Trace metals in the environment: why they matter

Did you know that your food may contain toxic levels of trace metals or your drinking water may contaminate with toxic levels of trace metals? How can we ensure that trace metal levels stay within safe limits in our foods, in our water?

What are these trace metals? and how they enter into our environment?

Trace metals are elements such as iron (Fe), copper (Cu), zinc (Zn), chromium (Cr), cobalt (Co), nickel (Ni), Manganese (Mn), vanadium (V), and molybdenum (Mo) that are normally occur at very low concentrations in the environment. Sources of trace metals in the environment can be natural (geogenic) or anthropogenic. Natural processes include breakdown of rocks, volcanic activities, and spreading of mid-ocean ridges. Human activities including mineral resource extraction, fossil fuel combustion, industrial manufacturing, and wastewater disposal release trace metals in to the environment. Most of the usual things we use in our day to day life like oil and lubricants, cosmetics and personal care products, medicines, and fertilizers and pesticides contain trace metals and we release them into the environment as waste.

Natural Copper Ore

Some trace metals are inorganic micronutrients that are required by living things, in very low concentrations, but ingestion of, or exposure to, excessive quantities can be toxic. For example, Fe is an essential element in human blood which transports oxygen around the body. However, if too much of Fe is consumed, it can be toxic to human body. The toxicity of trace metals depends not only on the concentration in the environment, but also where it is found in the environment (water, soil, air), chemical forms of the metals (species), acidity of the environment, source of the metal (natural or anthropogenic) etc.

Trace metal contamination in aquatic ecosystems

Human activities have resulted in widespread contamination of aquatic ecosystems by a wide range of inorganic substances, including numerous trace metals (including metalloids and non-metals with metal-like properties). Trace metal contamination in aquatic environments is a ubiquitous, persistent and complex problem, often with significant consequences for ecological and human health. Anthropogenic inputs from activities including mineral resource extraction, fossil fuel combustion, industrial manufacturing and other non-point sources are overwhelmingly the primary cause of most metal contamination in aquatic ecosystems and have made metals much more bioavailable. Unlike organic contaminants, inorganic trace metal contaminants do not decompose over time into less toxic substances, but accumulate and persist in a range of chemical forms (species) with varying biological availabilities and toxicities. While some trace metals have no positive biological role (e.g. Hg, Cd, Pb, As, U), many are essential micronutrients (e.g. Cu, Zn, Fe, Ni and Cr) with a significant role in metabolic pathways, are co-factors for many enzymes and have structural functions when associated with carbohydrates, nucleic acids and proteins. Aquatic organisms have therefore evolved to take up trace metals at typical background concentrations and many have developed complex biochemical pathways. However, at elevated metal concentrations or with high proportions of bioavailable species, many organisms find it difficult to adequately regulate their tissue levels and trace metals become toxic.

Therefore, how these metals dissolved and move around in water and what other chemicals they attach to are important. Metals in aquatic systems have the tendency to bind to organic matter, or suspended particles, and thus accumulate within fine-grained sediments. However, with changing oxygen concentrations, redox conditions or pH, metals can be remobilized into pore waters and the overlying water column, and/or accumulate within benthic organisms and the associated food webs. Therefore, sediments act as long-term sinks, but also as potential sources of metal contaminants in aquatic systems.

More sources of metal poisoning:

Mercury (Hg) poisoning; Minamata disease in Japan in 1956

Cadmium (Cd) poisoning; itai-itai disease in Japan

Arsenic (As) contamination in drinking water in Bangladesh

If you like to read more about the sources, sinks, and internal cycling of trace elements in ocean please visit international GEOTRACES website

Credit: Nadeeka Rathnayake

How to build a den: outdoor activity

Den building is a fantastic activity for all ages. You can do it at any time of year, but also rmember to use fallen leaves and branches. by doing this your are practising the principles of Leave No Trace.

Dens make perfect birdwatching hides, as well as shelters and basecamps for woodland walks. Building a den is also great fun for the whole family and a wonderful way to spend time together, so head outdoors and try out our top tips.

Den-building materials

Get everyone to set about collecting natural materials from the woodland floor. Make sure kids aren’t breaking off living branches or damaging trees. If you use any unnatural materials such as string or rope, remember to take them home at the end of the day.

You will need:

  • long, straight branches and sticks
  • lots of thin, bendy sticks
  • materials to cover your den, such as dried leaves, twigs and grass

Beware. Make sure to avoid picking or walking through bracken, as it can be home to ticks.

Why not hold a den-building competition?

How to build your den

Coming up with your own den design is part of the fun, but here are a couple of simple ideas to get you started.

Teepee-style den

  1. Find a tree with a fork in the branches that’s quite low down.
  2. Make a frame by propping some long, straight sticks in the fork and fanning them out. Also make sure that any branches are really secure – you don’t want them slipping.
  3. Weave bendy sticks in and out of the upright sticks to make the walls. Leave a gap at head height for a window.
  4. Cover your den with natural materials so it’s camouflaged and weatherproof. You could use mud to stick them on.
  5. Scatter a carpet of dried leaves on the floor to make your den extra cosy.

Tent-shaped den

  1. Find two forked trees that are close together and place a long stick between them.
  2. Prop a row of sticks against it on each side so you end up with a tent shape.
  3. Weave your bendy sticks in and out of the upright and add your plant materials.

Make a mini den

This activity is a lovely way for very small children to have a go at den building. Simply collect a handful of small sticks and prop them up against a tree trunk or fallen branch to make a mini den. Make the inside of your shelter nice and cosy with some fallen leaves. Now it’s ready for child’s favourite teddies or dolls.

Don’t forget to dismantle your den and Leave No Trace of your visit.

Before you head home, please remember to take your den down. On your next visit you can have fun building it all over again, or you can experiment with a different design!

Cosy dens for toys are great fun to build.

Credit: Adam Burton / WTML

Den building has lots of benefits for children of all ages. It gets little brains thinking creatively and solving problems. It encourages youngsters to work together and helps them develop their communication skills. Plus, it’s active play that gets kids moving in the fresh air. So thumbs up all round! for more great activities visit

Insect counts

Want to do a bit of community science? Flower-Insect Timed Counts are a fun and hugely useful way to contribute to our scientific knowledge about pollinators. You’ve probably heard people voicing concern that bees and other pollinating insects are in decline, and you can help scientists collect the data they need to study the problem.

All you need is a sunny day, a tape measure, a patch of flowers, and a recording sheet.

Get the recording sheet and full instructions from the National Biodiversity Data Centre here: Flower-Insect Timed Count

And upload your records to National Biodiversity Data Centre: here

And here’s a video from the National Biodiversity Data Centre showing just how simple it is.

Rock Pooling

Summer is a great time to get outside and learn more about the environment.

Rock pooling and enjoying the ocean is a great way to spend the afternoon. This hands-on experience will introduce kids to the wide variety of sea creatures that lurk on our shores. Getting their hands wet will make an everlasting experience for them.

What you need:

  • Buckets or clear tupperware containers
  • A field guide or ID sheet
  • Sturdy footwear
  • A Camera and or pens and paper
  • An adult to help you keep an eye on the tide.

On the day:

Half fill your buckets or containers with seawater. Have more than one to keep bad tempered animals apart. Use your hands to carefully lift crabs, starfish and other sea creatures into your containers.

  • Nets can cause damage to rockpools and are best avoided.

Use a guide to identify your creatures. Take notes, sketch them or photograph them. Return the animals to where you found them and you’ve finished looking. Wash your hands before eating.

Here’s some tips to keep the rockpool safe for future generations and to leave no trace of your visit:

  • Don’t take living animals or plans with you…
  • Don’t prise limpets, anemones or seaweed from their rocky homes.
  • Be careful not to damage delicate animals.
  • Replace rocks to the same position once you’ve looked underneath.

If you would like further information on the rockpools around our coast follow the link to

Oceans of Learning

Today’s post is a really short one. Today we are highlighting a fabulous collection of information and activities put together by Ireland’s Marine Institute. The Marine Institute is the State agency that provide scientific and technical advice on all things marine to the government. But they also have great educational resources and they’ve pulled lots of these together into “Oceans of Learning”. It’s a huge site, with competitions, art, videos, activities. The one thing drawing it all together is that it’s all about the sea! Check it out here:

Oceans of Learning

Bird Bingo

We have another fine game of bingo for your to play this weekend. Bird Bingo! All you need to do is download and printout our bingo card and then race your friends and neighbours to get either a row, or the whole card. Tested in a 1 km radius from my house in Galway City – there’s nothing too difficult in here. If you’ve missed our previous bingo games, and want more to do this weekend, then why not try Tree Bingo and Seashore Bingo too.

Learn about rocks

Different Types of Rocks
This activity makes the rock cycle real for your child. Processes that take millions
of years can be recreated at far lower temperatures in your kitchen. You and your
child can also finally make use of all those broken crayons you have in the cupboard.
Just be prepared for a bit of a mess. This is also a good opportunity to discuss the Leave No Trace Principle of ‘leave what you find’ with your child and explain the importance of not removing rocks from their natural setting.
What You Need:
At least 5 full sized different colored crayons
Measuring spoons
Iron, ideally that you don’t use much anymore
Two thin cloths that you don’t care about
Metal spoon you don’t care about
Small (approximately 3 x 3) metal tin you don’t care about
Oven glove or Mitt
What You Do:

  1. Cover your work area with newspaper.
  2. Remove the paper from the crayons. If you don’t have five whole crayons,
    just pick up enough pieces of different colors to total about five crayons.
  3. Grate the crayons into the bowl, using one of the smaller sets of holes.
    Because the grater is sharp and the crayons are hard, an adult should take the lead. Tell your child that this process is like the process of weathering which, over millions of years, wears rock down to gravel, sand and mud. You need about 10 teaspoons of grated crayons to make all the rocks and have some left over to compare with your crayon rocks.
  4. Help your child cut three 4 x 6 inch pieces of foil.
  5. Tell your child that you first will make sedimentary rock, which is made when sediments, like sand, are buried and pressed by tons of overlying layers.
  6. Ask your child to measure 3 tsp of the grated crayons into the center of one of the pieces of foil. The pile of grated crayons should be about 1.5 x 1.5 inches.
  7. Help your child fold over both edges of the foil to cover the pile of grated crayons.
  8. Next, on a hard smooth surface, not carpeted, ask your child to stomp on the foil wrapped crayons. Have your child move around to make sure all the parts are crushed together.
  9. Help your child unwrap the crushed crayon. The particles should be partially fused together, but crumbly, and the different colors of crayons will still be visible.
  10. Tell your child the next type you will be making is metamorphic rock, which forms when rock layers are buried so deeply that the Earth’s heat and pressure changes them.
  11. Ask your child to measure 3 tsp of the grated crayons to put in the center of one of the pieces of foil. The pile of grated crayons should be about 1.5 x 1.5 inches.
  12. Help your child fold over both edges of the foil to cover the pile of grated crayons.
  13. Ask your child to wrap the crayons with another piece of foil.
  14. Heat up the iron to low heat. Cover the ironing board with one piece of cloth, cover the crayon covered foil with another piece of cloth. The crayon wax can melt quickly, and you don’t want it getting into your iron or ironing board.
  15. Press the warm iron upon the cloth covered foil until the foil feels warm. An adult should take the lead here.
  16. Let cool for a few minutes.
  17. Help your child carefully open the foil. The crayon pieces should be more fused than with the sedimentary rock. Some parts might have melted, but individual crayon colors should still be visible.
  18. The third type of rock your child will make is an igneous rock. Igneous rocks form when the rock melts completely.
  19. Help your child construct a mould for his igneous rock by folding a piece of foil into a 3 x 3 inch tray. The sides should be about an inch high, creating a 1 inch space on the bottom. Place mould on dish in case it leaks.
  20. Have your child measure three teaspoons of the grated rock into the pie tin.
  21. Heat the tin over the stove at low heat, stirring constantly.
  22. Remove after the crayon melts completely, which won’t take long.
  23. Pour the liquid into the mold. Explain to your child that the liquid represents lava, or liquid rock at the earth’s surface. It would be called magma if it melted below the earth’s surface.
  24. Let cool for several minutes.
  25. Help your child remove his igneous rock from the mold. Once your child has made all of his rocks, have him arrange them in a circle. Challenge him to describe how the sedimentary rock could be changed into metamorphic (more heat), and how the material in an igneous rock could become part of a sedimentary rock
    (weathering, burial and pressure). This activity will help your child appreciate how rocks change, given enough time.

Nature Diary Late July

We’ve had a let up from the constant rain in the west these last few days and the garden is buzzing with pollinators again. There are different plants in flower now, so new places to look for dragonflies and other pollinators. This red-tailed bumblebee photobombed the selfheal picture above! Download the Nature Diary for the next fortnight to see what else to look for.

Do one simple thing for nature today

This poster is designed to make it really easy for children to take that first step outside and start interacting with the natural world. take as

Each of these tear-off tasks is simple to do and can take as short or as long a time as you or your child wants.

  1. Download the file and print it onto recycled paper.
  2. Cut along the lines between each task so that they can be easily torn off at the top.
  3. Tear off the one on the far left so it’s clear to the children that they should do the same.
  4. Put it up where it can be seen like a noticeboard or on the refrigerator.
  5. Invite the children to tear off a task that resonates with them.