Optical properties and 14C ages of stream DOM from agricultural and forest watersheds during storms.

Forest and agricultural land use affects the concentration and composition of dissolved organic carbon (DOC) in streams and rivers. To elucidate the impacts of forest and agricultural land use on stream DOC during storm events, we investigated DOC concentration ([DOC]), optical properties of dissolved organic matter (DOM), and Δ14C-DOC in both forest- and agriculture-dominated headwater streams in South Korea in the summer of 2012. One forested and five agricultural streams were investigated. During storms, the peak [DOC] of forest stream increased to 5.8 mg L-1, approximately two times larger than that of the most agricultural stream (3.2 mg L-1), demonstrating the weaker storm responses of the [DOC] of agricultural streams to hydrological change. Five PARAFAC components were identified, including three terrestrial humic-like substances (C1, C2, C3), one microbial humic substance (C4), and one microbial protein-like substances (C5). The mean (C4+C5)/(C1+C2+C3) of all storm events at the most agricultural stream was 1.5 times larger than that of the most forested stream, suggesting that more protein-like DOM is exported from agricultural watersheds. Whereas a forest stream was primarily composed of terrestrially derived and 14C-enriched modern DOC, the 14C-age of the most agricultural stream was up to ∼1000 years old. The results suggest that agricultural practices could decrease the old organic carbon pools from soils. However, how quickly the aged DOC can be degraded to CO2 in streams is unknown, warranting future investigation on lability of the aged DOC and their effects on CO2 evasion from rivers and estuaries downstream.

Application of Lateral Approach for the Removal of Migrated Interbody Cage: Taphole and Fixing Technique.

When a revision surgery related with removal of failed interbody cage is required, going through the previous passage can lead to a higher risk of neurological deficits or incidental dural injuries. Recently, the lateral approach has become a popular method instead of the conventional anterior or posterior approaches. The lateral approach is also useful method to remove failed interbody cage previously placed and re-do interbody fusion with lower risks compared to revision surgery via previous passage. However, there is still some difficulty in retrieving the interbody cage from the intervertebral space because of no spacious passage, subsidence, and uncontrolled movable cage. In this study, we introduce our experience that we removed failed interbody cage more easily with only the simple additional steps of making a taphole and fixing the cage using a thread-tipped stick.