engleski

Recovery of Black pine (Pinus nigra Arn.) needles in response to lowered SO2 in the air - a case study of Plomin thermal power plant (Croatia)

The impact of SO2 emitted from the Plomin thermal power plant (Croatia) was monitored for about fifteen years by measuring S-concentration in the needles of Black pine grown at different distances from the power plant. Since 1999 the emission of SO2 was significantly lowered, but expected decrease in S-concentrations in needles was not observed in the same and the following (2000) year. The aim of present study was to determine the time needed for the recovery of Black pine needles regarding to the S-concentrations. Several basic biochemical parameters were measured as well in order to assess the physological status of investigated needles. Current- and previous-year needles were collected from the upper crown of Black pine (Pinus nigra Arn.) trees grown at different distances from the Plomin thermal power plant: zone I - less than 10 km, zone II - 10-20 km and zone III - 20-30 km. The performed chemical and biochemical analyzes included the measurement of N, P, K, Ca, Mg and S concentrations, as well as the percentage of dry weight, total soluble proteins and photosynthetic pigment content. The obtained results were arranged according to the sampling zones and tested against each other, using the t-test. S-concentrations in both needle generatins were practically the same for all three zones, without any statistical significance. Although S-concentrations decreased in comparison to the values reported for previous years, they were still designated as elevated in current-year needles, while in previous-year needles these concentrations belonged to low level class. Concentration of other elements (N, P, K, Ca and Mg) also showed similar values between investigated zones. Values for K, Ca and Mg could be designated as adequate to optimal, while the P-content for all sample plots was low. The N-content values showed certain veriability among investigated zones. The results of soluble proteins and photosynthetic pigment content, as well as the percentage of dry weight further confirmed that physiological status of investigated needles was not disturbed. Based on presented results, it can be concluded that the lowering of S-concentrations, approaching the values that could be considered as low. Mineral nutrition cannot be considered as the main reasosn for slow lowering rate of S-concentrations in needles. Measured biochemical parameters confirmed that there were no significant differences in physiological status of investigated needles between all three zones.

Pinus nigra; air polution; SO2; mineral nutrition; photosynthetic pigments; proteins

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