11 research outputs found
Detecting dominant changes in irregularly sampled multivariate water quality data sets
Time series of groundwater and stream water quality often exhibit substantial
temporal and spatial variability, whereas typical existing monitoring data
sets, e.g. from environmental agencies, are usually characterized by
relatively low sampling frequency and irregular sampling in space and/or
time. This complicates the differentiation between anthropogenic influence
and natural variability as well as the detection of changes in water quality
which indicate changes in single drivers. We suggest the new term dominant
changes for changes in multivariate water quality data which concern
(1)Â multiple variables, (2)Â multiple sites and (3)Â long-term patterns and
present an exploratory framework for the detection of such dominant changes
in data sets with irregular sampling in space and time. Firstly, a non-linear
dimension-reduction technique was used to summarize the dominant
spatiotemporal dynamics in the multivariate water quality data set in a few
components. Those were used to derive hypotheses on the dominant drivers
influencing water quality. Secondly, different sampling sites were compared
with respect to median component values. Thirdly, time series of the
components at single sites were analysed for long-term patterns. We tested
the approach with a joint stream water and groundwater data set quality
consisting of 1572 samples, each comprising sixteen variables, sampled with a
spatially and temporally irregular sampling scheme at 29 sites in northeast
Germany from 1998 to 2009. The first four components were interpreted as
(1)Â an agriculturally induced enhancement of the natural background level of
solute concentration, (2)Â a redox sequence from reducing conditions in deep
groundwater to post-oxic conditions in shallow groundwater and oxic
conditions in stream water, (3)Â a mixing ratio of deep and shallow
groundwater to the streamflow and (4)Â sporadic events of slurry application
in the agricultural practice. Dominant changes were observed for the first
two components. The changing intensity of the first component was interpreted
as response to the temporal variability of the thickness of the unsaturated
zone. A steady increase in the second component at most stream water sites
pointed towards progressing depletion of the denitrification capacity of the
deep aquifer.</p
Pond research and management in Europe: "Small is Beautiful"
The phrase "Small is Beautiful" was first used by the talented scholar Leopold Kohr (1909 131994), but it becames more popular thanks to the essays of one of his students, the British economist E. F. Schumacher, and it was coined as a response to the socially established idea that "Big is Powerful". It could be argued that this desire for "bigness" explains why current legal frameworks and the conservation planning and management related to standing waters often overlook ponds, despite their well-known value in terms of biodiversity and socio-economic benefits (Oertli et al., 2004; Cereghino et al., 2008). Of course, this is only one of several possible explanations, but it is important to understand that such long-established ideas can have a lasting effect upon the efficiency of our conservation actions. Beyond this social perspective, the history of science can also provide some explanation as to why ponds have been undervalued for so long
Untersuchungen zur Gewaesserbeschaffenheitsentwicklung der Spree. Teilprojekt 4: Stoffumsatz im Spreewald unter Beruecksichtigung der diffusen Eintraege und der Wechselwirkungen zwischen Sediment und Wasser sowie Torfmineralisierung infolge Degradierung von Niedermooren Schlussbericht
SIGLEAvailable from TIB Hannover: F03B930+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany); Saechsisches Landesamt fuer Umwelt und Geologie, Radebeul (Germany); Landesumweltamt Brandenburg, Potsdam (Germany)DEGerman