102,510 research outputs found
Simulation and Analysis of Phosphorus Transformation and Phytoplankton Dynamics in Relation to the Eutrophication of Lake Balaton
A mathematical model of phosphorus transformations has been applied to a real set of physical, biological, chemical observation data in Lake Balaton. The model includes dissolved oxygen and five phosphorus forms in water environments: phytoplankton phosphorus, bacterial phosphorus, dissolved inorganic phosphorus, dissolved organic phosphorus, and unliving particulate phosphorus, and also three phosphorus forms in interstitial water: inorganic, organic, and particulate phosphorus fractions.
The purpose of this report was to present the best possible calibration between existing observation data from 1977 and model output. This is one of the important steps that must be performed before application of the model for prediction and management purposes.
Hypothesis about three populations of phytoplankton give a model output that agreed reasonably well with the observation data for total P, dissolved P, dissolved organic and inorganic phosphorus, particulate organic phosphorus, and phytoplankton chlorophyll "a" in all basins simultaneously. This provides indirect evidences that the model considered is a reasonable representation of a complex ecological process in phosphorus transformation and phytoplankton dynamics in Lake Balaton
Phosphorus Dynamics in Dingle Marsh, Idaho
Phosphorus mass-balance studies of Dingle Marsh, Idaho indicated that the marsh was an annual net sink for total suspended sol ids and all forms of phosphorus under consideration: total phosphorus, particulate phosphorus, total dissolved phosphorus, dissolved organic phosphorus, and orthophosphate phosphorus. During some months, however, more phosphorus was exported from the marsh than entered.
Phosphorus mass-balance dynamics were compared between night and day. Total suspended solids and particulate phosphorus dynamics were controlled by sedimentation of particulate material, a physical process, and were unaffected by light conditions. Dissolved organic and ortho-phosphorus were affected by light conditions indicating, at least indirectly, that biological processes were affecting dissolved phosphorus dynamics. These phosphorus fractions were occasionally released in large amounts by the marsh at night.
An in situ enclosure experiment was performed to determine major sites of phosphorus uptake/release. A twentyfour-hour rate of particulate phosphorus decrease in the enclosures could be predicted (r2=0.89) by knowing the initial concentration of total suspended solids. On a twentyfour-hour basis, periphyton, detritus, and live bulrushes tended to remove more dissolved organic phosphorus from the water than they added to it while plankton and sediments added dissolved organic phosphorus to the water. Orthophosphates were removed from the water by plankton, detritus, and periphyton with plankton dominating the changes. Live bulrushes or sediments within the bulrush system tended to be a source for orthophosphates.
The open water ecosystem was a greater net source for dissolved organic phosphorus than the bulrush system. The open water system was a greater net sink, however, for orthophosphates, than was the bulrush community
Nitrogen phosphorus and carbox flux in Chesapeake Bay marshes
Annual nitrogen, phosphorus and carbon budgets for two Virginia salt marshes were determined .by monthly measurements of water discharge and constituent concentrations over tidal cycles.
Considering all three forms of phosphorus measured (total, dissolved organic and orthophosphate) there was a net loss from the estuary to the marches. The data reveal a loss of particulate phosphorus of estuarine origin to marsh sediments and mineralization of this phosphorus in the marshes with subsequent export of dissolved inorganic and organic phosphorus back to the estuary.
Nitrogen flux data show a loss of nitrate and nitrite to the marshes. Particulate nitrogen is imported to the marshes where it is mineralized and returned to the estuary as ammonia and dissolved organic nitrogen. The magnitude of nitrogen export suggests significant fixation of atmospheric nitrogen by marsh flora with subsequent export as dissolved species.
Carbon flux data show significant contributions of both particulate and dissolved organic carbon to the estuary from the marshes. Estimates of export, based on marsh grass productivity, suggest a loss of 36 and 49 percent of a year\u27s primary production on the marshes as detritus for Ware and Carter Creeks respectively
Phosphorus imbalance in the global ocean?
The phosphorus budget of the pre-human modern ocean is constrained applying the most recent estimates of the natural riverine, eolian, and ice-rafted input fluxes, the phosphorus burial in marine sediments, and the hydrothermal removal of dissolved phosphate from the deep ocean. This review of current flux estimates indicates that the phosphorus budget of the ocean is unbalanced since the accumulation of phosphorus in marine sediments and altered oceanic crust exceeds the continental input of particulate and dissolved phosphorus. The phosphorus mass balance is further tested considering the dissolved phosphate distribution in the deep water column, the marine export production of particulate organic matter, rain rates of phosphorus to the seafloor, benthic dissolved phosphate fluxes, and the organic carbon to phosphorus ratios in marine particles. These independent data confirm that the phosphate and phosphorus budgets were not at steadystate in the pre-human global ocean. The ocean is losing dissolved phosphate at a rate of ≥ 11.6 x 1010 mol yr-1 corresponding to a decline in the phosphate inventory of ≥ 4.5 % kyr-1. Benthic data show that phosphate is preferentially retained in pelagic deep-sea sediments where extended oxygen exposure times favor the degradation of particulate organic matter and the up-take of phosphate in manganese and iron oxides and hydroxides. Enhanced C : P regeneration ratios observed in the deep water column (>400 m water depth) probably reflect the preferential burial of phosphorus in pelagic sediments.
Excess phosphate is released from continental margin sediments deposited in low-oxygen environments. The dissolved oxygen threshold value for the enhanced release of dissolved phosphate is ~20 ÎĽM. Benthic phosphate fluxes increase drastically when oxygen concentrations fall below this value
Mathematical Modeling of Phosphorus Transformation in the Lake Balaton Ecosystem
An ecological model of the phosphorus system is described. This model includes five phosphorus forms found in water, namely: phytoplankton-P, bacterial-P, dissolved inorganic-P, dissolved organic-P and nonliving particulate-P, and also three phosphorus forms in interstitial water: inorganic, organic and particulate phosphorus fractions. It is assumed that this model will be used as a tool for synthesizing and analyzing the phenomena of eutrophication in Lake Balaton's ecosystem.
The purpose of this study was to obtain the best calibration between existing observation data on Lake Balaton from 1977 and model output. This is considered one of the important steps that must be carried out before application of the model for prediction and management purposes. A hypothesis of three seasonal phytoplankton groups yielded model output that agreed reasonably well with the observation data for total-P, dissolved-P, dissolved organic and inorganic phosphorus, particulate organic-P and phytoplankton chlorophyll "a" in the water of the different basins in Lake Balaton. This provides indirect evidence that the model considered, is a reasonable representation of complex ecological processes in phosphorus transformations and phytoplankton dynamics in the lake. On the basis of simulation results for 1977, the phosphorus material flows and the turnover times of phosphorus fractions in the lake are evaluated. These data provide additional insights for understanding the conditions of phosphorus cycling and the eutrophic state of the basins within Lake Balaton
Changes of organic phosphorus in river waters in northern Bangladesh
The variability in phosphorus concentrations and the decomposition rates of organic phosphorus were measured in five selected rivers through four surveys in July and November of 2012, and February and May of 2013. After collection the water samples were incubated for 20 days in a dark incubator and the change of forms of phosphorus such as particulate organic phosphorus (POP), dissolved organic phosphorus (DOP) and dissolved inorganic phosphorus (DIP) were analyzed. By fitting the changes to two types of models, the decomposition rates of organic phosphorus were determined. The mean total organic phosphorus (TOP) decomposition rate coefficients in the studied rivers was 0.039 day-1. The average POP decomposition rate coefficient (POP?DOP?DIP model) was 0.038 day-1 while the mean DOP decomposition rate coefficient was 0.251 day-1. The decomposition rate coefficients measured in this study might be applicable for modeling of river water quality.Int. J. Agril. Res. Innov. & Tech. 5 (2): 31-36, December, 201
Function of marshes in reducing eutrophication of estuaries of the Middle Atlantic Region
Annual nitrogen, phosphorus and carbon budgets for two Virginia salt marshes were determined by monthly measurements of water discharge and constituent concentrations over tidal cycles.
Considering all three forms of phosphorus measured (total, dissolved organic and orthophosphate) there was a net loss from the estuary to the marshes. The data reveal a loss of particulate ÎĽhosphorus of estuarine origin to marsh sediments and mineralization of this phosphorus in the marshes with subsequent export of dissolved inorganic and organic phosphorus back to the estuary.
Nitrogen flux data show a loss of nitrate and nitrite to the marshes. Particulate nitrogen is imported to the marshes where it is mineralized and returned to the estuary as ammonia and dissolved organic nitrogen. The magnitude of nitrogen export suggests significant fixation of atmospheric nitrogen by marsh flora with subsequent export as dissolved species.
Carbon flux data show significant contributions of both particulate and dissolved organic carbon to the estuary from the marshes. Estimates of export, based on marsh grass productivity, suggest a loss of 36 and 49% of a years primary production on the marshes as detritus for Ware and Carter Creeks respectively
Laboratory Methods for the Advancement of Wastewater Treatment Modeling
To achieve the low levels of total phosphorus required in wastewater treatment plant effluent all chemical forms of phosphorus should be removed. The most refractory phosphorus in terms of removal is so-called “organic phosphorus”. This thesis explores potential relationships between dissolved organic matter and organic phosphorus and methods of removing organic phosphorus from waste water. Fluorescence spectroscopy will be used to characterize dissolved organic matter (DOM) in wastewater. The fluorescent DOM will then be monitored throughout the various wastewater treatment plants to investigate any changes throughout the treatment train. Correlations between fluorophore concentrations (concentrations determined for the different classifications of fluorescent DOM) and non-reactive phosphorus will be examined in hopes to discover implications for phosphorus removal. Screening of bench top wastewater treatment technologies for phosphorus removal looks into preexisting wastewater treatments for a cost effective and efficient method to breakdown refractory (organic) phosphorus. This thesis also investigates current limitations pH simulation in the wastewater treatment process. In order to optimize any type of nutrient removal pH simulation must be as advanced as the wastewater treatment technologies. Simulation of pH is very important for almost all wastewater treatment processes. Current modeling determines pH based on the concentrations of strong base cations, strong acid anions, weak acids and ammonia. This causes an underestimation of pH because the modeling does not take into account positively charged surface reactive sites in wastewater solids
Dissolved organic nutrient uptake by riverine phytoplankton varies along a gradient of nutrient enrichment
The concentration of dissolved organic matter (DOM) in freshwaters is increasing in large areas of the world. In addition to carbon, DOM contains nitrogen and phosphorus and there is growing concern that these organic nutrients may be bioavailable and contribute to eutrophication. However, relatively few studies have assessed the potential for dissolved organic nitrogen (DON) or dissolved organic phosphorus (DOP) compounds to be bioavailable to natural river phytoplankton communities at different locations or times. Temporal and spatial variations in uptake, relative to environmental characteristics were examined at six riverine sites in two contrasting catchments in the UK. This study also examined how the uptake by riverine phytoplankton of four DON and four DOP compounds commonly found in rivers, varied with concentration. Total nitrogen (TN) and phosphorus (TP) concentrations, the proportion of inorganic nutrient species, and nutrient limitation varied temporally and spatially, as did the potential for DON and DOP uptake. All eight of the DOM compounds tested were bioavailable, but to different extents. Organic nutrient use depended on the concentration of the organic compound supplied, with simple compounds (urea and glucose-6-phosphate) supporting algal growth even at very low concentrations. DON use was negatively correlated with the TN and ammonia concentration and DOP use was negatively correlated with soluble reactive phosphorus (SRP) and dissolved organic carbon (DOC) concentration. The evidence indicates that DOM in rivers has been overlooked as a potential source of nutrients to phytoplankton and therefore as an agent of eutrophication
Some effects of tropical storm Agnes on water quality in the Patuxent River estuary
A post Agnes study emphasizing environmental factors...weekly sampling at eight stations from 28 June to August 30, 1972. Spatial and temporal changes in the distribution of many factors, e.g., salinity, dissolved oxygen (DO), seston, particulate carbon and nitrogen, inorganic and organic fractions of dissolved nitrogen and phosphorus, and chlorophyll a were studied and compared to earlier extensive records. Patterns shown by the present data were compared especially with a local heavy storm that occurred in the Patuxent drainage basin during July 1963.
Some interesting correlations were observed in the data. (PDF has 39 pages.
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