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This study compared soil CO2 efflux rates in three adjacent coniferous plantations consisting of larch (Larix leptolepis Gordon), red pine (Pinus densiflora S. et Z.) and rigitaeda pine (P. rigitaeda: P. rigida Mill × P. taeda L.) species planted in the same year (1963). Soil CO2 efflux, litter fall carbon (C) and root decomposition rates were measured with soil environmental factors for two years. The mean annual soil CO2 efflux rates (g CO2 m−2 hour−1) were the highest in rigitaeda pine (0.30), followed by red pine (0.27) and larch (0.24) plantations. An exponential regression of the CO2 efflux rates against their corresponding soil temperatures showed a significant (P < 0.05) relationship (red pine R2 = 0.69; rigitaeda pine R2 = 0.67; larch R2 = 0.63). The soil CO2 efflux rates were negatively correlated with soil pH, but the soil water and soil organic C content were not significantly correlated with the CO2 efflux rates. Soil CO2-C efflux rates were correlated by litter fall C inputs in the larch and red pine plantations, and the decomposition rates of 5–10 mm diameter roots in the larch plantation. This result is useful in understanding potential responses of soil CO2 efflux rates with changes in stand and soil environmental factors induced by different tree species.
63 congeners of chloronaphthalene represented by 53 peaks fractionated and separated using two-dimensional HPLC and DB-17 capillary column were quantified using HRMS in ten samples of pine needles collected in 1999 around Tokyo Bay in Japan. Similarities and differences of chloronaphthalene concentrations and patterns between 10 sampling sites were studied using multivariate analysis. Total PCN concentrations ranged from 250 to 2100 pg/g wet weight. Except for one site, tri- and tetra-CNs highly dominated (from 54 to 80%) in CN homologue patterns of pine needles. At the easternmost site near the town of Tateyama in Chiba Prefecture the contribution from octaCN was ~20 %, while that of tri- and tetra-CNs ~42 %. Pine needles sampled from the sites around the innermost part of Tokyo Bay showed the highest load of PCNs. A multivariate analysis using the three most significant principal components explained 91% of the total variance in the measurement data. The greatest positive loading to PC1 is from the CN congeners nos. 13, 14/21/24, 15, 16, 17, 18, 19, 20, 22/23, 25, 26, 27, 28/36, 29, 30/32, 31, 33/34/37, 35, 40, 42, 43/45, 44, 47, 49, 50, 51, 52/60, 53, 57, 58, 59, 61, 62, 64, 65, 66/67, 68, 69, 71 and 72, and explains 65% variance in the data set. For PC2 the largest positive loading is from CNs nos.74 and 75, and negative load from CN nos. 38, 41, 46 and 48, which explains 17% of the variance. In case of PC3 the largest negative load is from CNs nos. 54, 56, 63, 70 and 73. A profile of the combustion process related CN congeners measured such as nos. 44, 48 and 54 didn’t show any specific trend implying pollution from diffused sources of various types.
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