Short-Term Temporal Variation in PM2.5  Mass and Chemical Composition during the Atlanta Supersite Experiment, 1999

Shallow fluvial lakes are heterogeneous ecosystems in which marked spatio-temporal variation renders difficult the analysis of key ecological processes, such as growth. In this study, we used generalized additive modelling of the RNA/DNA ratio, an index of short-term growth, to investigate the influence of environmental variables and spatio-temporal variation on growth of yellow perch (Perca flavescens) in Lake St. Pierre, Quebec, Canada. Temperature and water level had seemingly stronger effects on short-term growth than seasonal change or spatial variation between and along the lakeshores. Consistent with previous studies, the maximum RNA/DNA ratio was found at 20.5 °C, suggesting that our approach provides a useful tool for estimating thermal optima for growth in the field. The RNA/DNA ratio showed a positive relationship with water level, as predicted by the flood pulse concept, a finding with implications for ecosystem productivity in fluvial lakes. The RNA/DNA ratio was more variable along the north than the south shore, possibly reflecting exposure to more differentiated water masses. The negative influence of both high temperatures and low water levels on growth points to potential impacts of climatic change on fish production in shallow fluvial lakes.

Download Full-text

Spatial and Temporal Variation of Rainwater Chemistry in Ile-Ife and Its Environ, Osun State, Nigeria

Journal of Sustainable Development ◽

10.5539/jsd.v10n2p203 ◽

2017 ◽

Vol 10 (2) ◽

pp. 203 ◽

Cited By ~ 1

Author(s):

Aderonke Adetutu Okoya ◽

Bamikole Walter Osungbemiro ◽

Temi E. Ologunorisa

Keyword(s):

Land Use ◽

Chemical Composition ◽

Temporal Variation ◽

Major Ions ◽

Rain Water ◽

Spatial And Temporal Variation ◽

Rainwater Chemistry ◽

Water Composition ◽

Physico Chemical ◽

The Impact

The study of the chemical composition of rain water was conducted in Ile – Ife and environs, an agrarian, commercial, residential and semi-industrialised center of Osun state Nigeria. This was with a view to assessing the impact of land use activities on rain water composition and the temporal variation of rainwater chemistry. Physico-chemical parameters such as Turbidity, pH, TDS, Conductivity, Oxygen parameters, Alkalinity, Acidity, Hardness and Major ions (Ca2+, Mg2+, K+, Na+, NO3-, SO4-, HCO3-) were determined, predominant ions were identified. Turbidity, pH, Conductivity, TDS, D.O B.O.D, Alkalinity, Acidity Hardness ranged between 2.90 - 42.84 NTU, 5.65 - 7.40, 6.71 – 122.33 µScm-1, 4.10 –73.27 mg/L, 3.60 – 10.60 mg/L, 0.13 – 7.20 mg/L, 0.33 – 22.0 mg/L, 2.00 – 15.00 mg/L, 0.04 – 1.23 CaCO3mg/l respectively. The dominant ions detected in the study were HCO3-, Mg2+, Na+ and Ca2+. Generally, the mean concentration of ions as expressed in milli-equivalent per Litre showed order of dominance as HCO3- > NO3- > SO42- for the anions and Mg2+ > Na+ > Ca2+ > K+ for cations. The study concluded that land use activities had influence on all the chemical composition of rain water in the study area but more on pH, alkalinity, acidity, bicarbonate. Except sulphate and Nitrate, all other parameters recorded high values in dry season.

Download Full-text

Short-term modifications of soil microbial community structure and soluble organic matter chemical composition following amendment with different solid olive mill waste and their derived composts

Applied Soil Ecology ◽

10.1016/j.apsoil.2017.06.014 ◽

2017 ◽

Vol 119 ◽

pp. 234-241 ◽

Cited By ~ 12

Author(s):

Ermanno Federici ◽

Luisa Massaccesi ◽

Daniela Pezzolla ◽

Laura Fidati ◽

Elena Montalbani ◽

...

Keyword(s):

Organic Matter ◽

Community Structure ◽

Microbial Community ◽

Chemical Composition ◽

Soluble Organic Matter ◽

Short Term ◽

Soil Microbial Community Structure ◽

Soil Microbial ◽

Mill Waste ◽

Olive Mill

Download Full-text

Sargassum stenophyllum (Fucales, Ochrophyta) responses to temperature short-term exposure: photosynthesis and chemical composition

Revista Brasileira de Botânica ◽

10.1007/s40415-020-00639-y ◽

2020 ◽

Vol 43 (4) ◽

pp. 733-745

Author(s):

Vanessa Urrea-Victoria ◽

Allyson E. Nardelli ◽

Eny I. S. Floh ◽

Fungyi Chow

Keyword(s):

Chemical Composition ◽

Short Term ◽

Short Term Exposure

Download Full-text

Short term spatial and temporal variation of phytoplankton in a shallow tropical oligotrophic reservoir, southeast Brazil

Hydrobiologia ◽

10.1007/s10750-004-8332-z ◽

2005 ◽

Vol 542 (1) ◽

pp. 235-247 ◽

Cited By ~ 69

Author(s):

Maria Rosélia Marques Lopes ◽

Carlos E. de M. Bicudo ◽

M. Carla Ferragut

Keyword(s):

Temporal Variation ◽

Spatial And Temporal Variation ◽

Short Term ◽

Southeast Brazil

Download Full-text

Short-term spatial and temporal variation of sediment oxygen dynamics in a tropical tidal salt flat

Wetlands Ecology and Management ◽

10.1007/s11273-011-9223-5 ◽

2011 ◽

Vol 19 (5) ◽

pp. 389-395 ◽

Cited By ~ 2

Author(s):

Vinícius Peruzzi de Oliveira ◽

Luiz Fernando Jardim Bento ◽

Alex Enrich Prast

Keyword(s):

Temporal Variation ◽

Spatial And Temporal Variation ◽

Short Term ◽

Salt Flat ◽

Oxygen Dynamics

Download Full-text

Spatial and Temporal Variation in PM 2.5 Chemical Composition in the United States for Health Effects Studies

Environmental Health Perspectives ◽

10.1289/ehp.9621 ◽

2007 ◽

Vol 115 (7) ◽

pp. 989-995 ◽

Cited By ~ 338

Author(s):

Michelle L. Bell ◽

Francesca Dominici ◽

Keita Ebisu ◽

Scott L. Zeger ◽

Jonathan M. Samet

Keyword(s):

United States ◽

Chemical Composition ◽

Temporal Variation ◽

Health Effects ◽

The United States ◽

Spatial And Temporal Variation ◽

Pm 2.5

Download Full-text

Removing Time Variation with the Anti-Hebbian Differential Synapse

Neural Computation ◽

10.1162/neco.1991.3.3.312 ◽

1991 ◽

Vol 3 (3) ◽

pp. 312-320 ◽

Cited By ~ 42

Author(s):

Graeme Mitchison

Keyword(s):

Temporal Variation ◽

Time Variation ◽

Synaptic Weight ◽

Receptive Fields ◽

Learning Rule ◽

Temporal Changes ◽

Short Term ◽

Conservation Condition ◽

Rule Changes ◽

Synaptic Learning

I describe a local synaptic learning rule that can be used to remove the effects of certain types of systematic temporal variation in the inputs to a unit. According to this rule, changes in synaptic weight result from a conjunction of short-term temporal changes in the inputs and the output. Formally, This is like the differential rule proposed by Klopf (1986) and Kosko (1986), except for a change of sign, which gives it an anti-Hebbian character. By itself this rule is insufficient. A weight conservation condition is needed to prevent the weights from collapsing to zero, and some further constraint—implemented here by a biasing term—to select particular sets of weights from the subspace of those which give minimal variation. As an example, I show that this rule will generate center-surround receptive fields that remove temporally varying linear gradients from the inputs.

Download Full-text