Field Evidence of the Mobility of Manufactured Nanoparticles

There is little evidence of the mobility of mNPs in the field, largely because mNPs are a relatively new potential pollutant and measurement is problematic. Most work has been undertaken in the context of nNP-facilitated radioactive nuclide transport. However, we [12, 3] have sampled groundwaters from urban and rural areas in a UK sandstone aquifer, and found a distinct difference (Table 16.1), the urban groundwaters containing significantly more metal-containing particles (sub-ppb), interpreted as unintentional mNPs. These results suggest that some mNPs may be mobile, at least over the distances from ground surface to the base of the well casing,

Table 16.1 Summary of colloid (1 nm-1 mm) particle compositions from wellwaters from the Birmingham and Nottingham urban Permo-Triassic Sandstone aquifers, UK, and a rural Permo-Triassic Sandstone aquifer, UK, as determined by electron microscope EDX analysis (Modified after Kleinert et al. [12])

Property

Birmingham

Nottingham

Lower Mersey Basin

Population (p/l)

1010-1011

1011-1013

1010-1011

Main inorganic comp

Al/Si, Si

Al/Si, Si

Al/Si, Si

Organic

Very few

Very few

None seen

Bacteria

Moderate freq

Mod freq

Low

Occurrence of metals

High freq

Moderate freq

Low freq

Metals assoc with

Inorganic coll

Inorganic coll

-

Metals detected

Ni, Cr, Ti, Zn, Co, Sn,

Fe, Ni, Pt, Ti, Zn,

Fe

Fe, Al, Mn, As, Zr

Pb, Mn, Cr

usually around 30-40 m, and potentially much further. However, even these data are not unequivocal: some particles may have been mobilized by pumping, and some particles may have been the product of precipitation within the aquifer (probably < likely). Even with these uncertainties, results suggest that some mNPs particles can be mobile in at least some intergranular flow dominated aquifers: in fracture flow dominated aquifers, transport is likely to be much easier.

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