Trends in arthroscopy-documented cartilage injuries of the knee and repair procedures among 15-60-year-old patients.

We validated a registry-based method of identifying patients with knee cartilage injury and estimated temporal changes in the incidence of arthroscopy-documented cartilage injuries of the knee and the proportion leading to repair procedures in Denmark. After excluding patients with diagnosed osteoarthritis, we identified 21,392 patients aged 15-60 years with a first recorded procedure code indicating knee cartilage injury in the Danish National Registry of Patients (DNRP) from 1996 to 2011. Using the surgical descriptions of arthroscopy findings in medical records as gold standard, the positive and negative predictive value of procedure codes for knee cartilage injury was 88% and 99%, respectively. The arthroscopy-documented overall incidence of cartilage injury of the knee was 40/100,000 person-years (py) [95% confidence interval (CI): 39.5-40.6] during the period 1996-2011. The arthroscopy-documented age-standardized annual incidence of knee cartilage injury increased from 22 (95% CI: 20.5-23.7) in 1996 to 61 (95% CI: 58.7-64.0) in 2011, per 100,000 py. An increase occurred in all age groups and both sexes. Only 1/6 (17%) patients with knee cartilage injury had a repair procedure. The validity of procedure codes for knee cartilage injury in the DNRP is high. The arthroscopy-documented incidence of knee cartilage injuries increased substantially during the 15-year period.

Do concepts about catchment cycling of methylmercury and mercury in boreal catchments stand the test of time? Six years of atmospheric inputs and runoff export at Svartberget, northern Sweden.

Previous studies at the Svartberget catchment in northern Sweden have identified potential terrestrial sources of methylmercury (MeHg) and total mercury (THg) in runoff as well as processes controlling MeHg/Hg transfers from soil to runoff water. This paper considers whether the concepts based on a few seasons of observations are consistent with catchment budgets of MeHg/THg over half a decade. Inter-annual and seasonal variations in the input and output fluxes of THg/MeHg, in open field wet deposition (OF), litterfall (LF) and runoff water are evaluated together with more recently measured concentrations that include the throughfall water (TF) data. The input and output flux data of THg and MeHg from the Svartberget catchment are also compared to those from the Gårdsjön Catchment. The average annual MeHg input fluxes in OF, TF and LF are 0.08, 0.17 and 0.3 g km(-2) year(-1), respectively. The comparable inputs for THg are 7, 15 and 17 g km(-2) year(-1). Thus, LF is as important as TF for THg inputs, while LF is twice as important as TF for MeHg inputs. The annual output flux of MeHg varied between 0.05 and 0.14 g km(-2) year(-1). The annual output flux of THg varied between 1 and 3.4 g km(-2) year(-1). The large inter-annual variations in catchment output did not follow the smaller variations in atmospheric input. This suggests that changes in climate can effect terrestrial outputs of THg/MeHg to surface water more than atmospheric deposition. These data do not contradict the earlier findings that it is the hydrological and biogeochemical processes in the riparian zone that have a central role in determining the amount of MeHg reaching surface waters from forested catchments. The juxtaposition of major flow paths and organic-rich soils in the riparian zone may create the locations of most importance for net MeHg production, runoff export and a larger pool of MeHg.

Sampling and analysis of gas-phase methylmercury in ambient air.

A procedure for sampling gaseous methylmercury (MeHg) in ambient air using a refluxing mist chamber (MC) has been developed. The MC consists of a glass bulb with an air inlet tube at the bottom. Via a capillary mounted adjacent to the inlet tube, the solution inside the MC is pulled from the bottom of the bulb to form a mist inside the chamber. Two different aqueous sampling solutions were tested and evaluated, a dilute HCl (0.003 M) solution and a solution containing the chelating agent ammonium salt of pyrrolidine-1-dithiocarboxylic acid. The airflow rate through the sampler was 10-15 l min(-1). The sampling time was 6 h when using dilute HCl as an extraction solution, and 3 h when using the solution containing the chelating solution. Determination of atmospheric MeHg collected in the aerated water sample was accomplished using GC/CVAFS after aqueous phase ethylation, and pre-collection onto carbotrap column. To test the reproducibility and accuracy of the method, parallel sampling, and standard additions tests were carried out. Other quality control tests, i.e. procedure blanks and duplicated analysis have also been performed. The detection limit, based on three times the standard deviation of total blank (including sampling, distillation, and analysis) is 2 pg, which corresponds to a procedural detection limit of approximately 1 pgm(-3) in ambient air when sampling for 3 h. Measurements performed on the roof of the IVL building yielded concentrations from 3 to 22 pgm(-3) corresponding to 0.3-1% of the total gaseous mercury in ambient air.

A device for sampling and determination of total particulate mercury in ambient air.

A miniaturized device, which serves as both particulate trap and pyrolyzer for airborne particulate mercury species, is described. It has been used in combination with amalgamation/thermal desorption/cold vapor atomic fluorescence spectrometry detection for the determination of total particulate mercury (TPM) associated with atmospheric aerosols. A standard reference material (SRM 1633b, NIST) has been used for validating of the pyrolysis technique, and a relative error smaller than 3% has been obtained. Contrary to most methods currently employed, this new technique does not require any sample preparation (e.g., extraction/digestion), no manual sample transfer or sample handling, and no addition of chemicals or reagents. Hence the risk of contamination is low. The time for complete analysis is less than 10 min per sample. The concentrations of TPM determined in metropolitan Toronto ranged from 3 to 91 pg m(-)(3) with standard deviations of <±2 pg m(-)(3) for simultaneous sets of four samples. These atmospheric TPM concentration values fall within the range reported in the literature. Good agreement was obtained by the three methods compared in a field study at Ny-Ålesund (78°54'N, 11°53'E), Svalbard. The elevated values of TPM concentrations obtained using the method developed in this work may arise from the Arctic springtime conversion of atmospheric mercury from gas-phase to particulate-phase Hg species.