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Changes of Organic Phosphorus in River Waters in Northern Bangladesh

M.J. Islam
Department of Agricultural Chemistry, Hajee Mohammad Danesh Science and Technology University, Dinjapur-5200, Bangladesh

M.S. Rahman
Department of Agricultural Chemistry, Hajee Mohammad Danesh Science and Technology University, Dinjapur-5200, Bangladesh

Rubeca Fancy
Department of Agricultural Chemistry, Hajee Mohammad Danesh Science and Technology University, Dinjapur-5200, Bangladesh

A.K.M.S. Rahman
Department of Agricultural Chemistry, Hajee Mohammad Danesh Science and Technology University, Dinjapur-5200, Bangladesh

M. Shamsuzzoha
Department of Chemistry, Hajee Mohammad Danesh Science and Technology University, Dinjapur-5200, Bangladesh

M.A.H. Siddiqi
Department of Agricultural Chemistry, Hajee Mohammad Danesh Science and Technology University, Dinjapur-5200, Bangladesh

Abstract/ Executive Summary:

Study and information on the river water quality with emphasis on concentration and decomposition of minerals is crucial for enhancement of productivity.The variability in phosphorus concentrations and the decomposition rates of organic phosphorus were measured for five selected rivers through four surveys conducted 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.

Keywords: Organic Phosphorus, Decomposition, River Water

Location: Dinajpur District. Punarbhaba River (4 sites), the Atrai River (4 sites), the Kharkharia River (4 sites) , the Jamuna River(4 sites) and the Tulsi Ganga River (2 sites)

Start Date: 00-00-2012

End Date: 00-00-2013

Program Area: Resource Development and Management

Commodity: Organic fertilizer

Objectives:

1. To assess the decomposition rates of organic Phosphorous (P) thereby influencing P availability.

2. To investigate on the algal growth in the river water and thus overall impacts of P in the river ecosystem.

Methodology:

Representative samples from five selected rivers were collected in 20 L plastic bottles and processed for physical, chemical and biological analyses following tandard recommended procedures. The sampling sites of the 5 rivers were the Punarbhaba River (4 sites), the Atrai River (4 sites), the Kharkharia River (4 sites), the Jamuna River(4 sites) and the Tulsi Ganga River (2 sites) of Dinajpur District. Temperature, pH and EC were measured in situ with a YSI model 600 multi-parameter water analyzer. Chlorophyll concentration was determined by spectrophotometric method using acetone extraction. For the measurements of BOD, sample aliquots were incubated in 300 ml glass BOD bottles at 20°C for 5 days in the dark. Dissolved oxygen (DO) was measured by DO meter. For COD , samples (30 ml) were treated with 5 mN KMnO4 in 1 % NaOH for 1 hour at 100 °C in an autoclave. Total phosphorus (TP) concentration was determined by persulfate digestion followed by the ascorbic acid method for ortho-phosphate analysis. Total nitrogen (TN) was determined by auto analyzer (SKALAR 5100) employing Cd reduction column after decomposing sample by persulfate digestion. Nitrate was determined by Cd reduction method. 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 change to two types of models the decomposition rates of organic phosphorus were determined. The total organic phosphorus (TOP) decomposition rate coefficient indicates combined overall decomposition rate coefficients of POP and DOP. Within the models, it is assumed that conversion of POP and DOP to phosphate proceeds through hydrolysis and mineralization. Decomposition rates of organic phosphorus were measured at 0, 1, 2, 3, 5, 7, 10, 15 and 20 days after beginning of incubation at 20°C. The DIP (dissolved inorganic P), DTP (dissolved total P) and TP (total P) concentrations of the water samples were measured for P content. The dissolved and particulate fractions are usually distinguished by filtration through a 0.45-μm membrane that separates most bacteria, algae and mineral particles from the dissolved phase but fails to separate colloidal particles. The DIP was analyzed after GF/F filtration (0.45 μm) by applying the molybdenum blue method at 880 nm, according to the American Public Health Association. The DTP was estimated from the filtered sample as the DIP after persulfate digestion. The DOP was obtained by subtracting the DIP from the DTP. The TP was analyzed from the unfiltered sample as the DIP after persulfate digestion and determined after the Mo-blue method, according to APHA. In this study the following four different models were employed for simulating phosphorus cycle in river water. Each decay model was fitted to the data collected from incubation experiment and rate coefficients were determined by optimization.

Source of Information: Int. J. Agril. Res. Innov. & Tech. 5 (2): 31-36, December, 2015; ISSN: 2224-0616

Article Link (Online Journal): Available online at http://www.ijarit.webs.com

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Even though there was a little difference in the decomposition rates under constant temperature perhaps; due to aerobic and anaerobic conditions; in most cases, the data were well fitted with the model simulation. Every model, whether it relies on a simple conceptual or a fully mechanistic approach, certainly run into the limits if other factors of decomposition go down to a level where distinct changes in the overall structure of the ecosystem appear. The model equations employed here lend themselves well in determining the rate of decomposition of organic P because it makes no assumptions what microorganisms are involved in the decomposition process. This study suggests that, the respective decomposition rate coefficients are fairly constant. The decomposition coefficients measured in this study would obviously give a guideline to the selection of parameters in modeling the river water quality.

Knowledge Management: Journal