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Article

Urban Geochemical Contamination of Highland Peat Wetlands of Very High Ecological and First Nations Cultural Value

by
Ian A. Wright
1,*,
Holly Nettle
2,
Uncle David King
3,
Michael J. M. Franklin
1,4 and
Amy-Marie Gilpin
1,4
1
School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
2
Department of Microbiology and Immunology, University of Melbourne, Melbourne, VIC 3010, Australia
3
Gundungurra Traditional Custodians
4
Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
*
Author to whom correspondence should be addressed.
Water 2025, 17(16), 2385; https://doi.org/10.3390/w17162385
Submission received: 18 June 2025 / Revised: 22 July 2025 / Accepted: 22 July 2025 / Published: 12 August 2025
(This article belongs to the Section Water Quality and Contamination)
Browse Figures
Versions Notes

Abstract

Temperate Highland Peat Swamps on Sandstone (THPSS) are wetlands in the Blue Mountains, south-eastern Australia. The wetlands have legislative protection as endangered ecological communities. They have long-standing cultural significance for Gundungurra Traditional Custodians. Previous studies document their degradation by urban development and vulnerability to extreme weather. Water quality in our study was assessed at wetlands in protected areas and compared with others exposed to urban development. We derived water quality guidelines that are intended to help future water quality assessment at THPSS and, in particular, to detect any impact from urban development on these wetland systems. Water quality in urban swamps was consistent with the freshwater salinisation syndrome despite all the swamps having relatively low electrical conductance (<140 µS cm−1). Urban swamp water had salinity (mean 87.3 µS cm−1) three times that of non-urban swamps (mean 28 µS cm−1). The ionic composition of urban swamp water was dominated by calcium and bicarbonate, consistent with urban alkalisation syndrome. Our guidelines instead recommend limits for pH, salinity, turbidity, dissolved oxygen, and metals detected in greater concentrations that were found in urban swamps (iron, manganese, barium, and strontium). Our results support the theory that the dissolution of urban concrete materials is a degradation process that contributes to the impairment of urban swamp water quality.

1. Introduction

The global spread and intensification of urbanisation is resulting in substantial increases in coverage of impervious surfaces in urban areas, which is modifying catchment hydrology and freshwater ecosystems [1]. This has been described as a key driver of the urban stream syndrome, which explains how urbanisation triggers a series of complex physical, chemical and biological changes to urban freshwater ecosystems [2]. Compared to their non-urban counterparts, urban landuses increase the coverage of catchment watersheds by impermeable materials such as roofs, roads, car parks and other man-made materials [3]. The connection between catchment imperviousness and the degradation of water quality is well established in Australia [4] and overseas [5].
Blue Mountains Temperate Highland Peat Swamps on Sandstone (THPSS) are unique freshwater wetlands found within, and surrounding, the Greater Blue Mountains World Heritage Area (GBMWHA) [6]. They occur on sandstone at altitudes >650 m above sea level [6]. THPSS contain several endemic and endangered species of flora and fauna and provide essential ecosystem services, including water filtration, element cycling, and carbon sequestration [7]. Many are also located within major catchments that supply drinking water for the greater Sydney region [8]. THPSS are listed as an endangered ecological community under Australia’s Environment Protection and Biodiversity Conservation Act 1999 (Commonwealth) due to their unique biodiversity values, restricted geographic distribution (less than 3000 ha remaining), and vulnerability to anthropogenic threats [6,9]. The Blue Mountains region is vulnerable to disturbance from urban development, as it contains 27 small to medium-sized urban townships, supporting more than 80,000 residents, developed on some of the highest elevations adjacent to protected areas of the GBMWHA [10,11].
THPSS are high-conservation value wetlands that are culturally significant for the First Nations people, the Gundungurra, of the Blue Mountains [12]. The THPSS were important for sustaining the lives of the Gundungurra for millennia, contributing to a long-standing cultural and spiritual relationship. Indigenous people did not focus on sustaining just their lives; they also sustained the environment. These wetlands, which are often circular in shape, are quite often referred to as ‘circles of life’. This connection and understanding ensured that with each clan’s return, the life within an area (flora and fauna) would still be there. No extinction, just constant good health, food, and life (Uncle David King). Recognising the cultural importance of THPSS to the Gundungurra is consistent with the growing international recognition that Indigenous–water relationships are important for environmental and water governance [13,14].
Despite their legislative protection and proximity to the GBMWHA, the ecological condition of many THPSS, particularly those exposed to urban landuses, is substantially degraded [11,15,16,17]. Runoff from urban surfaces also results in short periods of higher stormwater volume and energy [2], contributing to the erosion, sedimentation, and channelisation of urban THPSS [8,17]. THPSS have a unique chemical makeup, including a naturally acidic pH (<6 pH) and frequently lack any buffering due to undetectable concentrations of calcium or magnesium, making them particularly susceptible to chemical impacts of urbanisation [11]. Urbanisation contributes to the impairment of urban THPSS water quality through increased pH, salinity, and alteration to ionic and metal composition [11,17,18].
Laboratory studies have further validated the theory that urban concrete materials leach contaminants that increase pH and salinity, and add to ionic modification of water in urban THPSS [19,20,21,22,23]. Recently published research also revealed that water collected from a pristine THPSS was exposed in a laboratory study to concrete and resulted in increased growth of the invasive weed Salix sp., which is commonly known as Willow [24]. This species is one of the nine most problematic invasive weeds identified in THPSS [25].
The nature of the urban water contamination in many THPSS (higher pH, salinity, and alkalinity) conforms with the growing body of international research documenting the freshwater salinisation syndrome (FSS) [26,27]. FSS can impair freshwater systems by altering the availability and toxicity of metals and reducing the buffering capacity of waterways, particularly those with a naturally low buffering capacity [26,27]. Compounding these threats in the Blue Mountains region are the impacts of extreme weather-related events, such as drought, storms, and wildfire, which have adversely affected the condition of many THPSS [17].
The most recent Conservation Outlook Assessment by the International Union for Conservation of Nature (IUCN) classified the GBMWHA as of significant concern [16]. A total of 71% percent of the GBMWHA was affected by wildfires that were active for over three months between October 2019 and February 2020 and burnt peat in many THPSS that were very dry due to several years of drought [10,17]. Some Blue Mountains swamps, Newnes Plateau Shrub Swamps, were severely damaged from the combined loss of groundwater from coal-mine subsidence and wildfire [28]. Following the wildfires in February 2020, torrential flooding compounded the loss of plant growth and peat from wildfires, and resulted in increased erosion of THPSS [17]. The impacts of extreme weather, associated with climate change, on THPSS are predicted to continue to escalate, with increasing temperatures, drought and wildfires [16].
The aim of this study was to collect and compare water quality data from both urban and non-urban THPSS to derive THPSS-specific water quality guidelines. The research gap that we sought to address was to collect data, and review previously collected data, to derive water quality guidelines that we intended to help detect pollution and assist with the ongoing management of the THPSS. We followed a water guideline development methodology, based on collecting results from reference THPSS in non-urban catchments, that was recommended for developing area-specific water quality guidelines by the Australian and New Zealand Governments [29]. To contribute to the development of appropriate guidelines, along with collecting water quality data, we also reviewed previously published information and conducted the investigation with the cooperation of Gundungurra Traditional Custodians of the Blue Mountains.

2. Materials and Methods

2.1. Study Area

This study took place in the Blue Mountains region of south-eastern Australia, approximately 50 to 90 km west of the central business district of Sydney. Sampling was conducted at eight THPSS, with four located in urbanised catchments and four in non-urban naturally vegetated catchments (Table 1; Figure 1). Each non-urban THPSS were located at least 2 km from the nearest urban area. The degree of urbanisation within each THPSS catchment was classified by measuring the percentage of directly connected impervious surfaces (% IS). This was achieved through the Sutherland [30] (2000) method by using the percentage total impervious area, which was derived through calculating impervious surfaces in THPSS catchments from Geographic Information System (GIS) mapping. The non-urban THPSS had largely unmodified catchments that retained natural vegetation cover, and the wetlands were typically dominated by native sphagnum bogs and fens, while sedge and shrub associations occurred in the drier parts. In contrast, invasive weeds were typically abundant in urban THPSS across the study area [25]. All the THPSS exit streams had permanent flow for the duration of the investigation.
One of the THPSS that was investigated in this study, known as Garguree or ‘The Gully’, has particularly important cultural significance for the Gundungurra Traditional Custodians and Gully Traditional Owners [11]. The following paragraph is a personal communication provided by Uncle David King to explain the cultural importance of upland swamps and particularly ‘Garguree’.
For thousands of years the upland swamps of the Blue Mountains formed significant connections. The upland swamp area that forms a part of Garguree (The Gully Katoomba) was a campsite for thousands of years. Colonisation forced the Traditional Custodians to use the site as a permanent campsite to survive. Eventually, perceived colonial economic values of the landscape forced the Traditional Custodians to be evicted without any consultation or rights. The upland swamp that formed Garguree in its natural form was destroyed. Over the last 15 years, the Gully Traditional Owners and Garguree Swampcare have been working to try and reverse this destruction (Uncle David King).

2.2. Collection of Water Quality Data and Water Samples

Water quality data was collected from all eight THPSS (Table 1, Figure 1) on four occasions between August 2023 and March 2024. The sampling was conducted in the exit stream emerging from the lowest point of each wetland. The exit streams were often very small streams of flowing water, often just one metre in width and between five and 20 cm deep. The sampling point was between one and 20 metres downstream from the lowest margins of the peat swamp. Water physicochemical properties were recorded, with five replicate readings, collected from the sampling point in each THPSS exit stream. The instrument probes were placed in the exit stream in flowing water, ensuring that the probes were completely immersed. Water turbidity was measured at all the sampling locations, on each occasion, using a HACH 2100 P Turbidimeter. Additionally, pH (pH units) and electrical conductivity (EC; µS cm−1) were measured using a calibrated TPS Aqua-CP/A waterproof conductivity–pH–temperature meter (supplied by TPS PTY Ltd., Brendale, QLD, Australia) with an accuracy of +/− pH units and +/−0.2% for EC. Dissolved oxygen was measured in mg L−1 and as percentage saturation (%) using a calibrated YSI ProODO meter with an accuracy of +/−1%. The YSI ProODO meter was also used to measure water temperature (°C) with an accuracy of +/−1%.
Duplicate samples of water were collected at each site on each sampling occasion in unused plastic 50 mL sample containers that were provided by the commercial analytical testing laboratory (Envirolab Services Sydney, Chatswood, NSW, Australia). Water samples for metal determination were collected using unused 50 mL bottles that had been pretreated with nitric acid. Samples were chilled (<2 °C) and delivered to the laboratory for analysis. All the samples that were analysed in the laboratory used appropriate methods [31]. The methods were ‘Metals-020’: inductively coupled plasma (ICP) atomic emission spectroscopy (ICP-AES); and ‘Metals-022’: ICP mass spectrometry (ICP-MS). The laboratory methods are endorsed by the National Association of Testing Authorities (NATA) for measurement of anions (method: ‘Inorg-081’); cations (calcium, potassium, sodium, magnesium, bicarbonate, carbonate, sulphate, chloride, and hardness); and total nitrogen (method: ‘Inorg-055/062/127’).

2.3. Deriving THPSS Water Quality Guideline Values

Currently, there are no water quality guidelines that apply to THPSS, although it is known that when exposed to urban land, they are subject to impaired water quality. All natural waterways across Australia and New Zealand, freshwater to marine, had default guidelines developed in 2000 according to broad regions of Australia and New Zealand [29]. For THPSS the appropriate region is ‘south-eastern Australia’. However, for the category of ‘wetlands’ in south east Australia, for many indicators, such as nutrients, dissolved oxygen and pH, there are currently no Australian guidelines provided [29]. However, a recommended process for deriving local guidelines is provided using the collection of water quality data from several THPSS that represent the reference condition [29] (Figure 2). To derive specific guidelines for urban THPSS, we used the methodology recommended for developing locality-specific guidelines [29] for the purpose of deriving trigger values for detecting urban water quality impairment in THPSS. The concept of trigger values is that they provide an early warning to trigger action, before more harmful levels of pollutants cause ecological damage. The ANZECC guidelines recommend that baseline data be gathered from at least three to five reference locations over a period of at least three years wherever possible [29]. A limitation of our study was that we were unable to collect water quality data over the recommended period. However, our results from the current investigation were compared with several previous studies of urban and non-urban THPSS that had previously been conducted over the previous decade [11,19,22]. The Australian and New Zealand Governments [29] recommend defining trigger values using a conservative percentile value. We followed this recommendation by deriving trigger values for THPSS using the 80th percentile (20th percentile for dissolved oxygen) of data obtained from the reference site THPSS [29].

2.4. Data Analysis

All water quality data that were tested for normality of distribution were often found to have abnormal distributions. As this fails the assumption of normal distribution for parametric data analysis, in response, we chose the non-parametric Independent Samples Mann–Whitney U test that was subsequently performed on the results from THPSS to test for significant differences between urban compared to non-urban catchments. We chose the Mann–Whitney U-test as the distribution of data at both the urban and non-urban THPSS was similar. Some water chemical attributes were not detected because they were lower than the laboratory detection limits. In these cases, for data analysis purposes, the result was assumed to be half of the detection limit [32]. Probability values less than 0.05 were considered significant. All the statistical analysis was performed using IBM SPSS Statistics version 30 [33]. The null hypothesis that we tested for each water quality variable was that the distribution of values was the same at THPSS in the urban compared to non-urban catchments.
The ionic composition of the urban THPSS surface water was compared with that of the non-urban THPSS surface water using the anion and cation models developed by Gibbs [34]. This allowed comparison of the results from the current study to the range of total dissolved salts across a representation of the world’s range of surface freshwaters.

3. Results

3.1. Water pH, Salinity, Turbidity, Nitrogen, and Dissolved Oxygen

Major geochemical differences were apparent comparing the water quality of the urban THPSS and non-urban THPSS (Table 2; Figure 3 and Figure 4). Water in the non-urban THPSS was acidic, with pH ranging from 4.24 to 6.21 (mean 5.31, 80th percentile 5.79). The pH of the urban THPSS was also acidic, but was generally higher, ranging from 5.38 to 6.86 (mean pH 6.19, Table 2). The mean salinity (EC) of the urban THPSS (87.3 µS cm−1) was three times the mean salinity of the non-urban THPSS (28 µS cm−1). The 80th percentile of salinity in the non-urban THPSS was 33.6 cm−1 (Table 2, Figure 3).
Water in the urban THPSS was also more than three times more turbid (mean 6.35 NTU) than water from the non-urban THPSS (mean 1.98 NTU, 80th percentile 2 NTU) (Table 2, Figure 3). The mean concentration of total nitrogen in the urban THPSS (210 µg/L−1) was more than twice that recorded at the non-urban THPSS (mean 60 µg/L−1). Dissolved oxygen (DO) in the non-urban THPSS ranged from 79.6 to 103.4% saturation (mean 89.8%, 20th percentile 82% saturation). In comparison, DO in the urban THPSS was considerably lower, ranging from 38.3 to 75.3% saturation (mean 58.3%) (Table 2; Figure 3).

3.2. Ionic Composition

For most major ions (calcium, potassium, magnesium, bicarbonate, and sulphate), the mean concentrations were either significantly higher in the urban THPSS or were only found at detectable concentrations in the urban THPSS (Table 2). Calcium, magnesium, and potassium were not recorded, on any occasion, at detectable concentrations in the non-urban THPSS. Sodium was the only cation found at detectable concentrations in both urban and non-urban THPSS. Overall, the sodium concentration at the urban THPSS (mean 5.36 mg L−1) was almost 35% higher than in the non-urban THPSS (mean 3.98 mg L−1) (Table 2).
Only one major anion, chloride, was consistently recorded at detectable concentrations in samples from both the urban and non-urban THPSS (Table 2). The mean concentration of chloride in the urban THPSS (mean 11.5 mg L−1) was 80% greater than the non-urban THPSS (mean 6.4 mg L−1). Bicarbonate (mean 19.6 mg L−1) and sulphate (mean 2.7 mg L−1) were consistently found in samples from the urban THPSS. In contrast, they were mostly undetected in the non-urban THPSS, each being recorded on a single occasion from one non-urban THPSS (Grand Canyon) (Figure 2).
All the non-urban THPSS waters in this study were dominated (according to mean concentration in mg L−1) by sodium and chloride ions (Table 2). However, the urban THPSS were dominated by calcium and bicarbonate ions, with sodium and chloride being subdominant. When these results, along with salinity (as TDS mg L−1), were plotted on the Gibbs [34] diagram, the urban and non-urban THPSS results each formed separate clusters (Figure 4). The non-urban THPSS cluster of samples was positioned at the extreme margin of the dilute ‘Na-Cl precipitation’ dominance zone (Figure 4). The urban THPSS samples clustered closer to the centre of the Gibbs [34] diagram, closer to the ‘rock dominance’ zones in the Gibbs [34] anion and cation models (Figure 4).

3.3. Other Metals

Only one metal, aluminium, was recorded at greater concentrations in the non-urban THPSS compared to the urban THPSS (Table 2, Figure 5). The mean aluminium concentration in the non-urban THPSS (101.3 µg L−1) was twice that in the urban swamps (47 µg L−1). Five metals (iron, manganese, zinc, barium, and strontium) were recorded at greater concentrations at the urban THPSS (Table 2). The metal with the greatest proportional difference in mean concentration between the urban and non-urban swamps was strontium, which was nearly 15 times greater in the urban THPSS (mean 28.9 µg L−1) compared to the non-urban THPSS (mean 1.96 µg L−1, 80th percentile 2.8 µg L−1) (Figure 5). The mean manganese concentration in the urban swamps (mean 56.4 µg L−1) was more than 10 times greater than in the non-urban swamps (mean 4.5 µg L−1, 80th percentile 9 µg L−1). The mean barium concentration in the urban swamps (mean 17.2 µg L−1) was nearly six times greater than in the non-urban swamps (mean 2.96 µg L−1, 80th percentile 5 µg L−1). Zinc was detected in the urban swamps (mean 12.4 µg L−1) at more than three times the concentration of the non-urban swamps (mean 3.9 µg L−1). The most abundant metal in swamp water was iron, with a mean iron concentration (3136 µg L−1) in the urban THPSS that was nearly seven times that in the non-urban THPSS (mean 414 µg L−1, 80th percentile 420 µg L −1) (Table 2, Figure 5).

4. Discussion

This study builds upon previous research that documented impaired water quality of THPSS in the catchments containing urban land [11,19,35]. The urban swamp water quality, in this current study, had three-fold greater salinity than the non-urban swamps. This is consistent with the freshwater salinisation syndrome (FSS) [26,27]. Our current study also helps explore the cocktail of chemicals [5] that separates urban THPSS water quality from non-urban swamps. Our research has documented a cocktail of contaminants in the water at THPSS swamps affected by runoff from urban lands. The cocktail includes greater concentrations of some metals (particularly manganese, iron, barium, and strontium), higher pH, greater turbidity, and elevated concentrations of calcium and bicarbonate in the water of THPSS exposed to urban development.
The salinity of the urban swamps (mean 87.3 µS cm−1) was three times that of non-urban THPSS (mean 28 µS cm−1). The salinity of all the swamps in this study may appear small when compared to other FSS studies, as all salinity values in THPSS would ordinarily be classified as ‘low salinity’ [26,27]. However, the scale of urban modification of the salinity of THPSS water becomes more apparent when the ionic modification, calcium and bicarbonate, contributing to the salinity results, are compared with the water from non-urban THPSS, using the Gibbs [34] model of world water chemistry. Both the Gibbs [34] cation (sodium and calcium versus salinity) and anion (chloride and bicarbonate versus salinity) models placed the non-urban samples in the dilute precipitation dominance sector. This was due to negligible calcium and bicarbonate ions in the non-urban swamps. In contrast, the urban swamp results were placed in the rock dominance sector of the Gibbs anion and cation models, suggesting a greater influence by geology. However, such ionic differences cannot be explained by variation in the natural geology of the urban and non-urban THPSS in this study. The entire study area, including the eight swamps in this investigation, all share a common Blue Mountains geology of Permo-Triassic quartz sandstone with interbedded clay stone [8,36,37].
The urban drainage system in Blue Mountains urban areas is likely to be a major anthropogenic driver [27] that is contributing to the water quality differences at urban versus non-urban THPSS due to urban areas containing many facets of the built environment containing concrete materials, particularly through the concrete urban drainage system [11]. The dissolution of concrete materials is likely to be a major source of increased pH, salinity, metal, and major ionic differences that were detected in urban THPSS [4]. Concrete dissolution has been reported to be a contributor to FSS through accelerated weathering of human-made materials, with widespread concrete materials in urban lands previously referred to as urban karst [38]. We suggest that the dissolution of concrete urban materials is a likely explanation for the clustering of the THPSS samples from the urban catchments, in the rock dominance sectors of the Gibbs [34] models.
The concrete-dominated construction of Blue Mountains urban drainage networks also provides a catchment runoff pathway that can directly link urban lands with many THPSS swamps in urban catchments [1]. This was demonstrated by Belmer [11] with the Bullaburra swamp, one of four THPSS in catchments affected by urbanisation in that study. In the Bullaburra swamp Belmer [11] recorded the largest concentrations of calcium (34 mg L−1), potassium (7.9 mg L−1), and bicarbonate (50.7 mg L−1) recorded in any Blue Mountains THPSS. This was attributed to a recent highway upgrade being directly connected to the head of the Bullaburra swamp by concrete road gutters and an underground network of concrete pipes [11]. The increased turbidity recorded in the urban THPSS was probably due to the flushing and mobilisation of particulates, such as soil and sediment from urban catchment activities, from urban areas through the connected drainage systems that convey urban runoff into downstream peat swamps, as per the urban stream syndrome [1,2].
Several studies in the Sydney area have previously investigated changes to water quality when water is modified by exposure to concrete materials [4,23,35,39]. Together with the results from the current study, these studies suggest that major water quality differences in urban THPSS broadly match the water quality signature produced when water quality is modified when water reacts with concrete materials. These studies have used a range of laboratory experiments involving water being recirculated through concrete pipes, gutters, or concrete fragments. Two studies have recirculated batches of water through concrete pipes for between 60 and 100 min [4,40]. Both reported increased pH, increased EC, and increased concentration of calcium, potassium, and bicarbonate ions after water from a clean source is experimentally exposed to concrete. For example, the study by Grella [40] recirculated 20 L of rainwater through an unused concrete pipe (1.6 m long, 375 mm internal diameter) for 100 min. This increased pH by 1.7 pH units, from an initial pH of 6.3 to a final pH of 8. That study [40] also recorded an increase in water EC from 26.6 µS cm−1, at the outset, rising to 62.3 µS cm−1 after 100 min.
A more recent study recirculating pristine THPSS water through concrete fragments of different sizes (10 mm, 20 mm, and 60 mm) resulted in increased metal concentration in addition to other changes in water quality (pH, salinity, calcium, and bicarbonate) [23]. The concentration of barium and strontium increased after water was recirculated through a plastic pipe containing concrete fragments [23]. Both were recorded, prior to the concrete exposure, at low concentrations (barium 2.5 µg L−1 and strontium 1.5 µg L−1). After the 60 min recirculation, the concentration of barium was 4 to 12 times greater, and strontium was between 30 and 105 times greater. This shares similarities to the current study that recorded trace concentrations of barium (2.96 µg L−1) and strontium (1.96 µg L−1) in the non-urban swamps. Our study also recorded greater mean concentrations of the two metals in the urban swamps (barium 17.2 µg L−1; strontium 28.9 µg L−1). Carroll [19] also recorded similar concentrations of barium and strontium in urban and non-urban THPSS.
This research provides the first ever guideline trigger values for water quality monitoring of THPSS to assess and help protect swamps exposed to urban landuses (Table 2 and Table 3). We followed the methodology for deriving locality-specific water guidelines recommended by Australia and New Zealand [29] using the results generated by the non-urban THPSS in this study as reference locations (Figure 2) [29]. Whilst we did not collect data over the 36-month time period recommended, we have compared our results with several similar previous studies using many of the same swamps (Table 3). Table 3 shows that our results were broadly representative of previous studies of water quality at urban and non-urban THPSS (Table 3) [11,19,22]. These three references are the most detailed and comprehensive water quality studies, to date, of both non-urban and urban THPSS and consequently were chosen to provide comparison with the results from the current study (Table 3). The mean water quality results (pH, EC, turbidity, barium, strontium, iron, and manganese) were always greater in the urban THPSS. The opposite was found for dissolved oxygen, which was at lower levels and was generally recorded at ecologically stressful levels in the urban swamps [29]. We suspect that different seasonal conditions during sample collection, such as during periods of drought or higher than normal rainfall, probably influenced the results in the current and previous studies. Our THPSS guidelines need further development over a longer period of time. We recommend that further testing and refinement of these guidelines be conducted on both urban and non-urban THPSS, under different weather and seasonal conditions, in the Greater World Heritage Area and surroundings, due to the high natural and cultural significance of these areas and their proximity to more intensive urbanisation. We also recommend that future research on testing and refining water quality guidelines for THPSS could include a larger selection of urban and non-urban wetlands and, in addition to water quality, could also include collecting data on wetland macroinvertebrates [41] and other ecological attributes [42], such as invasive plants [43,44], and/or algal diatoms [45,46]. Additionally, we recommend that a thorough hydrochemistry investigation be conducted on both non-urban and urban THPSS.
The limitations of the current study include that only a relatively small number (four) of urban and four non-urban swamps was included. As previously explained, we did not carry out the monthly study of the non-urban THPSS over 36 months as is recommended [29]. Another limitation is that the current study did not include any biological data and was only a water quality study.
Urbanisation is a global issue facing many sensitive environments. The THPSS are a small collection (<3000 ha) of fragile wetlands of very high environmental and cultural significance that are highly vulnerable to both extreme weather and urban landuses [8,19]. The combination of climate change and urban development threatens to accelerate the deterioration of wetland biodiversity [15,16]. Our suggested THPSS water quality guidelines are anticipated to accompany a future swamp water monitoring programme to help detect and provide an early warning of water quality changes triggered by urban development on THPSS. We anticipate that such guidelines in a monitoring programme could help detect the impairment of future water quality in these sensitive wetlands.

5. Conclusions

  • This study provides water quality guidelines, such as trigger values, for Blue Mountains Temperate Highland Peat Swamps on Sandstone.
  • These are the first water quality guidelines for fragile and vulnerable THPSS wetlands that are being damaged by urban development and climate change.
  • These wetlands have legislative protection as endangered ecological communities, but also have important cultural significance for Gundungurra Traditional Custodians.
  • The water quality guidelines include physical guidelines (dissolved oxygen, turbidity) and chemical guidelines (pH, barium, strontium, iron, and manganese).
  • An important source of urban water quality contamination appears to be linked to the dissolution of concrete materials.

Author Contributions

Conceptualisation, I.A.W., H.N., M.J.M.F., and U.D.K.; methodology, I.A.W., H.N., U.D.K., M.J.M.F., and A.-M.G.; formal analysis, I.A.W. and M.J.M.F.; investigation, I.A.W., H.N., and M.J.M.F.; resources, I.A.W.; data curation, I.A.W. and H.N.; writing—original draft preparation, I.A.W. and H.N.; writing—review and editing, I.A.W., H.N., M.J.M.F., U.D.K., and A.-M.G.; visualisation, I.A.W.; project administration, I.A.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data supporting the findings of this study are available from the corresponding author upon email request.

Acknowledgments

We would like to acknowledge Sue Cusbert (Western Sydney University) for her technical assistance with this project. Thanks also to the NSW National Parks and Wildlife Service for permission to collect water samples in the Blue Mountains National Park.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

The following abbreviations are used in this manuscript:
THPSSTemperate Highland Peat Swamps on Sandstone
FSSFreshwater Salinisation Syndrome
GBMWHAGreater Blue Mountains World Heritage Area
IUCNInternational Union for Conservation of Nature
GISGeographic Information System
DODissolved oxygen
ECElectrical conductivity

References

  1. Walsh, C.J.; Roy, A.; Feminella, J.; Cottingham, P.; Groffman, P.; Morgan, R., II. The urban stream syndrome: Current knowledge and the search for a cure. J. N. Am. Benthol. Soc. 2005, 24, 706–723. [Google Scholar] [CrossRef]
  2. Paul, M.J.; Meyer, J.L. Streams in the urban landscape. Annu. Rev. Ecol. Syst. 2001, 32, 333–365. [Google Scholar] [CrossRef]
  3. Tippler, C.; Wright, I.A.; Hanlon, A. Is catchment imperviousness a keystone factor degrading urban waterways? A case study from a partly urbanised catchment (Georges River, south-eastern Australia). Water Air Soil Pollut. 2012, 223, 5331–5344. [Google Scholar] [CrossRef]
  4. Davies, P.J.; Wright, I.A.; Jonasson, O.J.; Findlay, S.J. Impact of concrete and PVC pipes on urban water chemistry. Urban Water J. 2010, 7, 233–241. [Google Scholar] [CrossRef]
  5. Kaushal, S.S.; Wood, K.L.; Galella, J.G.; Gion, A.M.; Haq, S.; Goodling, P.J.; Haviland, K.A.; Reimer, J.E.; Morel, C.J.; Wessel, B.; et al. Making ‘chemical cocktails’–Evolution of urban geochemical processes across the periodic table of elements. Appl. Geochem. 2010, 119, 104632. [Google Scholar] [CrossRef] [PubMed]
  6. Department of Climate Change, Energy, the Environment and Water. Temperate Highland Peat Swamps on Sandstone. 2005. Available online: https://www.dcceew.gov.au/environment/biodiversity/threatened/assessments/temperate-highland-peat-swamps-2005 (accessed on 17 June 2025).
  7. Benson, D.; Baird, I.R.C. Vegetation, fauna and groundwater interrelations in low nutrient temperate montane peat swamps in the upper Blue Mountains, New South Wales. Cunninghamia 2012, 12, 267–307. [Google Scholar] [CrossRef]
  8. Fryirs, K.; Freidman, B.; Williams, R.; Jacobsen, G. Peatlands in eastern Australia? Sedimentology and age structure of Temperate Highland Peat Swamps on Sandstone (THPSS) in the Southern Highlands and Blue Mountains of NSW, Australia. Holocene 2014, 24, 1527–1538. [Google Scholar] [CrossRef]
  9. Gorissen, S.; Greenlees, M.; Shine, R. Habitat and Fauna of an Endangered Swamp Ecosystem in Australia’s Eastern Highlands. Wetlands 2017, 37, 269–276. [Google Scholar] [CrossRef]
  10. UNESCO (United Nations Educational, Scientific and Cultural Organization). Greater Blue Mountains Area. 2025. Available online: https://whc.unesco.org/en/list/917 (accessed on 17 June 2025).
  11. Belmer, N.; Wright, I.A.; Tippler, C. Urban geochemical contamination of high conservation value upland swamps, Blue Mountains Australia. Water Air Soil Pollut. 2015, 226, 332. [Google Scholar] [CrossRef]
  12. Blue Mountains City Council. A Heritage Study of the Gully Aboriginal Place, Katoomba, New South Wales. 2005. Available online: https://www.bmcc.nsw.gov.au/sites/default/files/document/files/2006-03-21_Item18Enc.pdf (accessed on 17 June 2025).
  13. Moggridge, B.J.; Thompson, R.M. Cultural value of water and western water management: An Australian Indigenous perspective. Australas. J. Water Resour. 2021, 25, 4–14. [Google Scholar] [CrossRef]
  14. Macpherson, E.; Turoa, H. Untapping the potential of Indigenous water jurisdiction: Perspectives from Whanganui and Aotearoa New Zealand. Humanit. Soc. Sci. Commun. 2025, 12, 86. [Google Scholar] [CrossRef]
  15. Christiansen, N.A.; Fryirs, K.A.; Green, T.J.; Hose, G.C. The impact of urbanization on community structure, gene abundance and transcription rates in microbes of upland swamps of Eastern Australia. PLoS ONE 2019, 14, e0213275. [Google Scholar] [CrossRef]
  16. IUCN (International Union for Conservation of Nature). Greater Blue Mountains Area 2020 Conservation Outlook Assessment. 2020. Available online: https://worldheritageoutlook.iucn.org/explore-sites/greater-blue-mountains-area (accessed on 17 June 2025).
  17. Carroll, R.; Reynolds, J.K.; Wright, I.A. Loss of soil carbon in a world heritage peatland following a bushfire. Int. J. Wildland Fire 2023, 32, 1059–1070. [Google Scholar] [CrossRef]
  18. Carroll, R.; Reynolds, J.K.; Wright, I.A. Impact of urban development on endangered wetland ecological communities in the Greater Blue Mountains World Heritage Area. In Proceedings of the 10th Australian Stream Management Conference 2021, Kingscliff, NSW, Australia, 2–4 August 2021; Available online: https://rbms.tempurl.host/wp-content/uploads/2021/08/50-rani-carroll.pdf (accessed on 17 June 2025).
  19. Carroll, R.; Reynolds, J.K.; Wright, I.A. Signatures of urbanization in Temperate Highland Peat Swamps on Sandstone (THPSS) of the Blue Mountains World Heritage Area. Water J. 2022, 14, 3724. [Google Scholar] [CrossRef]
  20. Carroll, R.; Reynolds, J.K.; Wright, I.A. Geochemical signature of urbanisation in Blue Mountains Upland Swamps. Sci. Total Environ. 2020, 699, 134393. [Google Scholar] [CrossRef]
  21. Wright, I.A.; Khoury, R.; Ryan, M.; Belmer, N.; Reynolds, J.K. Laboratory study of impacts of concrete fragment sizes on wetland water chemistry. Urban Water J. 2018, 15, 61–67. [Google Scholar] [CrossRef]
  22. Purdy, K. Impact of Concrete on Urban Stream Chemistry and Ecosystems. Master’s Thesis, Western Sydney University, Sydney, NSW, Australia, 2019. Available online: https://researchers-admin.westernsydney.edu.au/ws/portalfiles/portal/94926786/uws_58592.pdf (accessed on 17 June 2025).
  23. Wright, I.A.; Nettle, H.; Franklin, M.J.M.; Reynolds, J.K. Recirculating Water through Concrete Aggregates Rapidly Produced Ecologically Hazardous Water Quality. Water J. 2023, 15, 1705. [Google Scholar] [CrossRef]
  24. Purdy, K.; Reynolds, J.K.; Wright, I.A. The influence of contamination from concrete materials on the growth and accumulation of metals within an invasive weed (Salix spp.). Water Air Soil Pollut. 2024, 235, 647. [Google Scholar] [CrossRef]
  25. NSW Environment and Heritage. Blue Mountains Swamps in the Sydney Basin Bioregion-Vulnerable Ecological Community Listing. 2007. Available online: https://www.environment.nsw.gov.au/topics/animals-and-plants/threatened-species/nsw-threatened-species-scientific-committee/determinations/final-determinations/2004-2007/blue-mountains-swamps-sydney-basin-bioregion-vulnerable-ecological-community-listing (accessed on 17 June 2025).
  26. Kaushal, S.S.; Reimer, J.E.; Mayer, P.M.; Shatkay, R.R.; Maas, C.M.; Nguyen, W.D.; Boger, W.L.; Yaculak, A.M.; Doody, T.R.; Pennino, M.J.; et al. Freshwater Salinization Syndrome Alters Retention and Release of ‘Chemical Cocktails’ along Flowpaths: From Stormwater Management to Urban Streams. Freshw. Sci. 2022, 41, 420–441. [Google Scholar] [CrossRef] [PubMed]
  27. Maas, C.M.; Kaushal, S.S.; Rippy, M.A.; Mayer, P.M.; Grant, S.B.; Shatkay, R.R.; Malin, J.T.; Bhide, S.V.; Vikesland, P.; Krauss, L.; et al. Freshwater salinization syndrome limits management efforts to improve water quality. Front. Environ. Sci. 2023, 11, 1106581. [Google Scholar] [CrossRef] [PubMed]
  28. Krogh, K.; Gorissen, S.; Baird, I.R.C.; Keith, D.A. Impacts of the Gospers Mountain Wildfire on the flora and fauna of mining-impacted Newnes Plateau Shrub Swamps in Australia’s Eastern Highlands. Aust. Zool. 2022, 42, 199–216. [Google Scholar] [CrossRef]
  29. ANZECC (Australian and New Zealand Environment and Conservation Council). Australian and New Zealand Guidelines for Fresh and Marine Waters. In National Water Quality Management Strategy Paper No. 4; Australian and New Zealand Environment and Conservation Council: Canberra, ACT, Australia, 2001. Available online: https://www.waterquality.gov.au/anz-guidelines/resources/previous-guidelines/anzecc-armcanz-2000 (accessed on 17 June 2025).
  30. Sutherland, R. Methods for Estimating the Effective Impervious Area of Urban Watersheds: The Practice of Watershed Protection; Center for Watershed Protection: Ellicott City, MD, USA, 2000; pp. 193–195. [Google Scholar]
  31. APHA (American Public Health Association). Standard Methods for the Examination of Water and Wastewater, 20th ed.; American Public Health Association: Washington, DC, USA, 1998. [Google Scholar]
  32. Clarke, J.U. Evaluation of Censored Data Methods to Allow Statistical Comparisons among Very Small Samples with Below Detection Limit Observations. Environ. Sci. Technol. 1998, 32, 177–183. [Google Scholar] [CrossRef]
  33. IBM Corporation. SPSS Statistics, Version 30; IBM Corporation: Armonk, NY, USA, 2024. Available online: https://www.ibm.com/support/pages/downloading-ibm-spss-statistics-30 (accessed on 17 June 2025).
  34. Gibbs, R.J. Mechanisms controlling world water chemistry. Science 1970, 170, 1088–1090. [Google Scholar] [CrossRef]
  35. Purdy, K.; Reynolds, J.K.; Wright, I.A. Potential water pollution from recycled concrete aggregate material. Mar. Freshwater Res. 2020, 72, 58–65. [Google Scholar] [CrossRef]
  36. van der Beek, P.; Pulford, A. Cenozoic landscape development in the Blue Mountains (SE Australia): Lithological and tectonic. J. Geol. 2001, 109, 35–56. [Google Scholar] [CrossRef]
  37. Pickett, J. Layers of time: The Blue Mountains and their geology. In Blue Mountains and Their Geology; Alder, J.D., Ed.; Geological Survey of New South Wales: Sydney, NSW, Australia, 2011. [Google Scholar]
  38. Kaushal, S.S.; Duan, S.; Doody, T.R.; Haq, S.; Smith, R.M.; Newcomer-Johnson, T.; Delaney-Newcomb, K.; Gorman, J.; Bowman, N.; Mayer, P.M.; et al. Human-accelerated weathering increases salinization, major ions, and alkalinization in fresh water across land use. Appl. Geochem. 2017, 83, 121–135. [Google Scholar] [CrossRef]
  39. Wright, I.A.; Davies, P.J.; Jonasson, O.J.; Findlay, S.J. A new type of water pollution: Concrete drainage infrastructure and geochemical contamination of urban waters. Mar. Freshw. Res. 2011, 62, 1355–1361. [Google Scholar] [CrossRef]
  40. Grella, C.; Wright, I.A.; Findlay, S.J.; Jonasson, O.J. Geochemical contamination of urban water by concrete stormwater infrastructure: Applying an epoxy resin coating as a control treatment. Urban Water J. 2016, 13, 212–219. [Google Scholar] [CrossRef]
  41. Belmer, N.; Wright, I.A.; Tippler, C. Aquatic ecosystem degradation of high conservation value upland swamps, Blue Mountains Australia. Water Air Soil Pollut. 2018, 229, 98. [Google Scholar] [CrossRef]
  42. Hart, B.T.; Maher, B.; Lawrence, I. New generation water quality guidelines for ecosystem protection. Freshw. Biol. 1999, 41, 347–359. [Google Scholar] [CrossRef]
  43. King, S.A.; Buckney, R.T. Invasion of exotic plants in nutrient-enriched urban bushland. Austral Ecol. 2002, 27, 573–583. [Google Scholar] [CrossRef]
  44. Grella, C.; Renshaw, A.; Wright, I.A. Invasive weeds in urban riparian zones: The influence of catchment imperviousness and soil chemistry across an urbanization gradient. Urban Ecosyst. 2018, 21, 505–517. [Google Scholar] [CrossRef]
  45. Chessman, B.C. Diatom flora of an Australian river system: Spatial patterns and environmental relationships. Freshw. Biol. 1986, 16, 805–819. [Google Scholar] [CrossRef]
  46. Potapova, M.; Charles, D.F. Distribution of benthic diatoms in US rivers in relation to conductivity and ionic composition. Freshw. Biol. 2003, 48, 1311–1328. [Google Scholar] [CrossRef]
Water 17 02385 g001
Figure 1. Sampling site map. Wetlands in naturally forested (non-urban) catchments are white circles. Wetlands in catchments containing urbanisation are purple circles.
Figure 1. Sampling site map. Wetlands in naturally forested (non-urban) catchments are white circles. Wetlands in catchments containing urbanisation are purple circles.
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Water 17 02385 g002
Figure 2. Flow chart for the process used to derive trigger values for the protection of water quality at THPSS following the methodology recommended by the Australian and New Zealand Environment Conservation Council [29].
Figure 2. Flow chart for the process used to derive trigger values for the protection of water quality at THPSS following the methodology recommended by the Australian and New Zealand Environment Conservation Council [29].
Water 17 02385 g002
Water 17 02385 g003aWater 17 02385 g003b
Figure 3. Mean (plus/minus standard error of mean) value of water quality attributes (a) pH, (b) EC, (c)) turbidity, and (d) DO measured in water from exit streams emerging from each of the eight THPSS (August 2023 to March 2024). The first four swamps are non-urban and are unshaded (GC, HH, MH, and NN), and the next four are shaded urban-influenced (GU, LA, PG, and SW). Swamp location and catchment details are given in Table 1. The dotted line represents the 80th percentile (20th percentile for DO) of the results from the non-urban swamps.
Figure 3. Mean (plus/minus standard error of mean) value of water quality attributes (a) pH, (b) EC, (c)) turbidity, and (d) DO measured in water from exit streams emerging from each of the eight THPSS (August 2023 to March 2024). The first four swamps are non-urban and are unshaded (GC, HH, MH, and NN), and the next four are shaded urban-influenced (GU, LA, PG, and SW). Swamp location and catchment details are given in Table 1. The dotted line represents the 80th percentile (20th percentile for DO) of the results from the non-urban swamps.
Water 17 02385 g003aWater 17 02385 g003b
Water 17 02385 g004aWater 17 02385 g004b
Figure 4. Water samples collected from the THPSS in non-urban catchments (yellow triangles) versus THPSS in urban catchments (red diamonds) plotted on the Gibbs [34] anion (a,b) cation models. The urban and non-urban THPSS formed separate clusters in both cation and anion models. The urban THPSS samples clustered closer to the centre near the ‘rock dominance’ zones in the Gibbs [34] anion (a,b) cation models. The non-urban THPSS samples clustered in the dilute ‘Na-Cl precipitation’ dominance zones in both models.
Figure 4. Water samples collected from the THPSS in non-urban catchments (yellow triangles) versus THPSS in urban catchments (red diamonds) plotted on the Gibbs [34] anion (a,b) cation models. The urban and non-urban THPSS formed separate clusters in both cation and anion models. The urban THPSS samples clustered closer to the centre near the ‘rock dominance’ zones in the Gibbs [34] anion (a,b) cation models. The non-urban THPSS samples clustered in the dilute ‘Na-Cl precipitation’ dominance zones in both models.
Water 17 02385 g004aWater 17 02385 g004b
Water 17 02385 g005aWater 17 02385 g005b
Figure 5. Mean (plus/minus standard error of mean) value of total metal concentrations (a) manganese, (b) barium, (c) strontium, and (d) iron measured in water from exit streams emerging from each of eight THPSS (August 2023 to March 2024). The first four swamps are non-urban and are unshaded (GC, HH, MH, and NN), and the next four are shaded urban-influenced (GU, LA, PG, and SW). Swamp location and catchment details are given in Table 1. The dotted line represents the 80th percentile of results from non-urban swamps.
Figure 5. Mean (plus/minus standard error of mean) value of total metal concentrations (a) manganese, (b) barium, (c) strontium, and (d) iron measured in water from exit streams emerging from each of eight THPSS (August 2023 to March 2024). The first four swamps are non-urban and are unshaded (GC, HH, MH, and NN), and the next four are shaded urban-influenced (GU, LA, PG, and SW). Swamp location and catchment details are given in Table 1. The dotted line represents the 80th percentile of results from non-urban swamps.
Water 17 02385 g005aWater 17 02385 g005b
Table 1. Name, code, and location (including latitude and longitude) of urban and non-urban THPSS in the Blue Mountains, NSW. Total catchment area, size of swamp, and area of urban land in catchment (all in hectares). The proportion of urban landuse within the swamp catchment is provided as a percentage (%). m = metres. ha = hectares. ASL = above sea level. * the GC catchment includes about 4 ha of cleared land, with some small buildings, at the inactive Katoomba airfield.
Table 1. Name, code, and location (including latitude and longitude) of urban and non-urban THPSS in the Blue Mountains, NSW. Total catchment area, size of swamp, and area of urban land in catchment (all in hectares). The proportion of urban landuse within the swamp catchment is provided as a percentage (%). m = metres. ha = hectares. ASL = above sea level. * the GC catchment includes about 4 ha of cleared land, with some small buildings, at the inactive Katoomba airfield.
Name of Swamp (Code)LocationUrban or Non-UrbanLattitude (° North)Longitude (° East)mASLCatchment Area and (Size of Swamp) haUrban Land in ha (% of Total Catchment)
Grand Canyon (GC)BlackheathNon-urban−33.6624150.319893041.9 (1.46)0 (0) *
Hat Hill (HH)Bennetts CreekNon-urban−33.5983150.329092034.9 (2.1)0 (0)
Mount Hay (MH)LeuraNon-urban−33.6686150.346791011.4 (1.9)0 (0)
Narrow Neck (NN)Diamond CreekNon-urban−33.7437150.278395055.5 (1.5)0 (0)
Popes Glen (PG)BlackheathUrban−33.6335150.2926101573 (1.0)65.5 (89.7%)
Garguree (GU)KatoombaUrban−33.7122150.304897057 (2.9)22.2 (38.9%)
Scenic World (SW)KatoombaUrban−33.7273150.301294017.3 (0.6)12.8 (74%)
Lawson (LA)Wilson ParkUrban−33.7159150.426969073.6 (3.5)33.2 (54.9%)
Table 2. Independent Mann–Whitney U test significance results and summary statistics comparing the water physical and chemical results from the non-urban and urban THPSS. The significance level was <0.05. The minimum (Min.), maximum (Max.), and mean (median) of the results obtained from four non-urban THPSS (naturally vegetated catchments) and urban THPSS (catchments with some urban land) are provided. <LOR—below the limit of reporting. EC is electrical conductivity. DO % Sat. is dissolved oxygen percentage saturation. Total N is total nitrogen. In order to derive guideline trigger values according to [29], the 80th percentile is provided for water quality attributes from non-urban THPSS (pH, EC, turbidity, nitrogen, barium, strontium, manganese and iron) that are used to define the reference condition. The 20th percentile is provided for dissolved oxygen from the non-urban THPSS.
Table 2. Independent Mann–Whitney U test significance results and summary statistics comparing the water physical and chemical results from the non-urban and urban THPSS. The significance level was <0.05. The minimum (Min.), maximum (Max.), and mean (median) of the results obtained from four non-urban THPSS (naturally vegetated catchments) and urban THPSS (catchments with some urban land) are provided. <LOR—below the limit of reporting. EC is electrical conductivity. DO % Sat. is dissolved oxygen percentage saturation. Total N is total nitrogen. In order to derive guideline trigger values according to [29], the 80th percentile is provided for water quality attributes from non-urban THPSS (pH, EC, turbidity, nitrogen, barium, strontium, manganese and iron) that are used to define the reference condition. The 20th percentile is provided for dissolved oxygen from the non-urban THPSS.
Non-Urban THPSSUrban THPSS
Variable (Unit)Mann–Whitney U-Test Significance Min.–Max.Mean (Median)Min.–Max.Mean (Median)80th (20th) Percentile
pH (pH units)<0.0014.24–6.215.31 (5.4)5.38–6.86 6.19 (6.35)5.79
EC (µS cm−1)<0.00120.4–41.328 (25.6)48–138.287.3 (90.1)33.6
Turbidity (NTU)<0.0010.43–11.81.98 (1.39)1.12–15.26.35 (5.15)2
DO (% Sat.)<0.00179.6–103.489.8 (90.3)38.3–75.358.3 (58.6)82 (20th)
Calcium (mg L−1)-<LOR -3–17 7.74 (7.5)-
Potassium (mg L−1)-<LOR-<LOR–20.752 (0.7)-
Sodium (mg L−1)<0.0013–5.4 3.98 (4)3–9 5.36 (5)-
Magnesium (mg L−1)-<LOR <LOR–20.78 (0.8)-
Bicarbonate (mg L−1)<0.001<LOR–6-7–39 19.64 (17)-
Sulphate (mg L−1)<0.001<LOR–1 -1–72.7 (2.5)-
Chloride (mg L−1)<0.0014–9 6.4 (6)4–22 11.5 (9.5)-
Total N (µg L−1)<0.001<LOR–400 60 (<LOR)<LOR–400210 (200)-
Aluminium (µg L−1)<0.00150–180 101.3 (90)5–14047 (40)-
Barium (µg L−1)<0.001<LOR–72.96 (3)12–3017.2 (16)5
Iron (µg L−1)<0.001110–1800414 (265)1100–13,0003136 (1800)420
Manganese (µg L−1)<0.001<LOR–134.5 (2.5)18–22056.4 (49)9
Strontium (µg/L)<0.001<LOR–3.51.96 (2.5)17–48 (29.2)28.9 (29)2.8
Zinc (µg L−1)<0.001<LOR–173.9 (2)2–34 12.4 (11.4)-
Temperature (°C)0.1897.8–33.115.3 (13.4)9.4–22.114.1 (14)-
Table 3. Mean values of eight water quality attributes recorded at the non-urban compared to the urban THPSS in the current study and in previous studies [11,19,22]. The recommended THPSS guidelines are provided for the 80th percentile of the non-urban results, with the exception of dissolved oxygen (20th percentile for dissolved oxygen (DO) % saturation), calculated from the current study.
Table 3. Mean values of eight water quality attributes recorded at the non-urban compared to the urban THPSS in the current study and in previous studies [11,19,22]. The recommended THPSS guidelines are provided for the 80th percentile of the non-urban results, with the exception of dissolved oxygen (20th percentile for dissolved oxygen (DO) % saturation), calculated from the current study.
pH (pH Units)EC(µS cm−1)Turbidity (NTU)DO (% sat.)Ba (µg L−1)Sr (µg L−1)Fe (µg L−1L)Mn (µg/L)
Non-UrbanUrbanNon-UrbanUrbanNon-UrbanUrbanNon-UrbanUrbanNon-UrbanUrbanNon-UrbanUrbanNon-UrbanUrbanNon-UrbanUrban
This study5.316.192887.31.986.3489.858.32.9617.21.9929.241431555.2957.2
Carroll et al., 2022 [19]4.876.245.6116.33.013.5--5.5718.633.8537.328222889.9568.9
Purdy, 2019 [22]5.036.5736113--83.568.6
Belmer et al., 2015 [11]4.76.6261541.43.871.969.1
80th %ile5.79 33.6 2.0 5.0 2.8 420 9
20th %ile 82.0
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Wright, I.A.; Nettle, H.; King, U.D.; Franklin, M.J.M.; Gilpin, A.-M. Urban Geochemical Contamination of Highland Peat Wetlands of Very High Ecological and First Nations Cultural Value. Water 2025, 17, 2385. https://doi.org/10.3390/w17162385

AMA Style

Wright IA, Nettle H, King UD, Franklin MJM, Gilpin A-M. Urban Geochemical Contamination of Highland Peat Wetlands of Very High Ecological and First Nations Cultural Value. Water. 2025; 17(16):2385. https://doi.org/10.3390/w17162385

Chicago/Turabian Style

Wright, Ian A., Holly Nettle, Uncle David King, Michael J. M. Franklin, and Amy-Marie Gilpin. 2025. "Urban Geochemical Contamination of Highland Peat Wetlands of Very High Ecological and First Nations Cultural Value" Water 17, no. 16: 2385. https://doi.org/10.3390/w17162385

APA Style

Wright, I. A., Nettle, H., King, U. D., Franklin, M. J. M., & Gilpin, A.-M. (2025). Urban Geochemical Contamination of Highland Peat Wetlands of Very High Ecological and First Nations Cultural Value. Water, 17(16), 2385. https://doi.org/10.3390/w17162385

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