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    Assessment of heavy metal concentrations and behavior in cultivated soils under humid-subhumid environmental condition of the Black Sea region
    (Elsevier, 2023) Bayrakli, Betul; Dengiz, Orhan; Ozyazici, Mehmet Arif; Koc, Yusuf; Kesim, Emel; Turkmen, Ferhat
    In present time, contamination of soils with heavy metals has become a serious problem for the ecosystem, which is caused not only by industrial wastes but also by natural reasons such as geological origin and other human impact e.g., agricultural activities. This study discussed the sources of heavy metals, their spatial distribution, and factors affecting mobilization or retention mechanisms in soils. Soil pH (soil acidity), clay content, and soil organic matter content were studied as the main properties affecting the behavior of heavy metals in soil formed under humid and subhumid coastal environmental conditions. For this purpose, 3395 soil samples were collected from agricultural lands in the central and eastern Black Sea Regions. The results show that agricultural soils in the region have medium texture, high organic matter content, and an acidic response. While the average concentration levels of total heavy metal contents were determined as Fe > Mn > Ni > Zn > Cr > Cu > Pb > Co > Cd, the average levels of available heavy metal contents were Fe > Mn > Cu > Zn > Ni > Co > Cd > Cr in soil samples. When enrichment factor (EF) values of the soils were examined, the values of Cd and Pb were above 2, while the EF values of the other heavy metal elements were below 2; that is, they were classified as deficiency to minimal enrichment. It was also found that the heavy metals Cu and Cd had the highest availability ratio values (AR). In addition, a path analysis was carried out to determine the effects of pH, clay content, and soil organic matter content on the behavior of heavy metals. Direct effects on extractable and total forms of heavy metals was ranked as pH > OM = Clay, while the impacts on EF and AR was ranked as OM > pH > Clay.
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    Öğe
    Mapping and assessment-based modeling of soil fertility differences in the central and eastern parts of the Black Sea region using GIS and geostatistical approaches
    (Springer Heidelberg, 2017) Ozyazici, M. Arif; Dengiz, Orhan; Saglam, Mustafa; Erkocak, Aylin; Turkmen, Ferhat
    This study was carried out on arable lands of the central and eastern Black Sea regions including eight provinces (Artvin, Giresun, Gumushane, Ordu, Rize, Samsun, Sinop, and Trabzon). The present study aims to generate a soil fertility map for agricultural lands in the central and eastern parts of the Black Sea region. The main objective of this research is to quantify soil fertility by developing a soil fertility index (SFI) model at the regional level. The related objectives were to map the spatial distribution of soil fertility by using auxiliary variables and to model soil fertility within the study region. To accomplish this, a data set for soil fertility differences was collected and a model was developed to predict the spatial distribution of differences across the region. The study area was divided into 2.5 x 2.5-km grid squares. A total of 3400 soil samples were collected from the surface (020 cm) of each grid intersection point. The geostatistical method was used to generate the SFI distribution map of the study area for surface soils. Of the total study area, 93.76% had good (S1) or moderately fertile (S2) soil while 6.15% of the area had marginally fertile (S3) soil. Only a very small area (N) had low-fertility soil.