electronic supplementary material

sediments, sec 2 • physical and biogeochemical processes • research article

Phthalic acid esters inthe rhizosphere sediments of emergent plants from two shallow lakes

Aili Wang • Jie Chi

Received: 26 February 2012 / Accepted: 16 May 2012

© Springer-Verlag 2012

Responsible editor: Jan Schwarzbauer

A. Wang • J. Chi ()

School of Environmental Science and Engineering, TianjinUniversity, Tianjin, 300072, P. R. China

e-mail:

A. Wang

Department of Chemistry, DezhouUniversity, Dezhou Shandong 253023, P. R. China

() Corresponding author:

Jie Chi

Tel.: +86-22-27890550

Fax: +86-22-87402072

e-mail:

PLFA analysis method,physicochemical properties of the target compounds (Table S1), physicochemical characteristics of water and sediments, and root lipid contents in Qingnian Lake (QL) and Aiwan Lake(AL) (Table S2) and cluster analysis of PLFAs extracted from sediment samples (Fig. S1) are included.

PLFA analysis

PLFAs were extracted in three steps using a modified procedure (He et al. 2009). In brief, 2.0 g of freeze-dried sediment was extracted with a chloroform-methanol-citrate buffer mixture (1:2:0.8), and the sample was separated and cleaned by a silica gel column (6mm×100mm) to get rid of neutral and glycolipids The phospholipids were subjected to alkaline methanol, andthe fatty acid methyl esters (FAMEs) formed were extracted twice with 2 ml hexaneAfter evaporation of the solvent under nitrogen gas, the FAMEs were re-suspended in 100 µl hexane containing 2 µg nonadecanoic acid methyl ester (Sigma Chemical, Poole, UK) as an internal standard. FAMEs were quantified by GC-MS. A splitless injection was employed (injector at 250°C).The oven temperature was 80°C initially, then increased to 150°C at 30°C min-1, followed by an increase to 250°C at 3°C min-1 and held for 1 min. Finally, the oven temperature was increased to 280°C at 10°C min-1 and held for 3 min. Helium was used as carrier gas (1.0 ml min-1).

Fatty acids were designated as the total number of carbon atoms:the number of double bonds, followed by the position of the double bond from the methyl end (ω) of the molecule. Cis and trans configurations are indicated by c and t. The prefixes a- and i- indicate anteiso and iso branching; br indicates an unknown methyl branching position; 10Me indicates a methyl group on the 10th carbon atom from the carboxyl end of the molecule and cy refers to cyclopropane fatty acids.

The total microbial biomass was estimated by the total amount of extracted PLFAs (nmolg-1 dry weight). The sum from the following PLFAs was used to measure total bacterial biomass: i15:0, a15:0, 15:0, i16:0, i17:0, a17:0, 17:0, 16:1ω7, 16:1ω9, 18:1ω7, 18:1ω9, cy17:0 and cy19:0 (He et al. 2009). The peak of PLFA 18:2ω6,9 was used to measure fungal biomass (He et al. 2009). The sum from the following fatty acids was considered to represent Gram positive bacteria: i15:0, a15:0, i16:0, i17:0 and a17:0 (Zelles 1997). The Gram negative bacteria were represented by the sum of 16:1ω7, 16:1ω9, 18:1ω7, 18:1ω9, cy17:0 and cy19:0 (Zelles 1997).

The diversity of microbial community was assessed by the Shannon index (H’), calculated for each sediment sample using the following formula:

(S1)

where H’ is the value of the Shannon index, pi is the concentration of ith individual fatty acid relative to the concentration of all fatty acids, and s is the number of species found in the community profile.

Cluster analysis of the PLFA profiles of the microbial community was performed using hierarchical clustering according to the between-groups linkage method with the software package SPSS 13.0 for Windows.

Table S1 The physicochemical properties of the target compounds

DBPa / DEHPa / MBP / MEHP
molecular structure / / / /
water solubility (mg l-1) / 11.2 / 0.4 / 893b / 111b
vapor pressure (mm Hg 25°C) / 2.7E-5 / 1.0E-7 / - / -
pKa / - / - / 4.2c / 4.2c
lgKow / 4.45 / 7.50 / 2.84b / 4.73b
hydrolysis/photolysishalf-lives / 22 years /
0.6-6.0 days / 2000 years /
0.2-2.0 days / - / -

a The physicochemical properties of DBP and DEHP refer to Staples et al. (1997);bthe water solubility and lgKow of MBP and MEHP refer to Scholz (2003); c the pKavalues of MBP and MEHP refer to Blair et al. (2009).

Table S2 Physicochemical characteristics of water and sediments, and root lipid contents in QL and ALa,b

Sample / Water / Sediment / Root
pH / TN
(mg l-1) / TP
(mg l-1) / DOC
(mg l-1) / pH / TOC
(%) / lipid content
(%)
QL / TR / 8.9 / 9.28 (1.20) / 0.040 (0.002) / 19.0 (1.8) / 7.0 / 2.40 (0.02) / 0.50 (0.02)
PR / 7.3 / 3.49 (0.03) / 0.43 (0.01)
N / 7.6 / 2.20 (0.01)
AL / TR / 8.8 / 5.85 (0.80) / 0.020 (0.001) / 13.3 (1.5) / 7.2 / 8.17 (0.08) / 0.24 (0.05)
PR / 7.4 / 2.54 (0.02) / 0.37 (0.01)
N / 7.5 / 1.53 (0.01)

a QL- Qingnian Lake; AL- Aiwan Lake; TR- T. orientalisrhizosphere sediment; PR-P. australisrhizosphere sediment; N-non-rhizosphere sediment.b The values in parentheses are standard deviation.

Fig.S1 Cluster analysis of PLFAs extracted from sediment samples. AN- non-rhizosphere sediments collected fromAiwanLake. QN- non-rhizosphere sediments collected from Qingnian Lake; APR- P. australisrhizosphere sediments collected from Aiwan Lake; QPR- P. australisrhizosphere sediments collected from Qingnian Lake; QTR- T. orientalisrhizosphere sediments collected from Qingnian Lake; ATR- T. orientalisrhizosphere sediments collected from Aiwan Lake

References in Supplementary Material

Blair JD, Ikonomou MG, Kelly BC, Surridge B, Gobas F (2009) Ultra-trace determination ofphthalate ester metabolites inseawater, sediments, and biotafrom an urbanized marine inlet byLC/ESI-MS/MS.Environ Sci Technol43:6262-6268

He Y, Xu JM, Lv XF, Ma ZH, Wu JJ, ShiJC (2009) Does the depletion of pentachlorophenol in root–soil interface follow a simplelinear dependence on the distance to root surfaces? Soil Biol Biochem 41:1807-1813

Scholz N (2003) Ecotoxicity and biodegradation of phthalate monoesters. Chemosphere 53:921-926

Staples CA, Peterson DR, Parkerton TF,AdamsWJ (1997) The environmental fate of phthalate esters: a literature review. Chemosphere35:667-749

Zelles L(1997)Phospholipid fatty acids profiles in selected members of soil microbial communities. Chemosphere 35:275-294