Nutrient transfer from soil to surface waters: Differences between nitrate and phosphate

Abstract.: Nitrate (NO3 -) and soluble reactive phosphorus (SRP), the two major dissolved N and P species available to aquatic biota, respond differently to varying water discharge rates (Q) in agricultural drainage pipes and rivers (Fig. 1): SRP concentrations are positively related to Q, whereas NO3 - concentrations decrease with increasing discharge rates. In addition, NO3-N concentrations exceed (in mass units) SRP concentrations up to 700-fold even though the liquid manure applied to agricultural fields has a N:P ratio equal to only about 5. Preferential flow of rainwater across the soil column and different affinities of the two nutrients for the soil matrix explain these differences in behaviour and mobility: i. Concentrations of substances that have a high sorption affinity for the soil matrix (such as SRP) tend to increase in drainage pipes and streams as water discharge increases. ii. Concentrations of species that are not retarded by sorption processes (such as NO3 -) and, hence, do not accumulate in the topsoil, tend to be negatively related to discharge rate. Differences in the availability and pool size of NO3 - and SRP in the topsoil explain the different hysteresis patterns if NO3 - and SRP concentrations are plotted versus the corresponding discharge rate during precipitation events (Fig. 2

Nutrient uptake and benthic regeneration in Danube Delta Lakes

We investigated the nutrient uptake capacity of three lakes (Uzlina, Matita and Rosu) within the Danube Delta during high water level in June and low water level in September 1999. Special emphasis was placed on nutrient cycling at the sediment-water interface and on the self-purification capacity of the lakes in the Danube Delta. In order to estimate the nutrient uptake of selected lakes we present in this paper the results of water analyses, benthic flux chamber experiments and deck incubation experiments of 15N-labeled sediment cores at the inflow and the outlet of the lakes. The external input of dissolved inorganic nitrogen and silica into the lakes decreases with increasing distance to the main Danube branches whereas the total dissolved phosphorus input is independent of the hydrological distance to the main branches. The nutrient loading is highest in the inflow channels, and decreases towards the outflow of the lakes. In June, the uptake of NO3 −, TDP and Si(OH)4 in the lakes was higher than in September. In contrast, NH4 + uptake was more intense in September, when benthic release was more intense as well. On average, about 76% of the external plus internal nitrogen and phosphorus input into the lakes was taken up by macrophytes and phytoplankton during the growing season, whereas the uptake of external nutrient input amounted to about 43%. The benthic release of ammonia and silica increases from June to September and indicates, that part of the nutrients taken up during the growing season might be released during winter. We estimate the net impact of the Delta on the nutrient reduction of the Danube during the growing season is about 4.3%, assuming 10% of the Danube water is flowing through the Delt

Macroinvertebrate as indicators of acidification in high altitude alpine lakes

No abstract availableCinque laghi svizzeri vengono presi come esempio per valutare il recupero dall\u27acidificazione evidenziato per gli aspetti chimici a partire dalla met? degli anni \u2790, ma i metodi per la valutazione del livello di acidit? basati sui macroinvertebrati sono stati sviluppati in Nord Europa e su corsi d\u27acqua e quindi sembra poco credibile poterli utilizzare per acque lacustri. Questo contributo vuole quindi evidenziare quali fra le metriche applicate, e generalmente in uso a livello europeo, riflette meglio le variazioni di acidit? presenti nei diversi laghi classificati come sensibili (2 laghi), con bassa alcalinit? (2), e alcalini (1). I laghi e i loro emissari vengono presentati sulla base delle loro caratteristiche chimiche e faunistiche secondo i principali gruppi di interesse ai fini di una loro classificazione. Le metriche applicate sono raccolte in due gruppi: metriche generali (abbondanze relative per i diversi gruppi, ecc) e metriche specifiche (diversi indici). Le metriche vengono applicate in due diverse tipologie di ambienti, acque ferme e acque correnti appartenenti ai medesimi laghi. Dai risultati si rileva che lungo il litorale solo poche metriche fra quelle scelte danno indicazioni di differenze faunistiche correlate ai diversi livelli di acidificazione raggiunti dai laghi, mentre nelle acque correnti sono molte di pi? le metriche applicabili, perch? molte delle specie prese in considerazione dalle metriche sono specifiche di questi ambienti e non si trovano nelle acque ferme dove altri fattori, pi? importanti, determinano le differenze di popolamento fra un lago ed un altro. Concludendo si pu? affermare che: i macroinvertebrati d\u27acqua corrente sono migliori indicatori di acidit?, l\u27identificazione tassonomica a livello di specie di chironomidi ed oligocheti ? utile per migliorare la valutazione del livello di acidit? di ambienti d\u27alta quota

Trends and patterns in surface water chemistry in Europe and North America between 1990 and 2016, with particular focus on changes in land use as a confounding factor for recovery

The report presents trends in sulphate, nitrate, chloride, base cations, ANC (acid neutralising capacity), pH and DOC at circa 500 ICP Waters sites in Europe and North America for the period 1990-2016. Time series were analysed for trends in annual median values, annual extreme values and change points, that indicate years with sudden changes in trend or level. Also provided is a brief overview of possible implications of land use change for recovery of acidified surface waters

Responses of benthic invertebrates to chemical recovery from acidification

Prosjektleder: Heleen de WitThe report provides an assessment of biological recovery from acidification in freshwater environments in Europe. The report consists of two parts, a regional data analysis based on an international dataset of biological and water chemical records, and a collection of national contributions on monitoring and assessment of biological recovery in different countries. The regional analysis showed that 47% of all included rivers (21 sites, for the period 1994-2018) and 35% percent of all lakes (34 sites, for the period 2000 to 2018) showed significant increases in species richness. Correlations between species diversity and water chemical components (ANC, pH, SO4) were found, supporting that the biological responses were related to chemical recovery. Additionally, the composition of functional traits in rivers underwent significant changes over time. Both parts of the report demonstrate ongoing biological recovery from acidification in European acid-sensitive freshwater environments.Norwegian Ministry of Climate and Environment, United Nations Economic Commission for Europe (UNECE)publishedVersio

Trends and patterns in surface water chemistry in Europe and North America between 1990 and 2020, with a focus on calcium

Prosjektleder: Rolf David VogtThe report presents trends in major anions and cations, pH, TOC and bicarbonate in surface waters in Europe and North America from 1990 to 2020. Special attention is given to trends in calcium, which showed some unexpected increases. The trends in calcium are analysed in relation to changes in bicarbonates, organic anions, and deposition loads. The surface waters show strong signs of chemical recovery.Norwegian Ministry of Climate and Environment, United Nations Economic Commission for Europe (UNECE)publishedVersio

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Nutrient uptake and benthic regeneration in Danube Delta Lakes

We investigated the nutrient uptake capacity of three lakes (Uzlina, Matita and Rosu) within the Danube Delta during high water level in June and low water level in September 1999. Special emphasis was placed on nutrient cycling at the sediment-water interface and on the self-purification capacity of the lakes in the Danube Delta. In order to estimate the nutrient uptake of selected lakes we present in this paper the results of water analyses, benthic flux chamber experiments and deck incubation experiments of 15N-labeled sediment cores at the inflow and the outlet of the lakes. The external input of dissolved inorganic nitrogen and silica into the lakes decreases with increasing distance to the main Danube branches whereas the total dissolved phosphorus input is independent of the hydrological distance to the main branches. The nutrient loading is highest in the inflow channels, and decreases towards the outflow of the lakes. In June, the uptake of NO3 −, TDP and Si(OH)4 in the lakes was higher than in September. In contrast, NH4 + uptake was more intense in September, when benthic release was more intense as well. On average, about 76% of the external plus internal nitrogen and phosphorus input into the lakes was taken up by macrophytes and phytoplankton during the growing season, whereas the uptake of external nutrient input amounted to about 43%. The benthic release of ammonia and silica increases from June to September and indicates, that part of the nutrients taken up during the growing season might be released during winter. We estimate the net impact of the Delta on the nutrient reduction of the Danube during the growing season is about 4.3%, assuming 10% of the Danube water is flowing through the Delt

Climate Change-Induced Changes in the Chemistry of a High-Altitude Mountain Lake in the Central Alps

Mountains are among the most sensitive ecosystems to climate change, and one of the most evident signs of climate-related effect is the continuous net loss of ice from the cryosphere. Several studies showed that meltwater from glaciated and perennially frozen areas can profoundly affect alpine aquatic ecosystems. Here, we present the impressive temporal increase in solutes in Lake Leit, a mountain lake in the Central Alps that is impacted by an active rock glacier. During the last 30 years, concentrations of sulfate and base cations increased by factors of 4 and 3, respectively. Atmospheric deposition, the only catchment external source, could be excluded as possible cause. The inlets have sulfate and base cations concentrations that were up to double the concentrations of the lake outlet confirming the presence of catchment internal sources. The highest concentrations were measured in the springs at the bottom of the rock glacier. Ground surface temperatures of the rock glacier indicated a high probability of permafrost occurrence, while the annual mean air temperature after the mid-1980s showed continuously positive deviations from the long-term average values (period 1961-1990) with increasing values after 2010. delta S-34 of sulfate in the inlets and the outflow indicated that sulfate in Lake Leit mainly derived from dissolution of gypsum/anhydrite even if its presence is not confirmed by the Geologic Atlas of Switzerland. Because of these results, we postulate the presence of subsurface traces of sulfate-bearing evaporites, probably associated with Triassic metasediments. These deposits are very common in the closer surroundings. We further hypothesize that the thawing of permafrost affects the flow path of water enabling its contact with fresh highly weatherable minerals increasing the overall weathering rate and shifting the relative ionic composition in the discharge toward the ions that originate from the most soluble minerals. This study shows that increased permafrost thawing in the future can influence water quality in high-alpine settings.ISSN:1380-6165ISSN:1573-142