Mineralogical and Chemical Composition of Dry Atmospheric Deposition on Jeddah City, Eastern Coast of the Red Sea

2008 ◽  
Vol 19 (1) ◽  
pp. 167-188 ◽  
Author(s):  
A. Rifaat ◽  
A. Basaham ◽  
M. El-Mamoney ◽  
M. El-Sayed
2018 ◽  
Vol 15 (17) ◽  
pp. 5365-5375 ◽  
Author(s):  
Mallory A. Sea ◽  
Neus Garcias-Bonet ◽  
Vincent Saderne ◽  
Carlos M. Duarte

Abstract. Mangrove forests are highly productive tropical and subtropical coastal systems that provide a variety of ecosystem services, including the sequestration of carbon. While mangroves are reported to be the most intense carbon sinks among all forests, they can also support large emissions of greenhouse gases (GHGs), such as carbon dioxide (CO2) and methane (CH4), to the atmosphere. However, data derived from arid mangrove systems like the Red Sea are lacking. Here, we report net emission rates of CO2 and CH4 from mangroves along the eastern coast of the Red Sea and assess the relative role of these two gases in supporting total GHG emissions to the atmosphere. Diel CO2 and CH4 emission rates ranged from −3452 to 7500 µmol CO2 m−2 d−1 and from 0.9 to 13.3 µmol CH4 m−2 d−1 respectively. The rates reported here fall within previously reported ranges for both CO2 and CH4, but maximum CO2 and CH4 flux rates in the Red Sea are 10- to 100-fold below those previously reported for mangroves elsewhere. Based on the isotopic composition of the CO2 and CH4 produced, we identified potential origins of the organic matter that support GHG emissions. In all but one mangrove stand, GHG emissions appear to be supported by organic matter from mixed sources, potentially reducing CO2 fluxes and instead enhancing CH4 production, a finding that highlights the importance of determining the origin of organic matter in GHG emissions. Methane was the main source of CO2 equivalents despite the comparatively low emission rates in most of the sampled mangroves and therefore deserves careful monitoring in this region. By further resolving GHG fluxes in arid mangroves, we will better ascertain the role of these forests in global carbon budgets.


Nature ◽  
1965 ◽  
Vol 206 (4991) ◽  
pp. 1345-1346 ◽  
Author(s):  
P. G. BREWER ◽  
J. P. RILEY ◽  
F. CULKIN

2015 ◽  
Vol 15 (11) ◽  
pp. 2449-2459 ◽  
Author(s):  
Y. Ben Ami ◽  
O. Altaratz ◽  
Y. Yair ◽  
I. Koren

Abstract. Thunderstorm activity takes place in the eastern Mediterranean mainly through the boreal fall and winter seasons during synoptic systems of Red Sea Trough (RST), Red Sea Trough that closed a low over the sea (RST-CL), and Cyprus Low (during fall – FCL and winter – WCL). In this work we used the Israeli Lightning Location System ground strokes data set, between October 2004 and December 2010, for studying the properties of lightning strokes and their link to the thermodynamic conditions in each synoptic system. It is shown that lightning activity dominates over sea during WCL and FCL systems (with maximum values of 1.5 in WCL, and 2.2 km−2 day−1 in FCL) and have a dominant component over land during the RST and RST-CL days. The stronger instability (high Convective Available Potential Energy (CAPE) values of 762 ± 457 J kg−1) during RST-CL days together with the higher altitude of the clouds' mixed-phase region (3.6 ± 0.3 km), result in a slightly higher density of ground strokes during this system but a lower fraction of positive ground strokes (3 ± 0.5 %). In general the fraction of positive strokes was found to be inversely correlated with the sea surface temperature: it increases from 1.2 % in early fall to 17.7 % in late winter, during FCL and WCL days. This change could be linked to the variation in the charge center's vertical location during those months. The diurnal cycle in the lightning activity was examined for each synoptic system. During WCL conditions, no preferred times were found through the day, as it relates to the random passage timing of the frontal systems over the study region. During the fall systems (FCL and RST-CL) there is a peak in lightning activity during the morning hours, probably related to the enhanced convection driven by the convergence between the eastern land breeze and the western synoptic winds. The distributions of peak currents in FCL and WCL systems also change from fall to winter and include more strong negative and positive strokes toward the end of the winter.


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