A Decision Support System for Water Pollution Assessment in Aquaculture

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A DECISION SUPPORT SYSTEM FOR WATER POLLUTION ASSESSMENT AND CONTROL IN AQUACULTURE POND
Abstract. In recent old ages, the aquaculture in China has been increased quickly and a significant addition being recorded in the aquaculture production. But H2O pollution has become the major factor damaging the sustainable development of aquaculture and the quality security of aquatic prod­uct in China. In this paper, we present a general model, utilizing a scientific system of attack, for developing a determination support system for measuring and commanding H2O pollution. The system consists of 3 degrees, the first is aimed for informations aggregation, the 2nd is responsible for theoretical accounts and the 3rd degree provides real-time determination support devising, informations distribution and visual image. The nucleus constituent of this determination support system includes H2O quality safety hazard rating theoretical account and economic loss appraisal theoretical account of H2O pollution. There are two chief decisions from this paradigm application. First, H2O quality safety hazard rating theoretical account is closed with H2O envi- ronmentaljjollutants denseness and aquaculture clip. Second, the economic loss appraisal theoretical account of H2O pollution is closed with the four factors: ( 1 ) the size of pollution of H2O resources ; ( 2 ) the size of H2O resource value ; ( 3 ) the grade of exposure to pollution of H2O resources ; ( 4 ) the cumulative consequence of contaminated H2O.
Keywords: H2O pollution, determination support system, economic loss, H2O quality, safety hazard.
AIMS AND BACKGROUND
In recent decennaries, due to the high denseness of genteelness and unreal eating, aquac­ulture non merely pollutes the encompassing H2O environment, and besides H2O quality impairment of its being has become progressively serious. Water pollution non merely straight increases the agriculture costs, but besides chance of happening of disease in the procedure of engendering. How to efficaciously forestall and command H2O pollution has become pressing to work out the great job. This paper introduces the development experience on the determination support system for appraisal and control H2O pollution ( WatPol ) in aquaculture.
In recent old ages, the aquaculture in China has been lifting quickly, and a sub­stantial addition being recorded in the aquaculture production. In 2007, aquatic
For correspondence.
merchandises reached a sum of 47.475 million T, of which, 21.966 million T of fresh 2ter merchandises ‘ . However, H2O pollution caused by aquaculture has besides become more and more serious.
Modern aquaculture pollution trades chiefly with three facets: the first one refers to self-purification capacity of H2O organic structures caused by over-farming can non maintain up ; the 2nd one refers to a big figure of nutrient-rich effluent caused by farm animal and domestic fowl manure thrown in reservoir lakes ; and the 3rd one, the most serious pollution, is from the all sorts of fertilizer inputs which pollute H2O quality, but besides straight endanger the safety of imbibing H2O for people and farm animal.
Water pollution non merely increases straight the agriculture costs, but besides influ­ences the chance of happening of disease in the procedure of engendering. At the same clip, the impairment of aquaculture environment straight inhibits fish reproduction and growing, affects reproduction of biological come-on, decreases fish nutrient beginnings and reduces the survival rate of fish and fish production.
Skinner2studied the environmental impacts of agricultural activities in the United Kingdom, concentrating on pollution jobs caused by pesticide application, livestock-waste discharge, dirt eroding, and alimentary losingss. One country of concern is the extent to which pesticides range rivers and lakes by leaching and run-off, since this may take to impacts on aquatic life and on worlds if taint extends to imbibing Waterss. In China at present, H2O pollution job has become more serious, it constrains sustainable economic and societal development, and even en­dangers people lives safety and wellness. It has become imperative to cognize how to work out an effectual manner of forestalling and commanding H2O pollution.
Obviously, there has been an increasing involvement and pressing need an environ­mental-friendly civilization to make the development and airing of a scope of fish civilization systems that are both environmentally and economically sustainable. Because there are many attacks to decision-making and because of the broad scope of spheres in which determinations are made, the construct of determination support system ( DSS ) is really wide3. This paper introduces the development experience on the determination support system for appraisal and control H2O pollution ( WatPol ) in aquaculture. The paper is organised as follows: subdivision 2 provides the proposal for the determination support system ; so the last subdivision draws decisions and farther betterment.
EXPERIMENTAL
System description. A DSS is a functionally incorporate and automated computing machine system which allows directors to integrate multiple aims and concerns of stakeholders, find the comparative influence of assorted beginnings of uncertainness, and gauge the fringy value of roll uping extra informations4.
For guaranting ultimate success for developing WatPol, the radical pro­totype theoretical account had adopted the development procedure or methodological analysis taking into history that prototyping procedure provides users with more chances to better their work, to verify that their demands are met and that the footings used in the interface of the designed system are consistent with those in usage in their work5. The undertaking had been initiated in 2006 and the paradigm was finished in 2007.
Systems design. The chief point of utilizing DSS is to supply a user with the possibil­ity to confer with with an machine-controlled system while doing determinations. DSS as a regulation, includes a set of processs, get downing from informations finding and processing, and coating by coevals and rating of options [ 1 ] . A paradigm system was built to prove the functional specifications. Meetings with the system development applied scientist and experts had been held until a consensus was reached on the objec­tives, restraints and specific undertakings that the WatPol must execute to carry through the design aims.

Fig. 1. The DSS model
Therefore, Fig. 1 shows the proposed determination support system architecture, which was developed in conformity with the typical construction of a DSS. The system con­sists of three degrees, the first is aimed for informations aggregation, the 2nd is responsible for theoretical accounts, and the 3rd degree provides real-time determination support devising, informations distribution and visual image3.
Data aggregation. This portion includes the aggregation and processing of informations. In prac­tice this portion identifies the beginnings of force per unit area represented by societal, demographic and economic developments. It acquires informations from diverse beginnings and in differ­ent format types. After saying the chief purpose of the work, an information hunt has proved to be compulsory, garnering the relevant background information and expert cognition.
Data semen from diverse beginnings and in different format types, such as:

Literature reappraisal. A literature reappraisal on H2O quality pollution, fish qual­ity safety hazard and patterning methods was conducted to supply a auxiliary beginning of cognition during system development to get the better of the hard caused by uncomplete cognition and information deficit. After the literature reappraisal, the unsmooth set theory ( RST ) was found frequently to be used to stand for the uncomplete cognition and the theory of SVM was more convenient and efficient to stand for the scarceness of informations due to its fewer free parametric quantities to find and the faster computational velocity than the BP nervous web ( BPNN ) does.
Lab experiments. Fishs are wholly dependent on H2O to take a breath, provender and grow. To a great extent H2O determines the success or failure of an aquaculture operation6. Laboratory experiment aims non merely to place and rank the factor influenced the H2O quality and fish quality hazard, but besides to get the day-to-day fluctuation via monitoring of pool H2O quality. For having pollutants factors, a series experiments had been conducted to get the trial informations from April to October, 2006 in Beijing. We take into history, at the clip, series of informations of CODchromium, which represent the degree of organic pollutant in the H2O. The concentra­tion of CODchromiumin the pool H2O is affected by a series of factors, such as dissolved O ( DO ) , H2O temperature, H2O hardness ( WH ) , nitrogen, P, etc. – The values fluctuation of chief pool H2O quality factors are shown in Table 1. The pollutants factor found in the experiment may be accumulated in fish organic structure and trigger oxidative emphasis in fish and impact their growing7. About 20 fish per hebdomad were caught at random in each of the pools. After gaining control, the livers, which was the chief detoxification organ in fish8, were dissected and weighed.

Table 1. Variation of average values of chief pool H2O quality factors
pH T DO CODchromiumTPWHTN
_____________ ( °C ) ( mg/1 ) ( mg/1 ) ( mg/1 ) ( mmol/1 ) ( mg/I )
Average 7.65 20.55 4.28 133.75 0.512.332.35
Range 7.4-8.1 11-28 2.08-8.98 72.37-167.32 0.38-0.651.81-3.021.12-5. ‘- factors, get the standards for fish quality safety and the direction procedure and schemes to cut down the losingss.
In the undertaking, 22 experts from different spheres of H2O quality and fish quality safety direction were involved in a multi-step procedure of knowledge- acquisition by the method of Delphi. Table 2 shows basic thresholds acquired from questionnaires.
Table 2. Class of H2O eutrophication appraisal




Class


Trophic position ( EI )




Benchmark


0-10




I


innutritive ( 10-13 )




N


alimentary ( 13-20 )




hello


low-eutrophic ( 20-35 )




Four


medium-eutrophic ( 35-80 )




Volt


high-eutrophic ( 80-95 )




RESULTS AND DISCUSSION MODEL ANALYSIS
This portion provides parametric quantity estimations from informations through a well-structured format. For an incorporate DSS model-based, the capablenesss of the theoretical accounts are cardinal in easing the major, if non the whole, decision-making procedure. Models with different complexnesss are frequently used in a DSS and there is a step of theoretical account, complexness. It contains two theoretical accounts, one is H2O quality safety hazard rating theoretical account, and th # other one refers to the economic loss appraisal theoretical account of H2O pollution.
Water quality safety hazard rating theoretical account. The theoretical account is an iterative-built 1 that analyses the relationship between H2O environmental pollutants and fish quality safety hazard. Analysis stairss are the undermentioned ( Fig. 2 ) :

Fig. 2. Water quality safety hazard rating theoretical account analysis stairss
Measure 1 – The accretion of pollutants in vivo is influenced by many fac­tors, such as pollutant concentration, the being itself, physical and chemical factors of H2O environment. We propose a theoretical account based on a normally used mechanistic theoretical account depicting alterations in chemical concentrations. The theoretical account assumes that the fluctuation of the bio-concentration in fish follows the first order reaction equation. The theoretical account is:
lg ( CT) = lg C0 + tkt,
» here C0is the initial pollutants concentration ; kt — a rate invariable and is modelled ii a map of fish exposure to pollutants in the pool H2O. A fish exposure can be expressed utilizing H2O column contamination concentration, the size of fish ( a alternate of age and nutrient ingestion ) , and other indexs of H2O environ­ment.
The necessary amendments to the theoretical account and the add-on of the other predic­tors can brace the theoretical account remainders harmonizing to existent state of affairs9. Based on the experimental ascertained informations, the concluding accretion of pollutants in vivo arrested development theoretical account is determined.
Refering the log fish tissue carbolic acid ( HB ) concentration arrested development theoretical account is:
lg ( Cft ) = P0 + ? ( P, + P2Cw + P3L ) + vitamin E.
This theoretical account describes the log fish tissue HB concentration [ lg ( CT) ] as a additive map of clip ( t, yearss ) and the incline as a additive map of H2O column HB concentration ( Ctungsten, mg/1 ) and fish length ( L, centimeter ) .
With this preparation, a multiple additive arrested development is used to gauge theoretical account coefficients ( Psand residuary criterion divergence a ) . The estimated theoretical account coefficients and their standard mistakes are listed in Table 3.
Table 3. Linear theoretical account coefficients estimated utilizing the ordinary least squares ( OLS ) methods and their standard mistake ( in parentheses )




Parameters


OLS estimations ( standard mistake )




Polonium


1.1882 ( 0.03 )




P,


0.014 ( 0.004 )




P2


0.35 ( 0.14 )




P3


-0.0004 ( 0.0001 )




Measure 2 – Using the Bayesian illation and Monte Carlo simulation, the theoretical account parametric quantities and predicted variables are analysed uncertainness. Algorithm flow is as follows ( Fig. 3 ) :

The fake arrested development parametric quantities and residuary criterion divergence are summarised in Table 4.
Table 4. Drumhead statistics of Monte Carlo simulation consequences
Parameters 2.5 % 25 % 50 % 75 % 97.5 %
Phosphorus01.132781.1690251.1883701.2078041.244873
( 3,0.006310.0114870.0139580.0165730.021196
P,0.083910.2671010.3597790.4484120.638810
Phosphorus3-0.00071-0.000533-0.000443-0.000346-0.000159
a,0.005000.0061300.0070210.0079470.101616
Measure 3 – For cumulative pollutants, the hazard is estimated from exposure cal­culated through a two-compartment kinetic theoretical account ( Fig. 4 – where PAC is the pre­dicted pollutants concentration of fish accumulate, SC – standard concentration. If PAC/SOl, it presents a grade of menace for the quality and safety of aquatic merchandises ) .

Fig. 4. Hazard appraisal
Economic loss appraisal theoretical account of H2O pollution. Aquaculture portions similar economic* rules with agribusiness and forestry, as the production map involves biological actives, conditions and civilization clip as specific factors. These conditions force the husbandman to bear uncertainnesss in production, monetary value and technol­ogy, among others10. As a consequence, H2O pollution is frequently caused by a assortment of common pollutants. In the short-run H2O pollution is really hard to reconstruct but H2O resources have multi-functional usage and can be besides reused, so ciphering the economic losingss caused by H2O pollution is closed with the value of H2O resources.
In the computation model four factors are taken into history: ( 1 ) the size of pollution of H2O resources ; ( 2 ) the size of H2O resource value ; ( 3 ) the grade of exposure to pollution of H2O resources ; ( 4 ) the cumulative consequence of contaminated H2O. Specific theoretical account ” :
F=CRQPJWb-Wc ) K.
where F is the economic losingss caused by H2O pollution, million RMB ; C – the cumulative consequence coefficient of contaminated H2O, dimensionless ; Q – contami­nated H2O volume ( m3) ; R – the coefficient reflect the unit value of H2O resources and pollution loss, dimensionless ; Wb – mass concentration of the background value of major pollutants ( mg/1 ) ; Wvitamin E– the radical value of the major pollutants ( mg/1 ) ; Ptungsten– the basic monetary value of H2O resources ( RMB/m3) .
DECISION SUPPORT MAKING
‘Decision doing ‘ recommends the most optimal discrepancies of computing machine simula­tion, which are selected by standard decision-making standards ( Bayes, minimax, etc. ) in understanding with its cognition.
Using the fake distribution, we can cipher the chance of fish tissue HB concentration transcending a known critical value. This hazard can be expressed as a map of the continuance an mean sized fish corsets in the contaminated pool ( Fig. 5 ) .

0 50 100 150 200%
clip ( twenty-four hours )
Fig. 5. Estimated chance of transcending China nutrient safety criterion for HB ( 5 g/mg ) as a map of civilization continuance ( in yearss ) ( The solid lines represent the 90th percentile of the estimated prob­abilities and the flecked lines are the fiftieth percentiles. The hazard is evaluated by utilizing the mean fish size and three different H2O column HB concentrations )
Using this chance as a step of fish taint hazard, we can deduce utile information for the direction of the fish pool and supply some valuable advice for directors. For case, when the H2O column HB concentration is reduced to 0.002 mg/1, fish can be harvested after 150 yearss.
SYSTEM DEVELOPMENT TOOLS AND RUN-TIME ENVIRONMENT
System development tools. This system is a web-based determination support system, which runs over the Internet. Therefore, the users can derive entree to the system on the Internet through any normally used commercial browser such as Internet Explorer, Netscape, etc. and need non to put in other package in any computing machine. There are many solutions for developing the web-based systems. The solution which is Microsoft Visual Studio.NET 2003+ASP.NET+MS SQL Server 2000 +IIS 6.0 + Software bundle, is adopted to develop the system.
System runtime environment. ( 1 ) Web Servers. Operating system is Windows 2000 Advance Server or Windows Server 2003, and put in IIS ( Internet Information

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