Heavy metal contamination in western Xiamen Bay sediments and its vicinity, China.
ABSTRACT Concentrations of selected heavy metals (Cu, Pb, Zn, Cd, Cr, Ni and Fe) in surface sediments from nine sites in western Xiamen Bay and its vicinity were studied in order to understand current metal contamination due to urbanization and economic development in Xiamen, China. The sediment samples were collected in December 2004 and July 2005 respectively in order to examine temporal variations. In this study, we found that heavy metal concentrations in surface sediments sampled in the western Xiamen Bay and adjacent Maluan Bay and Yuandang Lagoon varied from 19 to 97mg kg(-1) for Cu, 45 to 60mg kg(-1) for Pb, 65 to 223mg kg(-1) for Zn, 0.11 to 1.01mg kg(-1) for Cd, 37 to 134mg kg(-1) for Cr, 25 to 65mg kg(-1) for Ni and 3.08 to 4.81% for Fe. Although all metal concentrations in sediments meets Chinese National Standard Criteria for Marine Sediment Quality, both metal enrichment factors (EF) and geoaccumulation index (I(geo)) show that Pb contamination exists in the entire study area and contamination of other metals are also present in some locations depending on the sources, of which sewage outlets and commercial ports are the main sources of contaminants to the area. This study shows that using the sediment quality standard criteria only to assess sediments cannot properly reflect sediment contamination. A multiple approaches should be applied for the sediment quality assessment.
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ABSTRACT: The distribution characteristics of heavy metals for surface sediments in east oceanic dumping area (EDA) and west oceanic dumping area (WDA) are evaluated by grain sizes, minerals, sedimentation rates and compositions of heavy metals. The mean grain sizes in EDA and WDA range from to and to , respectively. These are mostly belonging to the M (mud) type. Minerals in the surface sediments consist of illite with chlorite, smectite, and kaolinite. Sedimentation rates estimated by method in EDA and WDA are 1.11 mm/yr1.73 mm/yr and 1.87 mm/yr, respectively. According to the interrelationship, concentrations of Ni, Cu, Cr, and Zn are closely associated with mean grain size, Al, and Fe, whereas concentrations of Cd and Pb are poorly associated with ones. The enrichment factors of these elements are higher than 1.5, suggesting that the concentrations of Cd and Pb in the surface sediments are affected by anthropogenic sources. The -class numbers of Cd and Pb in the surface sediments are mostly classified in 2 to 4, showing moderate to strongly polluted. These numbers in EDA are higher than that of WDA, and the highest number is 4, indicative of the strongly polluted class. Our results show that the disposed wastes at EDA include mineralogical wastes, dredged materials from sewage disposals, and sludges from constructions having materials of WDA. The annual amount of oceanic dumping in EDA is double than that in WDA.Economic and Environmental Geology. 01/2009; 42(2).
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ABSTRACT: Thirty years ago, Yundang Lagoon, located in the centre of Xiamen in southeast China, was heavily polluted. A series of clean-up projects have been implemented since the 1980s. After three phases of restoration projects, the lagoon's environment quality has improved significantly, although it is not fully restored. Clean-up activities are still ongoing. In 1994, Xiamen became the first city in China to adopt an Integrated Coastal Management (ICM) strategy to address its coastal environmental problems. The restoration of Yundang Lagoon remained a priority and has been a key issue in the development of the city's pollution abatement and environmental management strategy. This study reviews and examines the restoration efforts and management scheme of Yundang Lagoon from 1988 to the present, analyses the environmental changes, explores the challenges of its restoration and analyses the benefits of ICM to its long-term restoration by extracting six key principles. Specific suggestions are proposed for future restoration and management work. Findings from this review may have general implications for decision makers to formulate future sustainability and management strategies on coastal environment restoration programmes.Journal of Environmental Planning and Management 11/2014; 57(11). · 1.11 Impact Factor
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ABSTRACT: In this study, the sawdust was used as an abundant and inexpensive material for the removal of two heavy metals simultaneously from an aqueous solution. In order to evaluate the adsorbent potential of the sawdust, the effects of many operating parameters were studied. The metals considered were zinc and cadmium. The experiments were organized according to a well defined window of a statistical design of experiments. Starting from a large number of operating parameters (type, source, size and quantity of sawdust, temperature, pH, contact time, stirring speed, initial concentrations of cadmium, zinc and salt), a Plackett– Burman design was used to identify the most influential factors on the elimination performance of zinc and cadmium simultaneously with a minimum number of experiments. Effects of these factors were deduced from an interesting statistical treatment of experimental responses. For Zn sorption, the most important factors are mass of sawdust, initial concentration of zinc and time; while for Cd sorption, the most important factors are initial concentrations of zinc and cadmium, pH, mass, type and size of sawdust. The presence of cadmium decreased the removal of zinc considerably and the inverse did not happen. These effects were more remarkable for cadmium (sorption varied from 0 to 80%) than for zinc (sorption varied from 0 to 50%). These results allowed to choose the most important parameters which could be optimized using another designs of experiments, such as Box Behnken or full factorial, and response surface methodology to obtain the best performance of metals sorption.Desalination and water treatment 11/2012; 49:189-199. · 0.99 Impact Factor