14 research outputs found
Change in land cover type from 1990 to 2010 near South Padre, Texas.
<p>Change in land cover type from 1990 to 2010 near South Padre, Texas.</p
Confusion matrices depicting the accuracy of coastal Texas land cover classification in 2010 and 1990.
<p>Confusion matrices depicting the accuracy of coastal Texas land cover classification in 2010 and 1990.</p
Net change in (a) salt marsh and (b) mangrove area.
<p>Changes are broken down by land cover type and are summed across the entire Texas coast from 1990 to 2010.</p
Coastal Zone Management study area and Landsat 5 TM footprints.
<p>Coastal Zone Management study area and Landsat 5 TM footprints.</p
Generalized Two-Dimensional Perturbation Correlation Infrared Spectroscopy Reveals Mechanisms for the Development of Surface Charge and Recalcitrance in Plant-Derived Biochars
Fundamental knowledge of how biochars develop surface-charge
and
resistance to environmental degradation is crucial to their production
for customized applications or understanding their functions in the
environment. Two-dimensional perturbation-based correlation infrared
spectroscopy (2D-PCIS) was used to study the biochar formation process
in three taxonomically different plant biomass, under oxygen-limited
conditions along a heat-treatment-temperature gradient (HTT; 200–650
°C). Results from 2D-PCIS pointed to the systematic, HTT-induced
defragmenting of lignocellulose H-bonding network and demethylenation/demethylation,
oxidation, or dehydroxylation/dehydrogenation of lignocellulose fragments
as the primary reactions controlling biochar properties along the
HTT gradient. The cleavage of OH<sup>...</sup>O-type H-bonds, oxidation
of free primary hydroxyls to carboxyls (carboxylation; HTT ≤
500 °C), and their subsequent dehydrogenation/dehydroxylation
(HTT > 500 °C) controlled surface charge on the biochars;
while
the dehydrogenation of methylene groups, which yielded increasingly
condensed structures (R–CH<sub>2</sub>–R →RCH–R
→RCR), controlled biochar recalcitrance. Variations
in biochar properties across plant biomass type were attributable
to taxa-specific transformations. For example, apparent inefficiencies
in the cleavage of wood-specific H-bonds, and their subsequent oxidation
to carboxyls, lead to lower surface charge in wood biochars (compared
to grass biochars). Both nontaxa and taxa-specific transformations
highlighted by 2D-PCIS could have significant implications for biochar
functioning in fire-impacted or biochar-amended systems
Landsat 5 TM image locations, acquisition dates, and water level at time of image acquisition (select stations).
<p>NA indicates that water level data were not available for that date.</p><p>Landsat 5 TM image locations, acquisition dates, and water level at time of image acquisition (select stations).</p
Difference in the number of pre-imagery days with minimum temperatures below 0°C from November—February.
<p>Positive values (blue) indicate more freeze days in 2010 compared to 1990 (cooling trend). Negative values (red) indicate more freeze days in 1990 compared to 2010 (warming trend).</p
Change in land cover type from 1990 to 2010 near Port O’Connor, Texas.
<p>Change in land cover type from 1990 to 2010 near Port O’Connor, Texas.</p
The minimum recorded temperature (°C) at weather stations along the Texas coast, with the number of days with minimum temperatures below -6.7°C in parentheses.
<p>- indicates that data were not available. Weather data were obtained from the NOAA National Climatic Data Center (<a href="http://www.ncdc.noaa.gov/" target="_blank">http://www.ncdc.noaa.gov/</a>).</p><p>The minimum recorded temperature (°C) at weather stations along the Texas coast, with the number of days with minimum temperatures below -6.7°C in parentheses.</p
Average annual rates of change in relative sea level at stations on the Texas coast, listed from south to north.
<p>Rates are calculated from 1965 (or earlier) through 2006. Data are from <a href="http://tidesandcurrents.noaa.gov/sltrends/sltrends.html" target="_blank">http://tidesandcurrents.noaa.gov/sltrends/sltrends.html</a>.</p><p>Average annual rates of change in relative sea level at stations on the Texas coast, listed from south to north.</p