Amr Elmaradny - Academia.edu (original) (raw)
Papers by Amr Elmaradny
Aquatic Toxicology, 1991
There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through... more There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through adjacent waters, industrial and sewage discharges and air depositions. Polycyclic aromatic hydrocarbons (PAHs) are semi volatile ubiquitous anthropogenic pollutants detected in all environmental compartments. In the monitoring framework for the mangrove ecosystem along the Red Sea coast of Saudi Arabia, nine mangrove stands were examined for the accumulation of PAHs. Polycyclic aromatic hydrocarbons were measured using Gas Chromatography-Mass Spectrometry (GC-MS). The mean values detected for total PAHs in sediments, roots and leaf were 2.98, 8.57 and 23.43 ng/g respectively. The trend of the total PAHs concentration in all sites showed the descending order: leaf > roots > sediments. Beside the sandy nature of the sediments, the presences of all stands in remote areas fare from the direct anthropogenic effects lead to these relative low values. PAH bio-concentration factors for leaf are two to three magnitudes higher than that in roots, suggesting atmosphere deposition /leaf uptake mechanism in addition to the sediment/root mechanism. The diagnostic ratios revealed that the sources of PAHs are mainly pyrogenic.
Arabian Journal of Geosciences, 2010
Dissolved Cu, Ni, and Zn were measured in the surface coastal waters of Jeddah, eastern Red Sea d... more Dissolved Cu, Ni, and Zn were measured in the surface coastal waters of Jeddah, eastern Red Sea during October 2004 and April 2005. High values of trace metals, particularly Zn, were recorded in the Southern Corniche area close to a sewage effluent indicating a significant contribution from the wastewater. Concentrations of trace metals decreased northward and southward under the effect of dilution. Another hot spot was also observed in the vicinity of Jeddah Desalination Plant (JDP) during April 2005 indicating a possible contribution from the JDP to trace metal contents in the study area. Trace metals were correlated to salinity, nutrients and particulate organic carbon (POC). The good association between Zn and reactive silicate and Ni and ammonium is attributed to simultaneous biological utilization and regeneration. The behavior of copper suggested adsorption of Cu onto the POC during October 2004 whereas in April 2005 the most important process seems to be desorption of Cu from the particulate materials.
The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isola... more The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isolated and identified. In this study, the total crude organic matter of the sponge was extracted by solvents. The total crude extract was further separated by partitioning it with hexane and water, then with water and chloroform, and finally with water and t-butanol. The chloroform layer was subjected to separation by preparative layer chromatography on silica. One fraction contained four long-chain fatty acid esters, C28H56O2, C30H60O2, C32H62O2 and C36H70 O2. The second ester, C30H60O2, has been identified in the fire corals Millepora dichotoma and Millepora platyphylla. The others have not previously been reported from marine organisms; however similar long-chain esters with different long aliphatic chains and with different molecular weights have been identified from other marine organisms. These compounds are normally waxy and their presence in Chalinula saudensis plays a vital role in...
Organometallics, 1996
Photolysis of Cp*Fe(CO) 2 SiMe 3 (3) in the presence of p-TolGeH 3 (4) gave a mixture of cis and ... more Photolysis of Cp*Fe(CO) 2 SiMe 3 (3) in the presence of p-TolGeH 3 (4) gave a mixture of cis and trans mono(germylene)-bridged diiron complexes, Cp* 2 Fe 2 (CO) 2 (µ-CO)(µ-Gep-TolH) (cis-5, trans-5), a mixture of two kinds of trans bis(germylene)-bridged diiron complexes, Cp* 2 Fe 2 (CO) 2 (µ-Gep-TolH) 2 (syn-trans-6, anti-trans-6), and a complex with two Fe‚‚‚H‚‚‚Ge 3-center 2-electron bonds, Cp* 2 Fe 2 (CO) 2 (µ-Gep-TolH 2) 2 (7). A cis isomer of complex 6 (syncis(H)-6) was formed as the sole product by the thermolysis of complex 7. Photolysis of 7 or syn-cis(H)-6 resulted in the conversion to a mixture of syn-trans-6 and anti-trans-6. Reversible thermal and photochemical interconversion between cis and trans isomers of complex 5 was observed. The molar ratio of the cis and trans isomers of complex 5 in C 6 D 6 was 7:93 at thermal equilibrium at 55°C and 84:16 at the photostationary state at 6°C.
Indian Journal of …, 2009
Indian Journal of Marine Sciences Vol. 38 (4), December 2009, pp. 404-410 ... Fecal sterols and p... more Indian Journal of Marine Sciences Vol. 38 (4), December 2009, pp. 404-410 ... Fecal sterols and pahs in sewage polluted marine environment along the eastern ... Red Sea coast, South of Jeddah, Saudi Arabia ... Radwan K Al-Farawati* Amr El-Maradny & Gul R Niaz Faculty ...
Al-Arbaeen and Al-Shabab are two highly polluted lagoons lying along the Jeddah Coast. Surface se... more Al-Arbaeen and Al-Shabab are two highly polluted lagoons lying along the Jeddah Coast. Surface
sediments were collected from both lagoons to assess the levels and spatial distribution of polycyclic
aromatic hydrocarbons (PAHs), as well as study the effect of environmental conditions on PAH
concentrations. The concentration ranges for ∑38-PAHs in Al-Arbaeen and Al-Shabab lagoons were
5.4-5,372 ng/g (mean 1,637 ng/g) and 60-7,927 ng/g (mean 1,323 ng/g), respectively. Pollution levels in
both lagoons were in the low-very high range with dominance by three- and four-ring congeners. Pyrene
was the dominant congener, while benzo (a) pyrene represented the dominant carcinogenic congener in
the study area. The disappearance of most of the low molecular weight congeners may be attributed to
temperature and microbial activity. Carcinogenic PAHs contributed 59.9 and 23.6% for Al-Arbaeen and
Al-Shabab lagoons, respectively. The diagnostic ratios revealed that the source of PAHs are of mixed
origin and site specifi c. The probable toxic effects on organisms were examined for total and individual
PAHs with sediment quality guidelines (ERL-ERM). The detected PAHs levels in the present study were
compared with reported levels for coastal worldwide lagoons.
Aliphatic hydrocarbons including resolved aliphatics (C11C30), isoprenoids (phytane and pristane... more Aliphatic hydrocarbons including resolved aliphatics (C11C30), isoprenoids (phytane and pristane) and unresolved complex mixture, as well as total aromatic hydrocarbons were analyzed in 25 surface sediment samples represented five sites along Jeddah coast, Red Sea. The descending order of total petroleum hydrocarbons in the different sites along the coast was found as following: AlArbaeen Lagoon (site 2) 481 ppm > AlShabab lagoon (site 3) 410 ppm > Southern Corniche (site 1) 205.3 ppm > Northern Corniche (site 4) 172.7 ppm > Sharm Obhur (site 5) 23.6 ppm. The concentrations of total aliphatic hydrocarbons were ranged between 2.18 and 492 ppm dry weights, while the range for the total poly aromatic hydrocarbons was from 2.67 to 160.6 ppm dry weight. The highest concentrations for hydrocarbons were recorded at site 2 (AlArbaeen lagoon, station 8). The indices used to evaluate the probable origin of hydrocarbons indicated petroleum origin with high degradation process in most stations as well as fresh oil inputs in few stations at sites 1 and 4. The levels of total aromatic hydrocarbons for 80% of studied stations were exceeding effects rangemedian value (ERM) for the sediment quality guideline (SQG).
There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through... more There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through adjacent waters, industrial and sewage discharges and air depositions. Polycyclic aromatic hydrocarbons (PAHs) are semi volatile ubiquitous anthropogenic pollutants detected in all environmental compartments. In the monitoring framework for the mangrove ecosystem along the Red Sea coast of Saudi Arabia, nine mangrove stands were examined for the accumulation of PAHs. Polycyclic aromatic hydrocarbons were measured using Gas Chromatography-Mass Spectrometry (GC-MS). The mean values detected for total PAHs in sediments, roots and leaf were 2.98, 8.57 and 23.43 ng/g respectively. The trend of the total PAHs concentration in all sites showed the descending order: leaf > roots > sediments. Beside the sandy nature of the sediments, the presences of all stands in remote areas fare from the direct anthropogenic effects lead to these relative low values. PAH bio-concentration factors for leaf are two to three magnitudes higher than that in roots, suggesting atmosphere deposition /leaf uptake mechanism in addition to the sediment/root mechanism. The diagnostic ratios revealed that the sources of PAHs are mainly pyrogenic.
Brazilian Journal of …, 2011
The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isola... more The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isolated and identified. In this study, the total crude organic matter of the sponge was extracted by solvents. The total crude extract was further separated by partitioning it with hexane and water, then with water and chloroform, and finally with water and t-butanol. The chloroform layer was subjected to separation by preparative layer chromatography on silica. One fraction contained four long-chain fatty acid esters, C28H56O2, C30H60O2, C32H62O2 and C36H70 O2. The second ester, C30H60O2, has been identified in the fire corals Millepora dichotoma and Millepora platyphylla. The others have not previously been reported from marine organisms; however similar long-chain esters with different long aliphatic chains and with different molecular weights have been identified from other marine organisms. These compounds are normally waxy and their presence in Chalinula saudensis plays a vital role in the biosynthetic pathways. They also act as insulators against seasonal variations.
Aquatic Toxicology, 1991
There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through... more There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through adjacent waters, industrial and sewage discharges and air depositions. Polycyclic aromatic hydrocarbons (PAHs) are semi volatile ubiquitous anthropogenic pollutants detected in all environmental compartments. In the monitoring framework for the mangrove ecosystem along the Red Sea coast of Saudi Arabia, nine mangrove stands were examined for the accumulation of PAHs. Polycyclic aromatic hydrocarbons were measured using Gas Chromatography-Mass Spectrometry (GC-MS). The mean values detected for total PAHs in sediments, roots and leaf were 2.98, 8.57 and 23.43 ng/g respectively. The trend of the total PAHs concentration in all sites showed the descending order: leaf > roots > sediments. Beside the sandy nature of the sediments, the presences of all stands in remote areas fare from the direct anthropogenic effects lead to these relative low values. PAH bio-concentration factors for leaf are two to three magnitudes higher than that in roots, suggesting atmosphere deposition /leaf uptake mechanism in addition to the sediment/root mechanism. The diagnostic ratios revealed that the sources of PAHs are mainly pyrogenic.
Arabian Journal of Geosciences, 2010
Dissolved Cu, Ni, and Zn were measured in the surface coastal waters of Jeddah, eastern Red Sea d... more Dissolved Cu, Ni, and Zn were measured in the surface coastal waters of Jeddah, eastern Red Sea during October 2004 and April 2005. High values of trace metals, particularly Zn, were recorded in the Southern Corniche area close to a sewage effluent indicating a significant contribution from the wastewater. Concentrations of trace metals decreased northward and southward under the effect of dilution. Another hot spot was also observed in the vicinity of Jeddah Desalination Plant (JDP) during April 2005 indicating a possible contribution from the JDP to trace metal contents in the study area. Trace metals were correlated to salinity, nutrients and particulate organic carbon (POC). The good association between Zn and reactive silicate and Ni and ammonium is attributed to simultaneous biological utilization and regeneration. The behavior of copper suggested adsorption of Cu onto the POC during October 2004 whereas in April 2005 the most important process seems to be desorption of Cu from the particulate materials.
The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isola... more The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isolated and identified. In this study, the total crude organic matter of the sponge was extracted by solvents. The total crude extract was further separated by partitioning it with hexane and water, then with water and chloroform, and finally with water and t-butanol. The chloroform layer was subjected to separation by preparative layer chromatography on silica. One fraction contained four long-chain fatty acid esters, C28H56O2, C30H60O2, C32H62O2 and C36H70 O2. The second ester, C30H60O2, has been identified in the fire corals Millepora dichotoma and Millepora platyphylla. The others have not previously been reported from marine organisms; however similar long-chain esters with different long aliphatic chains and with different molecular weights have been identified from other marine organisms. These compounds are normally waxy and their presence in Chalinula saudensis plays a vital role in...
Organometallics, 1996
Photolysis of Cp*Fe(CO) 2 SiMe 3 (3) in the presence of p-TolGeH 3 (4) gave a mixture of cis and ... more Photolysis of Cp*Fe(CO) 2 SiMe 3 (3) in the presence of p-TolGeH 3 (4) gave a mixture of cis and trans mono(germylene)-bridged diiron complexes, Cp* 2 Fe 2 (CO) 2 (µ-CO)(µ-Gep-TolH) (cis-5, trans-5), a mixture of two kinds of trans bis(germylene)-bridged diiron complexes, Cp* 2 Fe 2 (CO) 2 (µ-Gep-TolH) 2 (syn-trans-6, anti-trans-6), and a complex with two Fe‚‚‚H‚‚‚Ge 3-center 2-electron bonds, Cp* 2 Fe 2 (CO) 2 (µ-Gep-TolH 2) 2 (7). A cis isomer of complex 6 (syncis(H)-6) was formed as the sole product by the thermolysis of complex 7. Photolysis of 7 or syn-cis(H)-6 resulted in the conversion to a mixture of syn-trans-6 and anti-trans-6. Reversible thermal and photochemical interconversion between cis and trans isomers of complex 5 was observed. The molar ratio of the cis and trans isomers of complex 5 in C 6 D 6 was 7:93 at thermal equilibrium at 55°C and 84:16 at the photostationary state at 6°C.
Indian Journal of …, 2009
Indian Journal of Marine Sciences Vol. 38 (4), December 2009, pp. 404-410 ... Fecal sterols and p... more Indian Journal of Marine Sciences Vol. 38 (4), December 2009, pp. 404-410 ... Fecal sterols and pahs in sewage polluted marine environment along the eastern ... Red Sea coast, South of Jeddah, Saudi Arabia ... Radwan K Al-Farawati* Amr El-Maradny & Gul R Niaz Faculty ...
Al-Arbaeen and Al-Shabab are two highly polluted lagoons lying along the Jeddah Coast. Surface se... more Al-Arbaeen and Al-Shabab are two highly polluted lagoons lying along the Jeddah Coast. Surface
sediments were collected from both lagoons to assess the levels and spatial distribution of polycyclic
aromatic hydrocarbons (PAHs), as well as study the effect of environmental conditions on PAH
concentrations. The concentration ranges for ∑38-PAHs in Al-Arbaeen and Al-Shabab lagoons were
5.4-5,372 ng/g (mean 1,637 ng/g) and 60-7,927 ng/g (mean 1,323 ng/g), respectively. Pollution levels in
both lagoons were in the low-very high range with dominance by three- and four-ring congeners. Pyrene
was the dominant congener, while benzo (a) pyrene represented the dominant carcinogenic congener in
the study area. The disappearance of most of the low molecular weight congeners may be attributed to
temperature and microbial activity. Carcinogenic PAHs contributed 59.9 and 23.6% for Al-Arbaeen and
Al-Shabab lagoons, respectively. The diagnostic ratios revealed that the source of PAHs are of mixed
origin and site specifi c. The probable toxic effects on organisms were examined for total and individual
PAHs with sediment quality guidelines (ERL-ERM). The detected PAHs levels in the present study were
compared with reported levels for coastal worldwide lagoons.
Aliphatic hydrocarbons including resolved aliphatics (C11C30), isoprenoids (phytane and pristane... more Aliphatic hydrocarbons including resolved aliphatics (C11C30), isoprenoids (phytane and pristane) and unresolved complex mixture, as well as total aromatic hydrocarbons were analyzed in 25 surface sediment samples represented five sites along Jeddah coast, Red Sea. The descending order of total petroleum hydrocarbons in the different sites along the coast was found as following: AlArbaeen Lagoon (site 2) 481 ppm > AlShabab lagoon (site 3) 410 ppm > Southern Corniche (site 1) 205.3 ppm > Northern Corniche (site 4) 172.7 ppm > Sharm Obhur (site 5) 23.6 ppm. The concentrations of total aliphatic hydrocarbons were ranged between 2.18 and 492 ppm dry weights, while the range for the total poly aromatic hydrocarbons was from 2.67 to 160.6 ppm dry weight. The highest concentrations for hydrocarbons were recorded at site 2 (AlArbaeen lagoon, station 8). The indices used to evaluate the probable origin of hydrocarbons indicated petroleum origin with high degradation process in most stations as well as fresh oil inputs in few stations at sites 1 and 4. The levels of total aromatic hydrocarbons for 80% of studied stations were exceeding effects rangemedian value (ERM) for the sediment quality guideline (SQG).
There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through... more There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through adjacent waters, industrial and sewage discharges and air depositions. Polycyclic aromatic hydrocarbons (PAHs) are semi volatile ubiquitous anthropogenic pollutants detected in all environmental compartments. In the monitoring framework for the mangrove ecosystem along the Red Sea coast of Saudi Arabia, nine mangrove stands were examined for the accumulation of PAHs. Polycyclic aromatic hydrocarbons were measured using Gas Chromatography-Mass Spectrometry (GC-MS). The mean values detected for total PAHs in sediments, roots and leaf were 2.98, 8.57 and 23.43 ng/g respectively. The trend of the total PAHs concentration in all sites showed the descending order: leaf > roots > sediments. Beside the sandy nature of the sediments, the presences of all stands in remote areas fare from the direct anthropogenic effects lead to these relative low values. PAH bio-concentration factors for leaf are two to three magnitudes higher than that in roots, suggesting atmosphere deposition /leaf uptake mechanism in addition to the sediment/root mechanism. The diagnostic ratios revealed that the sources of PAHs are mainly pyrogenic.
Brazilian Journal of …, 2011
The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isola... more The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isolated and identified. In this study, the total crude organic matter of the sponge was extracted by solvents. The total crude extract was further separated by partitioning it with hexane and water, then with water and chloroform, and finally with water and t-butanol. The chloroform layer was subjected to separation by preparative layer chromatography on silica. One fraction contained four long-chain fatty acid esters, C28H56O2, C30H60O2, C32H62O2 and C36H70 O2. The second ester, C30H60O2, has been identified in the fire corals Millepora dichotoma and Millepora platyphylla. The others have not previously been reported from marine organisms; however similar long-chain esters with different long aliphatic chains and with different molecular weights have been identified from other marine organisms. These compounds are normally waxy and their presence in Chalinula saudensis plays a vital role in the biosynthetic pathways. They also act as insulators against seasonal variations.