Algal blooms in high turbidity, a result of the conflicting consequences of turbulence on nutrient cycling in a shallow water estuary

Le devenir des nutrients inorganiques dissous, de la matière organique particulaire et des chloropigments a été étudié dans un estuaire peu profond (Great Ouse, Angleterre) de mars 1990 à janvier 1991). Des blooms phytoplanctoniques caractérisés par des concentrations en chlorophylle a supérieures à 100 ug 1-1 et un comportement non conservatif des nutrients sont observés au début du printemps et en été. Cette étude montre que malgré la très faible épaisseur de la zone euphotique les processus de mélange verticaux autorisent le développement phytoplanctonique dans les estuaires présentant une forte turbidité et de faibles profondeurs; les mécanismes mis en jeu sont discutés. (Résumé d'auteur

Isotopic and biochemical composition of particulate organic matter in a shallow water estuary (Great Ouse, North Sea, England)

The biogeochemistry of particulate organic matter was studied in the Great Ouse estuary draining to the North Sea embayement known as the Wash from March 1990 to January 1991. Eleven locations were sampled monthly on a 50 km transect across the shallow estuary from the tidal weir to the middle of the Wash. Particulate organic carbon (POC) and total carbohydrate, protein and lipid analyses were combined with the determination of stable carbon isotopes... The proportional importance of the uncharacterized fraction of POC, which is considered as complex organic matter, was high from September to January and low from March to August. During most of the year, the biochemical compositions of particulate matter was high from September to January and low from March to August. During most of the year, the biochemical compositions of particulate organic matter in the turbidity maximum an the rest of the estuary were similar. (D'après résumé d'auteur

Atmospheric aerosols at the Pierre Auger Observatory and environmental implications

The Pierre Auger Observatory detects the highest energy cosmic rays. Calorimetric measurements of extensive air showers induced by cosmic rays are performed with a fluorescence detector. Thus, one of the main challenges is the atmospheric monitoring, especially for aerosols in suspension in the atmosphere. Several methods are described which have been developed to measure the aerosol optical depth profile and aerosol phase function, using lasers and other light sources as recorded by the fluorescence detector. The origin of atmospheric aerosols traveling through the Auger site is also presented, highlighting the effect of surrounding areas to atmospheric properties. In the aim to extend the Pierre Auger Observatory to an atmospheric research platform, a discussion about a collaborative project is presented.Comment: Regular Article, 16 pages, 12 figure

Studies of trace elements in the Sargasso Sea and the Mid Atlantic Bight

SIGLEAvailable from British Library Document Supply Centre- DSC:D73652/87 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Algal blooms in high turbidity, a result of the conflicting consequences of turbulence on nutrient cycling in a shallow water estuary

Le devenir des nutrients inorganiques dissous, de la matière organique particulaire et des chloropigments a été étudié dans un estuaire peu profond (Great Ouse, Angleterre) de mars 1990 à janvier 1991). Des blooms phytoplanctoniques caractérisés par des concentrations en chlorophylle a supérieures à 100 ug 1-1 et un comportement non conservatif des nutrients sont observés au début du printemps et en été. Cette étude montre que malgré la très faible épaisseur de la zone euphotique les processus de mélange verticaux autorisent le développement phytoplanctonique dans les estuaires présentant une forte turbidité et de faibles profondeurs; les mécanismes mis en jeu sont discutés. (Résumé d'auteur

Climate change and coupling of macronutrient cycles along the atmospheric, terrestrial, freshwater and estuarine continuum

This paper provides an introduction to the Special Issue on “Climate Change and Coupling of Macronutrient Cycles along the Atmospheric, Terrestrial, Freshwater and Estuarine Continuum”, dedicated to Colin Neal on his retirement. It is not intended to be a review of this vast subject, but an attempt to synthesize some of the major findings from the 22 contributions to the Special Issue in the context of what is already known. The major research challenges involved in understanding coupled macronutrient cycles in these environmental media are highlighted, and the difficulties of making credible predictions of the effects of climate change are discussed. Of particular concern is the possibility of interactions which will enhance greenhouse gas concentrations and provide positive feedback to global warming

Organic nitrogen in the atmosphere – where does it come from? A review of sources and methods

This review considers the ways in which atmospheric organic nitrogen has been measured and linked to potential sources. Organic N exists in gas, particle and dissolved phases and represents a large (ca. 30%) fraction of total airborne nitrogen, but with large variability in time and space. Although some components (e.g. amines) have been the subject of several studies, little information is available for the many other components of organic N that have been identified in individual measurements. Measurements of organic N in precipitation have been made for many decades, but both sampling and chemical analytical methods have changed, resulting in data that are not directly comparable. Nevertheless, it is clear that organic N is ubiquitous and chemically complex. We discuss some of the issues which have inhibited the widespread adoption of organic N as a routine analyte in atmospheric sampling, and identify current best practice. Correlation analysis is the most widely used technique for attributing likely sources, examining the co-variation in time and/or space of organic N with other components of precipitation or particulate matter, yet the shortcomings of such simple approaches are rarely recognized. Novel measurement techniques which can identify, if not yet quantify, many of the components of particulate or dissolved organic N greatly enhance the data richness, thereby permitting powerful statistical analyses of co-variation such as factor analysis, to be employed. However, these techniques also have their limitations, and while specific questions about the origin and fate of particular components of atmospheric organic N may now be addressed, attempts to quantify and attribute the whole suite of materials that comprise atmospheric organic N to their sources is still a distant goal. Recommendations are made as to the steps that need to be taken if a consistent and systematic approach to identifying and quantifying atmospheric organic N is to progress. Only once sources have been recognised can any necessary control measures to mitigate adverse effects of atmospheric organic N on human health or ecosystem function be determined

Dedication of the special issue to Colin Neal

This Special Issue, “Climate change and coupling of macronutrient cycles along the atmospheric, terrestrial, freshwater and estuarine continuum” is dedicated to the career of Colin Neal, whose work over the years has generated so many concepts and so much data to support on-going research in this important research area. This note is concerned with Colin and his contributions to the scientific literature

Trends in the solubility of iron, aluminium, manganese and phosphorus in aerosol collected over the Atlantic Ocean

Climate change and earth-ocean atmosphere systems