Christian Christiansen

Changes in the C, N, P burial rates in some Baltic Sea sediments over the last 150 years - relevance to P regeneration rates and the phosphorus cycle

Three major depositional basins (the Gdansk, Bornholm and Eastern Gotland basins) of the Baltic Proper, which together account for .50% of the depositional areas in the entire Baltic Sea, have accumulated increased amounts of sediment and organic carbon during the last 50 years, as is shown in 210 Pb-dated sediment cores. The shallow Arkona Basin has had constant accumulation rates and rate increases of bulk sediment, organic carbon and aluminium in the Bornholm Basin are parallel and are interpreted to reflect increased material input from land or from erosion of shallow-water areas. In the Gdansk and Eastern Gotland basins, the accumulation rates of mineral matter have risen at lower rates than those of organic carbon and point to preferential enrichment of organic matter. At increasing rates of burial, the material in the Gdansk and Eastern Gotland basins appears to have been depleted in phosphorus relative to nitrogen and organic carbon. Using C:N:P ratios from a sediment trap mooring in the Gotland Basin and from fluffy layer material in the Pomeranian Bight as characteristic ratios for sedimenting material, we find evidence for significant increases in the ratios of C to P in sediments younger than 15‐25 years in cores from the Eastern Gotland basin, coincident with H2S build-up in deep waters. Paired oxygen and phosphorus concentration data from the sub-halocline water column of the Gotland Basin covering the time since 1970 suggest that the phosphate reflux is fed from two sources: At the transition from oxic to anoxic conditions, iron-bound phosphate is suddenly liberated at the sediment‐water interface and results in a concentration jump of approximately 2 mmol dm 23 phosphate in deep water. During anoxic periods with H2S in bottom waters, phosphate diffuses out of the sediment and adds to the dissolved phosphate pool. Our data imply that the sediment contributed approximately 14,000 t a 21 of phosphorus to the water column of the deep Gotland Basin since the early 1970s. Compared to total P input to the Baltic Sea (1993: 39,000 t), the reflux of P from anoxic sediments in the Gotland Basin thus is a major source of P for the Baltic Sea. On time scales of years and decades, the reflux of phosphorus from the sediments may be the reason for discrepancies between the ratios of nitrogen and phosphorus in the Baltic Sea and for a lack of effects of declining phosphate discharge into this large ecosystem. q 2000 Elsevier Science B.V. All rights reserved.

A Comparison of Epidural Analgesia With Combined Continuous Femoral-Sciatic Nerve Blocks After Total Knee Replacement

Epidural analgesia remains the “gold standard” of pain relief after total knee replacement. However, peripheral nerve block is gaining popularity because the incidence of side effects may be reduced. Our study tests this postulate. Sixty patients were prospectively randomized to receive either epidural infusion or combined continuous femoral and sciatic nerve blocks. Ropivacaine 2 mg/mL plus sufentanil 1 &mgr;g/mL was given either epidurally or through the femoral nerve catheter, and ropivacaine 0.5 mg/mL was given through the sciatic nerve catheter using elastomeric infusers (delivering 5 mL/h for 55 h). The primary outcome measure was the total incidence of side effects (urinary retention and moderate to severe degrees of dizziness, pruritus, sedation, and nausea/vomiting on the first postoperative day). Intensity of motor blockade, pain at rest and on mobilization, and rehabilitation indices were also registered for 72 h. One or more side effects were present in 87% of patients in the epidural group whereas only 35% of patients in the femoral and sciatic block groups were affected on the first postoperative day (P = 0.0002). Motor blockade was more intense in the operated limb on the day of surgery and the first postoperative day in the peripheral nerve block group (P = 0.001), whereas the non-operated limb was more blocked in the epidural group on the day of surgery (P = 0.0003). Pain on mobilization was well controlled in both groups and there were no differences in the length of hospital stay. Rehabilitation indices were similar. The results demonstrate a reduced incidence of side effects in the femoral/sciatic nerve block group than in the epidural group on the first postoperative day.

Long term variations in backbarrier salt marsh deposition on the Skallingen peninsula - the Danish Wadden Sea

Abstract Accretion on a natural backbarrier salt marsh was determined and modeled as a function of high tide level, initial salt marsh level and distance from the salt marsh edge. Accretion measurements were based on up to 67-year-old marker horizons, supplemented by 210Pb/137Cs datings. The salt marsh is situated on the backbarrier of the Skallingen peninsula in the northern part of the Danish Wadden Sea. The tidal range (mean 1.5 m) is strongly affected by wind tide which occasionally adds up to about 3 m to the astronomical high tide level. Accretion is restricted to a narrow vertical band from about 0.1 m below to about 0.7 m above the mean high water level. In the outer part of the backbarrier (close to the tidal flat) mean accretion is about 4 mm yr−1 and in the inner part it is about 2 mm yr−1. The decrease takes place in a similar manner as the decrease across a flood plain. The major part of salt marsh accretion is associated with high water levels corresponding to weather conditions characterized by gales. The long term variation of salt marsh accretion correlates with variations in the North Atlantic Oscillation winter index. The number of over-marsh high tides decreases exponentially with high tide level. The function constants controlling this distribution vary in direct ratio to the mean sea level. Plausible near future scenarios of tidal development were obtained by extrapolating this relation. Three sea level scenarios were tested: (i) sea level rise continues at a constant (long term) rate of 2.3 mm yr−1, (ii) sea level rise continues at a constant (short term) rate of 4.2 mm yr−1 and (iii) sea level rise accelerates to a constant rate of 6.4 mm yr−1. In the first case accretion on the salt marsh will keep pace with the high water level rise. In the second case deposition in the inner part of the salt marsh will lag behind while that of the outer part of the salt marsh will keep pace with the rising high water level. In the third case, corresponding to a ‘worst case’ scenario for the 21th century, the salt marsh will gradually drown.

Transient neurologic symptoms after spinal anesthesia with lidocaine versus other local anesthetics : a systematic review of randomized, controlled trials

Lidocaine has been used for spinal anesthesia since 1948, seemingly without causing concern. However, during the last 10 years, a number of reports have appeared implicating lidocaine as a possible cause of neurologic complications after spinal anesthesia. Follow-up of patients who received uncomplicated spinal anesthesia revealed that some of them developed pain in the lower extremities—transient neurologic symptoms (TNS). In this study, we sought to compare the frequency of 1) TNS and 2) neurologic complications after spinal anesthesia with lidocaine with that after other local anesthetics. Published trials were identified by computerized searches of The Cochrane Library, MEDLINE, LILAC, and EMBASE and by checking the reference lists of trials and review articles. The search identified 14 trials reporting 1347 patients, 117 of whom developed TNS. None of these patients showed signs of neurologic complications. The relative risk for developing TNS after spinal anesthesia with lidocaine was higher than with other local anesthetics (bupivacaine, prilocaine, procaine, and mepivacaine), i.e., 4.35 (95% confidence interval, 1.98–9.54). There was no evidence that this painful condition was associated with any neurologic pathology; in all patients, the symptoms disappeared spontaneously by the 10th postoperative day.

Material transport from the nearshore to the basinal environment in the southern Baltic Sea I. Processes and mass estimates

Abstract Processes involved in erosion, transport and deposition of cohesive materials are studied in a transect from shallow (16 m) to deep (47 m) water of the SW Baltic Sea. The wave- and current-induced energy input to the seabed in shallow water is high with strong variability and suspended matter concentrations may double within a few hours. Primary settling fluxes (from sedimentation traps) are less than 10 g m −2 day −1 , whereas resuspension fluxes (evaluated from sedimentation flux gradients) are 15–20 times higher and the residence time for suspended matter in the water column is 1–2 days. Settling velocities of aggregates are on average six times higher than for individual particles resulting in an enhanced downward transport of organic matter. Wave-induced resuspension (four to six times per month) takes place with higher shear stresses on the bottom than current-induced resuspension (three to five times per month). The short residence time in the water column and the frequent resuspension events provide a fast operating benthic–pelagic coupling. Due to the high-energy input, the shallow water areas are nondepositional on time scales longer than 1–2 weeks. The sediment is sand partly covered by a thin fluff layer during low-energy periods. The presence of the fluff layer keeps the resuspension threshold very low ( −2 ) throughout the year. Evaluated from 3-D sediment transport modeling, transport from shallow to deep water is episodic. The net main directions are towards the Arkona Basin (5.5×10 5 t per year) and the Bornholm Basin (3.7×10 5 t per year). Energy input to the bottom in deep water is low and takes place much less frequently. Wave-induced resuspension occurs on average once per month. Residence time of particles (based on radioactive isotopes) in the water column is half a year and the sediment accumulation rate is 2.2 mm year −1 in the Arkona Basin.

Material transport from the near shore to the basinal environment in the southern Baltic Sea II: Synthesis of data on origin and properties of material

The Pomeranian Bight (southern Baltic Sea) is a mixing zone between waters of the Baltic Proper and the river Oder, which drains a densely populated and highly industrialised catchment of central Europe. The bight is a nondepositional area, and all material produced in its water column, from erosion of strata at the seafloor and cliffs, and delivered by rivers, is transported near the seafloor to the depositional areas of the Arkona, Bornholm and Gdansk basins. In this contribution, we assess the origin, transformation and mass fluxes of material through the bight based on an integrated field study conducted in the period 1996–1998. The transport mechanism is by wave- and current-induced resuspension and settling cycles, which effectively enrich organic-rich material and associated substances (organic pollutants, heavy metals) in deeper water; the estimated transport time is less than 6 months. The phases in which the material is transported are suspended matter in the water column, a particle- and aggregate-rich benthic boundary layer of 20 m water depth), the fluffy layer is not readily distinguished from the underlying soft, organic-rich sediment and the change in physical and chemical properties is gradual. The organic matter passing through the coastal zone in the southern Baltic is unaffected by biological or chemical modifications in composition. We find no evidence for a preferential removal of nitrogen or phosphorus, even if the speciation of phosphorus changes from biological compounds to minerals. The compositional changes which we see, i.e., in the nitrogen isotopic composition and in trace metal concentrations, are mainly caused by dilution of the river signal. In the case of

The impact of degenerative conditions in the spine on bone mineral density and fracture risk prediction

We examined the impact of degenerative conditions in the spine (osteophytosis and endplate sclerosis) and aortic calcification in the lumbar region on bone mineral content/density (BMC/BMD) measured in the spine and forearm by absorptiometry and on fracture risk prediction. The radiographs of 387 healthy postmenopausal women, aged 68–72 years, were assessed in masked fashion for the presence of osteophytosis, endplate sclerosis and aortic calcification in the region from L2 to L4. Vertebral deformities/fractures were assessed by different definitions. Osteophytes larger than 3 mm and in numbers of 3 or more resulted in a significantly (12%) higher spinal bone mass (p<0.001). Endplate sclerosis had a similar effect (p<0.001). In subjects with both degenerative conditions the BMC/BMD in the spine and forearm were significantly higher than in unaffected women (19% in the spine, 10% in the forearm;p<0.001). The spinal BMD values were significantly lower in fractured women if both degenerative conditions were absent (p<0.001), whereas fractured and unfractured women had similar values if degenerative conditions were present. Degenerative conditions did not alter the ability of forearm BMC to discriminate vertebral or peripheral fractures. Receiver operating characteristic (ROC) curves (true positive fraction versus false positive fraction) were generated for BMD of the lumbar spine and BMC of the forearm with regard to the discrimination between women with vertebral and peripheral fractures and healthy premenopausal women. The ROC curves for women without degenerative conditins were consistently above the curves for women affected by osteophytosis and endplate sclerosis in the lumbar spine (p<0.001). In conclusion, osteophytes and endplate sclerosis have a considerable influence on spinal bone mass measurements in elderly postmenopausal women and affect the diagnostic ability of spinal scans to discriminate osteoporotic women. Our data suggest that in elderly women, unless the spine is radiologically clear of degenerative conditions, a peripheral measurement procedure should be considered an alternative for assessment of bone mineral content/ensity.

Estimation of the Effect of Salmon Calcitonin in Established Osteoporosis by Biochemical Bone Markers

We reviewed data on 42 postmenopausal women with established osteoporosis (forearm fracture or a low bone mass0 who had been randomly treated for 1 year with either rectal salmon calcitonin (sCT), 100 IU daily (n=25) or nasal sCT, 200 IU daily (n=17) applying an estimation algorithm for bone loss rates. Both groups received a daily calcium supplement of 500 mg. A group of 18 age-matched women who received no treatment served as controls. The bone mineral content of the distal forearm (BMCarm) was measured every 3 months by single photon absorptiometry. The individual rates of change during the 1-year period were calculated by linear regression analysis (αBMCarm). Bone loss rates were estimated initially and after 1 year of therapy by measurements of serum alkaline phosphatase, plasma bone Gla protein, and fasting urinary hydroxyproline and calcium (both corrected for creatinine excretion) according to the estimation algorithm. Both administration forms revealed significant control group-corrected decreases in serum and urine markers of bone turnover of 15–40% (P<0.05–0.01) and positive outcomes of 2% in αBMCarm (P<0.01). The estimated effect on bone mass was expressed as the difference between the bone loss estimated after 1 year and initially (ΔESTBIO). A significant correlation was seen between αBMCarm and ΔESTBIO (r=0.5, P<0.0001). We conclude that the effect of sCT on bone can be followed up by biochemical markers for bone turnover, i.e., by an annual blood and fasting urine sample, applying an estimation algorithm for the rate of bone loss.

Sedmentation in the Central Baltic Sea as Viewed by Non-Destructive Pb-210-dating

Abstract Geografisk Tidsskrift, Danish Journal of Geography 98:1–9. A non-destructive gamma-spectrometric method was used to assay the sedimentation in the central Baltic Sea. Three cores from the Gotland Deep with water depths exceeding 230 m showed relatively high Pb-210 and Cs-137 but relatively little variation between cores in the curves for unsupported Pb-210. A constant rate of supply (CRS) modelling of the data revealed that there is a tendency of increasing linear sedimentation rates, from 0.5 to 2 mm a−1, since 1950. With the measured bulk density profiles this is accompanied by increasing sediment accumulation rates (from about 200 to 600 g m−2 a−1) There are generally moderately increased Cs-137 values found in the deep and these may mainly be ascribed to the Chernobyl accident. A core from the central Gdansk Basin taken at a water depth of 117 m shows relatively lower Pb-210 values and a more structured unsupported Pb-210 distribution with depth. A very high activity (about 4000 Bq kg−1) sedi...

Effects of morphological changes on metal accumulation in a salt marsh sediment of the Skallingen peninsula, Denmark

In 1931 a red-colored, sandy marker horizon was placed on the emergingSkallingen salt marsh. Sedimentation on top of the marker horizon sincethen shows two opposing tendencies. Coincident with salt marshdevelopment the sediments display up to 1964 a fining upward sequencewith an increasing content of organic matter. Since 1964 a nearby creekhas meandered towards the sampling plot. Consequently, the sedimentsbecome coarser with a decreasing organic matter content. Themorphological induced changes in sedimentary conditions strongly influencemetal content in the sediments and thereby hide anthropogenic inducedconcentration variations. Thus, an apparently diminishing Zn content (perkg dry weight) since 1964 could indicate lesser load to the area. However,corrected for grain size effects there is an increasing content of Zn. Othermetal concentrations (e.g. Cu) show a diminishing trend when corrected forgrain size effects and therefore indicate a reduced anthropogenic inducedload of these metals to the salt marsh.