Capital Cardiff

After visiting Worcester on the Monday, the very next day (12/11/24) we caught the train to Cardiff for another away day. Mary said she hadn't been to Cardiff before until I reminded her we had visited the Ikea store there; this would have been 15 or so years ago when we were setting up a couple of letting rooms for students. I had visited Cardiff a number of times during my BP career because I tutored a couple of PhD students there. On this visit, the main attraction was Cardiff Castle following a recommendation from Mary's sister who had visited last year.

After entering the castle via the South Gate, the central area was a hive of activity getting ready for the Winter Wonderland event due to open in a few days time.

Photo 1: View from Entrance Looking North to the Norman Keep

Photo 2 was taken from the eastern battlements near the entrance to the wartime tunnels. A trebuchet can be seen in the foreground, while along the skyline from left to right are the South Gate (and Black Tower),  the Clock Tower, the Manor House (centre) and the Norman keep (far right).

Photo 2: Inside Cardiff Castle Looking Westward (November 2024)

Entry to the castle costs £15.50 per adult or £12.50 if you are old codgers like us. We paid an extra £4 pp for a guided tour of the House which was well worth the extra.

First port of call was the cafe, located in the same building as the ticket office, for a cup of tea and a toasted teacake. The staff were very friendly as you would expect in Wales. In the basement of this building is a mural called the Roman Chariot Corner ...

Photo 3: Roman Chariot Corner

The mural was designed and made by artist Frank Abraham between 1981-1983, using cement and plaster with a metallic gold paint finish. Photo 3 shows only a small part of the mural albeit the most impressive part. Entrance to the Firing Line, a museum dedicated to Welsh soldiers, can also be found in the basement.

We dashed off for our midday tour of the house and spent an hour looking around this ornate Victorian makeover. The first room we entered was in the Clock Tower (Photo 4) ...

Photo 4: The Clock Tower

... and was the Winter Smoking Room (Photo 5) where the gentlemen retired after dinner for drinks and smoking ...

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Photo 5: The Winter Smoking Room

... followed by the children's nursery with its painted mural depicting various fairy tales ...

Photo 6: Children's Nursery

The Banqueting Hall was magnificent having originally been 5 bedrooms before its makeover ...

Photo 7: The Banqueting Hall

Photo 8: Minstrels' Gallery, Banqueting Hall

As with lots of artefacts in the house, there are stories to be told. For example, the fireplace (Photo 9) depicts Robert, 1st Earl of Gloucester, as a knight on horseback (Robertus Consul). An illegitimate son of King Henry I, he was the chief military supporter of his half-sister, Empress Maud, in the civil war (The Anarchy) against Stephen, King of England. Just to the left of Robert, there is a person behind bars - this is Robert Curthose, the eldest son of William the Conqueror, who was imprisoned (house arrest) in Cardiff Castle for the last 8 years of his life until he died aged 83.

Photo 9: Fireplace, Banqueting Hall

A rather unusual room, The Roof Garden, is only open to those paying extra for the guided tour. Roman-themed, it sits at the top of the Bute Tower and was open to the outside elements. Unfortunately, the rain for which Wales is famous was damaging the structure and furnishings; it is now protected by a plastic tarpaulin which you can see above the tiled roof.

Photo 10: The Roof Garden

One of the last rooms we visited was The Arab Room, possibly the most ornate of all the rooms. We were told the room itself was valued at £15 million, presumably because of the copious use of gold leaf in the decorative finish.

Photo 11: Ceiling of the Arab Room

Thanks to the immense wealth acquired by the 2nd Marquess of Bute from the development of Cardiff Docks, the 3rd Marquess of Bute had an open chequebook to restyle Cardiff Castle - and his chosen architect, William Burges, spared no expense.

After another visit the the Castle cafe, this time for soup and bread, we headed off to the National Museum Wales but only had time to look around the natural history section before heading for our train back to Hereford.

A tiring but rewarding day. Another visit is planned to cover the bits we didn't see (e.g. Cardiff Bay, Techniquest) and a deeper dive into the National Museum.

Royal Worcester

We had a couple of days with nothing planned so, rather than stay at home, we decided on two day trips. The first was to Worcester, the historic county seat (town) of Worcestershire. There are excellent road and rail links between Hereford and Worcester; the 25-30 mile journey takes about the same time (45 minutes) whether travelling by car or train. So we took the latter.

Photo 1: A Gulp of Magpies, Hereford (November 2024)

The walk to the station is just under a mile and takes about 20 minutes at Mary's walking speed. On the way, Mary spotted a rather large number of magpies roosting in a tree on a bit of wasteland as we approached the station. There was probably a score or more - not all of them in the picture I took - of non-breeding magpies. In the garden we usually see anything from one to three magpies in a group. A group of magpies is known by many names including, but not exclusively, a conventicle, a gulp, a mischief, a tiding, a tribe and a tittering.

Worcester is famous for many things, among them are Lea & Perrins Worcestershire Sauce, Royal Worcester Porcelain, and the composer Edward Elgar but not the monkey wrench (as Google's Gemini reported) - that was Worcester, USA! Unfortunately, being a Monday, quite a few places were shut including the Museum of Royal Worcester.

One thing Worcester does have in abundance is swans ...

Photo 2: Swans on the River Severn at Worcester (November 2024)

... largely down to the establishment of swan sanctuary along this stretch of the River Severn in the 1980s; angling is banned in the sanctuary which has reduced accidental deaths by ingestion of lead fishing weights¹ and entanglement in discarded fishing line. The Swan Food Project was set up to provide a source of nutritious pellets for the swans - available to buy at local retailers.

[Note 1: Fishing with lead weights was banned in 1987 though legacy lead weights still turn up every now and then]

This explained why the mute swans made a beeline for the river path shore, where we were standing, in the hope of a food bonanza.

Photo 3: Hungry Swans?

We spent a little while in The Hive, the main city and university library, before heading via the swans to the Watergate entrance to Worcester Cathedral. This is the final resting place of John, King of England (1199 - 1216) ...

Photo 4: King John's Tomb, Worcester Cathedral (November 2024)

Photo 5: Worcester Cathedral from the River (Severn) Path (November 2024)

Worcester Cathedral (length = 130 m, width = 44 m, height = 62 m) is noticeably longer than Hereford Cathedral (length = 104 m, width = 78 m, height = 50 m) though not as wide.

Photo 6: Looking towards the West Window

Photo 7: Worcester Cathedral Looking towards the High Altar

Levels of ornamentation are much higher in Worcester Cathedral whether that is the painted ceilings ...

Photo 8: Painted Ceiling, Worcester Cathedral

... or the grandiose tombs ...

Photo 9: Tomb of a Local Dignitory

I have to include a photograph of the altar frontal. Mary, as head broderer at Hereford Cathedral, wasn't overly impressed ...

Photo 10: Altar Frontal, Worcester Cathedral (November 2024)

And, finally, there was a photographic exhibition in the Chapter House showing the naves of all 42 Anglican Cathedrals ...

Photo 11: Peter Marlow, The English Cathedral Exhibition

One thing we didn't see were the peregrine falcons that nest regularly at Worcester Cathedral - wrong time of year.

We made our way slowly back to the railway station (Foregate Street) arriving back home in the dark around 6 pm. Tired (14,000 steps) but happy.

Great White Egret at Brockhall Gravel Pits Nature Reserve (8th November 2024)

 

Photo 1: Great White Egret (Brockhall Quarry, 8/11/24)

It was a dank grey mizzly November day where the temperature struggled, but failed, to reach double figures. Just the weather for sitting by a warm cosy fire reading a book. For some reason, we decided to go for a walk around a nearby nature reserve, Brockhall Gravel Pits (aka Brockhall Quarry and Sugwas Pools). We parked the campervan in the lay-by on the A438, carefully crossed the road (it can get busy), took the house-lined side road to our right for 50 yards before disappearing down a ginnel towards the woods and emerging onto the grassland with the waters ahead of us. Fuller details with photos on how to access the nature reserve can be found here.

Figure 1: Brockhall Gravel Pits/Sugwas Pools (Google Maps)

This was the eastern edge of the ice sheets covering Herefordshire during the Last Glacial Maximum, 20,000 to 25, 000 years ago. You can read about the ice age ponds found in this area here and here.

This is a popular place for spotting waterfowl, waders and migrant species. Check the website of the Herefordshire Ornithological Club for details of the site (Brockhall Gravel Pits) and a list of birds regularly seen.

We did the circular walk around the lake - about 3 kilometres. On the water we saw, in addition to the Great White Egret, a Grey Heron, lots of Tufted Ducks, Coots, Mallards, Mandarin Ducks, several Great Crested Grebes and a Common Gull. In the surrounding woodland there was a flock of long-tailed tits, robin, blue tits, rook, crow, blackbird, jay and kestrel (Photo 2).

Photo 2: Kestrel at Brockhall Gravel Pits (8/11/24)

The star of the show was undoubtedly the Great White Egret easily discernible from its smaller cousin, the Little Egret, by its yellow beak and black feet (the other way round for the Little Egret!). If you are lucky enough to observe the Great White Egret next to our more familiar Grey Heron (as we were on this occasion), you will immediately see their similar sizes whereas the Little Egret is much smaller. 

Photo 3: Great White Egret, Brockhall Gravel Pits (8th November 2024)

We tried to get closer but every time we approached within about 50 metres of the bird, it flew away. The short video below shows the third time (of four) that the bird did this. By the way, the noise in the background is from the shooting range at the nearby Credenhill Barracks.

Video 1: Great White Egret, Brockhall Gravel Pits (8/11/24)

It was 2 pm and we were ready for a hot drink and a bite to eat. The nearest establishments are the Hereford Garden Centre (heading back into Hereford) and Timothy & Birch (in the opposite direction). Both serve excellent food but Timothy & Birch is hard to beat for the quality of the food and the friendliness of the service. Don't forget to have a look round the shop packed with lots of ideas for presents, either for yourself or that special friend/relative.

Citizen Science - Turbidity (Part 3)

In two earlier posts, here and here, the importance of turbidity and how we measure it were discussed. In this post, I will be looking at a novel way to measure turbidity using a Hanna  Checker colorimeter designed to quantify the phosphate content of water.

Photo 1: Hanna Low Range Phosphate Checker and Cuvette

The optical layout of the Hanna Checker is basically the same as a turbidimeter (see here) insomuch as it measures the amount of light transmitted through the sample. It uses a green LED as the light source which is not ideal (white light or near infrared would be better) but you have to work with what you've got.

I did not calibrate the Hanna for turbidity using formazin standards as this is only a preliminary study. The procedure is very simple. Fill one cuvette with either distilled or de-ionised water; this represents 0 NTU. Vigorously shake the sample to be measured and fill the second cuvette (pre-washed with sample). Insert the 0 NTU cuvette and press C1 (to zero the colorimeter). Take the sample cuvette, invert five times to resuspend any sediment, place it in the cell compartment and press C2 briefly. Record the reading on the screen.

A suite of 14 river samples, collected as part of a citizen science project, with turbidities ranging from 7 NTU to 325 NTU were analysed using the Hanna Checker. The Hanna results, along with the measured turbidities by Nephelometry and Secchi Tube, are collated in Table 1.

Table 1: Hanna Phosphate Checker Readings and Measured Turbidities (NTU) using Nephelometry and Secchi Tube 

Hanna Reading	Turbidity (Nephelometer)	Turbidity (Secchi Tube)
0.01	7	<12
0.04	11	<12
0.05	14	15
0.05	19	21
0.11	26	25
0.22	56	50
0.24	41	25
0.40	69	40
0.48	74	40
0.71	134	100
0.76	122	75
1.11	221	190
1.45	228	200
1.82	325	>240

Note 1: Hanna readings are the mean of five measurements

Note 2: In Figure 2, data points with Secchi turbidities <12 NTU  or >240 NTU excluded from the linear regression analysis

Figure 1 is the linear regression plot of Nephelometric Turbidity vs Hanna Reading. The correlation is very good (R² = 0.984) over a wide range of turbidity values (7 NTU to 325 NTU). The practical range is estimated to be 15 - 400 NTU.

Figure 2 is the linear regression plot between Secchi Tube Turbidity (NTU) and Hanna Readings. The correlation is fair (R² = 0.909) over a more limited turbidity range (15 - 200 NTU) due to the lower precision and accuracy of the Secchi Tube method.

The Hanna Checker has a green LED as its light source and is, therefore, expected to show some dependence on the colour of the sample. Early results suggest this may be the case but further work is required. This method shows some promise as a technique for measuring turbidity in natural waters - albeit with a site-specific calibration.

Water Bills

 A few years ago, we switched from an unmetered potable water supply to a water meter. For the first 18 months or so, I kept a monthly check on water usage to reassure myself that everything was going to plan (i.e. lower water charges¹). Since then I've just monitored the costs on a 6-monthly basis when I receive a notification from our water company, Dwr Cymru (aka Welsh Water).

Note 1: includes sewerage charges

Photo 1: Water Meter

The supply of potable water and the treatment of sewage is, to be honest, a bit of a shambles in the United Kingdom. Prior to 1989, these services were performed by public bodies (i.e. owned and operated by the government). Under the Conservative government of Margaret Thatcher (1979 - 1990), there was a huge drive to sell off (i.e. privatise) government assets including the regional water companies.

The reasons given for selling the family silver were various and included reducing National Debt, lowering Government spending and improving efficiency through increased competition (which would lead to lower household bills). Other less palatable reasons were ideological (Margaret Thatcher was a big fan of neoliberal polices such as small government, reduced regulation and low tax), financial (cash for giveaway tax cuts), and gerrymandering (your archetypal Conservative voter is a home owner, holds investments such as stocks & shares, and wants low taxation so they can keep more of their hard-earned money).

According to Wikipedia, a total of £47 billion was raised from the sale of:

• Britoil (1982)
• Amersham Internation (1982)
• British Telecom (1984)
• Sealink (1984)
• British Petroleum (1979-1987)
• British Aerospace (1985-1987)
• British Gas (1986)
• Rolls Royce (1987)
• British Leyland/Rover Group (1988)
• British Steel Corporation (1988)
• British Rail (1993)*
• Sale of Council Houses (1979 to 2024 and beyond)**

* Conservative government with John Major as Prime Minister

** Conservative (1979-1997), Labour (1997-2010), Conservative-LibDem Coalition (2010-2015), Conservative (2015-2024), Labour (2024-)

Private financial institutions, neoliberal economists and conservative political parties will happily sing the praises of privatization . Apparently, it never fails ad everyone benefits. Certainly, some privatisations do work although they are usually in business areas where governments should only be regulators rather than owners (oil & gas, telecoms, manufacturing, etc). When it comes to public services (e.g. water, electricity, rail transport), however, dissatisfaction levels are much higher and so are the failures. The two main reasons why such public utilities fail when privatized are: (i) a fragmented industry (necessary to introduce competition) increases inefficiency and adds a huge amount of complexity (e.g. a plethora of new ticketing options in the rail industry that nobody understands and simply costs more to administer); (ii) if the privatized industry is still a monopoly - for example, I cannot choose my water company.

Anyway, back to our water bills. Before changing to a metered supply, our last unmetered annual water bill was £1,124.70 (1st April 2019 to 31st March 2020). This was an increase of £25.72 on the previous year's bill. The regulatory body for the water companies (England & Wales) is Ofwat who set the amounts by which bills are allowed to increase each year. On this (approximate) basis, I guess we would now be paying around £1,250 per year (1st April 2024 to 31st March 2025).

We pay for our metered supply by monthly direct debit. This started out at £41 per month in 2020, when the meter was first installed, but is set at only £30 per month for the coming year. On that basis, we are only paying about one quarter the amount for our water supply (and sewerage) than we would if we were still on an unmetered supply.

So I ask the question: are we especially frugal when it comes to our water usage? For the UK, the average water use is approximately 150 litres per person per day. The Dwr Cymru website provides a handy little graphic showing our average daily use (based on just two readings a year) - see Figure 1.

Figure 1: Our Daily Water Usage

We were obviously quite profligate in our water use to begin with; averaging about 165 litres per person per day. The high points in Figure 1 cover the summer months when garden watering is occasionally required. Through a number of water saving measures, we have brought this down to around 115 litres/person/day. These include: 2,400 litres of stored rainwater in water butts, using a bowl in the washing up sink to collect grey water for the garden, not flushing the loo every time, only running the washing machine and dishwasher when full, showers only, don't wash the car, jet wash the patio every 2-3 years, spot watering in the kitchen garden.

Figure 2 compares our per person use of water against a typical Welsh person.

Figure 2: Our Water Usage vs the Average Welsh Person

Despite a largish garden (and kitchen garden) to maintain, we are now below average in the amount of water we use. And the only downsides are a dirtier car and patio!

In Figure 3, our average daily water use (litres) is plotted against the Day Number since the meter was installed. A noticeable decline though possibly levelling off. Further savings will be much harder to achieve. The rationale behind installing water meters was that it would result in more efficient (i.e. less) water usage - this has been borne out empirically.

Figure 3: Decline in Water Use with Time

Smart water meters are the next planned development. In addition to providing real time usage data to the householder, they will also enable the water companies to quickly identify and fix water leaks.

Citizen Science - Turbidity (Part 2)

 In an earlier post (Citizen Science - Turbidity (Part 1)), I gave a brief introduction on why we choose to measure turbidity as part of the citizen science project monitoring pollution in the River Wye. 

Photo 1: Secchi Tube (use in upright position when filled with water!)

The majority of CSs use a Secchi Tube with a turbidity range of 12 - 240 NTU. Secchi tubes (Photo 1) are inexpensive and easy to use. Simply fill with river water until the black & white quadrants on the Secchi disc at the bottom of the tube are just no longer visible. Read off the turbidity value (NTU) printed on the side of the tube at the meniscus level. This simple procedure has low precision and accuracy because of the non-linear turbidity scale and the subjective nature of the test.

Note 1: Nephelometric Turbidity Units (NTU) are the most widely used units for quantifying turbidity and are based on 90⁰ scattering of white light (EPA Method 180.1). Formazin Nephelometric Unts (FNU) are similar (and often used interchangeably with NTU) and are based 90⁰ scattering of near infrared light (860 nm) according to the ISO 7027 method.

The only practical alternative is an optical instrument: either a turbidimeter or a nephelometer. The turbidimeter measures the amount of light passing through (transmitted by) a sample while the nephelometer measures the amount of light (usually at 90⁰ to the incident light) scattered by the particles in the liquid (Scheme 1). Turbidimeters are best suited to highly turbid fluids (> 100 NTU) whereas nephelometers work better with low turbidity fluids (< 50 NTU).

Scheme 1: Difference between Turbidimeter and Nephelometer

Professional-quality turbidimeters/nephelometers do not come cheap, typically >£1000. Fortunately, there are a range of Chinese-made instruments that are more reasonably priced for citizen science projects. The ZD2A nephelometer that I purchased is currently available for the relatively low price of £70-75 including shipping.

Photo 2: Generic Chinese Nephelometer (Model ZD2A)

My ZD2A nephelometer requires a 0.0 NTU turbidity standard and a 100 NTU turbidity standard to calibrate the nephelometer. I prepared my own nominal 0.0 NTU standard by filtering de-ionised water through a 0.22 μm membrane. The instrument came with a small bottle of 400 NTU formazin standard along with instructions for diluting to a 100 NTU standard. This is a simple dilution procedure provided you have the necessary volumetric glassware (or an accurate balance) to, for example, take a 2.5 ml aliquot and make up to 10 ml with distilled or de-ionised water. I chose to purchase a Stablcal 100 NTU standard directly to simplify the calibration procedure.

Note 2: Turbidity is calibrated using Formazin standards that have short shelf lives (from days to a few months). Stabilised Formazin Standards (e.g. Stablcal and T-CAL) have longer shelf lives (typically 1 - 2 years).

Since we have several years of turbidity data measured using Secchi tubes, one of the first tasks was to compare turbidity values measured using both techniques (Secchi vs Nephelometry). Along with a couple of fellow citizen scientists (Alan & Maggie), I collected river samples in clean 100 ml polyethylene bottles (the retention sample). To make the comparison as valid as possible, the retention samples were taken directly from the Secchi tube used to measure and record the turbidity of the river sample.

On returning home, the retention samples were analyzed using the ZD2A nephelometer. First the nephelometer was calibrated with the 0.0 and 100 NTU standards, followed by analysis of the retention samples. Retention samples were vigorously shaken for 10 seconds (to resuspend any settled particles), the sample cell was rinsed three times with sample, filled, capped, inverted 5 times and placed in the sample compartment. Turbidity readings were taken after 30 seconds, once the instrument had stabilised, and are collated in Table 1.

TABLE 1: Turbidity Values (NTU) Measured By Secchi Tube and Nephelometry
Secchi Tube (NTU)	Nephelometry (NTU)
<12	7
<12	11
15	14
21	19
25	26
25	41
40	69
40	75
50	56
75	122
100	134
190	221*
200	228*
>240	325*

Note 3: Samples with Secchi Tube values were excluded from the linear regression analysis (Figure 1)

Note 4: Samples marked with an asterisk (*) were accurately diluted by weight with de-ionised water before applying a dilution factor to the nephelometry result.

Figure 1 is the resultant linear regression analysis of the data from Table 1 (n= 11). The correlation (R² = 0.964) is better than I expected considering the relatively poor precision of the Secchi Tube method.

Despite some valid concerns regarding the accuracy and precision of the Secchi tube method, it does a remarkably good job of quantifying turbidity for this suite river samples. Further work is planned.