Evidence for Very Tight Sequestration of BTEX Compounds in Manufactured Gas Plant Soils Based on Selective Supercritical Fluid Extraction and Soil/Water Partitioning

Benzene, toluene, ethylbenzene, o-, m-, and p-xylenes (BTEX), and polycyclic aromatic hydrocarbons (PAHs) were extracted from eight manufactured gas plant (MGP) soils from sites that had been abandoned for several decades. Supercritical fluid extraction (SFE) with pure carbon dioxide demonstrated the presence of BTEX compounds that were highly sequestered in both coal gas and oil gas MGP soils and soots. Benzene was generally the slowest compound to extract from all samples and was even more difficult to extract than most two- to five-ring PAHs found on the same samples. Since the solubility of benzene in carbon dioxide is 2−5 orders of magnitude higher than the solubilities of PAHs, these results demonstrate that benzene was more tightly sequestered than toluene, ethylbenzene, xylenes, or the multi-ring PAHs. Additional evidence for very tight binding was based on the fact that BTEX concentrations determined using either SFE or with methylene chloride sonication were much higher than those obtained by the U.S. EPA purge-and-trap method, especially for benzene (whose concentration was underestimated by as much as 1000-fold by the EPA method). However, soil/water desorption showed little benzene mobility, and Kd values for benzene were 1−2 orders of magnitude higher than those calculated based on literature sorption KOC values. These results indicate that environmentally relevant concentrations of benzene may be better represented by mild extraction methods than by methods capable of extracting tightly bound benzene

The Acrocalcin and calmodulin proteins interact <i>in vitro</i>.

<p>(A) Purity of preparations of the recombinant proteins used in the <i>in vitro</i> interaction experiments: <i>Acropora</i> calmodulin carrying an N-terminal GST-tag (GST-AmCaM; ∼42 KDa) and Acrocalcin bearing an N-terminal poly-His tag (His-AmAC; ∼24 KDa). (B) Polyclonal antibody against human canonical calmodulin specifically recognises recombinant AmCaM (black arrow), whereas recombinant AmAC (red arrow) is not recognised. (C) In the presence of Ca²⁺ (right panel), AmCaM is retained on a Ni-NTA affinity column via its interaction with the recombinant AmAC that attaches to the matrix via the poly(His) tag that it contains, whereas in the absence of Ca²⁺ (left panel) neither protein is retained by the column. (D) Recombinant AmAC is co-precipitated with AmCaM after incubation with antibody against human calmodulin (agarose-conjugated human CaM-I antibody; Santa Cruz) both in the presence (right panel) and absence (left panel) of Ca²⁺. GST-AmCaM (black arrows). His-AmAC (red arrows). Flow through (F), Elution 1 (E1), Elution 2 (E2). Protein markers (asterisks).</p

Expression of calmodulin and Acrocalcin during coral development.

<p>(A) The canonical calmodulin AmCaM is expressed at a relatively constant level during development as a ∼ 1500 bp transcript. (B) The ∼2500 bp Acrocalcin (AmAC) transcript is present at low levels at the late gastrulation stage, after which levels are relatively constant from the pear stage through to post-settlement. An early and a late pear stage were tested for AmCaM and AmAC transcripts. (C) The faint salt-and-pepper pattern visible at gastrulation reflects AmAC expression in the endoderm (b). A relatively constant expression level was observed from late gastrulation onward, sphere through post-settlement (c–g). No staining was detected in corresponding controls incubated with sense RNA probes (b′, c′, e′). Nucleic acid markers (asterisks). Pre-gastrulation (prawn chip, a). Gastrulation (donut, b). Late gastrula (sphere, c). Early planula (pear, d). Planula (e). Settlement and metamorphosis (f). Settled polyps (g). Control stages (b′, c′, e′), respectively.</p

Primary structure of the coral EF-hand proteins.

<p>(A) As in the canonical calmodulins of a wide range of other eukaryotes, the AmCaM protein contains four predicted EF-hand motifs, each of which fulfils the criteria for activity. Genbank identifiers for the sequences: <i>Acropora</i> Cluster 043479; <i>Nematostella</i> XP_00163858.1; <i>Homo</i> NP_001734.1; <i>Drosophila</i> NP_523710.1; <i>Aedes</i> XP_001662431.1; <i>Suberites</i> O97341; <i>Trichoplax</i> EDV29861.1; <i>Monosiga</i> XP_001749021.1; <i>Schizosaccharomyces</i> XP_002175972. (B) The coral Acrocalcin (AmAC) protein is a typical member of the NCS-B class, possessing an N-terminal myristoylation site (MGK, orange box), three EF-hand motifs (indicated by red boxes) and a predicted CaM-binding site (blue box). Genbank identifiers for sequences: <i>Acropora</i> Cluster 013002; <i>Nematostella1</i> XP_001639634.1; <i>Nematostella2</i> XP_001639635.1; HS (<i>Homo sapiens</i>) hippocalcin NP_002140.2; HS (<i>Homo sapiens</i>) neurocalcin NP_114430; <i>Drosophila</i> NP_788543.1; <i>Aedes</i> XP_001648788.1; <i>Amphimedon</i> XP_003386697.1; <i>Trichoplax</i> EDV23214.1; <i>Monosiga</i> EDQ90181.1.</p

Day and Night Combined Counts

Combined count data from the mapped reads for each sample. BWA parameters were -n 0.05 and -k

Variables used as inputs.

<p><i>I</i>_<i>1</i> to <i>I</i>_<i>36</i> 36 variables are selected as the inputs of the forecasting model. The name and description of the variables are shown in the 1^st column and the 2^nd column, respectively.</p><p>Variables used as inputs.</p

Positive selection candidates of <i>Acropora</i>.

<p>Significance level: *0.05.</p

Diagram of (2D)²PCA+RBFNN forecasting model.

<p>The model is divided five modules, including the database of stock market, variables calculated module, sliding window, dimension reduction module and RBFNN predictor.</p

Amino acid similarity and E value of ESTs between <i>Acropora palmata</i> and <i>A. millepora</i>, <i>Hydra magnipapillata</i>, <i>Nematostella vectensis</i>.

<p>N/A means that putative EST could not be available due to an E value>10⁻¹⁰. Bold font indicates a higher amino acid similarity to <i>H. magnipapillata</i> or to <i>N. vectensis</i> than to <i>A. millepora</i>.</p

Millepora annotation file

Acropora millepora GO annotation fil