Hypothetical Modeling of the Pump & Fertilize in Turkey
Pump and fertilize, while removing the nitrate in the groundwater, can also reduce nitrate and pesticide requirement (King, et al., 2012). Even though the valorization of the groundwater contamination sounds simple, there are only a couple of case studies with 1-year field experiments (Francis & Schepers, 1994), (Liang et al., 2016), (Libutti & Monteleone, 2017). This makes the feasibility assessment for the process impossible. Thus, prior to the very laborious and costly experimental studies for the evaluation of pump & fertilize process, a general modeling study to find out under what conditions of climate and in which soils this process is promising, is required.
I have constructed unsaturated zone groundwater models via HYDRUS 1D for prevalent soil types in Turkey, with relevant climates for maize production. Maize was chosen as it is globally the most produced crop and at the same time removes more than 240 kg nitrogen in 1 ha in 1 year through 10000 kg/ha grain generating hybrid (Doerge, et al., 1991). Beside 5 major soil types in Turkey, general soil textures (excluding silt and silty clay) were also modeled to evaluate the effect of the changes in parameters more clearly. Soil parameters were generated from texture variables by Rosetta Lite v1.1, and climate parameters were generated from freely available data on the internet through Criwar 3.0 using the Penman-Monteith method.
As a result, among the climates used, which are Eskişehir [Csb], Adana [Csa], Şanlıurfa [Bsh-Bsk], Düzce [Cfb], Rize[Cfa], (Köppen-Geiger classification in square brackets), the dryest climate (Şanlıurfa) performed better as plants were passively able to uptake nitrate more since more irrigation water required for plants, indicating more nitrate removal. Nitrate leaching both depends on the hydraulic conductivity of the soils, and also the ability of plants nitrate uptake, and very low and very high permeable soils were unsuitable for this purpose. Loamy soils were in general much better than the rest, and Cambisol in prevalent soil types in Turkey was the best choice to realize pump & fertilize.
The related publication is my M. Sc. thesis study, titled "Modeling the Effects of Irrigation by Contaminated Groundwater" (Hatipoğlu, 2018). I have also done an oral presentation related to this study (Hatipoglu & Kurt, 2018), and with some additional no-denitrification models and better explanation of the equations behind the models (peer review helps a lot, after all :] ) we also have an article, which is about to be opened to access for everyone in a few months (Hatipoğlu & Kurt, 2019).
Green Synthesis of Silver Nanoparticles
In an analytical chemistry laboratory in the Chemistry Department, I first synthesized silver nanoparticles through a tetrahydroborate pathway according to a procedure. The actual research was synthesizing nanoparticles from Artemisia absinthium extracts. We first mimicked the study of Ali et al. (2016), and then tried various extraction ways; as leaving overnight, boiling water extraction, cold extraction, overnight shaking. Through zeta potential measurements and UV-Visible spectrophotometry spectrums, we found out the formed particles size distributions. The particle sizes were in range of 30 nm to 90 nm, mostly around 50 nm. Of course size of the particle in nanometer dimensions make much difference (see the figure below). Yet this was a very good initial step in green synthesis of silver nanoparticles, especially if the target is not directly having 10 nm sized particles, but an average of 50 nm. We were unable to take SEM or TEM as the project was done without any funding.
NOX, O3, BTEX Concentrations in Air
This is, not directly a research subject, but I have conducted a significant amount of chemical analyses, placed and collected passive samplers and at the same time worked with a private company on regular air pollution measurements in various cities in Turkey. The instruments I myself used were UV-Visible Spectrophotometry and Gas Chromatography-Flame Ionization Detector (GC-FID) with Thermal Desorber, in conjunction with EPA's standard methods. I have also trained several students in conducting analyses with both of these instruments.
Ali, M., Kim, B., D. Belfield, K., Norman, D., Brennan, M., & Ali, G. S. (2016). Green synthesis and characterization of silver nanoparticles using artemisia absinthium aqueous extract — a comprehensive study. Materials Science and Engineering: C, 58, 359-365. doi: https://doi.org/10.1016/j.msec.2015.08.045
Doerge, TA, Roth, RL, & Gardner, BR. (1991). Nitrogen fertilizer management in Arizona. University of Arizona College of Agriculture. Arizona. USA. 191025. Retrieved September 1, 2018 from https://cals.arizona.edu/crop/soils/nitfertmgtAZ.pdf
Francis, D. D., & Schepers, J. S. (1994). Nitrogen uptake efficiency in maize production using irrigation water high in nitrate. Fertilizer research, 39(3), 239-244. doi: 10.1007/BF00750252
Hatipoğlu, Y. G. (2018). Modeling the effects of irrigation by contaminated groundwater. (Master Thesis). Middle East Technical University. Ankara, Turkey. Retrieved from : https://etd.lib.metu.edu.tr/upload/12622682/index.pdf
Hatipoğlu, Y. G., Kurt, Z. (2018, October). Application of Finite Element Method by HYDRUS 1D for assessing the effects of Irrigation by Contaminated Groundwater in Turkey, oral presentation given at the Beyond: Workshop on Computational Science and Engineering. Ankara, Turkey Retrieved from http://files.iam.metu.edu.tr/workshop_cse/abstracts/guray_hatipoglu.pdf
Hatipoğlu, G., Kurt, Z. (2019). Modeling irrigation with nitrate contaminated groundwater. Pamukale University Journal of Engineering Science. doi:10.5505/pajes.2019.38963
Liang, H., Qi, Z., Hu, K., Prasher, S. O., & Zhang, Y. (2016). Can nitrate contaminated groundwater be remediated by optimizing flood irrigation rate with high nitrate water in a desert oasis using the WHCNS model? Journal of Environmental Management, 181, 16-25. doi: 10.1016/j.jenvman.2016.05.082
Libutti, A., & Monteleone, M. (2017). Soil vs. groundwater: The quality dilemma. Managing nitrogen leaching and salinity control under irrigated agriculture in Mediterranean conditions. Agricultural Water Management, 186, 40-50. doi: 10.1016/j.agwat.2017.02.019