To assess the contamination trends and potential bio-availability of sediment-bound heavy metals,concentrations of heavy metals in acid-leaching fraction and in bulk sediments from the two typical bays(the Meiliang Ba...To assess the contamination trends and potential bio-availability of sediment-bound heavy metals,concentrations of heavy metals in acid-leaching fraction and in bulk sediments from the two typical bays(the Meiliang Bay and Xuhu Bay) of the Taihu Lake,East China,were studied.Pb and Zn showed elevated concentrations in the sediments from both areas,although sedimentation history and degree of pollution are different between the two bays.In the Meiliang Bay,both Pb and Zn pollutions started in the late 1970's,the same time as the beginning of eutrophication of the lake,while the in the Xuhu Bay the metal contamination started since recent 10 years.The concentrations of acid-leachable Pb in the sediments from the Meiliang Bay are correlated with the historical eutrophication process.Before the eutrophication and heavy metal pollution,the chemical properties of the lake sediments were the same as the source compositions of the Xiashu loess.Both Pb and Zn in the sediments mainly occur in leachable forms by nitric or hydrochloric acid,whilst most of Cu is in residual fraction.The results indicate that both Pb and Zn may have higher mobility and bioavailability in water and biology than Cu.展开更多
More than 40 national and regional geochemical mapping projects in the world carried out from 1973 to 1988 do not conform to common standards. In particular they have many analytical deficiencies. In the period 1988 t...More than 40 national and regional geochemical mapping projects in the world carried out from 1973 to 1988 do not conform to common standards. In particular they have many analytical deficiencies. In the period 1988 to 1992, the International Geochemical Mapping project （Project 259 of UNESCO＇s IGCP Program） prepared recommendations designed to standardize geochemical mapping methods. The analytical requirements are an essential component of the overall recommendations. They included the following： 71 elements should be analyzed in future mapping projects; the detection limits of trace and ultratrace elements must be lower than the corresponding crustal abundances; and the Chinese GSD and Canadian STSD standard sample series should be used for the correlation of global data. A proposal was also made to collect 5000 composite samples, at very low sampling densities to cover the whole Earth＇s land surface. In 1997 an IUGS Working Group on Global Geochemical Baselines was formed to continue the work which began with IGCP 259. From 1997 up to now, new progress has been made especially in China and FOREGS countries under the aegis of this working group, including the study of suitable sampling media, development of a multi-element analytical system, new proficiency test for selection of competent laboratories and role of wide-spaced mapping in mineral exploration. One of the major problems awaiting solution has been the inability of many laboratories to meet the IGCP recommendations to generate high quality geochemical maps. Fortunately several laboratories in China and Europe have demonstrated an ability to meet the requirements and they will be well placed to render technical assistance to other countries.展开更多
基金supported by 973 Project on the Processes of Lake Eutrophication and the Mechanism of Cyanobacterial Blooming (2002CB412300)National Survey of Land and Source (200420130002)
文摘To assess the contamination trends and potential bio-availability of sediment-bound heavy metals,concentrations of heavy metals in acid-leaching fraction and in bulk sediments from the two typical bays(the Meiliang Bay and Xuhu Bay) of the Taihu Lake,East China,were studied.Pb and Zn showed elevated concentrations in the sediments from both areas,although sedimentation history and degree of pollution are different between the two bays.In the Meiliang Bay,both Pb and Zn pollutions started in the late 1970's,the same time as the beginning of eutrophication of the lake,while the in the Xuhu Bay the metal contamination started since recent 10 years.The concentrations of acid-leachable Pb in the sediments from the Meiliang Bay are correlated with the historical eutrophication process.Before the eutrophication and heavy metal pollution,the chemical properties of the lake sediments were the same as the source compositions of the Xiashu loess.Both Pb and Zn in the sediments mainly occur in leachable forms by nitric or hydrochloric acid,whilst most of Cu is in residual fraction.The results indicate that both Pb and Zn may have higher mobility and bioavailability in water and biology than Cu.
文摘More than 40 national and regional geochemical mapping projects in the world carried out from 1973 to 1988 do not conform to common standards. In particular they have many analytical deficiencies. In the period 1988 to 1992, the International Geochemical Mapping project （Project 259 of UNESCO＇s IGCP Program） prepared recommendations designed to standardize geochemical mapping methods. The analytical requirements are an essential component of the overall recommendations. They included the following： 71 elements should be analyzed in future mapping projects; the detection limits of trace and ultratrace elements must be lower than the corresponding crustal abundances; and the Chinese GSD and Canadian STSD standard sample series should be used for the correlation of global data. A proposal was also made to collect 5000 composite samples, at very low sampling densities to cover the whole Earth＇s land surface. In 1997 an IUGS Working Group on Global Geochemical Baselines was formed to continue the work which began with IGCP 259. From 1997 up to now, new progress has been made especially in China and FOREGS countries under the aegis of this working group, including the study of suitable sampling media, development of a multi-element analytical system, new proficiency test for selection of competent laboratories and role of wide-spaced mapping in mineral exploration. One of the major problems awaiting solution has been the inability of many laboratories to meet the IGCP recommendations to generate high quality geochemical maps. Fortunately several laboratories in China and Europe have demonstrated an ability to meet the requirements and they will be well placed to render technical assistance to other countries.
