Advances in Catchment Science, Hydrochemistry, and Aquatic Ecology Enabled by High-Frequency Water Quality Measurements

High-frequency water quality measurements in streams and rivers have expanded in scope and sophistication during the last two decades. Existing technology allows in situ automated measurements of water quality constituents, including both solutes and particulates, at unprecedented frequencies from seconds to subdaily sampling intervals. This detailed chemical information can be combined with measurements of hydrological and biogeochemical processes, bringing new insights into the sources, transport pathways, and transformation processes of solutes and particulates in complex catchments and along the aquatic continuum. Here, we summarize established and emerging high-frequency water quality technologies, outline key high-frequency hydrochemical data sets, and review scientific advances in key focus areas enabled by the rapid development of high-frequency water quality measurements in streams and rivers. Finally, we discuss future directions and challenges for using high-frequency water quality measurements to bridge scientific and management gaps by promoting a holistic understanding of freshwater systems and catchment status, health, and function.

[The usefulness of a computer program Oxygen Status Algorithm (OSA) with particular consideration of oxygen parameters in the Clinic of Chest Diseases]

The traditional parameters such as the oxygen tension (pO2) and the haemoglobin oxygen saturation (sO2) obtained from arterial blood samples are not always sufficient in clinical practice. The purpose of the study is to present the examples where pO2 and sO2 even in combination may provide misleading information. We examined patients with bronchial asthma, respiratory insufficiency and with extrinsic allergic alveolitis who had been admitted to the Chest Disease Department. We used the Oxygen Status Algorithm (OSA) to calculate the new oxygen parameters. These new parameters are: 1) oxygen extraction tension px defined as the tension required to extract 2.3 mmol of oxygen per liter of blood, 2) the concentration of extractable oxygen cx defined as the concentration of oxygen extracted per liter of blood at a tension of 5.0 kPa, 3) the oxygen compensation factor (Qx), derived as 2.3 mmol/l/cx. This data defines the blood oxygen availability. Additional parameters such as effective hemoglobin concentration ceHb (equivalent of oxygen capacity) and the hemoglobin oxygen affinity (p50) inform us of the oxygen supply to the tissue. The results show that the new oxygen parameters are helpful in undertaking decisions of starting therapy and its duration.

[Effect of hemodialysis on the level of serum digoxin-like substance and sodium-potassium pump activity in erythrocytes from patients with chronic renal failure]

Digoxin-like immunoreactivity (DLS) and erythrocyte sodium-potassium pump (PSP) activity were measured in a group of 16 patients with chronic renal failure (CRF) before and just after haemodialysis and in a group of 9 healthy persons. Before haemodialysis DLS was present in the blood of most CRF patients, at the mean concentration of 0,14 +/- 0,13 micrograms/l. After haemodialysis DLS concentration decreased to 0,09 +/- 0,09 microgram/l (p less than 0,01). In the control group blood DLS concentration was nondetectable. In the CRF group PSP activity was higher before than after haemodialysis (p less than 0,01; 12,1 +/- 1,8 and 7,6 +/- 1,4 muMol Pi/h/g Hb. PSP activity in the control groups was 10,3 +/- 1,9 muMol Pi/h/g Hb). In the CRF group PSP activity was higher before haemodialysis (p less than 0,05) and lower after haemodialysis (p less than 0.01) than in the control group. Our results confirmed the presence of DLS in the blood of the majority of CRF patients. DLS concentration decreased after haemodialysis but we did not found any parallel increase in PSP activity in these patients. These results did not confirm the hypothesis that DLS might inhibit PSP activity in red blood cells from CRF patients.