ABSTRACT
Dissolved organic matter (DOM) and its composition in aquatic ecosystems is a key indicator of ecosystem function and an important component of the global carbon cycle. Tropical rainforest headwaters play an important role in global carbon cycling. However, there is a large uncertainty on how DOM sources interact during mobilisation and the potential fate of associated carbon and nutrients. Using field techniques to measure dissolved organic carbon (DOC) concentration and composition, changes in DOM source from headwaters to larger downstream rivers were observed. This study shows that the hydrological connectivity, developed during the transition from dry to wet seasons, changes the DOM supply and transport across a tropical river catchment. The observed variability in the DOC-river discharge relationship provides further evidence of the changes in the DOM supply in a small headwater. This novel insight into the seasonal changes of the dynamics of DOM supply to the river helps understanding the mobilization of terrestrial DOM to tropical headwaters and its export from smaller to larger rivers. It also highlights the data gap in the study of smaller headwaters which may account for uncertainty in estimating the terrestrial carbon transported by inland waters.
ABSTRACT
National registries provide valuable bases for comparisons and aid innovative policies. Iran, with 70 million inhabitants, has a governmentally supported system of organ and tissue procurement and transplantation. By two acts of legislation, first in 1997 regarding governmental rewarding living kidney donation and second in 2000 regarding cadaveric transplantation, this field has had remarkable growth in the last decade, under the supervision of the Ministry of Health. Since the beginning of each organ or tissue transplantation activity up to 2006, 21,359 kidneys, 338 livers, 122 hearts, 20 lungs, 7 pancreas, 1898 bone marrows, 28,838 corneas, 1380 heart valves, and 1366 bones were transplanted in our country. Increases in the number of live kidney transplantations are taking place, but cannot keep pace with the increasing number of patients. It is highly recommended that we try to increase cadaveric transplantation in coming years.
