Contents of heavy metals, polycyclic aromatic hydrocarbons （PA Hs）, dichlorodiphenyltrichloroethanes （DDTs） and hexachlorcy- clohexanes （HCHs） in surface sediments from mangrove areas of the Leizhou Peninsula we...Contents of heavy metals, polycyclic aromatic hydrocarbons （PA Hs）, dichlorodiphenyltrichloroethanes （DDTs） and hexachlorcy- clohexanes （HCHs） in surface sediments from mangrove areas of the Leizhou Peninsula were analyzed in July and November 2005. Risk assessment criteria applied by Long E R et al. （1995） and Long E D et al. （1995） （effects range low, ERL; effects range mean, ERM） of chemicals in sediments from the gulf or estuary were used to assess the potential ecological risks of heavy metals, PAHs, DDTs and HCHs to aquatic organisms in the studied area. The results indicated that the average contents of zinc, nickel, chromium, lead, copper, arsenic and mercury were （61.97 ± 55.87）, （59.99 ± 39.01 ）, （47.93 ± 28.37）, （26.64± 13.00） , （23.45 ± 41.96）, （9.32 ± 3.62）, （0.14 ± 0.18） mg/kg in dry weight in the sediment samples col- lected from five studied sites in the Leizhou Peninsula, respectively. Cadmium was not calculated due to its content being below the detection limit （ 〈 0.3 mg,/kg）. The average levels of Cr, Cu, Ni, Pb, Zn and Hg exceed their background values. The average contents of Ni were higher than ERM. The contents of PAHs in the sediments from the five studied sites were （79.78 ± 43.70） ng/g in dry weight, far lower than ERL（4 022 ng/g）. The contents of DDE, DDD and DDTs in the sediments from five studied sites were （2.60 ± 4.68）, （ 17.52 ± 27.25 ）, （27.78 ± 46.64） ng/g in dry weight respectively, clearly higher than ERL, and the average contents of DDT were （7.66 ± 15.93） ng/g in dry weight, much higher than ERM. HCHs could be detected in the sediments only from Gaoqiao sampling site, with the average contents （0.07 ± 0.08） ng/g in dry weight.展开更多
Based on plant specimen data,sediment samples,photos,and sketches from 45 coastal cross-sections,and materials from two recent countrywide comprehensive investigations on Chinese coasts and is-lands,this paper deals w...Based on plant specimen data,sediment samples,photos,and sketches from 45 coastal cross-sections,and materials from two recent countrywide comprehensive investigations on Chinese coasts and is-lands,this paper deals with China’s vegetative tidal-flats:salt marshes and mangrove swamps.Thereare now 141700 acres of salt marshes and 51000 acres of mangrove swamps which together cover about30% of the mud-coast area of the country and distribute between 18°N(Southem Hainan Island)and41°N(Liaodong Bay).Over the past 45 years.about 1750000 acres of salt marshes and 49400 acres ofmangrove swamps have been reclaimed.The2.0×10~9 tons of fine sediments input by rivers into the Chinese seas form extensive tidal flats,the soil basis of coastal helophytes.Different climates result inthe diversity of vegetation.The 3～8m tidal range favors intertidal zone development.Of over 20plant species in the salt marshes,native Suaeda salsa,Phragmites australis,Aeluropus littoralis,Zoysiamaerostachys,Imperata cylindrica and展开更多
A field survey was carried out to determine the vegetation structure of the Lukanga Swamp Ramsar site in central Zambia. The aim of the study was to identify the different vegetation communities, species composition a...A field survey was carried out to determine the vegetation structure of the Lukanga Swamp Ramsar site in central Zambia. The aim of the study was to identify the different vegetation communities, species composition and distribution patterns for improved habitat management. Sampling was conducted in all recognizable vegetation communities. The results of the survey showed that the swamp was a littoral palustrine wetland predominantly characterized by the dominance of Leersia hexandria Swartz (42.02%), Typha capensis Rohrb (62.43%), Phragmites australis (Cav.) Trin. ex Steud (33.61%), Aeschynomeme fluitans Peter (31.58%) and Polygonum senegalense Meisn (48.8%). The occurrence of Vossia cuspidata Griff and Cyperus papyrusL was restricted to small and isolated locations. Short Termitaria was generally covered by Acrocerus macrum Stapf (35.25%) while tall Termitaria was dominated by Panicum maximum Jacq. (26.00%). The most important woody plant species included Combretum ghasalense Engl. et Diels (I. V = 62.88), Pseudolachnostylis maprouneifolia Pax ((I. V = 90.48), Albizia adianthifolia (Schmacher) W.F. Wight (I. V = 135.63) Isoberlinia angolensis Hyle and Brenan (I. V = 87.25). The current structure of the hydrophytes composition observed in this study was an indication of a generally silting wetland, while the dominant occurrence of understorey woody plants in the surrounding vegetation signified degraded miombo vegetation. It was concluded that the ecological status of wetland habitat was potentially threatened by mainly anthropogenic activities such as;wildfires, and unsustainable exploitation of surrounding vegetation. Further research is required to examine water flows, eutrophication and the long-term effects of deforestation on the ecological functioning of the wetland.展开更多
基金Zhang Hongda Science Research Fund of Sun Yat-sen Universitythe Young and Middle-aged Excellet Reacher's Research Fund of Guangdong Education Institute in China.
文摘Contents of heavy metals, polycyclic aromatic hydrocarbons （PA Hs）, dichlorodiphenyltrichloroethanes （DDTs） and hexachlorcy- clohexanes （HCHs） in surface sediments from mangrove areas of the Leizhou Peninsula were analyzed in July and November 2005. Risk assessment criteria applied by Long E R et al. （1995） and Long E D et al. （1995） （effects range low, ERL; effects range mean, ERM） of chemicals in sediments from the gulf or estuary were used to assess the potential ecological risks of heavy metals, PAHs, DDTs and HCHs to aquatic organisms in the studied area. The results indicated that the average contents of zinc, nickel, chromium, lead, copper, arsenic and mercury were （61.97 ± 55.87）, （59.99 ± 39.01 ）, （47.93 ± 28.37）, （26.64± 13.00） , （23.45 ± 41.96）, （9.32 ± 3.62）, （0.14 ± 0.18） mg/kg in dry weight in the sediment samples col- lected from five studied sites in the Leizhou Peninsula, respectively. Cadmium was not calculated due to its content being below the detection limit （ 〈 0.3 mg,/kg）. The average levels of Cr, Cu, Ni, Pb, Zn and Hg exceed their background values. The average contents of Ni were higher than ERM. The contents of PAHs in the sediments from the five studied sites were （79.78 ± 43.70） ng/g in dry weight, far lower than ERL（4 022 ng/g）. The contents of DDE, DDD and DDTs in the sediments from five studied sites were （2.60 ± 4.68）, （ 17.52 ± 27.25 ）, （27.78 ± 46.64） ng/g in dry weight respectively, clearly higher than ERL, and the average contents of DDT were （7.66 ± 15.93） ng/g in dry weight, much higher than ERM. HCHs could be detected in the sediments only from Gaoqiao sampling site, with the average contents （0.07 ± 0.08） ng/g in dry weight.
基金The project was supported by the NSFC(No.49476281)
文摘Based on plant specimen data,sediment samples,photos,and sketches from 45 coastal cross-sections,and materials from two recent countrywide comprehensive investigations on Chinese coasts and is-lands,this paper deals with China’s vegetative tidal-flats:salt marshes and mangrove swamps.Thereare now 141700 acres of salt marshes and 51000 acres of mangrove swamps which together cover about30% of the mud-coast area of the country and distribute between 18°N(Southem Hainan Island)and41°N(Liaodong Bay).Over the past 45 years.about 1750000 acres of salt marshes and 49400 acres ofmangrove swamps have been reclaimed.The2.0×10~9 tons of fine sediments input by rivers into the Chinese seas form extensive tidal flats,the soil basis of coastal helophytes.Different climates result inthe diversity of vegetation.The 3～8m tidal range favors intertidal zone development.Of over 20plant species in the salt marshes,native Suaeda salsa,Phragmites australis,Aeluropus littoralis,Zoysiamaerostachys,Imperata cylindrica and
文摘A field survey was carried out to determine the vegetation structure of the Lukanga Swamp Ramsar site in central Zambia. The aim of the study was to identify the different vegetation communities, species composition and distribution patterns for improved habitat management. Sampling was conducted in all recognizable vegetation communities. The results of the survey showed that the swamp was a littoral palustrine wetland predominantly characterized by the dominance of Leersia hexandria Swartz (42.02%), Typha capensis Rohrb (62.43%), Phragmites australis (Cav.) Trin. ex Steud (33.61%), Aeschynomeme fluitans Peter (31.58%) and Polygonum senegalense Meisn (48.8%). The occurrence of Vossia cuspidata Griff and Cyperus papyrusL was restricted to small and isolated locations. Short Termitaria was generally covered by Acrocerus macrum Stapf (35.25%) while tall Termitaria was dominated by Panicum maximum Jacq. (26.00%). The most important woody plant species included Combretum ghasalense Engl. et Diels (I. V = 62.88), Pseudolachnostylis maprouneifolia Pax ((I. V = 90.48), Albizia adianthifolia (Schmacher) W.F. Wight (I. V = 135.63) Isoberlinia angolensis Hyle and Brenan (I. V = 87.25). The current structure of the hydrophytes composition observed in this study was an indication of a generally silting wetland, while the dominant occurrence of understorey woody plants in the surrounding vegetation signified degraded miombo vegetation. It was concluded that the ecological status of wetland habitat was potentially threatened by mainly anthropogenic activities such as;wildfires, and unsustainable exploitation of surrounding vegetation. Further research is required to examine water flows, eutrophication and the long-term effects of deforestation on the ecological functioning of the wetland.
