug via buccal mucosa is a modern alternative for overcoming low bioavailability, enzymatic inactivation and/or drug degradation in gastrointestinal tract, hence showing rapid onset of action. The aim of the study was to develop doxycycline (antibiotic) loaded buccal films for the treatment of a wide range of systemic and non-systemic bacterial and protozoa infections. The bases of each film were prepared using mucoadhesive polymers, plasticizer, cellulose gums, and instant release film former and penetration enhancer. Optimized films were characterized for weight, width. Length, thickness, surface pH, percentage swelling index, percentage elongation, percentage moisture content, percentage moisture uptake, hydration and in vitro drug release studies. Concentration of different polymers tailored the increase in release rate of doxycycline from the mucoadhesive buccal films. In conclusions, mucoadhesive buccal films can be a substitute route for the delivery of doxycycline as antibacterial or antiprotozoal drug with a faster release rate to reach the site of action.

scholarly journals First record of the endemic phytophilous cladoceran Celsinotum candango Sinev & Elmoor-Loureiro, 2010, in Minas Gerais state, in a threatened shallow lake at Serra do Gandarela

2015 ◽  
Vol 15 (4) ◽  
Author(s):  
Francisco Wagner Moreira ◽  
Emerson Silva Dias ◽  
Eneida Maria Eskinazi Sant'Anna
Keyword(s):  
Shallow Lakes ◽  
Shallow Lake ◽  
Aquatic Ecosystems ◽  
National Park ◽  
Federal District ◽  
First Record ◽  
Minas Gerais ◽  
Mountain Ridge ◽  
Aquatic Biodiversity ◽  
Minas Gerais State

This study describes the occurrence of the phytophilous cladoceran Celsinotum candango, which has been considered, up to now, an endemic species of the Brazilian Cerrado, with only two previous records in the wetlands of Brasilia, Federal District. The cladoceran has now been registered at Coutos Lake (“Lagoa dos Coutos”), an altitudinal, temporary shallow lake, located in ironstone outcrops at Serra do Gandarela, Minas Gerais state. This mountain ridge was recently turned into an integral protection conservation unit, the Gandarela National Park. However, many shallow lakes, including this one, were excluded from the delimited area of the park, and are now at risk of disappearing due to expansion of mining activities. The information provided here reveals the importance of these shallow lakes to aquatic biodiversity, and reinforces the need for the inclusion of these rare aquatic ecosystems into the recently created Gandarela National Park.

scholarly journals Effects of Human Activities on the Diversity of Waterbirds Wintering in a Shallow Lake of the Middle and Lower Yangtze River Floodplain, China

Diversity ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 302
Author(s):  
Xinjian Wang ◽  
Jinyun Chen ◽  
Lizhi Zhou
Keyword(s):  
Species Composition ◽  
Human Activity ◽  
Shallow Lakes ◽  
Shallow Lake ◽  
Yangtze River ◽  
Paddy Fields ◽  
Aquaculture Ponds ◽  
Lower Yangtze ◽  
Lake Wetlands ◽  
Wetland Habitats

Human activity is the major factor driving the wetland degradation in shallow lakes. Human exploitation of lake wetlands alters the habitats of wintering waterbirds, and, in turn, waterbird diversity in the shallow lakes. In the present study, we surveyed species composition, abundance, and habitat characteristics of waterbirds in three types of wetland habitats (natural lakeside wetlands, paddy fields, and aquaculture ponds) at Caizi Lake, a shallow lake in the middle and lower Yangtze River during the wintering period, and investigated the effects of habitat change driven by human activity on the diversity of wintering waterbirds. There were significant differences in species composition and abundance among the three wetland habitats (natural lakeside wetlands, aquaculture ponds, and artificial paddy fields); however, there were no significant differences among the habitats with respect to the number of waterbirds. The numbers of overwintering waterbird species and waterbird individuals in aquaculture ponds and lakeside wetlands were significantly higher than the numbers in the paddy fields, indicating that wintering waterbirds prefer natural lake wetlands and aquaculture ponds. Principal component analysis of the three wetland habitat types revealed that factors influencing waterbird diversity include wetland area, vegetation cover, water level, and degree of human interference. Therefore, minimizing human interference and ensuring suitable habitats at specific periods could facilitate the maintenance of waterbird diversity.

scholarly journals Influence of environmental and spatial factors on the distribution of surface sediment diatoms in Chaohu Lake, southeast China

2012 ◽  
Vol 71 (2) ◽  
pp. 299-310 ◽  
Author(s):  
Xu Chen ◽  
Xiangdong Yang ◽  
Xuhui Dong ◽  
Enfeng Liu
Keyword(s):  
Surface Sediment ◽  
Dominant Species ◽  
Trophic Status ◽  
Chaohu Lake ◽  
Diatom Assemblages ◽  
Southeast China ◽  
Spatial Variables ◽  
Spatial Factors ◽  
Aulacoseira Granulata ◽  
Planktonic Species

Abstract- The spatial distribution of surface sediment diatoms in Chaohu Lake (southeast China), and their relationships with environmental and spatial variables were analyzed in this study. The diatom assemblages were dominated by planktonic species. Three dominant speciesCyclostephanos dubius,Aulacoseira granulataandAulacoseira alpigenaare unevenly distributed across the lake. The distribution of surface sediment diatoms must be subject to trophic status, hydrodynamics and other spatial variables in the lake.

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