On the issue of limiting nutrient and predictions of cyanobacteria in aquatic systems

This study aims at bridging the gap between freshwater and marine eutrophication studies by presenting (1) a cross-system analysis of the relationship between chlorophyll and the total nitrogen (TN) to total phosphorus (TP) ratio (2) a general model to predict concentrations of cyanobacteria from data on TP, the TN/TP ratio, salinity and temperature, and (3) a general trophic level classification for aquatic systems based on chlorophyll classes (for oligo-, meso-, eu- and hypertrophic systems). The data compiled in this study concerns more than 500 lakes and coastal areas covering a very wide domain in terms of nutrient concentrations and salinity. There was no simple relationship between the TN/TP ratio and empirical chlorophyll concentrations or concentrations of cyanobacteria. Variations in TP rather than TN generally seem to be more important to predict variations among systems in chlorophyll-a and cyanobacteria. Different “bioavailable” forms of the nutrients (DIN, DIP, phosphate, nitrate, etc.) have been shown to have very high coefficients of variation (CV), which means that many samples are needed to obtain reliable empirical data which are necessary in models aiming for high predictive power and practical usefulness

Legal description of the coup in Latvia

Pirmajā nodaļā darba autore ir apskatījusi notikumus pasaulē laika periodā no 1920.gada līdz 1934.gada 15.maijam, izvērtējusi politiskos notikumus un dažādu politisko režīmu izplatību. Otrā nodaļa veltīta Latvijas politiskās situācijas izpētei, pastiprināta uzmanība ir pievērsta Satversmes pieņemšanai 1922.gada 15.februārī, Latvijas kā parlamentāras republikas pastāvēšanai līdz Kārļa Ulmaņa vadītajam valsts apvērsumam 1934.gada 15.maijā. Trešās nodaļas ietvaros ir apzināti jēdziena ,,apvērsums” skaidrojumi, meklēti tam sinonīmi jeb vārdi ar līdzīgu nozīmi. Ceturtā nodaļā ir veikta Ministru prezidenta tiesību analīze, izpētot tā robežas kopumā, ir apskatīta Kārļa Ulmaņa kā Ministru prezidenta kompetence.In the first chapter the author of the thesis has examined the events in the world during the period of 1920 till May 15, 1935, has considered political events and dissemination of diverse political regimes.In the second chapter the Latvian political situation has been examined, greater attention has been drawn to the adoption of the Satversme in February 15, 1922, existence of Latvia as a parliamentary republic until the coup leaded by Karlis Ulmanis in May 15, 1934.Interpretations of the concept “coup” have been studied in the third chapter, and some synonyms or words with a similar meaning have been searched for.Analysis of the rights of a Prime minister has been carried out in the chapter four, examined its boundaries in general, area of authority of Karlis Ulmanis as a Prime ministe

A new general approach to quantify nitrogen fixation exemplified for the Baltic Proper

This work uses empirical data from the HELCOM database and a new empirically-based model to predict the concentration of cyanobacteria in the Baltic Proper. The aim has been to estimate nitrogen fixation. The inherent variabilities/patchiness in the variables regulating nitrogen fixation are great. This means that different approaches may provide complementary information so that several relatively uncertain estimates may together provide less uncertainty in the estimate for nitrogen fixation in a given system. We show that there is marked variability in nitrogen fixation among different years (a factor of 20 between the year 2001 with the smallest value and 2005 with the highest value of about 900 kt/yr of N-fixation). The mean value for the period from 1997 to 2005 was 190 kt/yr. TN/TP based on median monthly data has been higher than the Redfield ratio of 7.2 since 1994. 6.5% of all individual data (n = 3001) from the surface-water layer (44 m) in the Baltic Proper for samples with temperatures higher than 15°C (when risks of getting cyanobacteria blooms are favoured) have TN/TP lower than 7.2. The mean TN/TP is 20 for surface-water sites with temperatures higher than 15°C, indicating that the average trophic conditions in the Baltic Proper are likely more limited by phosphorus than nitrogen. Nitrogen fixation is an important contributor to the nitrogen concentration and we give overall budgets for nitrogen and phosphorus in the Baltic Proper, including nutrient data from land uplift, which is the most important contributor for nutrients and often neglected in discussions about sources of nutrients to the Baltic Sea.Thresholds, 6th framework, E

Evaluating common drivers for color, iron and organic carbon in Swedish watercourses

The recent browning (increase in color) of surface waters across much of the northern hemisphere has important implications for light climate, ecosystem functioning, and drinking water treatability. Using log-linear regressions and long-term (6-21 years) data from 112 Swedish watercourses, we identified temporal and spatial patterns in browning-related parameters [iron, absorbance, and total organic carbon (TOC)]. Flow variability and lakes in the catchment were major influences on all parameters. Co-variation between seasonal, discharge-related, and trend effects on iron, TOC, and absorbance were dependent on pH, landscape position, catchment size, latitude, and dominant land cover. Large agriculture-dominated catchments had significantly larger trends in iron, TOC, and water color than small forest catchments. Our results suggest that while similarities exist, no single mechanism can explain the observed browning but show that multiple mechanisms related to land cover, climate, and acidification history are responsible for the ongoing browning of surface waters