Deep instability of deforested tropical peatlands revealed by fluvial organic carbon fluxes.

Tropical peatlands contain one of the largest pools of terrestrial organic carbon, amounting to about 89,000 teragrams (1 Tg is a billion kilograms). Approximately 65 per cent of this carbon store is in Indonesia, where extensive anthropogenic degradation in the form of deforestation, drainage and fire are converting it into a globally significant source of atmospheric carbon dioxide. Here we quantify the annual export of fluvial organic carbon from both intact peat swamp forest and peat swamp forest subject to past anthropogenic disturbance. We find that the total fluvial organic carbon flux from disturbed peat swamp forest is about 50 per cent larger than that from intact peat swamp forest. By carbon-14 dating of dissolved organic carbon (which makes up over 91 per cent of total organic carbon), we find that leaching of dissolved organic carbon from intact peat swamp forest is derived mainly from recent primary production (plant growth). In contrast, dissolved organic carbon from disturbed peat swamp forest consists mostly of much older (centuries to millennia) carbon from deep within the peat column. When we include the fluvial carbon loss term, which is often ignored, in the peatland carbon budget, we find that it increases the estimate of total carbon lost from the disturbed peatlands in our study by 22 per cent. We further estimate that since 1990 peatland disturbance has resulted in a 32 per cent increase in fluvial organic carbon flux from southeast Asia--an increase that is more than half of the entire annual fluvial organic carbon flux from all European peatlands. Our findings emphasize the need to quantify fluvial carbon losses in order to improve estimates of the impact of deforestation and drainage on tropical peatland carbon balances.

A comparison of pain levels after the Biering-Sorensen and the modified 20-metre shuttle test in patients with chronic low back pain.

BACKGROUND AND OBJECTIVE: The Biering-Sorensen Test (BST) is a useful and well validated assessment tool in patients with chronic lumbar pain. However there is sometimes concern that it may lead to an unwarranted increase in pain. This study compared pain levels before and after the BST against a currently accepted functional assessment tool- the modified 20-metre shuttle test (MST)- in military patients with chronic low back pain. METHODS: 56 patients with non-specific lumbar pain of more than three months duration were tested on admission and discharge from a three week in-patient rehabilitation programme using the BST and the MST. A questionnaire was used to assess pain levels before and after both tests on admission and discharge from the group. The BST was carried out before the MST, with a time delay of 30-60 minutes. RESULTS: There were significant increases in pain immediately after both the MST and the BST (range of mean increase: 2.2 to 3.2 points, p< 0.001). The mean absolute levels of pain after the BST on admission and discharge were 0.26 and 0.80 more than the levels after the MST. The mean increases were 0.36 and 1.16 more after the BST compared to that after the MST. Pain levels returned to normal within 60 minutes of the BST being completed. CONCLUSION: Using either comparison method, although the initial increases after the BST were slightly more, the amounts were comparable and much less that the minimal clinically important difference in pain which is 1.5.