Tree ring analysis for determination of pollution history of Chengde City，north China

Air pollution history of sulphur and heavy metals since 1800 in Chengde City , north China,was studied by analyzing the concentrations of sulphur and heavy metals in growth rings of Pinus tabulaeformis Carr. Sulphur concentrations in the tree rings of 1910-1920, 1970-1980,and 1980-1990 have increased 1-2 , 3-5 and 10 times respectively as those in the tree ring of 1810-1820 (P<0. 05). This is ascribed to the result of urbanization, especially the appearance and aggravation of industrialization, in the city of Chengde since 1950s. Fe appeared to increase during 1920-1940, possibly due to the opening of Damiao Iron Mine by the Japanese in 1927; Mn increased throughout the whole history, from 4. 1 μg/g(1840- 1850) to 10. 4 μg/g (1980 1990,P <0. 05);Pb did not increase until 1980 but increased sharply during the last 10 years by 560%(P<0. 001). This is caused by the increased number of automobiles in the city. The contents of Cu,Zn, Ni have changed little. The concentrations of sulphur and heavy metals in the tree rings at the beginning of 1800s were the lowest and could be regarded as the background concentrations.We calculated that S, Fe, Pb, Mn, Ni, and Zn in the tree rings have increased 10, 2.4,1.8,1.5,1.0 and 0. 8 times respectively during the past 190 years or so. The results showed that serious environmental pollution, especially air pollution of SO2,has occurred since 1949 when the People's Republic of China was founded.

Increasing Anthropogenic Mercury Pollution over the Last 200 Years Revealed by Lagoonal Sediments from Hainan Island,South China

The toxic heavy metal mercury(Hg)has significantly enhanced the global Hg cycle influenced by human activities over the last century.In this study,we presented a high-resolution Hg deposition history between∼1780 and 2015 AD in a sediment core from Xincun Lagoon,located in the southeastern Hainan Island,South China,and analyzed it in conjunction with geochemical elements,grain-size distribution,organic matter,and HYSPLIT backward trajectory simulation.The objective was to investigate the influencing factors affecting historical Hg deposition in relatively remote regions and assess the extent of the effects of natural background and human activities.The results showed that the Hg in the sediment was deposited primarily through atmospheric deposition,which was closely related to regional and even global human activities.Anthropogenic Hg contamination increased gradually from the 1830s to 1850s,possibly due to Hg emissions from Opium Wars I and II occurring in southeastern China.High broad peaks of anthropogenic Hg were observed during the 1910s to 1950s and in the 1980s,likely associated with the two world wars and modern Chinese wars.In addition,a further sharp increase in anthropogenic Hg from the mid-1970s to the present occurred,likely originating from the intense industrial activities in China triggered by the reform and opening-up policy of China in 1978 and some countries in Southeast Asia.

Risk assessment and identification of factors influencing the historical concentrations of microcystin in Lake Taihu, China

Understanding the history of microcystins(MCs)pollution in large lakes can help inform future lake management.We collected sediment cores from Lake Taihu to:investigate the long-term record of MCs(MC-LR,MC-YR,and MC-RR),explore the main environmental drivers of MCs,and assess their public health and ecological risks.Results showed that MCs content in all cores increased over time.The core from north Taihu had the highest MC concentrations,with an average total MCs(sum of MC-LR,MC-YR,and MC-RR=TMCs)content of(74.31±328.55)ng/g.The core from eastern Taihu showed the lowest average TMCs content of(2.91±3.95)ng/g.PCA showed that sediment MCs at the three sites were positively correlated with sediment chlorophyll-a.MC-LR and MC-YR in northern and western Taihu negatively correlated with both the sediment total organic carbon/sediment total nitrogen ratio(STOC/STN)andwater nitrate(NO_(3)^(−)-N)concentration,but three MC congeners at eastern Taihu showed positive correlations with water orthophosphate(PO_(4)^(3−)-P),NO_(3)^(−)-N,and STOC/STN.Generalized additive model analysis at each site revealed that NO_(3)^(−)-N was the main TMCs driver in northern andwestern Taihuwhere phytoplankton dominated,whereasPO_(4)^(3−)-P was the main TMCs driver in eastern Taihu where macrophytes dominated.At the whole lake scale,total phosphorus(TP)andPO_(4)^(3−)-P were the most important environmental drivers influencing MCs;TP explained 47.4%,44.2%,and 47.6%while orthophosphate explained 34.8%,31.2%,and 34.7%of the deviance on TMCs,MC-LR,and MC-YR,respectively.NO_(3)^(−)-N also showed a strong effect on MCs variation,especially on MC-YR.Risk assess-ment showed that both ecological and public health risk has increased in recent years.We conclude that while control of phosphorus and nitrogen input should be a major focus for future lake management,lake zone-specificmanagement strategiesmay also be important.