J. A. Morguí

Tropospheric winds from northeastern China carry the etiologic agent of Kawasaki disease from its source to Japan

Significance Kawasaki disease (KD), the leading cause of acquired heart disease in children worldwide, has remained a mystery for more than 40 y. No etiological agent has yet been identified. By using simulations with the flexible particle dispersion model from different Japanese cities from each single high (low) KD incidence day, the source region KD is retrieved in cereal croplands in northeastern China. We infer the incubation time for KD ranges from 6 h to 2 d, thus favoring an antigenic or toxic exposure as the trigger. Candida sp. is reported as the dominant fungal species collected aloft (54% of all fungal DNA clones) demonstrating the potential for human disease in aerosols transported by wind currents traveling long distances. Evidence indicates that the densely cultivated region of northeastern China acts as a source for the wind-borne agent of Kawasaki disease (KD). KD is an acute, coronary artery vasculitis of young children, and still a medical mystery after more than 40 y. We used residence times from simulations with the flexible particle dispersion model to pinpoint the source region for KD. Simulations were generated from locations spanning Japan from days with either high or low KD incidence. The postepidemic interval (1987–2010) and the extreme epidemics (1979, 1982, and 1986) pointed to the same source region. Results suggest a very short incubation period (<24 h) from exposure, thus making an infectious agent unlikely. Sampling campaigns over Japan during the KD season detected major differences in the microbiota of the tropospheric aerosols compared with ground aerosols, with the unexpected finding of the Candida species as the dominant fungus from aloft samples (54% of all fungal strains). These results, consistent with the Candida animal model for KD, provide support for the concept and feasibility of a windborne pathogen. A fungal toxin could be pursued as a possible etiologic agent of KD, consistent with an agricultural source, a short incubation time and synchronized outbreaks. Our study suggests that the causative agent of KD is a preformed toxin or environmental agent rather than an organism requiring replication. We propose a new paradigm whereby an idiosyncratic immune response, influenced by host genetics triggered by an environmental exposure carried on winds, results in the clinical syndrome known as acute KD.

Phosphorus budgets and forms of phosphorus in the Sau reservoir sediment: An interpretation of the limnological record

The phosphorus compounds in the sediment of Sau reservoir have been analysed and related to the annual phosphorus budgets from 1965 to 1969. With the increase of eutrophy, the phosphorus inputs leave the water in two ways: to the sediment and to the water outflow. The second way becomes more important throughout the eutrophication process.

Factors controlling seasonal variability of benthic ammonium release and oxygen uptake in Alfacs Bay (Ebro Delta, NW Mediterranean)

The seasonal variability of sediment–water ammonium flux andoxygen uptake was studied in an estuarine bay (Alfacs Bay, Ebro Delta, NWMediterranean) influenced by temporal freshwater discharges. Three stationswith different organic loading were sampled. The relationships of benthicfluxes to bottom water (temperature, dissolved oxygen, ammonium, nitrateplus nitrite) and to sediment (porosity, chlorophyll a derivative pigments,organic carbon and nitrogen) variables were examined. Oxygen uptake rangedfrom 0.3 to 2.5 mmol m−2 h−1 and ammoniumrelease ranged from 6 to 230 µmol m−2 h−1.The lowest value was recorded at the station furthest from the freshwaterinputs, and the highest was at the littoral station nearest the freshwaterdischarge channels (for oxygen uptake) and at the deep station at the saltwedge front (for ammonium flux). Water temperature and the concentration ofchlorophyll a derivative pigments on the surface sediment were revealed asthe main variables to be taken into account to explain the variabilityfound. Changes in fluxes reflecting temperature changes were found at thestation furthest from the freshwater inputs, while at the other, fluxvariability was found to be related to the cycle of functioning offreshwater discharge channels. The different patterns of variability arediscussed in relation to the dynamics of the estuary and to the mainfeatures of benthic nitrogen cycling.

Phosphate and calcium carbonate saturation in a stratified coastal lagoon

Seasonal variation of phosphate concentration and saturation index for calcite in water of a small stratified coastal lagoon have been studied. In surface waters, where salinity was low and pH high, the saturation index increased to values near 20, whereas in bottom water, with high salinity and low pH, they were usually lower. The ionic product for H3PO4 was strongly correlated with the ionic product of Ca(OH)2 in surface and bottom waters, and with the ionic product of CaCO3 in bottom, which suggested that chemical composition was mainly controlled by a calcium-phosphate solid phase.The low concentrations of phosphate in surface were due to chemical precipitation and organic sedimentation, whereas in bottom, calcium phosphate redissolved and organic matter was mineralized producing high concentrations of soluble phosphate (> 60 µmol l−1).Decrease of calcium-bound phosphate in the upper layers of sediment was in agreement with a diminution of calcium-phosphate precipitation, probably due to a lower influence of seawater in the past.

Factors controlling spatial variability in ammonium release within an estuarine bay (Alfacs Bay, Ebro Delta, NW Mediterranean)

Sediment-water ammonium fluxes, oxygen uptake and sediment characteristics were studied in an estuarine bay influenced by temporal freshwater discharges. Sediment at seven stations representing a gradient imposed by freshwater inputs was sampled for sediment-water ammonium and oxygen fluxes, chlorophyll a derivative pigments, organic content, porosity and elemental composition (Fe, Mn, Si, Al). Oxygen uptake decreased along the gradient and correlated with total chlorophyll a derivatives indicating the close coupling between aerobic metabolism and short-time sedimentation events. Ammonium release showed a discontinuous pattern of decrease along the gradient and only correlated with the Fe:Mn atomic ratio. Correlation between the structural properties of the sediment (Si:Al atomic ratio, porosity and organic content) and ammonium release was also found (excluding data from the station with the highest ammonium flux). The extent of the influence of metabolism and sediment structure on ammonium release is discussed.

Close and delayed benthic-pelagic coupling in coastal ecosystems : the role of physical constraints

We aimed to analyse the temporal scales of the variability of benthic ammonium flux using data from an estuarine bay (Alfacs Bay, N. W. Mediterranean). Several nitrogen (N) pools in the sediment, their reactivities and their associated fluxes were estimated. Decomposition of labile buried N (4.5 mol N m-2) was found to cause an ammonium flux of 0.1 mmol N m-2 d -1, referred to as background flux. The fluxes measured from bell-jar incubations were usually higher, between 2 and 6 mmol N m-2 d -1, which reflects mineralization of recent sedimentation. A typical sedimentation event was found to account for 25 – 75 mmol m-2 of freshly settled N, which should bring on an ammonium flux of about 1.7–5.0 mmol N m-2 d -1, referred to as fast flux. The concordance between measured and computed benthic fluxes is associated with the coupling of benthic fluxes to production and sedimentation. Close benthic–pelagic coupling was observed in winter and early spring, while a delayed flux response to sedimentation, with transient variations of pore water ammonium profiles, showing surface peaks and decreasing concentrations with depth, was found in autumn. Structures, such as viscous layers, which develop over the sediment–water interface, were found to be essential to the regulation of benthic processes and to lead to transient variations of pore water nutrient concentrations and associated fluxes. The temporal scales of the benthic flux response to sedimentation were discussed in terms of the physical structures involved in decomposition (the bulk sediment, the viscous layers or the fresh settled layer), the processes controlling kinetics and diffusion laws. Several scenarios for the benthic- pelagic coupling in Alfacs Bay, in which local (estuarine circulation) and climatic components combine to yield the variability observed, were examined.

Significant physiographic disturbances in the Ebro basin reservoirs (N.E. Spain) reflected by Oligochaeta size spectra

Benthic fauna size distribution, water and sediment composition, and physiographic features of catchments were used to classify ten reservoirs in the Ebro basin, Spain. Three reservoirs (Alloz, Urrunaga and Barasona) diverged from the rest. Environmental factors (water and sediment characteristics) that accounted for the separation of these three reservoirs were directly linked to minor features of the watersheds (high chloride water concentration in Alloz reservoir, iron loading in Barasona reservoir, and Na-rich silicates in sediments from Urrunaga reservoir).

Revisiting the role of environmental and climate factors on the epidemiology of Kawasaki disease

Can environmental factors, such as air‐transported preformed toxins, be of key relevance to the health outcomes of poorly understood human ailments (e.g., rheumatic diseases such as vasculitides, some inflammatory diseases, or even severe childhood acquired heart diseases)? Can the physical, chemical, or biological features of air masses be linked to the emergence of diseases such as Kawasaki disease (KD), Henoch–Schönlein purpura, Takayasus aortitis, and ANCA‐associated vasculitis? These diseases surprisingly share some common epidemiological features. For example, they tend to appear as clusters of cases grouped geographically and temporarily progress in nonrandom sequences that repeat every year in a similar way. They also show concurrent trend changes within regions in countries and among different world regions. In this paper, we revisit transdisciplinary research on the role of environmental and climate factors in the epidemiology of KD as a paradigmatic example of this group of diseases. Early‐warning systems based on environmental alerts, if successful, could be implemented as a way to better inform patients who are predisposed to, or at risk for, developing KD. Further research on the etiology of KD could facilitate the development of vaccines and specific medical therapies.

Influence of long-range atmospheric transport pathways and climate teleconnection patterns on the variability of surface 210 Pb and 7 Be concentrations in southwestern Europe

The variability of the atmospheric concentration of the 7Be and 210Pb radionuclides is strongly linked to the origin of air masses, the strength of their sources and the processes of wet and dry deposition. It has been shown how these processes and their variability are strongly affected by climate change. Thus, a deeper knowledge of the relationship between the atmospheric radionuclides variability measured close to the ground and these atmospheric processes could help in the analysis of climate scenarios. In the present study, we analyze the atmospheric variability of a 14-year time series of 7Be and 210Pb in a Mediterranean coastal city using a synergy of different indicators and tools such as: the local meteorological conditions, global and regional climate indexes and a lagrangian atmospheric transport model. We particularly focus on the relationships between the main pathways of air masses and sun spots occurrence, the variability of the local relative humidity and temperature conditions, and the main modes of regional climate variability, such as the North Atlantic Oscillation (NAO) and the Western Mediterranean Oscillation (WeMO). The variability of the observed atmospheric concentrations of both 7Be and 210Pb radionuclides was found to be mainly positively associated to the local climate conditions of temperature and to the pathways of air masses arriving at the station. Measured radionuclide concentrations significantly increase when air masses travel at low tropospheric levels from central Europe and the western part of the Iberian Peninsula, while low concentrations are associated with westerly air masses. We found a significant negative correlation between the WeMO index and the atmospheric variability of both radionuclides and no significant association was observed for the NAO index.