Citizen Science in Action II

 It was only a couple of weeks ago that our little group of citizen scientists reported a pollution incident to the Environment Agency (EA). Fortunately, the EA reacted quickly and put a stop to it before there was too much ecological damage.

While the pollution event above was initially identified thanks to a member of the public, the next incident was the result of our twice a week testing schedule. The first indication that something was amiss was a significant increase in the concentrations of orthophosphate (OP) and total ammonium nitrogen (TAN) at one of our site (U034). This regular test site on the Newton Brook is marked by the black spot in Figure 1.

Figure 1: Google Map Showing All the Test Locations 

Figure 1 is a Google Map showing the Newton Brook tributary to the River Wye. As we move upstream along the Newton Brook from the River Wye (top to bottom of Figure 1), I have marked 5 locations:

1. Test Site U034, part of the Wye Alliance Test Network (black spot) 
2. Confluence of the two branches of the Newton Brook & downstream of the pollution source (red spot)
3. Pollution site (green spot)
4. Upstream of the pollution (blue spot)
5. Outlet from the former Three Counties Pool, see earlier blog (brown spot)

The first indication of a potential pollution incident was the sudden increase in OP and TAN values measured on the 13th July 2025 (see Figure 2). The following two measurements (16th and 20th July) showed decreasing values suggesting the pollution was dissipating slowly. Generally, point source pollution events dissipate quickly (sometimes within minutes or hours) but the water levels in Newton Brook are so low (the lowest we have seen in 4 years of testing) that the reduced flows are less efficient at diluting away pollutants.

Figure 2: Orthophosphate (OP) and Total Ammonium Nitrogen (TAN) Measurements at Site 1 (U034)

The next 3 measurements (23rd, 25th, 27th July), however, showed OP/TAN levels similar to or higher than those observed on the 13th July. Clearly there was an issue that required investigation. On the 25th July, I made a quick sortie upstream to the outflow from the Three Counties Hotel pool (Site 5, brown spot in Figure 1) to take some measurements. I also retested Site 1 (U034, black spot in Figure 1) on my return for comparison. Why choose Site 5 for testing? Firstly, the side brook (labelled as Newton Brook in Figure 1) was dry so an unlikely pollution source. Secondly, Site 5 was the upstream limit of the brook as it exited the Three Counties Hotel pool. If Site 5 was pollution-free then the pollution source was somewhere between Site 1 and Site 5. The results for these two sites are reported in Table 1.

Table 1: Water Analysis of Site 1 and Site 5 on 25th July 2025
Site Location	Site 1 (U034, black spot)	Site 5 (brown spot)
OP* (ppm)	4.2	0.93
TAN** (ppmN)	6.3	0.12
TON*** (ppmN)	2	2
Nitrite, [NO2]-, (ppmN)	0.3	0
Conductivity (μS/cm)	645	549
Temperature (oC)	19.6	18.6
Turbidity (NTU)	4.5	9.5
pH	7.8	7.8
Dissolved Oxygen (mg/L)	3.2	5.0
% Dissolved Oxygen	34.8	53.9

*Orthophosphate (OP) determined using the Molybdenum Blue method; **Total Ammoniacal Nitrogen (TAN) determined using the Nessler method; ***Total Oxidised Nitrogen (nitrogen in the form of both Nitrate and Nitrite) determined using Hach colourimetric test strips.

Clearly, the Orthophosphate (OP) and Total Ammoniacal Nitrogen (TAN) concentrations were much higher downstream (Site 1) compared to the upstream (Site 5) values (Table 1). Our pollution source was somewhere between these two sites. The drop in dissolved oxygen (DO) measurements as the brook water travelled downstream was also a strong indicator of pollution; low DO levels would explain the high concentrations of nitrite and TAN which are both reduced forms of nitrate (reference the Nitrogen Cycle)

Alan & I carried out a more detailed investigation on the 27th July 2025. As we walked upstream from Site 1, we noticed some pollution at the confluence of the two arms of Newton Brook (Site 2, red spot). This is shown in Photo 2, taken 3 days later (30th July) when the pollution had dissipated somewhat. The steps are actually part of the Newton Brook (Figure 1) but this section had dried up. The pollution, a whitish surface layer, is less evident in this photo (taken 30th July) compared to our previous visit 3 days earlier when we collected samples.

Photo 1: Confluence of the Two Arms of Newton Brook

Further upstream, we encountered a strong candidate for the pollution source (Photo 2) located between two blocks of houses at Site 3 (green spot in Figure 1).

Photo 2: Main Pollution Site (green spot in Figure 1)

My first instinct was that this might be a laundry or cleaning product discharged from one or more of the nearby houses (see Figure 1), although another possibility was this road drainage grid (Photo 3) about one metre away from the pollution seen in Photo 2.

Photo 3: Drainage Grid Adjacent to the Main Brook Pollution

In the UK, most houses built after 1970 have separate drains for disposing of rainwater/surface water and foul water/wastewater. The former can be returned to a nearby watercourse without treatment whereas the latter must be treated at the sewage works before being returned to a watercourse. Prior to 1970, most houses had a combined system so all the water had to be treated; potentially overwhelming the capacity of the sewage works as well as wasting resources and energy. Some useful background information on this topic can be found here.

The advantage of separate drainage systems can be lost if household appliances (e.g. washing machines, dishwashers, showers) are misconnected to the rainwater drain instead of the wastewater drain. While this may be a bigger issue with do-it-yourself plumbing installations, even trained plumbers may take short cuts and connect to the wrong waste pipe.

So, back to the sortie upstream. Alan & I took samples at Site 1, Site 2 and Site 4 performing some on-site tests before returning back to base for the remaining tests (OP, TAN, Turbidity). No sample was taken at the main pollution site (Site 3, green spot, Figure 1) because (i) health & safety considerations regarding an unknown pollution source, and (ii) potentially severe contamination of our testing equipment with highly polluted water. The analytical results for Site 1, Site 2 and Site 4 are reported in Table 2:

TABLE 2: Water Analysis at Site 1, Site 2  and Site 4 on 27th July 2025
Site Location	Site 1 (U034, black spot)	Site 2 (red spot)	Site 4 (blue spot)
OP* (ppm)	5.6	7.8	1.24
TAN (ppmN)	9.9	15.9	0.15
TON* (ppmN)	2	0****	2
Nitrite, [NO2]-, (ppmN)	0.15	0****	0
Conductivity (μS/cm)	668	730	560
Temperature (oC)	17.0	16.6	17.3
Turbidity (NTU)	5.0	77	2.5
pH	7.7	7.8	7.9
Dissolved Oxygen (mg/L)	3.5	3.5	5.5
% Dissolved Oxygen	35.6	35.8	57.1

*Orthophosphate determined using the Molybdenum Blue method

**Total Ammonium Nitrogen determined using the Nessler method;  

***Total Oxidised Nitrogen (nitrogen in the form of both Nitrate and Nitrite)

****Test strip reading not possible due to the water pollution

The first thing to note is that the analytical results for Sites 4 & 5, taken on different days, are very similar (Tables 1 & 2). These analyses set the baseline for 'unpolluted' brook water and clearly indicate a huge increase in pollution downstream (Site 2) with some dissipation of pollutants further downstream (Site 1). Comparing Site 4 versus Site 2 (unpolluted vs polluted, Table 2), there is an approximate 100-fold increase in TAN, a 6-fold increase in OP, a 30-fold increase in turbidity and a 40% drop in dissolved oxygen content as a result of the water pollution. The situation at the main pollution site (Site 3, green spot) will, of course, be significantly worse than this.

With photographic evidence backed up by analytical data, I reported this pollution incident on 31st July 2025 to the Environment Agency (EA). I also notified Dwr Cymru (Welsh Water) because it was possible the pollution source was a domestic property and, if so, its resolution would be down to the local water company. The EA do not provide updates on their investigations of reported pollution incidents; however, the Wye Alliance could follow this up during their regular meetings with the EA. Fortunately, Dwr Cymru do provide feedback on reported incidents and, a few days later, I heard from one of their environmental field officers that the source had been identified and they would be visiting the property to confirm and pass on the information to the Local Authority (Herefordshire Council).

Have we seen any signs that the pollution has decreased since I reported the incident (⬇) on the 31st July? Yes, indeed. In Figure 3, I have plotted the TAN/OP ratios as a time series (Figure 3) for Site 1 which Alan monitors on a twice weekly basis (so plenty of data!). Why TAN:OP Ratio? Because both TAN & OP increased as a result of the pollution but the most important pollutant was TAN (>100-fold increase).

Figure 3: TAN:OP Ratio Time Series at Site 1

It is clear from Figure 3 that the pollution first identified on 13th July had subsided by 10th August, some ten days after it was first reported, thanks to Dwr Cymru's quick response.

We can also see evidence of pollution in the dissolved oxygen measurements, as shown in Figure 4. The data are noisier but the pollution incident can still be seen by comparing Figure 3 and Figure 4.

Figure 4: Dissolved Oxygen (mg/L) Time Series

An excess of ammonium ions, [NH4]+, may be drawing down the dissolved oxygen content in the water in order to accomplish the conversion of ammonium ions to nitrite and then nitrate by nitrifying bacteria (i.e. Nitrogen Cycle: Ammonium + O2    bacteria_＞ Nitrite  bacteria_＞ Nitrate). Alternatively, the lower dissolved oxygen content caused by the pollution may be limiting the conversion efficiency of the nitrifying bacteria.

Finally, I have tested my home distilled water (collected from a heat pump tumble dryer) and found it contains significant amounts of TAN, typically 2 - 3 ppmN. This is lower than that observed in the polluted Newton Brook samples; however, the brook samples were not distilled! I suspect the high TAN values come from laundry products and, particularly, fabric softeners. Fabric softeners contain quaternary ammonium salts ('quats') as their main active ingredient and these will break down during the washing & drying process to produce 'ammonium' ions detected by our test method. Modern fabric conditioners are designed to be biodegradable so will break down more readily into ammonium ions - an unintended consequence of the move to eco products?

Pigeon Post Again

 First sight of the new arrival today (21st August) ...

Photo 1: Wood Pigeon Chick (21st August 2025)

It was pecking Mum's (or Dad's) beak to let its parent know it was hungry. Not surprised the rate they grow. I can only see one chick at the moment ...

Photo 2: New Arrival (22nd August 2025)

Considering how close I am to the nest (my head is about two feet away from the nest), the parent on the nest remains calm & still while always keeping a beady eye on me. This is the exact opposite of their normal behaviour when even the slightest noise disturbs them.

The Fruit Garden (2025)

 It is mid-August and we have already harvested all the blackcurrants, redcurrants, gooseberries and some of our apples (Rev W Wilks).

Photo 1: Some of this year's Rev W Wilks Apple Crop

We started picking strawberries in May and raspberries in June ...

Photo 2: Raspberries Picked on the 14th June 2025

... and will contimue to pick them until the first frost (October/November). Our thornless blackberry is also coming to the end of its cropping season.

A few days ago, we picked our first plums (Cox's Emperor), a couple of weeks early due to the warmth of late Spring/early Summer ...

Photo 3: First ever Cox's Emperor Plums (early August 2025)

This is the first year this tree has produced fruit with two of the three plums on exhibit in Photo 3. Hoping for a bigger crop next year, perhaps similar to this year's Jubilee plum tree where 30-40 plums are ripening up nicely ...

Photo 4: Jubilee Plums (August 2025)

As mentioned above, we have already harvested our Rev W Wilks cookers. As these apples are very susceptible to brown rot, most of the crop has either been eaten (apple and blackberry/raspberry/rhubarb/gooseberry crumbles) or frozen; leaving the remaining 'good' apples to store briefly before eating (Photo 1).

The eating apples are ripening up nicely for picking from September onwards ...

Photo 5: Red Falstaff Apples (mid-August 2025)

Photo 6: Gala Mist Apples (mid-August 2025)

Photo 7: Blenheim Orange Apple (mid-August 2025)

... and finally, on the apple front, the ever-reliable Red Windsor ...

Photo 8: Red Windsor Apples (mid-August 2025)

We lost our Comice pear tree last year but the dependable Concorde has plenty of fruit on it ...

Photo 9: Concorde Pear (mid-August 2025)

We've not eaten much rhubarb this year because of all the other fruit that has been available. Fortunately, the variety we have (Livingstone) crops from Spring to Autumn without a break so there is still plenty of time to make rhubarb pies, crumbles and cordial. 

Photo 10: Rhubarb Livingstone (mid-August 2025)

The last couple of year's have not been good for our two grapevines, especially white variety. However, this year has seen a big improvement and we should get a fair crop if the autumn weather is kind to us. I'd like to think that this year's improvement id down to my pruning expertise but I'm not sure what, if anything, I did different in preparation for this year's growing season. Since the grapes are seeded, we will probably do our usual thing and make grape juice.

Photo 11: Black Grapevine (mid-August 2025)

Photo 12: White Grapevine (mid-August 2025)

We also grow medlars, crab apples, rosehips and chokeberries in the garden which find their way into jams and preserves. But that will have to wait! Those strawberries, blackberries and raspberries wont pick themselves ...

GuppyFriend Washing Bag - Addressing the Microplastics Problem

 Microplastics are water-insoluble synthetic (polymeric) particles measuring between 1 and 5000 μm (0.001 - 5 mm). They are considered a pollutant when found in the natural biosphere. They are in the news a lot these days due to their ubiquitous nature. For example, see here, here, here, here, and here. They can be found in fresh and marine waters, the air we breathe and the food we eat. Scientists are now finding microplastics throughout the human body and we do not yet understand how this will affect human health.

While some microplastics are deliberately made (e.g. microbeads in cosmetics), the majority of microplastics are generated by general wear and tear (e.g. clothes, tyres) and/or environmental degradation of polymer products exposed to the natural environment. Studies have shown that up to 90% of the microplastics found in the ocean are derived from domestic and commercial clothes-washing. Washing your clothes at home is, therefore, an important and significant source of microplastics that end up in the environment.

It is incumbent upon us all to minimise the release of microplastics in the wastewater from our laundry. Essentially, there are three options: (A) filter the wastewater (here and here), (B) put clothes in a fine mesh bag, (C) use an in-wash filter ball. Option A is the most expensive though, ultimately, likely to be the most efficient. Options B & C have similar cost outlays; B wins because of its higher efficacy at trapping microplastics.

Before describing my first impressions of the GuppyFriend, it is worth mentioning a few low technology options that can reduce the amount of microfibres generated during domestic laundering:

• Buy fewer clothes and wash them less frequently
• Use lower wash temperatures
• Use shorter wash cycles
• Don't tumble dry, use a wash line or clothes airer
• Run full loads rather than small loads

So, having reviewed the options (A, B, C), I plumped for the GuppyFriend Washing Bag based on its low cost/high efficiency. This edition of Sliced Bread (a UK radio programme) discusses ecolaundry products including microfibre filters (note: I'm not sure the link works outside the UK). It should be noted that clothes made from natural fibres (e.g. wool, cotton, linen) also discharge microfibres during the laundry process. These are generally considered less harmful than microplastics because they degrade much faster (months/years rather than decades/centuries).

I bought two GuppyFriend washing bags from WWF (£50 plus postage) because, I thought, I might as well help an environmental charity at the same time. 

Photo 1: GuppyFriend Packaging

Two bags would allow me to run a full load whilst only filling the washing bags two-thirds full (recommended). Just place the laundry items in the bags, being careful not to overfill, and close the zip (Photo 2).

Photo 2: GuppyFriend Filled with Laundry & Ready to Go

It is recommended that any obvious stains are pre-treated before placing in the bag. My laundry items consisted of natural, synthetic and mixed fabrics. You can, if you wish, just put the synthetic and mixed fabrics (if part synthetic) in the washing bag and just add natural fabrics to the machine as normal. To be honest, I'm not 100% certain which laundry items are made wholly or partly of synthetic polymers, so I save some sorting time by just putting everything in a bag! It is important to make sure the pull tab of the zip fastener is tucked away in its sleeve (Photo 3) so that the bag is correctly sealed.

Photo 3: Zip Safely Tucked Into Its Sleeve

I use a short 70 minute wash cycle at 40 ℃ with a 1400 rpm spin. I had some concerns about whether a cooler wash (e.g. 20 ℃ or 30 ℃) would have enough cleaning power due to the restricted movement of the laundry items in the bags. After about ten successful washes, there doesn't appear to be any issues on this front so I may try some cooler washes in future.

On completion of the wash, it's time to tip the clothes/bedding/towels out of the bags and transfer the wet laundry to the heat pump tumble dryer. I know I said that drying on a wash line or clothes airer was preferable but I use the distilled water recovered from the tumble dryer for watering indoor plants (like rainwater) and my citizen science work. Nobody is perfect!

Any microfibres/microplastics released during the wash are trapped in the corners around the zip ends You may need to very gently prize the seams apart a little to find and remove them (Photo 4 & Photo 5).

Photo 4: Trapped Microfibres/Microplastics

Photo 5: Trapped Microfibres/Microplastics

Photo 6: Recovered Microfibres & Microplastics

So, how much microfibre/microplastic is collected by the GuppyFriend during a normal wash? There is only one way to find out; set up some experiments. Two separate mixed fibre loads, each of 2.75 Kg (6 pounds), were washed at 40 ℃ using a mixed programme (70 minutes, 1400 rpm spin). Each load was split between two washing bags and contained both natural and synthetic items. After the wash, the clothes were extracted from the bags and any collected microfibres/microplastics removed and set aside to dry for 24 hours before weighing on a microbalance (0.001 g to 50.000 g).

One wash yielded 0.022 g and the other 0.010 g. As a percentage of the total wash load (2.75 Kg), this is a very small amount, between 0.0004% and 0.0008%; however, small quantities can soon become large amounts.  A year's washing (our two-person household, three washes/week) would yield only 2.5 g. However, there are 28.6 million households in the United Kingdom; pro rata this would equate to 71,500 metric tonnes per annum just from this one small country. 

My results were obtained on mixed (natural/synthetic) washes so not all the recovered material will be microplastics. When viewed under the microscope (400x), the synthetic plastic fibres show as uniform smooth and linear strands (Photo 7) whereas natural fibres are irregular with a greater variety of thicknesses and texture (Photo 8).

Photo 7: Synthetic Fibres Collected by the GuppyFriend

Photo 8: Natural Fibres Collected by the GuppyFriend

I estimate that natural fibres made up the bulk of the recovered material from the GuppyFriend Washing Bags. Which means I'm going to have to repeat these washing experiments with some all synthetic washes. If, or when, I do then I will update my estimates and provide an update.

Fruit Flies and Raspberries

 You have just picked a juicy red ripe raspberry and are about to pop it into your mouth when you notice a small white wriggling grub (Photo 1). You suddenly lose your appetite! In all probability, this is the larva of the fruit fly, Drosophila susukii; more commonly referred to as the Spotted Wing Drosophila (SWD).

Photo 1: SWD Larva in Raspberry Fruit

As the name suggests this is an invasive species, originally from Japan. The female has a long sharp serrated (i.e. saw-like) ovipositor which is its secret weapon. The common fruit fly (Drosophila melangaster), often seen around the fruit bowl with the overripe banana, can only lay its eggs in rotting or fermenting fruit. The SWD, however, uses its serrated ovipositor to pierce the skin of unripe fruit thereby nullifying the simple pest control method of picking soft fruit before it is fully ripe.

You can make your own SWD trap using apple cider vinegar as the lure or purchase a commercial trap (here and here) with specially-formulated solutions to attract the fruit flies. These are generally sold as monitoring traps for identifying the presence of SWD. However, they also help to control an infestation when used in conjunction with good crop hygiene (e.g. remove & dispose of any ripe/mouldy fruit, regular crop picking) and crop protection techniques (e.g. insect-proof mesh).

I opted for the Drosal Pro Kit which includes five traps and 1L of attractant. Simply add some of the attractant liquid to the trap, fit the lid and hang up (1 metre high or more) near your raspberries (and/or other soft fruit bushes/canes). I spaced my traps about 5 metres apart in among the raspberry canes (Photo 2).

Photo 2: Drosal Pro Trap in Position

The liquid attractant will evaporate over time (Photo 3) so will need to be replaced every few weeks or so depending on how hot the weather and how shady the trap location is.

Photo 3: Fruit Fly Graveyard

The entrance holes of the traps are just the right size for SWD but too small for other beneficial insects. The commercial attractant (DrosaLure) is very effective but fairly expensive at around £15 per litre. Early days yet, but 1 litre should last the season. You can save some money by making your own attractant using apple cider vinegar and a few drops of washing up liquid; lower efficacy but also lower price!

After a few days, the trap had collected a good number of SWDs (Photo 4), mostly females (no spot on the wing) but also the odd male (Photo 5).

Photo 4: Spotted Wing Drosiphila, RIP

Photo 5: Male SWD (deceased)

I picked 250 g of fresh ripe raspberries yesterday and could find no evidence of the SWD larvae. So far, very happy with the protection these traps offer.

The Cabbage White Butterfly

For the gardener, the large (Pieris brassicae) and small white (Pieris rapae) butterflies can be a real pest as they lay their eggs on your prize brassica plants (kale, cabbage, broccoli, etc). Hence their common name: Cabbage White Butterflies. Once the eggs hatch, the caterpillars can demolish a plant in mere days. Undoubtedly, the large white is the more destructive of the two.

In this short video (Video 1), the female large white is stationary while the male does all the frantic fluttering. The male cabbage white butterfly did have a competitor so it is unclear whether the female had chosen her preferred partner or not.

Video 1: Male & Female Large White Butterflies

After fertilization, the female needs to find a host plant to lay her eggs. While her preference may be for a cultivated brassica (e.g. cabbage), she will use other plants such as turnip (Brassica rapa) and swede (Brassica napus) and may fly several miles to find them.

I always put my brassicas in a netted cage because, to be honest, I've got bigger and better things to do with my time than regular inspection of the Brassica patch for cabbage white eggs and caterpillars. The next video (Video 2) shows a female large white trying to access the underside of a cauliflower leaf to lay its eggs.

Video 2: Female Large White Butterfly Denied Access to My Brassica Plants!

I read somewhere that the future existence of these butterflies would be in doubt if they cannot access the right plants to lay their eggs on. I have not noticed a decline in either of these two species over the years I have been gardening so either that claim is an exaggeration or they are, indeed, finding alternatives to my brassica plants. Last year, I'm fairly certain they used my neighbour's small unnetted brassica patch as the caterpillar nursery.

Anyway, no time to waste. It is the high season (August) for the cabbage white caterpillars and I need to start harvesting the red cabbages and calabrese.