Precision requirements for space-based XCO2 data

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): D10314, doi:10.1029/2006JD007659.Precision requirements are determined for space-based column-averaged CO2 dry air mole fraction (XCO2) data. These requirements result from an assessment of spatial and temporal gradients in XCO2, the relationship between XCO2 precision and surface CO2 flux uncertainties inferred from inversions of the XCO2 data, and the effects of XCO2 biases on the fidelity of CO2 flux inversions. Observational system simulation experiments and synthesis inversion modeling demonstrate that the Orbiting Carbon Observatory mission design and sampling strategy provide the means to achieve these XCO2 data precision requirements.This work was supported by the Orbiting Carbon Observatory (OCO) project through NASA’s Earth System Science Pathfinder (ESSP) program. SCO and JTR were supported by a NASA IDS grant (NAG5-9462) to JTR

The geoaccumulation index and enrichment factor of mercury in mangrove sediment of Port Klang, Selangor, Malaysia.

Mangrove areas are important to the ecosystem. One of its crucial functions is as a sink of pollutants, especially metal ions. However, the accumulation of metals in mangrove sediment can generate negative impacts on plant growth, microbial activity, and soil fertility. Apart from that, the severity of the impact is highly influenced by the type of metal found in the sediment and the quality of sediment itself. One of the metals that have adverse effects on the environment is mercury. The objectives of this study are to determine the concentration and distribution of mercury and to assess the enrichment of mercury in Port Klang mangrove sediment by using geoaccumulation index and enrichment factor. Sediment samples were collected from 30 sampling points that cover Langat River and Klang River estuaries, Lumut Straits, Pulau Klang, and Pulau Indah. During sampling, water parameters such as pH, salinity, electrical conductivity, and total dissolved solids were measured in situ, whereas the total mercury in sediment samples was determined at the laboratory using inductively coupled plasma mass spectrometry. In this study, mercury was found to be concentrated along Lumut Strait especially in the mixing zone near the confluence of Langat River and at the jetty to Pulau Ketam. The geoaccumulation index and enrichment factor (calculated using logarithmized data of the reference element) found that three stations were enriched with mercury. In addition, geoaccumulation index was also observed to be more objective compared to enrichment factor whose results were influenced by the concentration of reference element used

Peridural scar and its relation to clinical outcome: a randomised study on surgically treated lumbar disc herniation patients

A prospective randomised 2-year follow-up study on patients undergoing lumbar disc herniation surgery. The objective was to investigate the relationship between peridural scarring and clinical outcome, the scar development 6 and 24 months postoperatively by using MRI, and if ADCON-L (a bioresorbable carbohydrate polymer gel) has an effect on scar size and/or improve patients’ outcome after lumbar disc herniation surgery. The association between peridural scarring and recurrent pain after lumbar disc herniation surgery is debated. Numerous materials have been used in attempts to prevent or reduce postoperative peridural scarring; however, there are conflicting data regarding the clinical effects. The study included 119 patients whose mean age was 39 years (18–66); 51 (47%) were women. Sixty patients (56%) were perioperatively randomised to receive ADCON-L, and 48 (44%) served as controls. All patients underwent MRI at 6 and 24 months postoperatively, and an independent radiologist graded the size, location and development of the scar, by using a previously described scoring system. Pre- and 2-year postoperatively patients graded their leg pain on a visual analogue scale (VAS). At the 2-year follow-up patients rated their satisfaction with treatment (subjective outcome) and were evaluated by an independent neurologist (objective outcome), using MacNab score. There was no relationship between size or localisation of the scar and any of the clinical outcomes (VAS, subjective and objective outcome). The scar size decreased between 6 and 24 months in 49%, was unchanged in 42% and increased in 9% of the patients. Patients treated with ADCON-L did not demonstrate any adverse effects, nor did they demonstrate less scarring or better clinical outcome than control patients. No significant association between the presence of extensive peridural scar or localisation of scar formation and clinical outcome could be detected in the present study. Further, no positive or negative effects of ADCON-L used in disc herniation surgery could be seen