Atmospheric mercury deposition in Guizhou, China

The atmospheric deposition of mercury including total gas phase mercury (TGM), gas phase divalent mercury (Hg2+), and gas phase monomethyl mercury (MMHg) was investigated. Samples were collected from central cities and nature reserve areas across the province. Techniques and equipment including moss bags, KCl-coated denuder and GARDIS-1A portable mercury vapor analyzer were employed for sample collection and analysis. The reliability of techniques and analytical methods used for the project was evaluated. The deposition of atmospheric mercury was reported in species in this important mercury polluted province for the first time. The spatial and temporal variability of mercury emissions were investigated and reported. Contribution of coal mercury emissions to the atmosphere mercury deposition of the province was also investigated.

Determination of methyl mercury in whole blood by ethylation-GC-CVAFS after alkaline digestion-solvent extraction.

A method for the determination of methyl mercury in whole blood samples based on ethylation-gas chromatography-cold vapor atomic fluorescence spectrometry after alkaline digestion-solvent extraction is described. The extraction procedure and conditions were optimized, and the matrix interference after extraction was critically investigated. The storage stability of MeHg in blood samples and a series of extracts was determined. The method detection limit was found to be approximately 0.02 ng/g for a 0.5-g blood sample with relative standard deviations of less than 10%. The accuracy and precision were evaluated by summarizing the quality-control (QC) data generated over a one and one half year period. Appropriate procedures for sample collection, transportation, and storage were adapted to the method. Using this method accompanied by explicit QC protocols and procedures, background levels of MeHg and total mercury in blood for 150 8-10-year-old Portuguese children with nonoccupational and nonamalgamal exposure were determined and reported with summarized QC data.

Determination of mercury in crude oil by in-situ thermal decomposition using a simple lab built system.

A simple system based on thermal decomposition for the one step determination of mercury has been built. This system was applied to the analysis of crude oil and related products. Samples were directly introduced into the system without the use of chemicals and digestion procedures. After 4 min, matrices and mercury compounds were decomposed, and elemental mercury was collected on a gold sand trap, and then detected by atomic fluorescence spectroscopy (AFS). In principle, any sample can be analyzed by this method provided the sample can be introduced into the system quantitatively. The method detection limit was approximately 0.2 ng/g for 0.04 g of crude oil introduced to the system. Various other samples including, biological, environmental, and general merchandise have been analyzed. Results obtained have been compared with established traditional methods including radiochemical neutron activation analysis (RNAA). Good agreement of results between methods was found. Recoveries were close to 100% for certified reference materials. Results were independent of mercury species and sample types.

Determination of arsenic in ambient water at sub-part-per-trillion levels by hydride generation Pd coated platform collection and GFAAS detection.

A method for trace determination of total arsenic in ambient waters is described. Arsenic is separated on-line from a large volume water sample by hydride generation and purging, pre-collected on a Pd coated pyrolytic platform cuvette using a simple and inexpensive system, and finally detected by GFAAS. Instrument parameters, hydride generation, transportation, and collection were optimized. The analytical behavior for major species including As(3+), As(5+), monomethyl As (MMA), and dimethyl As (DMA) were investigated individually. Problems arising from use of the system were discussed and eliminated. The necessity of sample digestion and an efficient digestion method were studied. Sample digestion for water with low organic content such as tap water and clean ground water and some clean surface water can be omitted. The method detection limit (MDL) is 0.3 ng l(-1) for a 25 ml water sample. Recoveries close to 100% with R.S.D.<5% can be easily achieved. Typical aqueous samples including tap, ground, lake, river, rain, sewage effluent, and saline water from different origins in the US, China, and Canada were collected and analyzed using ultra clean sampling and analysis techniques. The background levels of As in most water analyzed were established for the first time, and found to be far above the EPA's health effect criteria, 18 ng l(-1).