Relative contribution of DNAPL dissolution and matrix diffusion to the long-term persistence of chlorinated solvent source zones

2012 ◽  
Vol 134-135 ◽  
pp. 69-81 ◽  
Author(s):  
Mir Ahmad Seyedabbasi ◽  
Charles J. Newell ◽  
David T. Adamson ◽  
Thomas C. Sale
Keyword(s):  
Matrix Diffusion ◽  
Relative Contribution ◽  
Chlorinated Solvent ◽  
Source Zones ◽  
Dnapl Dissolution

scholarly journals Assessing the Contribution of Seasonality, Tides, and Microbial Processing to Dissolved Organic Matter Composition Variability in a Southeastern U.S. Estuary

2021 ◽  
Vol 8 ◽  
Author(s):  
Rachel P. Martineac ◽  
Alexey V. Vorobev ◽  
Mary Ann Moran ◽  
Patricia M. Medeiros
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Critical Role ◽  
Bacterial Cells ◽  
Secondary Importance ◽  
Relative Contribution ◽  
Doc Concentration ◽  
Compositional Changes ◽  
Dom Composition

Uncovering which biogeochemical processes have a critical role controlling dissolved organic matter (DOM) compositional changes in complex estuarine environments remains a challenge. In this context, the aim of this study is to characterize the dominant patterns of variability modifying the DOM composition in an estuary off the Southeastern U.S. We collected water samples during three seasons (July and October 2014 and April 2015) at both high and low tides and conducted short- (1 day) and long-term (60 days) dark incubations. Samples were analyzed for bulk DOC concentration, and optical (CDOM) and molecular (FT-ICR MS) compositions and bacterial cells were collected for metatranscriptomics. Results show that the dominant pattern of variability in DOM composition occurs at seasonal scales, likely associated with the seasonality of river discharge. After seasonal variations, long-term biodegradation was found to be comparatively more important in the fall, while tidal variability was the second most important factor correlated to DOM composition in spring, when the freshwater content in the estuary was high. Over shorter time scales, however, the influence of microbial processing was small. Microbial data revealed a similar pattern, with variability in gene expression occurring primarily at the seasonal scale and tidal influence being of secondary importance. Our analyses suggest that future changes in the seasonal delivery of freshwater to this system have the potential to significantly impact DOM composition. Changes in residence time may also be important, helping control the relative contribution of tides and long-term biodegradation to DOM compositional changes in the estuary.

scholarly journals Long-term historical trends in air pollutant emissions in Asia: Regional Emission inventory in ASia (REAS) version 3.1

2019 ◽  
Author(s):  
Junichi Kurokawa ◽  
Toshimasa Ohara
Keyword(s):  
Economic Growth ◽  
Growth Rates ◽  
Emission Inventory ◽  
Air Pollutant ◽  
Pollutant Emissions ◽  
Anthropogenic Sources ◽  
Gridded Data ◽  
Relative Contribution ◽  
The Republic

Abstract. A long-term historical emission inventory of air and climate pollutants in East, Southeast, and South Asia from 1950–2015 was developed as the Regional Emission inventory in ASia version 3.1 (REASv3.1). REASv3.1 provides details of emissions from major anthropogenic sources for each country and its sub-regions and also provides monthly gridded data with 0.25° × 0.25° resolution. The average total emissions in Asia during 1950–1955 and from 2010–2015 (growth rates in these 60 years) are as follows: SO2: 3.15 Tg, 42.4 Tg (13.5); NOx: 1.83 Tg, 47.6 Tg (26.0); CO: 62.2 Tg, 319 Tg (5.13); non-methane volatile organic compounds: 9.14 Tg, 61.8 Tg (6.77); NH3: 7.99 Tg, 31.3 Tg (3.92); CO2: 1.12 Pg, 18.3 Pg (16.3); PM10: 5.76 Tg, 28.4 Tg (4.92); PM2.5: 4.52 Tg, 20.3 Tg (4.50); black carbon: 0.751 Tg, 3.38 Tg (4.51); and organic carbon: 2.62 Tg, 6.92 Tg (2.64). Clearly, all the air pollutant emissions in Asia increased significantly during these six decades, but situations were different among countries and regions. Due to China's rapid economic growth in recent years, its relative contribution to emissions in Asia has been the largest. However, most pollutant species reached their peaks by 2015 and the growth rates of other species was found to be reduced or almost zero. On the other hand, air pollutant emissions from India showed an almost continuous increasing trend. As a result, the relative ratio of emissions of India to that of Asia have increased recently. The trend observed in Japan was different from the rest of Asia. In Japan, emissions increased rapidly during 1950s–1970s, which reflected the economic situation of the period; however, most emissions decreased from their peak values, which were approximately 40 years ago, due to the introduction of regulations and laws for air pollution. Similar features were found in the Republic of Korea and Taiwan. In the case of other Asian countries, air pollutant emissions generally showed an increase along with economic growth and motorization. Trends and spatial distribution of air pollutants in Asia are becoming complicated. Datasets of REASv3.1, including table of emissions by countries and sub-regions for major sectors and fuel types, and monthly gridded data with 0.25° × 0.25° resolution for major source categories are available through the following URL: http://www.nies.go.jp/REAS/.

Time-temperature and time-stress correspondence in nonlinear creep. Experimental behaviour of amorphous polymers and quantitative modelling approaches

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
José R. S. André ◽  
José J. C. Cruz Pinto
Keyword(s):  
Nonlinear Creep ◽  
Predictive Capability ◽  
Kinetic Formulation ◽  
Time Stress ◽  
Relative Contribution ◽  
Proposed Model ◽  
Fully Coupled ◽  
Experimental Behaviour ◽  
Modelling Approach

Abstract Non-linear creep is described by a non-simulative, analytical, dynamic molecular modelling approach. Elementary, molecular-scale, process-relevant frequencies are derived by adequate kinetic formulation. They follow almost exactly an Arrhenius-like behaviour with a range of activation enthalpies. Their relative contribution to the overall macroscopic behaviour of the materials is quantified to account for the materials’ retardation time spectra and final non-Arrhenius behaviour. A new creep compliance equation is derived, yielding a fully coupled timetemperature- stress formulation, with long-term predictive capability. Experimental data for poly(methyl methacrylate) are analysed to identify the extent to which timetemperature and time-stress correspondence relationships may be valid, and it is shown that they are approximations (especially the latter), limited to narrow ranges of experimental variables, in contrast to the proposed model, which more reasonably fits the experimental behaviour.

scholarly journals Limnological characterisation and phytoplankton seasonal variation in a subtropical shallow lake (Guaiba Lake, Brazil): a long-term study

2014 ◽  
Vol 26 (4) ◽  
pp. 442-456 ◽  
Author(s):  
Rodrigo da Rocha Andrade ◽  
Danilo Giroldo
Keyword(s):  
Shallow Lake ◽  
Soluble Reactive Phosphorus ◽  
Late Summer ◽  
Euphotic Zone ◽  
Subtropical Zone ◽  
Chl A ◽  
Relative Contribution ◽  
Long Term Study ◽  
Reactive Phosphorus

AIM: to provide a long-term limnological characterisation of a subtropical shallow lake in addition to verifying seasonal differences, including phytoplankton variation. METHODS: monthly sampling at sites IP, SJ and MD from 2000 to 2009 to analyse temperature - T; depth - Z; the depth of the euphotic zone - Zeu; Zeu/Z (%); total suspended solids - TSS; dissolved oxygen - DO; pH; electrical conductivity - EC; N-NH3, N-NO2, N-NO3; soluble reactive phosphorus - SRP; chlorophyll a - Chl-a and phytoplankton. RESULTS: low values of Z and Zeu characterised the shallow and turbid conditions of lake and corresponded to the contribution of nano-microflagellates (Chlamydomonas sp., Spermatozopsis sp., Cryptomonas sp. and Rhodomonas sp ) and diatoms (Aulacoseira granulata). Zeu/Z (%), SRP and Chl-a were significantly different at site IP (meso-eutrophic) compared to sites SJ and MD (eutrophic). Phytoplankton density was also significantly higher at sites SJ and MD, and the largest relative contribution of Actinastrum sp., Dictyosphaerium sp., Micractinium sp., Monoraphidium sp., Scenedesmus/Desmodesmus sp. and Euglena sp. corresponded to the most polluted waters at site SJ. The significantly higher T (ºC) in summer corresponded to significantly higher Chl-a as well as a greater richness and density of phytoplankton. Cocconeis sp., Gomphonema sp. and Pinnularia sp. (pennated diatoms) were negatively correlated with temperature and were therefore more representative at the three sites in winter. Asterionella formosa was correlated with SRP and vernal blooms were recorded (2000-2001). Planktothrix isothrix and Planktothricoides raciborskii were expressive in the summer/late summer (2004-2005), and were significantly correlated with Chl-a and low SRP in water column. CONCLUSIONS: The study corroborated the sensitivity of phytoplankton in characterising different stages of eutrophication at different sites and corresponding watersheds as well as in characterising different seasons in a shallow lake in the subtropical zone of Brazil.

scholarly journals ‘All in it Together’? Social Cohesion in a Divided Society: Attitudes to Income Inequality and Redistribution in a Residential Context

2014 ◽  
Vol 43 (3) ◽  
pp. 453-477 ◽  
Author(s):  
ADE KEARNS ◽  
NICK BAILEY ◽  
MARIA GANNON ◽  
MARK LIVINGSTON ◽  
ALASTAIR LEYLAND
Keyword(s):  
Social Cohesion ◽  
Ethnic Diversity ◽  
Ethnic Composition ◽  
Relative Contribution ◽  
Deprived Neighbourhoods ◽  
Current Trends ◽  
Residential Context ◽  
Wealth Inequalities ◽  
Levels Of Support

AbstractThis paper asks whether where someone lives bears any association with their attitudes to inequality and income redistribution, focusing on the relative contribution of neighbourhood income, density and ethnic composition. People on higher incomes showed higher support for redistribution when living in more deprived neighbourhoods. People with lower levels of altruism had higher levels of support for redistribution in neighbourhoods of higher density. People living in more ethnically mixed neighbourhoods had higher levels of support for redistribution on average, but this support declined for Whites with low levels of altruism as the deprivation of the neighbourhood increased. Current trends which sustain or extend income and wealth inequalities, reflected in patterns of residence, may undermine social cohesion in the medium- to long-term. This may be offset to some extent by trends of rising residential ethnic diversity.

14 years of OMI HCHO observations reveal VOC emission trends over large cities worldwide

2020 ◽  
Author(s):  
Maite Bauwens ◽  
Jenny Stavrakou ◽  
Jean-François Müller ◽  
Isabelle De Smedt ◽  
Nellie Elguindi
Keyword(s):  
Reanalysis Data ◽  
Anthropogenic Emissions ◽  
Gangetic Plain ◽  
Voc Emission ◽  
Large Cities ◽  
Relative Contribution ◽  
Biogenic Voc ◽  
Anthropogenic Contribution ◽  
Anthropogenic Contributions

<p>Formaldehyde (HCHO) observations from satellites have been widely used to constrain volatile organic compound (VOC) emission estimates. The oxidation of anthropogenic organic compounds accounts for only a small fraction(~7%) of the total HCHO column on global average (Stavrakou et al., 2009). Therefore, the use of satellite observations to infer information about anthropogenic VOC emissions is generally very challenging . However, the relative contribution of anthropogenic VOCs in and around metropolitan centers is expected to be significant. In this study, we use HCHO column data retrieved from the OMI sensor between 2005 and 2018, and calculate monthly averages for every city of more than 500,000 inhabitants based on data within 20 km of the city centers. Because of the dependence of the background and especially of the biogenic VOC source on temperature and solar radiation, and because these contributions might be significant even around large cities, it is not possible to directly infer the anthropogenic contribution to the long-term observed HCHO trends based on HCHO data. To remove these non-anthropogenic contributions, we first regress the monthly averaged columns either onto the monthly maximum surface temperature, obtained by ECMWF reanalysis data, or onto the monthly isoprene flux, calculated with the MEGAN-MOHYCAN model (Guenther et al., 2012, Stavrakou et al. 2018). Only cities for which anthropogenic emissions are estimated to exceed biogenic emission by more than a factor of 3 are considered. In this way, positive trends of up to 3% yr<sup>-1</sup> are found over many Asian cities, especially in China and in the Indo-gangetic Plain, whereas over European cities, South Africa and South America negative trends up to -2% yr<sup>-1</sup> are derived. The deduced trends are compared to the corresponding trends of global bottom-up anthropogenic VOC emission inventories and are found to be in good overall agreement. Model simulations are further needed to quantify the relationship between anthropogenic emission trends and HCHO columns, accounting for the effect of non-anthropogenic emissions and potential changes in the oxidizing capacity.</p>

Liquid−Liquid Mass Transfer of Partitioning Electron Donors in Chlorinated Solvent Source Zones

2011 ◽  
Vol 45 (4) ◽  
pp. 1547-1554 ◽  
Author(s):  
Natalie L. Cápiro ◽  
Emmie K. Granbery ◽  
Carmen A. Lebrón ◽  
David W. Major ◽  
Michaye L. McMaster ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Electron Donors ◽  
Liquid Mass ◽  
Chlorinated Solvent ◽  
Source Zones ◽  
Liquid Mass Transfer

scholarly journals SEISMICITY OF NORTHERN EURASIA in 2014

2020 ◽  
pp. 10-26
Author(s):  
Alexey Malovichko ◽  
Nataliya Petrova ◽  
Irina Gabsatarova ◽  
Oleg Starovoit ◽  
E. Rogozhin ◽  
...  
Keyword(s):  
Seismic Energy ◽  
Focal Mechanisms ◽  
Northern Eurasia ◽  
Seismic Process ◽  
Fold Belt ◽  
Seismic Regime ◽  
The Past ◽  
Source Zones ◽  
Regions Of Russia

An overview of Northern Eurasia seismicity in 2014 is given. This territory includes 16 regions of Russia and neighboring countries. Seismic monitoring was carried out by 618 stationary seismic stations, including 591 digital, 27 analog stations and eight seismic groups. Also, temporary stations operated in some re-gions. These networks have registered over 30 thousand tectonic and volcanic earthquakes, for 571 of them the focal mechanisms are determined. According to the data collected and presented in the Annual, 413 earthquakes were felt in settlements of Northern Eurasia in 2014, manifestations of 14 of them were surveyed and described in the special articles of this issue, together with data on the focal mechanisms, preceding seismicity, aftershock processes and seismotectonic conditions. Estimates of the number of earthquakes and seismic energy released in 2014 in the regions of Northern Eurasia in comparison with long-term characteristics of seismic regime indicate that in most regions the seismic process proceeded in the “background” or “background lowered” regimes accor-ding to the definition on the SOUS'09 scale. Only the level of seismicity in the Pribaikalye and Transbaikalia region is assessed as “background increased”. The intensification of seismicity in the source zones of the past strongest earthquakes in the Alpine-Himalayan collision-fold belt – Crimean 1927, Spitak 1988, Zakatala 2012 – is noted. The tangible earthquakes that occurred in the previously aseismic areas of the Siberian and Turan platforms – Gonam earthquake on January 4 with KP=14.2, I0=8, Boguchan earthquake on January 17 with KP=13.3, I0=7 and Karaganda earthquake on June 21 with KP=11.7, I0=5–6 – indicate the need to revise the concept of a low seismic hazard in these platform areas.

scholarly journals An extreme sea level indicator for the contiguous United States coastline

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Md. Mamunur Rashid ◽  
Thomas Wahl ◽  
Don P. Chambers ◽  
Francisco M. Calafat ◽  
William V. Sweet
Keyword(s):  
United States ◽  
Sea Level ◽  
Decadal Variability ◽  
Level Indicator ◽  
Relative Contribution ◽  
Level Data ◽  
Water Level Data ◽  
The Individual

AbstractWe develop an aggregated extreme sea level (ESL) indicator for the contiguous United States coastline, which is comprised of separate indicators for mean sea level (MSL) and storm surge climatology (SSC). We use water level data from tide gauges to estimate interannual to multi-decadal variability of MSL and SSC and identify coastline stretches where the observed changes are coherent. Both the MSL and SSC indicators show significant fluctuations. Indicators of the individual components are combined with multi-year tidal contributions into aggregated ESL indicators. The relative contribution of the different components varies considerably in time and space. Our results highlight the important role of interannual to multi-decadal variability in different sea level components in exacerbating, or reducing, the impacts of long-term MSL rise over time scales relevant for coastal planning and management. Regularly updating the proposed indicator will allow tracking changes in ESL posing a threat to many coastal communities, including the identification of periods where the likelihood of flooding is particularly large or small.

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