12 research outputs found
Arsenic in the Pak Pa-Nang River Basin, Thailand
The Pak Pa-Nang River Basin is located in southern Thailand. Its environmental
degradation has been arising because its catchment is mineralized with substantial
deposits of tin forming part of the SE Asian Tin Belt, with the presence of arsenopyrite
gives rise to high arsenic concentrations, mobilized during past mining activity. Suitable
techniques have been developed, for the extraction of arsenic species in a variety of
environmental and biological samples. Trypsin and cellulase enzymatic extraction
procedures were used to extract arsenic species from fish and plant samples,
respectively. Arsenic species in sediments were determined following 1 M H3P04
extraction in an open focused microwave system.
An anion-exchange HPLC system employing a step elution, with sulphate and
phosphate solution as the mobile phase coupled with ICP-MS was used for separation
and detection of the important arsenic species, e.g. AsB, DMA, MMA, and inorganic
arsenic in fish and plant samples. And species of AsIII, AsV, MMA and DMA were
determined in sediment samples. A nitric acid microwave digestion procedure, followed
by carrier gas nitrogen addition (N2)-ICP-MS analysis, to overcome argon chloride
(40Ar35Cl+) interference, was used to measure total arsenic. Validation for these
procedures was carried out using certified reference materials and real samples, mussel,
cockle, green seaweed, brown seaweed and sediment collected from the Tamar Estuary,
UK.
Fish samples from the Pak Pa-Nang Estuary showed a range for total arsenic
concentration, up to 17 ”g gËÂč dry mass. The highest total arsenic found in plant samples
was 189 ”g gËÂč (dry mass), in the root of rice plants. The major species of arsenic in all
fish samples was AsB, together with smaller quantities of DMA and, more importantly,
inorganic arsenic. The major species found in plant was MMA, together with inorganic
arsenic at various levels, ranging from minor to trace, dependent upon the part of the
plant. Total concentrations of arsenic in the sediments covered a range up to 285 ”g gËÂč,
and showed a steep decreasing concentration gradient downstream from the upper
mined areas to the estuary. AsV was the major species found in the sediment samples
with smaller quantities of AsIII and MMA. The presence of the more toxic inorganic
forms of arsenic in water, sediments and biota samples has implications for human
health, particularly as they are readily 'available'.
Considering the dynamic conditions found in the river basin between the dry and wet
(monsoon) season, the supply of these highly toxic arsenic species to humans and
environment is likely to continue. This may be for many years, particularly when the
levels of arsenic stored in river sediments are considered. Higher rainfall could
remobilize arsenic from the various main and intermediate sources and could be carried
on SPM, especially on fine particulate matter, to the Pak Pa-Nang Estuary and also the
Gulf of Thailand. From this study, the implications of arsenic transport within the water
management system for the Pak Pa-Nang River Basin are highlighted
Arsenic in freshwater systems: Influence of eutrophication on occurrence, distribution, speciation, and bioaccumulation
Presence and mobility of arsenic in estuarine wetland soils of the Scheldt estuary (Belgium)
Capillary electrophoresis with inductively coupled plasmaâmass spectrometric and electrospray time of flight mass spectrometric detection for the determination of arsenic species in fish samples
Arsenic speciation in polychaetes (Annelida) and sediments from the intertidal mudflat of Sundarban mangrove wetland, India
This paper documents the concentration of total arsenic and individual arsenic species in four soft-bottom benthic polychaetes (Perenereis cultifera, Ganganereis sootai, Lumbrinereis notocirrata and Dendronereis arborifera) along with host sediments from Sundarban mangrove wetland, India. An additional six sites were considered exclusively for surface sediments for this purpose. Polychaetes were collected along with the host sediments and measured for their total arsenic content using inductively coupled plasma mass spectrometry. Arsenic concentrations in polychaete body tissues varied greatly, suggesting species-specific characteristics and inherent peculiarities in arsenic metabolism. Arsenic was generally present in polychaetes as arsenate (AsV ranges from 0.16 to 0.50 mg kgâ1) or arsenite (AsIII ranges from 0.10 to 0.41 mg kgâ1) (30â53 % as inorganic As) and dimethylarsinic acid (DMAV <1â25 %). Arsenobetaine (AB < 16 %), and PO4-arsenoriboside (8â48 %) were also detected as minor constituents, whilst monomethylarsonic acid (MAV) was not detected in any of the polychaetes. The highest total As (14.7 mg kgâ1 dry wt) was observed in the polychaete D. arborifera collected from the vicinity of a sewage outfall in which the majority of As was present as an uncharacterised compound (10.3 mg kgâ1 dry wt) eluted prior to AB. Host sediments ranged from 2.5 to 10.4 mg kgâ1 of total As. This work supports the importance of speciation analysis of As, because of the ubiquitous occurrence of this metalloid in the environment, and its variable toxicity depending on chemical form. It is also the first work to report the composition of As species in polychaetes from the Indian Sundarban wetlands