hexachlorocyclohexanes in tree bark across chinese agricultural regions spatial distribution and...
TRANSCRIPT
Hexachlorocyclohexanes in Tree Bark across
Chinese Agricultural Regions: Spatial Distribution
and Enantiomeric Signatures
Reporter: Lili Niu
Adviser: Prof. Weiping Liu
Contents u Introduction
u Residue levels of HCHs in tree bark
u Spatial distribution of HCHs in tree bark
u Composition profiles of HCHs in tree bark
u Sources of HCHs in tree bark
u Factors influencing the residue characteristics of HCHs in tree bark
u Enantiomeric signatures of chiral α-HCH in tree bark
Introduction
Metals
POPs & EDCs
…… Pb, Cd, Zn, Cu
OCPs, PCBs PAEs ……
Persistent Toxic Substances, PTSs
Technical HCHs, 1950s-1980s
Lindane, 1950s-2000 α-HCH β-HCH
γ-HCH δ-HCH
Advantages
Understand the spatial
distribution and transport patterns
Explore enantiomeric signatures
of chiral α-HCH
Especially for POPs with high Koa (high lipid content and large surface area)
Easy to collect Fast Inexpensive
Accumulate both vapor- and particle-phase POPs
Integrate pollutant levels over a period of several years
April to May, 2013
Introduction
Table 1. Descriptive Statistical Summary of HCH Concentrations in Rural Tree Bark across China (ng/g tree bark)
aBDL: below detection level. bSD: standard deviation. cCV: coefficient variation. dDF: detection frequency
α-HCH β-HCH γ-HCH δ-HCH ∑HCHs
Mean 1.16 2.51 1.67 1.65 6.99
Median 0.965 1.32 1.28 0.734 4.55
Min BDLa 0.274 BDLa BDLa 1.47
Max 16.6 73.2 20.2 51.7 127
SDb 1.50 6.97 1.88 4.98 13.2
CVc 1.29 2.77 1.13 3.02 1.89
DF(%)d 98.3 100 97.5 88.4 100
Results and Discussion
Niu, Lili et al., Environmental Science & Technology, 2014, 48, 12031-12038
1. Residue levels of HCHs in tree bark
γ-HCH
α-HCH β-HCH
∑HCHs
δ-HCH
Results and Discussion
Niu, Lili et al., Environmental Science & Technology, 2014, 48, 12031-12038
2. Spatial distribution of HCHs in tree bark
a ng/g tree bark
α-HCHa β-HCHa γ-HCHa δ-HCHa ∑HCHsa α-HCH
%
β-HCH%
γ-HCH%
δ-HCH%
East (n=42) 1.43 3.76 2.02 3.00 10.2 14.0 36.8 19.8 29.4 Central (n=31) 1.03 2.15 1.42 0.952 5.56 18.6 38.7 25.6 17.1
West (n=39) 0.994 1.49 1.52 0.964 4.97 20.0 30.0 30.6 19.4 Northeast
(n=9) 1.08 2.35 1.51 0.692 5.63 19.2 41.8 26.8 12.3
Table 2. The Concentration and Relative Abundance of HCHs in Tree Bark from Four Geographic Regions of China
α-HCH: 0-42.7%, 20.7%
β-HCH: 10-71.1%, 30.4%
γ-HCH: 0-68.6%, 30.2%
δ-HCH: 0-67.4%, 18.7%
Results and Discussion
Niu, Lili et al., Environmental Science & Technology, 2014, 48, 12031-12038
3. Composition profiles of HCHs in tree bark
α-HCH β-HCH γ-HCH δ-HCH
α-HCH 1
β-HCH 0.927** 1
γ-HCH 0.904** 0.874** 1
δ-HCH 0.356** 0.534** 0.321** 1 ∑HCHs 0.864** 0.957** 0.827** 0.744**
**. Correlation is significant at the 0.01 level (2-tailed).
Table 3. Correlation of Total and Individual HCH Concentrations in Tree Bark across China
Results and Discussion
Niu, Lili et al., Environmental Science & Technology, 2014, 48, 12031-12038
4. Sources of HCHs in tree bark
Historical usage of technical HCHs and lindane
Influenced by neighbor countries
Technical HCHs: α- /γ-HCH: 4.64-5.83 α- /β-HCH : 11.8 Lindane : α- /γ-HCH: 0
Results and Discussion
Niu, Lili et al., Environmental Science & Technology, 2014, 48, 12031-12038
5. Factors influencing the residue characteristics of HCHs in tree bark
Environmental Conditions
With α-HCH concentration
With elevation
)]()/[()( −+++=EF
Results and Discussion
Niu, Lili et al., Environmental Science & Technology, 2014, 48, 12031-12038
6. Enantiomeric signatures of chiral α-HCH in tree bark
