Change in Nutrient Speciation in the Antarctic Soil by Increasing Temperature.

Increasing temperature may have an effect on soil enzyme and microbial activities.  It can alter the nutrient speciation in the soil ecosystem.  The objectives of this study are to evaluate the soil enzyme activities (β-glucosidase, ureases, acidic and alkaline phosphomonoesterase, and dehydrogenase) in response to the temperature and to compare the nutrient (carbon, nitrogen and phosphorus) speciation following the temperature difference.  Three PTFE bottles, filled with 10 cm of the composite sample on the sterilized sand, were incubated for 11 days at the different temperature ranges (0.9 ± 1.9 °C, 5.2 ± 0.7 °C, and 7.6 ± 0.7 °C).  The soil enzyme activities of composite and incubated samples were measured.  Also, total organic carbon (TOC), total nitrogen (TN), inorganic nitrogen (NH₄⁺, NO₂^-, and NO₃^-), total phosphorus (TP), exchangeable phosphorus (Ex-P), and available phosphorus (AP) of the samples were measured.  The test of significance between the nutrient concentrations and the temperature were carried out using SAS 9.2.  As the temperature became increased, the soil enzyme activities but ureases and acidic phosphomonoesterase were enhanced.  The loss rate of TOC was 3.4 % at the lowest temperature range (0.9 ± 1.9 °C), while the loss rate of TOC was 44.3 % at the highest temperature range (7.6 ± 0.7 °C).  TOC and inorganic nitrogen in response to the temperature range showed the significant difference at 5.2 ± 0.7 °C, and 7.6 ± 0.7 °C (p < 0.05).  Especially, the fraction of NO₃^- from inorganic nitrogen was reduced after incubation.  TN didn’t show the significant difference between the three temperature ranges (p < 0.05).  TP showed the significant difference at between 0.9 ± 1.9 °C and 7.6 ± 0.7 °C (p < 0.05).  Ex-P concentration at 0.9 ± 1.9 °C had the significant difference with the others (p < 0.05).  AP concentration after the three incubation was different with before incubation significantly (p < 0.05), especially, AP concentration at 0.9 ± 1.9 °C was the highest. These results suggest that as the temperature become high, the soil enzyme and microbial activities increase and the altered nutrient speciation may impact on microbial activity and ecosystem productivity.