نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایران
2 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه رازی، کرمانشاه، ایران.
3 گروه به‌نژادی و بیوتکنولوژی گیاهی، دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایران
4 گروه گیاهپزشکی، دانشکده کشاورزی، دانشگاه رازی ، کرمانشاه، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Soil hydrocarbons can affect the physical, chemical and biological characteristics. Soil samples were prepared from the oil-rich area of Kermanshah province, which have been under oil pollution for a long time. 120 soil samples were collected from a depth of 0-15 cm with three pollution levels of low (L), moderate (M) and high (H) and the physicochemical characteristics were measured. Then bacteria were counted in NA and CFMM media and a positive and significant correlation was observed between bacterial population and oil concentration. The mean of oil measured by Soxhlet method was 4.03%, 9.95% and 22.50% for L, M and H levels, respectively. With the increase of oil in soil samples, ACP and ALP increased. In all samples, ACP was lower than ALP. The highest ACP and ALP were obtained 45.78 and 84.90 (gPNP.g-1.h-1µ) respectively in soil with high pollution level. Regression analysis showed that the oil percentage, sand percentage and EC with an regression coefficient of 0.71 were effective variables on the ACP, and the oil and sand percentage were also effective variables on the activity of ALP with an regression coefficient of 0.43. PCA analysis was also performed and the results showed that the first two components explained 68% of the variance between the samples. Based on the results, it was observed that natural and long-term oil pollution, with the passage of time led to the adaptation of microbial communities resistant to pollution and the number of these microorganisms and the activity of phosphatase enzyme increased.
کلیدواژه‌ها [English]
Changes in the activity of acid and alkaline phosphatase enzymes in oil-contaminated soils
EXTENDED ABSTRACT
One of the most critical environmental pollutants is the presence of oil pollutants in the soil ecosystem, which can affect the soil's physical, chemical, and biological characteristics. Petroleum hydrocarbons are organic and persistent pollutants and can remain in a polluted environment for a long time. Soil microorganisms are in contact with soil particles and are very sensitive to environmental stress, and for this reason, they are considered indicators of soil quality and health. Soil enzymes are susceptible biological indicators that are used to detect and measure the amount and concentration of pollutants in such a way that they are used to detect the initial signs of pollution and the effective removal rate of pollutants and to obtain health and quality. They re-evaluate the soil. Soil phosphatases react very quickly to any disturbances in the biochemical state of the soil. The aim of this research is to investigate the effects of oil pollution on phosphatase activity, the presence or absence of differences between the sampling sites in terms of the measured traits, and the difference between There were different levels of oil pollution.
Soil samples used in this research were taken from the oil-rich area of Naft-Shahr located in the west of Kermanshah province. 30 soil samples were taken from four sampling locations, and out of these 30 samples, 10 soil samples were with low pollution (L), 10 soil samples were with medium pollution (M) and 10 soil samples were with heavy pollution (H). A Soxhlet apparatus was used to determine the concentration of oil pollutants (%Oil) in the soil samples taken according to the UNEP/IOC/IAEA method of the American Environmental Organization (L, M, and H). Some general characteristics of soil were measured based on standard methods. Cultivable microbial population was counted in NA (total population) and CFMM (oil-degrading microbial population). Phosphatase activity (acidic and alkaline) was determined using the method described by Tabatabai, 1994. According to the factors in this experiment, a completely random nested design was used for data analysis through SPSS software. The test factors included sampling location (four locations) and three different levels of oil pollution (L: low, M: moderate, and H: high).
The results showed that with the increase of oil concentration in the soil samples, the activity of acid (ACP) and alkaline phosphatase (ALP) increased. In all soils collected from four locations, ACP was lower than ALP. The highest ACP and ALP were obtained with values of 45.78 and 84.90 (gPNP.g-1.h-1µ) in H soils, respectively. In the regression analysis, it was observed that the percentage of oil, percentage of sand and EC with the regression coefficient of 0.71 were effective variables in ACP, and also the percentage of oil and sand were the effective variables on ALP with the regression coefficient of 0.43. In the end, PCA analysis was also performed and the results showed that 68% of the variation between the samples could be explained by the first two components (biochemical component and physical component). Petroleum pollutants that are naturally present in the soil for a long time, with the passage of time, lead to the adaptation of microbial communities resistant to pollution, and therefore we will witness an increase in their abundance and the activity of enzymes such as phosphatase. It seems that natural and long-term oil pollution has caused the natural selection of microbial species resistant to these conditions. An increase in oil concentration in soil samples led to an increase in acid and alkaline phosphatase activity, which was related to the phosphatase activity of oil-degrading microorganisms in the soil. Also, according to the appropriate pH for the maximum activity of acid and alkaline phosphatase and that the pH of the samples used in this research was in the neutral range, it was observed that the activity of alkaline phosphatase was higher than that of acid phosphatase.
If petroleum pollutants exist naturally and long-term in the soil, with the passage of time, soil microorganisms that have the ability to destroy petroleum hydrocarbons dominate in the environment, and in other words, soil microbial communities with soil pollution conditions. They adapt. Therefore, we will see an increase in some microbial activities as well as the abundance of the microbial population. The results of the experiments conducted in this research also indicated an increase in microbial abundance and the measurement of phosphatase enzyme activity (acidic and alkaline).
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