Arsenic, Earthworms and PBETS: Understanding Risk at Contaminated Sites. Mark Button a/b/c, Michael J, Watts b, Tim S, Brewer a and Chris F, Harrington c. Department of Geology, University of Leicester, UK, LE1 7RH (
[email protected]) b British Geological Survey, Keyworth, Nottingham, UK, NG12 5GG (
[email protected]).c Biocentre, University of Leicester, UK, LE1 7RH (
[email protected]).
Introduction:
Results/ Discussion:
Results:
Concern over the risk of human exposure to arsenic contaminated soil has increased markedly in recent times, particularly in areas such as the southwest where vast areas exceed the current SGV of 20 mg kg-1. As a result extensive research has been conducted into the appropriate assessment of risk at As contaminated sites, namely the speciation and bioaccesibility of As and its effect on organisms within the terrestrial ecosystem. Earthworms are known to inhabit arsenic contaminated soils and are frequently employed as a sentinel species in the biomonitoring of anthropogenic and geogenic toxins in the terrestrial environment. Aims:
Sample site
Soil Total As
Worm Total As
1 2 3 4 6 7 9 10 11 12 13 15 Control
3058 1564 996 238 11939 313 272 452 282 5232 2870 876 15.4
595 257 317 18.8 359 17.4 17.9 40.0 37.5 203 571 75.2 6.49
Stomach Stomach + Only Intestine 578 298 308 44.2 340 94.8 60.9 43.8 36.5 1595 848 158 4.6
To investigate the bioaccumulation of arsenic in earthworms from highly contaminated soils.
To assess whether the two methods can be used in conjunction to provide an integrated approach to understanding risk at contaminated sites Ca rmarthe n
The maximum bioaccessible As fractions at each site were similar for both the Stomach only and stomach + intestine phases of the UBM method. Except for sites 6 and 12 where a greater disparity between the bioaccessible As fractions was evident (Table 1).
10
Che ltenh am
Bioaccessible As Vs. Worm uptake Corr. Coeff. = 0.57 Total As Vs. Worm uptake Corr. Coeff. = 0.49
Devo n G rea t C Co on nso su ls ls Exe te r We ymou th
1 1
P lymo ut h
10
100
1000
10000
100000
Soil As (mg kg-1)
Penza nce
12 21 3 13
0
50
ยท
100 Kilometers
11
9 7 6
238 - 282 313 - 452 876 - 996 1564 - 3058
0.25
'
0.5 Kilometers
Figure 1. Map of DGC illustrating the position of sample sites and total arsenic concentrations (mg/kg-1) in the soil.
Devon Great Consols (DGC): DGC, formerly an arsenic mine, lies on the north bank of the River Tamar in the Tavistock district of Devon, UK (GR: SX 426 735. Fig. 1).
3
12 21 13
Methodologies: 4
Earthworms were collected from the soil surface (< 20cm) and sorted according to species. Depuration of gut contents was performed to remove soil prior to tissue analysis. Soil Approximately 1 kg was collected from the upper 20cm into paper packets, dried (40oC), sieved (
