The use of cokriging algorithm for arsenic mapping in groundwater systems

5th International Perspective on Water Resources & the Environment Conference (IPWE 2012), MoroccoAccurate mapping of the spatial distribution of arsenic in groundwater is an important but equally difficult task to complete due to a number of uncertainties. Classical univariate interpolation algorithms could sometimes be insufficient to capture high concentration and high gradient areas. Under these circumstances, the use of an auxiliary parameter could provide better estimates of arsenic distribution. Based on this premise, arsenic cokriging with a correlated parameter can improve the performance of interpolation and can enhance the quality of predictions. In order to test this hypothesis, a water quality dataset from an arsenic containing aquifer in Simav Plain, Turkey is used to develop arsenic distribution maps. Arsenic is cokriged with correlated parameters such as manganese, iron and dissolved oxygen; and the results are compared with univariate interpolation algorithms such as ordinary kriging and inverse distance weighing. The comparisons were performed with cross validation at sampling locations and assessed based on mean and root mean squared errors. The results revealed that maps developed using arsenic cokriging with iron have given the smallest error value and have shown closest fit to the extreme values in the dataset. Accordingly, arsenic cokriging with iron is believed to be a promising approach in mapping arsenic distributions in groundwater

Evidence for sea water intrusion in karstic aquifer of Karaburun Peninsula, NW Turkey

IWA 2nd Regional Symposium on water, wastewater and environment, 22-24 March 2017, Cesme, İzmirKarstic aquifers are considered to be significant sources of groundwater and are mostly under threat due to sea water intrusion in many parts of the world. Seawater intrusion is also a common problem on karstic aquifers of Karaburun Peninsula in north of Mediterranean Region. The hydrogeology of Karaburun Peninsula is fairly complex and is mostly characterized by highly permeable karstic formations with significant water storage in an otherwise water scarce area. The karstic aquifers of the region were recently found to be under severe salt water intrusion, which significantly altered the position of fresh water/sea water interface as a result of excessive pumping and fault zones controlling the karstic network.The Scientific and Technological Research Council of Turkey project number 113Y04

Investigation of sea water intrusion in coastal aquifers: A case study from Karaburun Peninsula, Turkey

36th IAHR World Congress, 28 June – 3 July, 2015, The Hague, the NetherlandsGroundwater is an important natural resource; as of today, more than 2 billion people depend on groundwater. Determination of the quantity of available water resources is crucial due to continuously increasing water demand and unequal spatial distribution of water in the world. Coastal areas are typically considered to be areas of limited supply and large demand and groundwater is mostly the resource that is used for water supply purposes for coastal communities. Thus, there exist numerous studies in literature that focus on the determination of the groundwater characteristics in coastal regions with particular emphasis on the geological, hydrogeological and hydrochemical properties of coastal groundwater. Coastal aquifers are considered to be significant water resources and are mostly under threat due to salt water intrusion. The reason for salt water intrusion is mostly anthropogenic such as over exploitation but occasionally natural causes like tectonic boundaries or fault lines could be influential. When coupled with low recharge rates that are common in semi-arid regions such as the Mediterranean, effective and sustainable supply of water with sufficient quality and quantity becomes a real challenge for coastal communities

Sample collection into sterile vacuum tubes to preserve arsenic speciation in natural water samples

The accurate speciation analysis of arsenic is a serious concern for water quality monitoring programs. Because the preservation of sample integrity until analysis is one of the most important aspects of speciation, this study aims to compare the performance of four different sample preservation methods under diverse conditions of sample quality. Natural samples with different characteristics were collected into the following containers to study their effectiveness: (1) standard high-density polyethylene bottle with no preservative; (2) empty, sterile Vacuette tube with no preservative; (3) sterile tripotassium ethylenediaminetetraacetic acid (K3EDTA) Vacuette tube with K3EDTA additive; and (4) empty, sterile Vacuette tube with added hydrochloric acid (HCl). Known concentrations of arsenite [As(III)] were also added to each container to monitor the oxidation of As(III) to arsenate [As(V)]. The results revealed recovery ratios exceeding 95% in all containers with sterile vacuum conditions. In particular, the K3EDTA Vacuette tube yielded a recovery very close to 100% of the spiked As(III), which is known to rapidly oxidize to As(V). Overall, collecting the sample into a container under sterile vacuum conditions and using a universally accepted preserving agent such as EDTA or HCl significantly improved the preservation of the original species distribution in the water matrix studied, compared to sampling without the use of preservation methods. After validation by future research, these sterile vacuum tubes can possibly be utilized for collecting and storing samples for the routine speciation analysis of other elements such as selenium, chromium, and antimony.Scientific and Technological Research Council of Turkey (109Y029

An integrated assessment of water quality in an arsenic containing aquifer: Milestones from hydrogeology to public health

5th International Perspective on Water Resources & the Environment Conference (IPWE 2012), MoroccoA multi-disciplinary research is being conducted in Simav Plain, Turkey where an arsenic containing aquifer is at the center of attention. The study is not only aimed to understand the sources and mechanisms of the presence of high arsenic levels in groundwater but also to determine the associated consequences with regards to human health. The high arsenic levels in most groundwater (N=33, avg. 162 ppb), surface water (N=9, avg. 76.6 ppb) and geothermal water (N=3, avg. 406 ppb) samples are strongly related to high occurrences of arsenic in rocks and soils of the plain, which range between 7.1 and 833.9 ppm with an average of 49 ppm. These values correspond to several orders of magnitude higher than international standards and world averages in water and soil, respectively. With this motivation, this research also focuses on human health in the study area associated with exposure to these high arsenic levels via numerous pathways. Consequently, more than 1000 individuals were personally surveyed by public health specialists to determine an inventory of diseases in the area. Furthermore, a verbal autopsy study was also conducted with relatives of the deceased, which were further verified with hospital records, to understand the underlying death cause. As a result, certain cancer rates were found to exceed national averages and the results statistically demonstrated a potential link with high arsenic levels mainly through oral exposure

Modeling of seawater intrusion in a coastal aquifer of Karaburun Peninsula, western Turkey

Seawater intrusion is a major problem to freshwater resources especially in coastal areas where fresh groundwater is surrounded and could be easily influenced by seawater. This study presents the development of a conceptual and numerical model for the coastal aquifer of Karareis region (Karaburun Peninsula) in the western part of Turkey. The study also presents the interpretation and the analysis of the time series data of groundwater levels recorded by data loggers. The SEAWAT model is used in this study to solve the density-dependent flow field and seawater intrusion in the coastal aquifer that is under excessive pumping particularly during summer months. The model was calibrated using the average values of a 1-year dataset and further verified by the average values of another year. Five potential scenarios were analyzed to understand the effects of pumping and climate change on groundwater levels and the extent of seawater intrusion in the next 10 years. The result of the analysis demonstrated high levels of electrical conductivity and chloride along the coastal part of the study area. As a result of the numerical model, seawater intrusion is simulated to move about 420 m toward the land in the next 10 years under “increased pumping” scenario, while a slight change in water level and TDS concentrations was observed in “climate change” scenario. Results also revealed that a reduction in the pumping rate from Karareis wells will be necessary to protect fresh groundwater from contamination by seawater.Scientific and Technological Research Council of Turkey (TUBITAK 113Y042

The psychometric properties of school belonging scale for primary school students: a validity and reliability study

This study aims at developing a valid and reliable scale to determine primary school students’ sense of school belonging. In this respect, the relevant literature on the concept of belonging was reviewed; interviews were conducted with field experts and primary school students to determine items to be included in the scale. An item pool was created based on the findings of these processes. Later, a pilot form was prepared by taking the opinions of 2 field and 2 measurement and evaluation experts to ensure that the scale items represent the structure measured. This form was administered to 254 primary school students studying in the 2018-2019 academic year, and the final scale was obtained as a result of exploratory factor analysis was applied to 287 primary school students in a different school. For validity evidence, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), convergent and discriminant analysis and item analysis; for reliability, findings of Cronbach Alpha and composite reliability coefficients were used. According to the exploratory factor analysis, the scale consisted of 3 factors with 13 items, and the total variance explained was 52.57%. As a result of the second-order confirmatory factor analysis of the obtained structure, the fit indices of the model showed that it was verified. The internal consistency coefficient of the developed model was α = .92 and the composite reliability coefficient was .93. These findings showed that the scale had psychometric properties to be used in future research

The infldence of the discharge of geothermal fluid on surface water quality: Case study Simav Plain (Kütahya)

Son yıllarda jeotermal enerji, temiz ve yenilenebilir bir enerji kaynağı olarak gündemdedir. Ancak, yüksek çözünmüş madde miktarı ve ısıl içeriği nedeniyle uygun şartlar altında önlem alınmadığı durumlarda jeotermal akışkanın yüzeysel su kalitesine önemli etkileri olacağı açıktır. Ülkemizde gelişen jeotermal enerji uygulamalarına paralel olarak, pek çok sahada atık jeotermal akışkana ilişkin sorunlar yaşanmaktadır. Bu sahalardan biri olan Simav Jeotermal Sahası'nda yürütülen bu çalışma ile atık jeotermal akışkanın kontrolsüz olarak yüzeysel sulara deşaıjının neden olduğır sorunlar incelenmiştir. Bölgedeki üç adet jeotermal sahadan (Eynal, Çitgöl ve Naşa) çıkan atıkjeotermal akışkanın ciddi bir ısıl ve kimyasal kirlenmeye neden olduğır tespit edilmiştir. Özellikle arsenik, bor, lityum v.b. toksik elementlerce zengin olan akışkanın herhangi bir kontrol tedbiri alınadan yüzeysel su kaynaklarına deşarjı, bu kaynakların olası diğer kullanınılarını olumsuz yönde etkilemektedir.In recent years, geotlıermal energy is on the agenda as a clean and renewable energy resource. However, witlı its high dissolved constituents and tlıermal content, geothermal fluid is known to have significant impacts on surface water quality when disposed in an urıcontrolled manner. In parallel to devetoping geotlıermal energy applications in our courıtry, many sites experience problems associated witlı waste geotlıermal fluid disposaL Being one of tlıese sites, Simav Geothermal Area is studied in this paper and problems associated witlı tlıe discharge of vaste geotlıermal fluid on surface water resources are assessed. The waste geotlıermal fluid originating from three locations (Eynal, Çitgöl and Naşa) in tlıe study area is fourıd to cause significant tlıermal and chemical contamination. Particularly, tlıe urıcontrolled discharge of geotlıermal fluid tlıat is rich in arsenic, boran, lithium and otlıer toxic elements in to surface water resources of tlıe area influences otlıer potential us es of tlıese resources

Evaluation of the environmental pressures on groundwater in Gedız Basin

67. Türkiye Jeoloji Kurultayı, 14-18 Nisan 2014, AnkaraSon yıllarda küresel iklim değişikliklerine bağlı olarak ülkemiz genelinde su potansiyelinin gerek kalite gerekse miktar açısından önemli oranda baskı altında olduğu ortaya çıkmıştır. Bu bağlamda, sürdürülebilir su potansiyelinin geliştirilmesine yönelik olarak bir takım önlemlerin alınması zorunlu hale gelmiştir. Bunun için öncelikli olarak, ülkemizde mevcut yeraltı su durumunun miktar ve kalite açısından belirlenmesi için havza bazında hidrojeolojik çalışmalar yapılmaktadır. Bunlardan biri ise Ege Bölgesinin en büyük nehir havzalarından biri olan Gediz havzasıdır. Gediz havzasında mevcut su potansiyelinin belirlenmesine yönelik olarak 2012 yılından bu yana hidrolojik, hidrojeolojik ve hidrojeokimyasal çalışmalar sürdürülmektedir. Gediz havzasında yapılan ve elde edilen ön bulgular bu çalışma kapsamında değerlendirilmiştir. Yapılan çalışmalar sonucunda 17146 km2’lik bir alanı kapsayan Gediz havzasında en önemli yeraltı suyu kütlelerinin, havza alanının %18’ini kaplayan alüvyonel birimler ve %12’sini kaplayan karstik kaya ortamlar (Mesozoyik kireçtaşları, Paleozoyik mermerler ve Neojen kireçtaşları) olduğu saptanmıştır

Estimation of hydraulic conductivity from specific capacity data for alluvial aquifer: A case study from Alaşehir Plain (Manisa)

71.Türkiye Jeoloji Kurultayı, 23-27 Nisan 2018, AnkaraAkiferlerin hidrolik iletkenliği, transmissibilitesi ve depolama katsayısı gibi hidrolik parametrelerinin pompaj kuyuları ile belirlenmesi oldukça zor ve pahalı bir işlemdir. Hidrolik iletkenliğin belirlenmesinde, debi, statik seviye, dinamik seviye ve etki yarıçapına ihtiyaç duyulmaktadır. Gözlem kuyuları olmadığı takdirde etki yarıçapı global rakamlarla ifade edilmektedir. Buna karşılık, statik su seviyesi, dinamik su seviye ve kuyu debisi kolaylıkla kuyu başında ölçülebilmektedir. Bu veriler ile kuyunun özgül debisi rahatlıkla hesaplanabilmektedir. Ülkemizde, binlerce su kuyusu alüvyon akiferde açılmaktadır. Kuyuların hidrolik parametreleri ise pompaj testlerinin uygulanamaması nedeni ile bilinmemektedir. Bu çalışma kapsamında ise hidrolik iletkenliğin bölgede aynı akiferden elde edilen özgül debi değerleri ile tahmin edilebilmesine gidilmiştir. Bu çalışma Alaşehir Ovası’nın en önemli yeraltı suyu akiferi olan alüvyon akiferde uygulanmıştır. Büyük miktarda çekilen yeraltısuyu çalışma alanında içme ve sulama amaçlı kullanılmaktadır. İnceleme alanında 120-150 m derinliğinde açılmış olan su kuyularından 5-30 L/s debi ile yeraltı suyu çekilebilmektedir. Açılan bu kuyularda çok az kullanılabilecek hidrolik parametre bulunmaktadır. Bu nedenle, kuyuların hidrolik parametrelerinin belirlenmesinde bilinen parametrelerden yola çıkarak bilinmeyeni tahmin eden yaklaşımlara ihtiyaç duyulmaktadır. Bu verilerden yola çıkarak, çalışma alanında düzgün verisi olan ve alüvyonda açılmış kuyu özgül debi değerleri ile kuyunun hidrolik iletkenliğinin belirlenmesine çalışılmıştır