Toprak Örneklerinde Polikorlubifenil (pcb) Kirliliğinin Araştırılması Ve Yasal Sınır Değerlerin Uygulanabilirliğinin Değerlendirilmesi

Abstract

Toprak, temas halinde olduğu su ve hava ortamlarında bulunan kirletici maddeler için nihai depolama yeridir. Diğer taraftan toprak, karasal ekosistemin taşıyıcı bir bileşeni olup, kalitesindeki değişim, gerek doğal ve gerekse tarım ekosisteminin verimliliğini doğrudan etkilemektedir. Bu nedenle, toprağın hangi kaynaklar tarafından ve hangi bileşenler (özellikle hangi kimyasallar) ile kirletilebileceğinin bilinmesi, alınacak tedbirlere karar verilmesi noktasında önem taşımaktadır. 8 Haziran 2010 tarihinde 27605 sayılı Resmi Gazete’de yayınlanan Toprak Kirliliğinin Kontrolü ve Noktasal Kaynaklı Kirlenmiş Sahalara Dair Yönetmelik’te jenerik kirleticiler listesinde bulunan poliklorlubifeniller, çevresel bileşenlere dolayısıyla insan sağlığına olan zararlı etkilerinden dolayı öncelikli incelenmesi gereken kirleticilerdendir. PCB’ler çevreye elektrikli ekipmanlar içerisinden dökülme ve sızıntılar ile uygunsuz bertaraf ve depolamalardan dolayı girmektedir. Öyle ki, üretilmiş PCB’lerin yarısından çoğu bu yollarla çevreye salınmıştır. Çevreye salındıkları anda bu kirleticiler çok uzun mesafeler kat edebildikleri gibi, özellikle toprak ve sedimente sıkıca bağlanabildiklerinden kalıcı organik kirletici olma eğilimindedirler. Bu çalışmada kentsel ve kırsal yerleşim alanları ile önemli sanayi kuruluşlarını ve geçiş yollarını bir arada bulunduran Kocaeli topraklarında 83 PCB türünün ölçülmesi hedeflenmiş olup bu amaçla deneysel bir çalışma yürütülmüştür. Elde edilen sonuçların 8 Haziran 2010 tarih ve 27605 sayılı Toprak Kirliliğinin Kontrolü ve Noktasal Kaynaklı Kirlenmiş Sahalara Dair Yönetmelik Ek 1’de verilen toprağın yutulması-deri teması taşınım yolu ile ilgili verilen sınır değerler ile uyumlu, yeraltı suyuna taşınım yolu ile ilgili verilen sınır değerlerin ise üstünde olduğu görülmektedir. Ölçülen PCB değerleri literatür ile karşılaştırıldığında Avrupa için verilmiş ortalama değerlerden düşük ve Asya ortalamasından yüksek olduğu görülmektedir. Çalışmada genel olarak PCB‘li türlerin baskın olarak düşük klorlu homolog gruplardan oluştuğu tespit edilmiş olup, Kocaeli topraklarında hâkim homolog türlerin sırasıyla pentaklorlubifeniller, tetraklorlubifeniller ve triklorlubifeniller olduğu gözlemlenmiştir. Bu sonuçlar ülkemizde yapılan çalışmalar ile uyumludur. Ortalama PCB konsantrasyonları yoğun olarak yerleşim bölgelerinde tespit edilmiş olup, beklenenin aksine yakma tesisine yakın numune alma noktalarında saptanan ortalama PCB konsantrasyonları yerleşim bölgelerindekilerden daha düşük tespit edilmiştir. Ölçüm yapılan her noktada dioksin benzeri türlere rastlanmış olup (PCB 77, 81, 126, 169, 105, 114, 149, 118, 123, 156, 157, 167ve 189) bu türlerin konsantrasyonları 5,86 ng/kg kuru ağırlık ile 940 ng/kg aralığında değişen değerlerde ölçülmüş tür ve 177,16 ng/kg olarak ortalama bir konsantrasyon saptanmıştır. İnsan sağlığı açısından tehlike arz eden türler ise daha çok dioksin benzeri PCB’lerdir.

As a result of industrialization, a variety of chemicals produced for industrial processes and as a conclusion they are released into the environment uncontrolled causing varying degrees of pollution. Among these pollutants, polychlorinated biphenyls (PCBs), owing to their chemical and thermal stability, have resulted in widespread pollution by being accumulated in soil, sediments, biota and aquatic environment, as well as being transported long distances in the atmosphere. From their first production in the 1930s, until their ban in the latest 1990s, approximately 1.3 million tons of PCBs have been produced, of which tens of thousands of tons are known to be released into the environment causing widespread pollution. Although the level of PCBs in the environment is declining due to a worldwide ban on their production, their physicochemical properties mean slow reduction rates in the terrestrial environment and coastal areas. PCB’s have been released into the environment through spills, leaks from electrical and other equipment, and improper disposal and storage. It is estimated that more than half of the PCB’s produced have been released into the environment. Once in the environment, PCB’s can be transported long distances and they bind strongly to soil and sediment so they tend to be persistent in the environment. International efforts, such as the Stockholm Convention on Persistent Organic Pollutants (POPs), enable coordination among countries for the phasing out of chemicals that remain in the environment for a long period of time and become widely distributed both in environmental media and in living organisms. The Stockholm Convention was adopted in 2001 and entered into force in 2004. According to the Convention, all parties should eliminate the use of equipment containing PCBs by 2025 and make determined efforts to achieve environmentally sound management of wastes containing greater than 50 ppm PCBs by 2028. Upon becoming a party to the Convention, every country is required to submit reports every 5 years to the governing body of the Convention on their progress in eliminating PCBs. In the case of Turkey, the decision to be a party was taken in the Grand National Assembly of Turkey in April 2009 (Official Gazette No: 27200) and accepted by the Council of Ministers in July 2009 (Official Gazette No: 27304). The legal procedure is completed as of January 2010 and Turkey is currently under the obligations of the Stockholm Convention. Hence, an important new stage has started for action to be taken to cease of use of PCB containing equipment, preparation of inventories, identification of polluted sites and eventually, environmentally safe disposal of wastes and remediation of contaminated sites. Identification of sites contaminated with POPs and their subsequent remediation is a major effort which initially requires a broader approach due to the relatively small amount of information currently present. Hence, many countries, including Turkey, need to gather all relevant information leading to the identification of pollution hot spots with the ultimate aim of environmentally sound remediation. With this study, it is aimed to evaluate the levels of PCB contamination in Kocaeli. Soil, which exposes with pollutants from water and air , is the final reservoir of them. On the other hand, since soil is the carrier compartment of the terrestrial ecosystem, changings of its quailty effects the efficiency of both efficiency of natural and agricultural ecosystems. Hence, it is important to determine which sources and contents (especially which chemicals) may contaminate soil, for deciding to take precautions. Polychlorinated biphenyls are one of the pollutants, which have been listed in the generic pollutants list in Turkish Regulation on Soil Pollution Control and Point-Source Contaminated Sites issued on 08.07.2010 with official gazette no: 27605, should be investigated primarily because of their adverse effects to human health and environment. In this study, an experimental study has been carried out for the aim of to measure of 83 PCB congeners, from the soils collected from Kocaeli province which encloses both urban and rural residental areas and the important industrial ares with important highways. The analysis results are evaluated according to the Regulation on Soil Pollution Control and Point-Source Contaminated Sites. According to the results it is detected that PCB concentrations are varying between 1446 ng/kg and 31455 ng/kg. These values indicates the minimum and maximum values respectively. It is thought that so many factors may effect these concentrations for example the residental or rural areas, prevailing wind direction, distance from Izaydas incineration plant…etc. İzaydaş incineration plant, has the license of disposal of PCB contaminated equipments and exhausted PCB containing equipment by incineration. As a result, it can be thought that this plant may cause PCB emmisions by its incineration activities while disposaling of PCB contaminated equipment. The mean concentrations of PCB’s were detected in residental areas higher. The concentrations meausered in the samples near incineration plant was lower than those measuered in residental areas on the contrary of expectations. While comparing the analysis results, a detailed literature investigation has been done and it is observed that the concentrations in the study area are higher than those given for Asia soils and lower than the European soils. Also, this study has aimed to compare the results with limitations given from the related regulation. Results are compatible with the limitations given for ingestion and skin exposure of the PCB contaminated soil, however higher than the exposure limitations for exposure from underground water. The study also indicates that, the dominant homologe groups in the study area.It is detected that low chlorinated species are dominant in Kocaeli soils.The dominant homolog groups are: pentachlorinated biphenyls, tetrachlorinated biphenyls and trichlorinated biphenyls respectively. The comparision by literature confirms these indications. Because it is known that the global production of PCB’s were dominantly based on (70%) pentachlorinated biphenyls, tetrachlorinated biphenyls and trichlorinated biphenyls. Recent studies also indicates that soils collected from residental and rural areas are dominated by pentachlorinated biphenyls. The dominated homologe group results are also compatible with the ones measured in Europe soils. Hexachlorinated biphenyls are not encountered commonly in residental and rural areas. The dioxin-like PCB’s (PCB 77, 81, 126, 169, 105, 114, 149, 118, 123, 156, 157, 167 and 189) were detected in every sampling points and concentrations are chancing beetween 5,86 ng/kg and 940 ng/kg , and the mean concentration was 177,16 ng/kg . It is known that the dioxin-like PCB’s are more hazardous for human health.