Globally, we dump 300 million tons of plastic each year, of which only 12 per cent is recycled

And as most litter is plastic, we have grown accustomed to seeing it.

So does it really matter about the odd plastic bottle floating down the river or discarded along the Ouse Valley Way? Yes, it really does!

Globally, we dump 300 million tons of plastic each year, of which only 12 per cent is recycled. The rest is burnt or buried in landfill or shipped to developing countries, moving the problem elsewhere.

But it is calculated that the litter from rivers is the major cause of 14 million tons of plastic ending up in the sea annually.

And consequently, it is predicted that by 2050 there will be more plastic than fish in the world’s oceans! What a disaster.

Already we can see the Great Pacific Garbage Patch, composed entirely of floating plastic waste, as a sign of things to come. It is three times the size of France and growing rapidly.

Plastic takes a very long time to break down - about 100 years.

That plastic bottle floating down the river will eventually degrade into tiny, almost invisible microplastics (A cup of sand typically contains 50-100 microplastic pieces).

These particles readily absorb PCBs (polychlorinated biphenyls), heavy metals and other dangerous and carcinogenic man-made materials.

Microplastics have been shown to adversely affect the immune and reproductive systems of many ocean mammals, such as whales and dolphins. They also enter our food chain via seafood.

Microplastics are now found everywhere - at the bottom of the deepest oceans and on top of the highest mountains.

Not surprisingly, they also occur in human lungs, blood and in the brain.

No one yet knows what long-term impacts these invisible pollutants will have or, probably, already are having on our bodies and our health.

That plastic bottle carelessly dropped in the River Great Ouse is an eye sore.

Soon it will be out to sea and out of our sight. But it is still our problem.

We know that our use and misuse of plastic affects us and our environment for generations to come. So isn’t it now time that we all try to do something about it?

We can start by asking manufacturers and supermarkets to reduce their reliance on single-use plastic.

And we can make sure we, and our children, leave only our footprints behind – not our litter!