Phytoremediation of MTBE from a groundwater plume.

The feasibility of phytoremediation to both remediate and hydraulically contain a methyl tert-butyl ether (MTBE)-contaminated groundwater plume was investigated in a three-phase study that included the following elements: (i) a laboratory bioreactor study that examined the fate and transport of 14C-radiolabeled MTBE in hybrid poplar trees, (ii) a novel approach for a mathematical modeling study that investigated the influence of deep-rooted trees on unsaturated and saturated groundwater flow, and (iii) a field study at a Houston site with MTBE-contaminated groundwater where hybrid poplar trees were planted. In the laboratory study, the predominant fate pathway was uptake and evapotranspiration of [14C]-MTBE from leaves and stems of poplar cuttings rooted in hydroponic solution. The modeling study demonstrates that phytohydraulic containment of MTBE in groundwater by deep-rooted trees can be achieved. The field study demonstrated significant groundwater uptake of groundwater by deep-rooted trees via direct measurement in the first three seasons. The use of vegetation may provide a cost-effective in-situ alternative for containment and remediation of MTBE-contaminated groundwater plumes.

Hb Anamosa or alpha 2(111)(G18)Ala-->Val beta 2 (alpha 2 mutation) and Hb Mulhacen or alpha 2(123)(H6)Ala-->Ser beta 2 (alpha 1 mutation) are two silent, stable variants detected by sequencing of amplified DNA.

We have identified silent amino acid substitutions in two alpha chain variants present in families from Iowa, USA, and Granada, Spain. Both involve an alanine residue in the core peptide, namely Ala-->Val at position 111 (codon change in the alpha 2 gene; GCC->GTC; Hb Anamosa) and Ala-->Ser at position 123 (codon change in the alpha 1 gene; GCC-->TCC; Hb Mulhacen). The two variants are stable. Sequencing of the amplified alpha 2- and alpha 1-globin genes greatly facilitated the characterization of the two variants.

Hb Davenport or alpha 2(78)(EF7)Asn----His beta 2.

Hb Davenport is a new, stable alpha chain variant, that was detected in two members of a Caucasian family living in Iowa. Hematological data were within normal limits. It is characterized by an Asn----His replacement at position alpha 78. Mild acidic hydrolysis of the large alpha T-9 peptide, separation of the resulting fragments by reversed phase high performance liquid chromatography, and sequence analysis of a few of these peptides greatly facilitated the identification of this substitution.