A dissertation submitted in partial fulfillment of the requirements for the award of the degree of. My sincere thanks to the Head of Department, Civil Engineering, for providing me with the necessary laboratory and research facilities.
C ontents
- Application of Environmetrics tools for geochemistry, water quality as-
- Indexing approach to assessing water quality depending on end-use of
- Assessment of sediment column quality with respect to heavy metals 211 1. Descriptive statistics of the sediment dataset 211
- Understanding the dynamics of heavy metals in a freshwater ecosystem
- Assessment of nutrient (N-P) dynamics in wetlands through a one-di- mensional model for assessing the eutrophication levels induced by
Phase II; Objective Ist: Application of environmental tools to geochemistry, water quality assessment and pollution separation. Phase III; Objective V: Evaluation of nutrient (N-P) dynamics in wetlands through a one-dimensional model for estimating eu-.
L ist of Figures
Estimated target hazard quotient (THQ) for individual metal of various organs of different fish species from the three zones of Deepor Beel. Lifetime cancer risk (TR) for adults and children from consumption of various organs of different fish species from the three zones of Deepor Beel.
L ist of Tables
Varimax rotated component matrix for different water quality parameters for 23 different monitoring locations of Deepor Beel (Rotation method: Varimax with Kai- . ser normalization). Varimax rotated component matrix for different water quality parameters for 23 different monitoring locations of Deepor Beel (Rotation method: Varimax with Kai- . ser normalization).
L ist of Abbreviations
TKN Total Kjeldahl Nitrogen TSS Total Suspended Solids WHO World Health Organization WQ Water Quality.
L ist of Notations
Pe Concentration of P in the outflowing water of the lake (g/m3/day) Pi Concentration of P in the inflowing water of the lake (g/m3/day) PN Plant Nitrogen. Yn Yield coefficient for nitrifying bacteria (mg VSS/mg N) θ1 Microbial growth temperature coefficient for ammonia θ2 Microbial growth temperature coefficient for nitrate.
A bstract
For short-term programs, the use of multivariate statistics, i.e. the use of HCA and PCA, rated as more suitable. The chemical speciation studies of seven heavy metals (Cr, Cd, Fe, Mn, Cu, Pb and Mg) were carried out to determine their available forms in the sediment column.
Introduction
- Overview
- Background of the research
- Need for the study
- Scope of the thesis
- Outline of the Thesis
This is primarily due to the negative impact on the human digestive, cardiovascular and central nervous systems of the accumulation of these heavy metals (Crespo-López et al. 2007). Based on the associated gaps in the published literature, the purpose of the study was formulated.
Bibliographical Research
A brief overview of wetlands
A broad classification of wetlands can be done as permanent wetlands, temporary wetlands and ephemeral wetlands. Permanent wetlands contain water throughout the year, while the temporal wetlands only have water during a particular season.
Wetland biodiversity and significance
In other words, the wetlands act as natural sponges, soaking in the runoff and mitigating flood hazards. The roots of the vegetation that thrive over the wetland slow down the flow of inflowing water and allow the sediment to settle into the inflowing water.
Attributes to wetland pollution
Correct management of the wetlands and sensible use of the wetlands' resources can significantly boost the tourism economy. When wetland waters receive excess nutrients, especially nitrates and phosphates, these nutrients can stimulate excessive plant growth (eutrophication), including algal blooms, leading to oxygen depletion, reduced biodiversity, changes in species composition and dominance, and degradation of water quality.
The Ramsar Convention
Introduction to Bibliometric analyses
Therefore, the scientific performance of the literature review needs attention, which can be achieved through the science mapping approach. The novelty of the current bibliographic research lies in (a) the application of science mapping in different research domains, which can minimize the subjectivity and bias in the review of published literature, (b) the analysis of the existing mainstream topics, ( c) a qualitative discussion, which explicitly points out the limitations and gaps in the existing literature, thus giving it a more comprehensive approach, and finally (d) proposes a research framework that will pave the way for future research works.
Water Quality
- An overview of the literature sample
- Journal Sources
- Co-occurrence of Keywords
- Co-authorship analysis
- Articles’ citations
- Countries active in the research domain of water quality indexing
- Qualitative Discussion related to water quality - Current research topics within
The data showed a general trend of water quality indexing research results. Relevant keywords that have appeared in the published water quality indexing literature. The most influential articles published in the field of water quality indexing were analyzed in VOSViewer.
5 shows a clearer picture of the different countries actively participating in the research domain of water quality indexing.
Sediment quality assessment
- An overview of the literature sample
- Journal Sources
- Co-occurrence of keywords
- Co-authorship analysis
- Articles’ citations
- Countries active in sediment contamination research domain
- Qualitative Discussion related to sediment contamination – Current research topics
Muniz etc. 2020) suggest a wide range of applications of water quality indexing. It was observed that most of the works were carried out in the years 2010, that is, from 2010 onwards. This suggests the dominance of Environmental Science in the field of sediment pollution.
Various studies have been carried out recently incorporating these indices to determine the pollution levels of the sediment columns in different aquatic ecosystems (Calace et al.
Anthropogenic influences on aquatic ecology and their model- ling
- An overview of the literature sample
- Science Mapping of Journal sources
- Analysis of co-occurrence of keywords
- Co-authorship analysis
- Articles’ citations
- Countries active in the research domain of ecological modelling
- Qualitative assessment - Current research topics within “eutrophication-based ecological modelling”
The first step involved in the modeling process is to determine the purpose of the model. It describes the relationship between the different state variables of the model using boxes and arrows. An overview of the annual distribution of published articles in the domain of eutrophication-based ecological modeling (Data extracted from the Scopus database).
Table 2 contains a detailed analysis of the most commonly used keywords in the research domain.
Summary
Away, away, from people and cities, To the wild forest and hills, - To the silent wilderness.
Research Gaps and Objectives
Research Gaps
- Research gaps relating to water quality
- Research gaps relating to sediment quality
- Research gaps in the domain of eutrophication-based ecological modelling While much work has been done on ecological modelling, the quest for better ecological mod-
Therefore, considerable scope exists in the application of various tools, mainly by introducing the concept of sensitivity analysis to the field of water quality indexing, which will help address the reliability of indices. Metal speciation analyzes provide strong indications of the forms of heavy metals present in the sediment columns, thereby helping to assess heavy metal toxicity levels. Finally, as it was observed that most of the studies concentrated on addressing the heavy metal contamination in the sediment column, there is minimal literature addressing the nutrient contamination levels.
Therefore, there is an existential need to study nutrient pollution in the sediment column.
Research Objectives
Only a handful of modelers have successfully proposed measures to evaluate the correctness of the model, which will solve real-world problems, for example using artificial neural networks, regression analyzes and machine learning approaches. Understanding the dynamics of heavy metals in a freshwater ecosystem through their toxicity and bioavailability assay. The fourth objective essentially focused on understanding the heavy metal dynamics in the entire wetland ecosystem.
The problem of eutrophication related to Deepor Beel was addressed by developing an ecological model based on eutrophication, taking into account the dynamics of nutrients (essentially nitrogen and phosphorus) in three different components of the wetland ecosystem, i.e. water, sediment and flora. .
Materials and methods
Design of research
We do not inherit the earth from our ancestors; we borrow it from our children.
LULC
Study area
- Ecological significance
- Land-use-land-cover of Deepor Beel
- Biodiversity of Deepor Beel
Economically, Deepor Beel supports about 30% of the 14 surrounding villages through fishing and agriculture (Mozumder et al. 2014). As already mentioned, many public institutions are located on the northern and northeastern side of the wetlands. There are also many brick kilns on the north side of the wetlands and a garbage dump.
Phytoplankton plays an important role among the lowest levels of producers in the Deepor Beel ecosystem.
Phase I: Sampling strategy and data acquisition
- Sample preservation
- Analytical procedures
- Additional data acquired
These three species were considered for their extensive use in the diet of the local population. Various water quality parameters analyzed in the study, their units of measurement and make and model of instruments used. During each sampling, water samples were collected from the mouth of the Basistha River and analyzed for various forms of nitrogen and phosphorus used in the model.
The monthly variation of various nutrients such as organic nitrogen, ammonia nitrogen, nitrate nitrate and total phosphorus in the running water of Basistha river is shown in Fig.
- Hierarchical Cluster analysis
- Discriminant analysis
- Principal component analysis
- Positive matrix factorization analysis
𝑃𝑖 represents the ith object, and 𝑄𝑖𝑗 is the value of variable j of the ith object. Wilk's lambda (λ) represents the ratio of variances measured within a group to the total variance. This will further lead to the formulation of the eigenvector matrix, represented by Eq.
The resulting input parameters were then classified based on the signal to noise (S/N) ratio for each of the parameters.
- Entropy as a tool for water quality assessment
- Existing methodology of assigning entropy weights and their ambiguities Assigning entropy weights to each parameter is based on the water quality dataset's random-
- Details of the conflicting factors to the existing assignment of entropy weight- ages for determining WQI
- Proposed novel methodology of assigning entropy weights
- Computation of WQI values employing multivariate statistics
- Sensitivity Assay
- Correctness of proposed WQIs
- Drinking suitability
- Irrigation suitability
- Heavy metal contamination
The multivariate statistical techniques (MSTs) provide, through factor analysis/principal component analysis (FA/PCA), considerable ease of understanding of the various pollution sources that affect water quality. Detailed methods for investigating the water quality follow in the subsequent subsections. First, it is observed that the value of 𝑃𝑎𝑏 is directly dependent on the observed value of the water quality parameters rather than taking into account the frequency factor.
In this study, water quality index (WQI) values based on multivariate statistics are proposed.
Phase II; III rd Objective: Assessment of sediment column quality with respect to heavy metals
- Metal contamination and risk assessment
- Heavy metal fractionation of sediment column
- Elemental analyses
Various tools were used to determine the heavy metal contamination of the sediment samples of Deepor Beel, as well as its potential ecological risk corresponding to each heavy metal. In the present study, the background concentrations of the metals are considered to be the reference values (Fukue et al. 2006). Furthermore, SEM-EDS quantitative analyzes were performed to determine the morphology and elemental composition of the sediment samples.
Elemental mapping of samples was done to determine the weight percentages of HMs present in those samples.
- Potential human health risk assessment (HRA)
- Bioaccumulation Factor (BAF)
For the sediment column, the average daily dose of heavy metals can be estimated by calculating the following equations (Ef. HRA involves the estimation of carcinogenic (surface sediment samples) and non-carcinogenic risk exposures (both water and sediment samples) in both adults and children through the bioavailability of the heavy metals Health risk associated with the consumption of fish was assessed by evaluating the estimated daily intake (EDI) of fish (Eq. 4. 72), followed by the target hazard quotient (THQ) (Eq. 4. 73) and the total target hazard quotient (TTHQ) (Eq. 4. 74).
The bioaccumulation of heavy metals in different fish organs is estimated through the bioaccumulation factor, governed by Eq.
Phase III; V th Objective: Assessment of nutrient (N-P) dynamics in wetlands through a one-dimensional model for assessing the eu-
- Model Conceptualization
The conceptual diagram for the one-dimensional ecological model of nutrient distribution in the wetland ecosystem is shown in Fig. OrgN in the water column is converted to NH3N, which is further converted to NO3N by ammonification and nitrification respectively. Nitrogen in water was thought to exist only in three forms: organic nitrogen, ammonia nitrogen and nitrate nitrogen.
Similarly, phosphorus in water is usually present in the form of phosphates (Metcalf & Eddy 2017).
Sediment ColumnWater Column
- Organic Nitrogen 𝑑(𝑂𝑟𝑔𝑁)
- Ammonia Nitrogen 𝑑(𝑁𝐻 3 𝑁)
- Nitrate Nitrogen 𝑑(𝑁𝑂 3 𝑁)
- Plant Nitrogen 𝑑(𝑃𝑁)
- Sediment Nitrogen 𝑑(𝑆𝑁)
- Total Phosphorus 𝑑𝑃
- Plant Phosphorus 𝑑(𝑃𝑃)
- Sediment Phosphorus 𝑑(𝑆𝑃)
- Sensitivity analysis
- Model calibration and validation
- Summary
On the other hand, all components of the model are varied simultaneously in the AAT method to understand the sensitivity of all components. The resulting changes in the values of the state variables provide a qualitative measure of the sensitivity of that submodel. Global sensitivity analysis of the one-dimensional ecological model was performed by One-At-a-Time (OAT) sampling approach, following the method described by Morris (1991).
As pointed out by King and Perera (2013), the Morris method requires 2k simulations of the model to determine the sensitivity of all the input variables.
Application of Environmetrics tools for geo- chemistry, water quality assessment and ap-
- Descriptive statistics of the WQ dataset
- Hierarchical clustering of sampling locations and its validation
- Discriminant analysis
- Latent pollution sources
- Source apportionment
The hierarchical grouping of the 23 sampling locations of Deepor Beel led to the classification of them into three main groups (clusters 1, 2 and 3), represented by a dendrogram (Fig. 5. 1a). Classification matrix for discriminant analysis of the spatial variation along Deepor Beel. 100.0% of original clustered cases correctly classified. This indicates the validity of the PCA due to their statistical significance between the variables (Kaiser 1974).
GIS map showing the distribution of (a) PC-1 and (b) PC-2 principal factors for each of the sampling sites.
