Contaminated.

Unfortunately, though we greatly prefer not to, from time to time necessity brings us to the Bridge of Dee Parking and Shopping Experience. It always leaves us feeling a bit dirty (metaphorically). Today, we learned that it literally makes us dirty, inside and out. Contaminated. Polluted.

Not in the least bit dehumanising.

One day soon, we'll do a full psychogeographical exposé of the zone which sits on the broad flat floodplain of the Ruthrieston Burn. But not today - we've got more indignant fish to fry.

A few years ago, following an overwhelming inflow of transatlantic capital, farmers co-operative ASDA became an arm of joint stock/private equity Wal-Mart and expanded exponentially on their site at the Bridge of Dee. Their premises and carpark were renewed and in the process part of the Ruthrieston Playing Fields was annexed. By way of a bewildering social payment sweetener the Wal-Mart management paid to also have part of the playing fields fenced off and covered in astroturf. Something to do with the formal to the real subsumption of leisure (as well as labour) under capital, probably.

We walked past this privatised and artificialised part of the playing fields on our way back to Pitmuxton via the Old Deeside Line. And a horrifying sight transfixed us.

Eeewww!

A great deal of snow fell on Aberdeen during November and December, and that snow, having been cleared from the pathways and carparks and the astroturf surface was piled up in huge berms. Over the weeks since, these snow-piles have been melting and leaving their formerly hidden toxic payload in situ.

This cargo of filth, this residue of disgusting dirt was consigned within the snow which had pulled it, dissolved it, from the very atmosphere through which it fell and which surrounded it as it lay in drifts and piles. Hidden in the pure white drifts and blankets, this toxic lading was concealed, now revealed as the water and ice which fixed it from the sky dissipates.

As we survey the huge double-deck Wal-Mart carpark, the carpark of Boots and PC World, the carparks of B&Q and Sainsbury's, so close to the playing fields where youngsters run and shout (albeit on an artificial surface, behind a fence, their leisure bought and paid for and itself generating revenue) we need not ask the source of this polluting filth, this literal and metaphorical stain.

But what we should ask is whether it is right for young people to be exercising aerobically in such a polluted atmosphere. We will not waste our effort in calling for a reduction in the provision of parking spaces; the exigencies of local realpolitic are far more likely to acknowledge the "facts on the ground" and close the playing fields - thus allowing Wal-Mart to further expand their car-park.

Splendid.