Biotransformation and Accumulation of Arsenic in Soil Amended with Seaweed
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- 作者：Hayley Castlehouse ; Cassandra Smith ; Andrea Raab ; Claire Deacon ; Andrew A. Meharg ; and Jö ; rg Feldmann
- 刊名：Environmental Science & Technology
- 出版年：2003
- 出版时间：March 1, 2003
- 年：2003
- 卷：37
- 期：5
- 页码：951 - 957
- 全文大小：140K
- 年卷期：v.37,no.5(March 1, 2003)
- ISSN：1520-5851
文摘
For many coastal regions of the world, it has beencommon practice to apply seaweed to the land as a soilimprover and fertilizer. Seaweed is rich in arsenosugars andhas a tissue concentration of arsenic up to 100 
g g-1.These arsenic species are relatively nontoxic to humans;however, in the environment they may accumulate in thesoil and decompose to more toxic arsenic species. Theaim of this study was to determine the fate and biotransformation of these arsenosugars in soil using HPLC-ICP-MS analysis. Data from coastal soils currently manuredwith seaweeds were used to investigate if arsenic wasaccumulating in these soils. Long-term application ofseaweed increased arsenic concentrations in these soilsup to 10-fold (0.35 mg of As kg-1 for nonagronomic peat,4.3 mg of As kg-1 for seaweed-amended peat). Thebiotransformation of arsenic was studied in microcosmexperiments in which a sandy (machair) soil, traditionallymanured with seaweed, was amended with Laminaria digitataand Fucus vesiculosus. In both seaweed species, thearsenic occurs in the form of arsenosugars (85%). Theapplication of 50 g of seaweed to 1 kg of soil leads toan increase of arsenic in the soils, and the dominatingspecies found in the soil pore water were dimethyl-arsinic acid (DMA(V)) and the inorganic species arsenate(As(V)) and arsenite (As(III)) after the initial appearanceof arsenosugars. A proposed decomposition pathwayof arsenosugars is discussed in which the arsenosugarsare transformed to DMA(V) and further to inorganicarsenic without appreciable amounts of methylarsonicacid (MA(V)). Commercially available seaweed-basedfertilizers contain arsenic concentration between 10 and50 mg kg-1. The arsenic species in these fertilizers dependson the manufacturing procedure. Some contain mainlyarsenosugars while others contain mainly DMA(V) andinorganic arsenic. With the application rates suggested bythe manufacturers, the application of these fertilizers is2 orders of magnitude lower than the maximum permissiblesewage sludge load for arsenic (varies from 0.025 kgha-1 yr-1 in Styria, Austria, to 0.7 kg ha-1 yr-1 in the U.K.),while a direct seaweed application would exceed themaximum arsenic load by at least a factor of 2.
g g-1.These arsenic species are relatively nontoxic to humans;however, in the environment they may accumulate in thesoil and decompose to more toxic arsenic species. Theaim of this study was to determine the fate and biotransformation of these arsenosugars in soil using HPLC-ICP-MS analysis. Data from coastal soils currently manuredwith seaweeds were used to investigate if arsenic wasaccumulating in these soils. Long-term application ofseaweed increased arsenic concentrations in these soilsup to 10-fold (0.35 mg of As kg-1 for nonagronomic peat,4.3 mg of As kg-1 for seaweed-amended peat). Thebiotransformation of arsenic was studied in microcosmexperiments in which a sandy (machair) soil, traditionallymanured with seaweed, was amended with Laminaria digitataand Fucus vesiculosus. In both seaweed species, thearsenic occurs in the form of arsenosugars (85%). Theapplication of 50 g of seaweed to 1 kg of soil leads toan increase of arsenic in the soils, and the dominatingspecies found in the soil pore water were dimethyl-arsinic acid (DMA(V)) and the inorganic species arsenate(As(V)) and arsenite (As(III)) after the initial appearanceof arsenosugars. A proposed decomposition pathwayof arsenosugars is discussed in which the arsenosugarsare transformed to DMA(V) and further to inorganicarsenic without appreciable amounts of methylarsonicacid (MA(V)). Commercially available seaweed-basedfertilizers contain arsenic concentration between 10 and50 mg kg-1. The arsenic species in these fertilizers dependson the manufacturing procedure. Some contain mainlyarsenosugars while others contain mainly DMA(V) andinorganic arsenic. With the application rates suggested bythe manufacturers, the application of these fertilizers is2 orders of magnitude lower than the maximum permissiblesewage sludge load for arsenic (varies from 0.025 kgha-1 yr-1 in Styria, Austria, to 0.7 kg ha-1 yr-1 in the U.K.),while a direct seaweed application would exceed themaximum arsenic load by at least a factor of 2.