Seaweed naturally contains high levels of arsenic
Excerpt 17E
Adapted from Castlehouse, H.; Smith, C.; Raab, A.; Deacon, C.; Meharg, A. A.; Feldmann, J. Biotransformation and Accumulation of Arsenic in Soil Amended with Seaweed. Environ. Sci. Technol. 2003, 37, 951–957.

http://www4.nau.edu/chemwrite/ch_XVII_web_exercises.doc


Seaweed was once widely used as a fertilizer in coastal regions of the Atlantic seaboard of Europe and elsewhere access to this resource was available and arable farming was conducted. It is rich in a wide range of nutrients, improves soil texture and quality, and is a renewable and sustainable resource as seaweed is deposited routinely in large quantities on many beaches. For coastal farms, this resource is on their doorstep and requires only limited transportation.
With the advent of modern fertilizers, it fell out of use because of the ease of application of formulated pesticides and because the contamination of seaweed washed up on beaches with plastic waste (fishing lines and ropes, bottles, etc.) led to a decline in use. With the onset of green agriculture and the increasing demand for organically farmed produce, seaweed use as a fertilizer has come back into fashion. . . .

One factor has been overlooked in this reversion to seaweed use. Seaweed naturally contains high levels of arsenic, typically between 20 and 100 mg kg-1 dry weight (dw). Thus, sustained use of seaweed may lead to the buildup of arsenic in soils. The dominant species of arsenic in these seaweeds are in the form of arsenoribofuranosides (arsenosugars). These are assumed to be relatively nontoxic to humans and animals as compared to inorganic species. The arsenosugars are metabolized to different organoarsenic species but mainly to DMA(V) (dimethylarsinic acid) when consumed as a food source.

http://www4.nau.edu/chemwrite/ch_XVII_web_exercises.doc





Arsenic in Dried Seafood Consumed in Hong Kong

http://www.springerlink.com/content/v2247v790x458q6j/


Journal Journal of Radioanalytical and Nuclear Chemistry
Publisher Akadémiai Kiadó, co-published with Springer Science+Business Media B.V., Formerly Kluwer Academic Publishers B.V.
ISSN 0236-5731 (Print) 1588-2780 (Online)
Subject Chemistry and Materials Science and Physics and Astronomy
Issue Volume 246, Number 1 / October, 2000
DOI 10.1023/A:1006778309309
Pages 157-160
SpringerLink Date Monday, November 01, 2004
C. K. Man1 and X. W. He2

(1) Department of Applied Physics, the Hong Kong Polytechnic University, Hung Hom, Hong Kong
(2) Joint Institute of Nuclear Technology, Shenzhen University, Shenzhen, P.R. China


Abstract The arsenic concentrations were determined by neutron activation analysis in some popular dried seafood and dried algae consumed in Hong Kong. It was found that dried scallop was the least contaminated, while most of the samples of dried shrimp, dried oyster and dried mussel contained arsenic less than the maximum permissible concentration (MPC). Dried squid was found to contain the highest arsenic and every sample measured contained arsenic higher than the MPC. Action to be taken was recommended.

http://www.springerlink.com/content/v2247v790x458q6j/







Evaluation of the contamination of marine algae (Seaweed) from the St. Lawrence River and likely to be consumed by humans.Phaneuf D, Cote I, Dumas P, Ferron LA, LeBlanc A.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uid...


CHUQ, Pavillon CHUL, 2705 Boulevard, Laurier, Sainte-Foy, Quebec, G1V 4G2, Canada.

The goal of the study was to assess the contamination of marine algae (seaweeds) growing in the St. Lawrence River estuary and Gulf of St. Lawrence and to evaluate the risks to human health from the consumption of these algae. Algae were collected by hand at low tide. A total of 10 sites on the north and south shores of the St. Lawrence as well as in Baie des Chaleurs were sampled. The most frequently collected species of algae were Fucus vesiculosus, Ascophyllum nodosum, Laminaria longicruris, Palmaria palmata, Ulva lactuca, and Fucus distichus. Alga samples were analyzed for metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn), iodine, and organochlorines. A risk assessment was performed using risk factors (e.g., RfD of the U.S. EPA, ADI of Health Canada, etc.). In general, concentrations in St. Lawrence algae were not very high. This was especially true for mercury and the organochlorines, concentrations of which were very low or below detection limits. Consequently, health risks associated with these compounds in St. Lawrence algae were very low. Iodine concentration, on the other hand, could be of concern with regard to human health. Regular consumption of algae, especially of Laminaria sp., could result in levels of Iodine sufficient to cause thyroid problems. For regular consumers, it would be preferable to choose species with low Iodine concentrations, such as U. lactuca and P. palmata, in order to prevent potential problems. Furthermore, it would also be important to assess whether preparation for consumption or cooking affects the iodine content of algae. Algae consumption may also have beneficial health effects. Scientific literature has shown that it is a good source of fiber and vitamins, especially vitamin B12. Copyright 1999 Academic Press.

PMID: 10092431 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uid...






Heavy metal contamination of brown seaweed and sediments from the UK coastline between the Wear river and the Tees river.Giusti L.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uid...

Department of Environmental Sciences, Faculty of Applied Sciences, University of the West of England, Bristol. [email protected]

The concentration of Fe, Mn, Zn, Cu, Pb, Ni, Cr, Cd, and Ag were determined in the brown alga Fucus vesiculosus and intertidal surface sediments from coastal locations of northeast England. Levels of heavy metals similar to those of polluted areas of the British coastline were detected. There is evidence of contamination (especially with Zn and Pb) in sediments from sites affected by colliery spoil and from the Wear estuary. The pelitic fraction ( < 63 microm) is usually more enriched in heavy metals, but it represents a very small percentage of the bulk samples. The fine-grained sand is a very important repository of contaminants especially where particles of colliery spoil, secondary mineral, and amorphous phases are present. Aqua regia-extracted Zn, Cu, and Pb in sediments are significantly correlated with those in seaweed. Despite the closure of all base metal and coal mines, and the cessation of many industrial activities in the region, sediments and brown algae are contaminated with heavy metals. The control site (Holy Island) and the Tees estuary appear to be the least affected.

PMID: 11341296 [PubMed - indexed for MEDLINE]

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uid...