The scope of this thesis is presented below:
• The derivation of basin-specific NBCs for the metals and metalloids in the Yeşilırmak River Basin
- The pre-treatment and compilation of metal concentration data - The implementation of outlier detection test
- The employment of data treatment for below-limit of detection values (below-LODs) with three different approaches
- The implementation of low percentile analysis
• The establishment of basin-specific EQSs for the metals and metalloids in the Yeşilırmak River Basin
• The identification of district-specific agricultural sources of the pesticide pollution within the boundaries of the Yeşilırmak River Basin
- The data collection and compilation regarding the information on the type, spraying frequency, and spraying timing of the agrochemicals against the district-specific and crop-specific pests by personally contacting the agricultural engineers of the District Directorates of Agriculture and Forestry
- The preparation of comprehensive inventories, which encompass the typical agricultural practices and crop-specific insecticide, herbicide and fungicide spraying schedules for each district where sampling stations are located
- The identification of the dominant crops grown in each district of the river basin by calculating areal shares of each crop at district scale and basin scale
- The analysis and determination of the type and the pollution level of the pesticides that exceeded their annual average EQS (AA-EQS) and maximum allowable concentration EQS (MAC-EQS) values at the sampling stations of each district
- The analysis and assessment of the temporal correlations between the agricultural activities and the pesticide occurrences observed at the sampling stations of each district
• The determination of spatial distribution pattern of the pesticide pollution across the Yeşilırmak River Basin
- The analysis and assessment of the relation between the spatial distribution of the agricultural areas and the pesticide occurrence pathway across the river basin
- The analysis and assessment of the impact of water and soil half-lives of the pesticides on their detection frequencies across the river basin - The analysis and assessment of the relation between the mobility of
the pesticides and their spatial distribution across the river basin - The analysis and assessment of the impact of district altitude on the
diversity of the pesticide types observed at the sampling stations of each district of the river basin
• The determination of temporal occurrence trend of the pesticide pollution across the Yeşilırmak River Basin
- The analysis and assessment of the relation between the precipitation trend and temporal occurrence trend of the pesticides in the river basin
Within the context of this thesis, in Chapter 1 (Introduction), general information about the Yeşilırmak River Basin, and the overall objective and scope of the thesis
In Chapter 2, Establishment of Normal Background Concentrations and Environmental Quality Standards for Metals in Yeşilırmak River Basin is studied and presented by pursuing a stepwise procedure (Introduction, Background, Methodology, Results and Discussion, Conclusion and Recommendations). Within the scope of Section 2.1 (Introduction), the importance of the establishment of river basin specific NBCs and EQSs were explained by providing the regulatory status of river basin specific EQS derivation both in Turkey and the European Union (EU). In addition, the objective and scope of the study are described in this section. In Section 2.2 (Background), the general information about metal pollution in the freshwater environment is provided. Furthermore, fate and typical sources of metals and metalloids in the environment, the use of “normal” and “natural” terms for background concentration concept in literature and literature review on background concentration assessment techniques are presented within the scope of Section 2.2.
In Section 2.3 (Methodology), the techniques and approaches that are addressed to derive and establish basin-specific NBCs and EQSs for the metals in the Yeşilırmak River Basin are explained in detail. In this section, data selection and compilation, outlier detection test: Adjusted Tukey’s Method, below-LOD treatment by introducing three different approaches, derivation of basin-specific NBCs by the low percentile analysis technique and the calculation method of the basin-specific EQSs are described and explained by presenting each of these steps in individual subsections. In Section 2.4, the results of data selection and compilation, outlier detection test, low percentile analysis results under the three different below-LOD treatment approaches, the derived specific NBCs and the calculated basin-specific EQSs for each metal and metalloid were presented and discussed, comprehensively. In Section 2.5 (Conclusion and Recommendations), the overall importance, benefits and outcomes of the study are summarized and recommendations for future research are proposed within the scope of Chapter 2.
In Chapter 3, Agricultural Source Identification of Pesticide Pollution in Yeşilırmak River Basin is studied and presented within the context of five main sections (Introduction, Background, Methodology, Results and Discussion, Conclusion and
Recommendations). In Section 3.1 (Introduction), the importance of target-specific agricultural source identification of pesticide pollution, and the relation between pesticide use and agricultural activities are explained by providing regulatory scope and status of plant protection products in Turkey and EU. In addition, detailed objective and scope of the study are given in this section. In Section 3.2 (Background), the impact of crop types and locality of farmlands on pesticide uses, fate of pesticides from agricultural fields to the freshwater environment and impact of physicochemical characteristics of pesticides on pesticide occurrences in the freshwater environment are individually explained and presented. In Section 3.3 (Methodology), the approaches that are followed in the data compilation and analysis, and in the selection of the basin-specific pesticides are presented.
Moreover, the procedures that are addressed for the assessment of the spatial distribution of the pesticide pollution across the river basin, the assessment of the temporal occurrence trend of the pesticide pollution across the river basin and district-specific identification of the agricultural sources for the pesticides in the river basin are described and presented within the scope of Section 3.3 (Methodology). In Section 3.4 (Results and Discussion), the results of data analysis, spatial distribution pattern and temporal occurrence trend of pesticides and district-specific source identification of pesticides were provided. In Section 3.5 (Conclusion and Recommendations), the importance and summary of the study and suggestions for future researches are presented within the scope of Chapter 3.
In Chapter 4 (Concluding Remarks), the overall summary of the studies that are performed within the scope of both in Chapter 2 and Chapter 3 are explained and presented to provide a clear picture and general perspective about the overall fulfillments of the thesis.
CHAPTER 2
2 ESTABLISHMENT OF NORMAL BACKGROUND CONCENTRATIONS AND ENVIRONMENTAL QUALITY STANDARDS FOR METALS IN YEŞİLIRMAK
RIVER BASIN