This page has only limited features, please log in for full access.

Unclaimed
Chris J. Curtis
Department of Geography, Environmental Management and Energy Studies, University of Johannesburg, PO Box 524, Auckland Park 2600, South Africa

Basic Info

Basic Info is private.

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

The user biography is not available.
Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Journal article
Published: 29 April 2021 in Water SA
Reads 0
Downloads 0

The Hartbeespoort Dam, located 40 km west of Tshwane on the Crocodile River, is an extremely eutrophic water body. Situated in one of the most economically active areas of South Africa, it receives a high nutrient input from wastewater treatment works (WWTW), leaking sewers, as well as urban and agricultural runoff. The Metsi a Me programme, which ran from 2006 to 2016, aimed to mitigate in-lake nutrient stocks using biomanipulation, including the physical removal of Eichhornia crassipes (water hyacinth) and Microcystis aeruginosa (blue-green algae). Using Department of Water and Sanitation water quality and flow data, the annual influxes and outfluxes of total nitrogen (TN) and total phosphorus (TP) to the Hartbeespoort Dam were calculated. Through literature review and comparison with previous studies, the relative importance of nutrient removal from biomass harvesting in relation to retained nutrients was assessed. The average nutrient influx from rivers during hydrological years 2010/11 to 2016/17 was 582 t∙a−1 TP and 4 687 t∙a−1 TN, with trends for both TN and TP being significantly positive over this period. TP influx increased by 77.8 t∙a−1 every year and TN influx increased by 456 t∙a−1, reversing a long-term negative trend. Average annual dam retention + removal (calculated as the difference between river inputs and outputs, i.e., including sedimentation, biomass removal and denitrification losses) was 358 t P and 2 195 t N. A best estimation of nutrient removal from water hyacinth and algal harvesting was 2.1 t∙a−1 P and 11.5 t∙a−1 N, and 3.9 t∙a−1 P and 40 t∙a−1 N, respectively. An estimated 341 t∙a−1 P and 674–1 288 t∙a−1 N was sedimented. Denitrification losses are poorly quantified but are possibly comparable to sedimentation. River outfluxes increased by 28.4 t∙a−1 TP and 110 t∙a−1 TN, smaller rates than the influxes, suggesting increasing retention per annum. Upgrading WWTWs in the catchment and refurbishing leaking and overflowing sewers is the most appropriate long-term solution.

ACS Style

Asd Carroll; Cj Curtis. Increasing nutrient influx trends and remediation options at Hartbeespoort Dam, South Africa: a mass-balance approach. Water SA 2021, 47, 1 .

AMA Style

Asd Carroll, Cj Curtis. Increasing nutrient influx trends and remediation options at Hartbeespoort Dam, South Africa: a mass-balance approach. Water SA. 2021; 47 (2 April):1.

Chicago/Turabian Style

Asd Carroll; Cj Curtis. 2021. "Increasing nutrient influx trends and remediation options at Hartbeespoort Dam, South Africa: a mass-balance approach." Water SA 47, no. 2 April: 1.

Article
Published: 13 February 2021 in Environmental Monitoring and Assessment
Reads 0
Downloads 0

As a historic gold mining area, the City of Benoni has numerous water bodies close to major tailings dams and mine dumps. Here we assess spatial patterns in the sediment geochemistry of five dams and four natural pans within a 5-km radius of the core mining area to determine the degree of contamination7 by mining-associated pollutants. XRF analysis was used with a geoaccumulation index to assess the degree of contamination above background levels. Prevailing winds blow from the north and north-west with less dominant winds from the east. Sediment concentrations of As, Cu, Pb, Ni and Zn are highly correlated across the region, suggestive of a common source. Except for one pan showing evidence of local industrial pollution, the most contaminated sites are the dams to the west of the mine dumps where concentrations of As, Cu, Pb and Zn increase towards the central mining area, with highest trace metal concentrations in Kleinfontein Dam, adjacent to a reworked mine dump. Sites upwind of the central mining area showed little evidence of mining-related contamination. Trace contaminant concentrations in sediments of these dams are much greater than those found in the nearby Springs-Blesbokspruit wetlands adjacent to more recently active mines. The potential risks to aquatic ecosystems and recreational users of these urban and suburban water bodies from these wind-blown, legacy mining contaminants merit further investigation.

ACS Style

D. M. du Plessis; C. J. Curtis. Trace element contaminants associated with historic gold mining in sediments of dams and pans across Benoni, South Africa. Environmental Monitoring and Assessment 2021, 193, 1 -17.

AMA Style

D. M. du Plessis, C. J. Curtis. Trace element contaminants associated with historic gold mining in sediments of dams and pans across Benoni, South Africa. Environmental Monitoring and Assessment. 2021; 193 (3):1-17.

Chicago/Turabian Style

D. M. du Plessis; C. J. Curtis. 2021. "Trace element contaminants associated with historic gold mining in sediments of dams and pans across Benoni, South Africa." Environmental Monitoring and Assessment 193, no. 3: 1-17.

Article
Published: 10 January 2021 in Climate Dynamics
Reads 0
Downloads 0

South Africa spans the subtropics at the interface between tropical, subtropical, and temperate weather systems, and consequently experiences distinct summer-, winter- and year-round rainfall zones (SRZ, WRZ and YRZ). Spatio-temporal characteristics of the various weather systems are broadly understood, however, the rainfall seasonality classification at the transition between these rainfall zones remains disputed. This surrounds the complexity of rainfall regimes, however, metrics with dissimilar rainfall seasonality definitions have been applied, hindering comparability. To address this dispute, meteorological data spanning 1987–2016 from 46 weather stations is used to assess the utility of a metric posited to quantify rainfall seasonality through a seasonality score derived from a ratio of monthly rainfall: temperature. This score statistically discriminates SRZ, WRZ and YRZ conditions, fulfilling an important requirement for a metric applied to South Africa. Nelspruit (NEL; score = 1.59) represents the strongest SRZ conditions across 30 eastern and central locations with scores > 0.30. Cape Town Wo (CTW; score = − 1.04) represents the strongest WRZ conditions across seven southwestern Cape and west coast locations with scores < − 0.30. Characterising the SRZ-to-WRZ transition region with scores from − 0.30 to 0.30, nine YRZ locations were classified. With the weakest score, Oudtshoorn (OUD; score = − 0.05), within the Cape Fold mountains, most represents YRZ conditions. Applicability across all weather stations, compatibility with known rainfall drivers, and agreement with known spatial rainfall seasonality characteristics demonstrates the ratio’s utility. Strong correspondence of scores between station and gridded data applications demonstrates additional confidence in the ratio, establishing its value for further application.

ACS Style

Sarah J. Roffe; Jennifer M. Fitchett; Christopher J. Curtis. Quantifying rainfall seasonality across South Africa on the basis of the relationship between rainfall and temperature. Climate Dynamics 2021, 56, 2431 -2450.

AMA Style

Sarah J. Roffe, Jennifer M. Fitchett, Christopher J. Curtis. Quantifying rainfall seasonality across South Africa on the basis of the relationship between rainfall and temperature. Climate Dynamics. 2021; 56 (7-8):2431-2450.

Chicago/Turabian Style

Sarah J. Roffe; Jennifer M. Fitchett; Christopher J. Curtis. 2021. "Quantifying rainfall seasonality across South Africa on the basis of the relationship between rainfall and temperature." Climate Dynamics 56, no. 7-8: 2431-2450.

Original paper
Published: 11 March 2020 in Theoretical and Applied Climatology
Reads 0
Downloads 0

Across South Africa, the timing of wet-season rainfall within the summer-, winter- and year-round rainfall zones (SRZ, WRZ and YRZ) influences activities including crop production and water resource management. While numerous start- and end-date definitions exist to classify the wet season, most rely on threshold values specified for local-scale application. Focusing on large-scale application, we critically apply an objective and consistent methodology, defining wet-season start and end dates at 10% and 90% of cumulative annual rainfall, using daily rainfall data spanning 1987–2016 for 46 South African weather stations. SRZ, WRZ or YRZ conditions are successfully quantified across all locations. The longest mean SRZ wet season spanned 223 days from 8 September to 18 April at East London Wo (ELW), along the southeast coast. Robertson (ROB), within the south-western region, had the longest mean WRZ wet season of 244 days from 9 March to 7 November. Nearby, Riversdale (RIV) had the longest mean YRZ wet season of 270 days from 17 February to 13 November. Consistency with literature regarding rainfall drivers, start and end dates and the spatial distribution of rainfall seasonality, confirms utility of this metric across South Africa. Therefore, it facilitates comparable rainfall seasonality investigations across regions, including the arid western coast and the southern coast YRZ, where previous methods lack utility, and the calculation of trends in seasonality changes across the country. While for most locations trends are not statistically significant, this method enables further monitoring.

ACS Style

Sarah J. Roffe; Jennifer M. Fitchett; Christopher J. Curtis. Determining the utility of a percentile-based wet-season start- and end-date metrics across South Africa. Theoretical and Applied Climatology 2020, 140, 1331 -1347.

AMA Style

Sarah J. Roffe, Jennifer M. Fitchett, Christopher J. Curtis. Determining the utility of a percentile-based wet-season start- and end-date metrics across South Africa. Theoretical and Applied Climatology. 2020; 140 (3-4):1331-1347.

Chicago/Turabian Style

Sarah J. Roffe; Jennifer M. Fitchett; Christopher J. Curtis. 2020. "Determining the utility of a percentile-based wet-season start- and end-date metrics across South Africa." Theoretical and Applied Climatology 140, no. 3-4: 1331-1347.

Journal article
Published: 29 January 2018 in Biogeosciences
Reads 0
Downloads 0

The relative roles of anthropogenic nitrogen (N) deposition and climate change in causing ecological change in remote Arctic ecosystems, especially lakes, have been the subject of debate over the last decade. Some palaeoecological studies have cited isotopic signals (δ(15N)) preserved in lake sediments as evidence linking N deposition with ecological change, but a key limitation has been the lack of co-located data on both deposition input fluxes and isotopic composition of deposited nitrate (NO3−). In Arctic lakes, including those in western Greenland, previous palaeolimnological studies have indicated a spatial variation in δ(15N) trends in lake sediments but data are lacking for deposition chemistry, input fluxes and stable isotope composition of NO3−. In the present study, snowpack chemistry, NO3− stable isotopes and net deposition fluxes for the largest ice-free region in Greenland were investigated to determine whether there are spatial gradients from the ice sheet margin to the coast linked to a gradient in precipitation. Late-season snowpack was sampled in March 2011 at eight locations within three lake catchments in each of three regions (ice sheet margin in the east, the central area near Kelly Ville and the coastal zone to the west). At the coast, snowpack accumulation averaged 181 mm snow water equivalent (SWE) compared with 36 mm SWE by the ice sheet. Coastal snowpack showed significantly greater concentrations of marine salts (Na+, Cl−, other major cations), ammonium (NH4+; regional means 1.4–2.7 µmol L−1), total and non-sea-salt sulfate (SO42−; total 1.8–7.7, non-sea-salt 1.0–1.8 µmol L−1) than the two inland regions. Nitrate (1.5–2.4 µmol L−1) showed significantly lower concentrations at the coast. Despite lower concentrations, higher precipitation at the coast results in greater net deposition for NO3− as well as NH4+ and non-sea-salt sulfate (nss-SO42−) relative to the inland regions (lowest at Kelly Ville 6, 4 and 3; highest at coast 9, 17 and 11 mol ha−1 a−1 of NO3−, NH4+ and nss-SO42− respectively). The δ(15N) of snowpack NO3− shows a significant decrease from inland regions (−5.7 ‰ at Kelly Ville) to the coast (−11.3 ‰). We attribute the spatial patterns of δ(15N) in western Greenland to post-depositional processing rather than differing sources because of (1) spatial relationships with precipitation and sublimation, (2) within-catchment isotopic differences between terrestrial snowpack and lake ice snowpack, and (3) similarities between fresh snow (rather than accumulated snowpack) at Kelly Ville and the coast. Hence the δ(15N) of coastal snowpack is most representative of snowfall in western Greenland, but after deposition the effects of photolysis, volatilization and sublimation lead to enrichment of the remaining snowpack with the greatest effect in inland areas of low precipitation and high sublimation losses.

ACS Style

Chris J. Curtis; Jan Kaiser; Alina Marca; N. John Anderson; Gavin Simpson; Vivienne Jones; Erika Whiteford. Spatial variations in snowpack chemistry, isotopic composition of NO3− and nitrogen deposition from the ice sheet margin to the coast of western Greenland. Biogeosciences 2018, 15, 529 -550.

AMA Style

Chris J. Curtis, Jan Kaiser, Alina Marca, N. John Anderson, Gavin Simpson, Vivienne Jones, Erika Whiteford. Spatial variations in snowpack chemistry, isotopic composition of NO3− and nitrogen deposition from the ice sheet margin to the coast of western Greenland. Biogeosciences. 2018; 15 (2):529-550.

Chicago/Turabian Style

Chris J. Curtis; Jan Kaiser; Alina Marca; N. John Anderson; Gavin Simpson; Vivienne Jones; Erika Whiteford. 2018. "Spatial variations in snowpack chemistry, isotopic composition of NO3− and nitrogen deposition from the ice sheet margin to the coast of western Greenland." Biogeosciences 15, no. 2: 529-550.

Preprint content
Published: 01 August 2017
Reads 0
Downloads 0
ACS Style

Christopher Curtis. Response to anonymous Reviewer 2. 2017, 1 .

AMA Style

Christopher Curtis. Response to anonymous Reviewer 2. . 2017; ():1.

Chicago/Turabian Style

Christopher Curtis. 2017. "Response to anonymous Reviewer 2." , no. : 1.

Preprint content
Published: 01 August 2017
Reads 0
Downloads 0
ACS Style

Christopher Curtis. Response to anonymous Reviewer 1. 2017, 1 .

AMA Style

Christopher Curtis. Response to anonymous Reviewer 1. . 2017; ():1.

Chicago/Turabian Style

Christopher Curtis. 2017. "Response to anonymous Reviewer 1." , no. : 1.

Preprint content
Published: 30 May 2017
Reads 0
Downloads 0
ACS Style

Chris J. Curtis; Jan Kaiser; Alina Marca; N. John Anderson; Gavin Simpson; Vivienne Jones; Erika Whiteford. Supplementary material to "Spatial variations in snowpack chemistry and isotopic composition of NO3− along a nitrogen deposition gradient in West Greenland". 2017, 1 .

AMA Style

Chris J. Curtis, Jan Kaiser, Alina Marca, N. John Anderson, Gavin Simpson, Vivienne Jones, Erika Whiteford. Supplementary material to "Spatial variations in snowpack chemistry and isotopic composition of NO3− along a nitrogen deposition gradient in West Greenland". . 2017; ():1.

Chicago/Turabian Style

Chris J. Curtis; Jan Kaiser; Alina Marca; N. John Anderson; Gavin Simpson; Vivienne Jones; Erika Whiteford. 2017. "Supplementary material to "Spatial variations in snowpack chemistry and isotopic composition of NO3− along a nitrogen deposition gradient in West Greenland"." , no. : 1.

Preprint content
Published: 30 May 2017
Reads 0
Downloads 0

Snowpack chemistry, nitrate stable isotopes and net deposition fluxes for the largest ice-free region in Greenland were investigated to determine whether there are spatial gradients from the ice sheet margin to the coast linked to a gradient in precipitation. Late-season snowpack was sampled in March 2011 at 8 locations within 3 lake catchments in each of 3 regions (ice sheet margin in the east, central area near Kelly Ville and the coastal zone to the west). At the coast, snowpack accumulation averaged 181 mm snow water equivalent (SWE), compared with 36 mm SWE by the ice sheet. Coastal snowpack showed significantly greater concentrations of marine salts (Na+, Cl−, other major cations), ammonium (regional means 1.4–2.7 µmol L−1), total and non-sea salt sulfate (total 1.8–7.7, non-sea salt 1.0–1.8 µmol L−1) than the two inland regions. Nitrate (1.5–2.4 µmol L−1) showed significantly lower concentrations at the coast. Despite lower concentrations, higher precipitation at the coast results in a strong deposition gradient for NO3− as well as NH4+ and non-sea salt sulfate (nss-SO42−) increasing from the inland regions to the coast (lowest at Kelly Ville 6, 4 and 3; highest at coast 9, 17 and 11 mol ha−1 yr−1 of NO3−, NH4+ and nss-SO42− respectively). The δ(15N) of snowpack NO3− shows a significant decrease from the ice sheet margin (−7.5 ‰) to the coast (−11.3 ‰). We attribute the spatial gradient of δ(15N) in SW Greenland to post-deposition processing rather than differing sources because of (1) the climatic gradient from ice sheet margin to coast, (2) within-catchment isotopic differences between terrestrial snowpack and lake-ice snowpack, and (3) similarities between fresh snow (rather than accumulated snowpack) at Kelly Ville and the coast. Hence the δ(15N) of coastal snowpack is most representative of snowfall in SW Greenland, but after deposition the effects of photolysis, volatilization and sublimation lead to enrichment of the remaining snowpack with the greatest effect in inland areas of low precipitation and high sublimation losses.

ACS Style

Chris J. Curtis; Jan Kaiser; Alina Marca; N. John Anderson; Gavin Simpson; Vivienne Jones; Erika Whiteford. Spatial variations in snowpack chemistry and isotopic composition of NO3− along a nitrogen deposition gradient in West Greenland. 2017, 1 -32.

AMA Style

Chris J. Curtis, Jan Kaiser, Alina Marca, N. John Anderson, Gavin Simpson, Vivienne Jones, Erika Whiteford. Spatial variations in snowpack chemistry and isotopic composition of NO3− along a nitrogen deposition gradient in West Greenland. . 2017; ():1-32.

Chicago/Turabian Style

Chris J. Curtis; Jan Kaiser; Alina Marca; N. John Anderson; Gavin Simpson; Vivienne Jones; Erika Whiteford. 2017. "Spatial variations in snowpack chemistry and isotopic composition of NO3− along a nitrogen deposition gradient in West Greenland." , no. : 1-32.

Journal article
Published: 15 December 2016 in African Journal of Aquatic Science
Reads 0
Downloads 0

Despite their remoteness from sources of atmospheric pollutant emissions, the Afromontane tarns in the Maloti-Drakensberg region are perfect candidates to study the negative effects of acidifying atmospheric pollution, because mountain lakes are widely recognised as sentinel ecosystems, unimpacted by direct human disturbance within their catchments. Thirty-four tarns were sampled in the Maloti-Drakensberg region and most were found to be extremely sensitive to acidic deposition, as indicated by their low acid neutralising capacity. There are very few studies of freshwater critical loads for any region within South Africa. The steady-state water chemistry model (SSWC) was adapted and used to determine critical loads, whereas exceedance was estimated relative to modelled regional deposition data, in order to understand the risk of harmful effects to aquatic ecosystems. Seventy-six percent of sampled sites across the Maloti-Drakensberg would exceed critical loads even at the lowest modelled deposition levels, but there are no current measured deposition data for the region. The sensitivity of the Maloti-Drakensberg tarns needs to be considered in future policy formulation regarding acceptable levels of acidifying atmospheric pollution from South Africa’s energy sector and indicates the need for assessing aquatic ecosystem impacts in other regions of South Africa.

ACS Style

Ja Dunnink; Cj Curtis; Johan Paul Beukes; Pieter van Zyl; Jan-Stefan Swartz. The sensitivity of Afromontane tarns in the Maloti-Drakensberg region of South Africa and Lesotho to acidic deposition. African Journal of Aquatic Science 2016, 41, 413 -426.

AMA Style

Ja Dunnink, Cj Curtis, Johan Paul Beukes, Pieter van Zyl, Jan-Stefan Swartz. The sensitivity of Afromontane tarns in the Maloti-Drakensberg region of South Africa and Lesotho to acidic deposition. African Journal of Aquatic Science. 2016; 41 (4):413-426.

Chicago/Turabian Style

Ja Dunnink; Cj Curtis; Johan Paul Beukes; Pieter van Zyl; Jan-Stefan Swartz. 2016. "The sensitivity of Afromontane tarns in the Maloti-Drakensberg region of South Africa and Lesotho to acidic deposition." African Journal of Aquatic Science 41, no. 4: 413-426.

Journal article
Published: 18 April 2016 in Science of The Total Environment
Reads 0
Downloads 0

For the Western North America Mercury Synthesis, we compiled mercury records from 165 dated sediment cores from 138 natural lakes across western North America. Lake sediments are accepted as faithful recorders of historical mercury accumulation rates, and regional and sub-regional temporal and spatial trends were analyzed with descriptive and inferential statistics. Mercury accumulation rates in sediments have increased, on average, four times (4 ×) from 1850 to 2000 and continue to increase by approximately 0.2 μg/m2 per year. Lakes with the greatest increases were influenced by the Flin Flon smelter, followed by lakes directly affected by mining and wastewater discharges. Of lakes not directly affected by point sources, there is a clear separation in mercury accumulation rates between lakes with no/little watershed development and lakes with extensive watershed development for agricultural and/or residential purposes. Lakes in the latter group exhibited a sharp increase in mercury accumulation rates with human settlement, stabilizing after 1950 at five times (5 ×) 1850 rates. Mercury accumulation rates in lakes with no/little watershed development were controlled primarily by relative watershed size prior to 1850, and since have exhibited modest increases (in absolute terms and compared to that described above) associated with (regional and global) industrialization. A sub-regional analysis highlighted that in the ecoregion Northwestern Forest Mountains, < 1% of mercury deposited to watersheds is delivered to lakes. Research is warranted to understand whether mountainous watersheds act as permanent sinks for mercury or if export of “legacy” mercury (deposited in years past) will delay recovery when/if emissions reductions are achieved.

ACS Style

Paul E. Drevnick; Colin A. Cooke; Daniella Barraza; Jules M. Blais; Kenneth H. Coale; Brian F. Cumming; Chris J. Curtis; Biplob Das; William F. Donahue; Collin A. Eagles-Smith; Daniel R. Engstrom; William F. Fitzgerald; Chad V. Furl; John E. Gray; Roland I. Hall; Togwell A. Jackson; Kathleen R. Laird; W. Lyle Lockhart; Robie W. Macdonald; M. Alisa Mast; Callie Mathieu; Derek C.G. Muir; Peter M. Outridge; Scott A. Reinemann; Sarah E. Rothenberg; Ana Carolina Ruiz-Fernández; Vincent L. St. Louis; Rhea D. Sanders; Hamed Sanei; Elliott K. Skierszkan; Peter C. Van Metre; Timothy J. Veverica; Johan A. Wiklund; Brent B. Wolfe. Spatiotemporal patterns of mercury accumulation in lake sediments of western North America. Science of The Total Environment 2016, 568, 1157 -1170.

AMA Style

Paul E. Drevnick, Colin A. Cooke, Daniella Barraza, Jules M. Blais, Kenneth H. Coale, Brian F. Cumming, Chris J. Curtis, Biplob Das, William F. Donahue, Collin A. Eagles-Smith, Daniel R. Engstrom, William F. Fitzgerald, Chad V. Furl, John E. Gray, Roland I. Hall, Togwell A. Jackson, Kathleen R. Laird, W. Lyle Lockhart, Robie W. Macdonald, M. Alisa Mast, Callie Mathieu, Derek C.G. Muir, Peter M. Outridge, Scott A. Reinemann, Sarah E. Rothenberg, Ana Carolina Ruiz-Fernández, Vincent L. St. Louis, Rhea D. Sanders, Hamed Sanei, Elliott K. Skierszkan, Peter C. Van Metre, Timothy J. Veverica, Johan A. Wiklund, Brent B. Wolfe. Spatiotemporal patterns of mercury accumulation in lake sediments of western North America. Science of The Total Environment. 2016; 568 ():1157-1170.

Chicago/Turabian Style

Paul E. Drevnick; Colin A. Cooke; Daniella Barraza; Jules M. Blais; Kenneth H. Coale; Brian F. Cumming; Chris J. Curtis; Biplob Das; William F. Donahue; Collin A. Eagles-Smith; Daniel R. Engstrom; William F. Fitzgerald; Chad V. Furl; John E. Gray; Roland I. Hall; Togwell A. Jackson; Kathleen R. Laird; W. Lyle Lockhart; Robie W. Macdonald; M. Alisa Mast; Callie Mathieu; Derek C.G. Muir; Peter M. Outridge; Scott A. Reinemann; Sarah E. Rothenberg; Ana Carolina Ruiz-Fernández; Vincent L. St. Louis; Rhea D. Sanders; Hamed Sanei; Elliott K. Skierszkan; Peter C. Van Metre; Timothy J. Veverica; Johan A. Wiklund; Brent B. Wolfe. 2016. "Spatiotemporal patterns of mercury accumulation in lake sediments of western North America." Science of The Total Environment 568, no. : 1157-1170.

Journal article
Published: 01 December 2015 in Science of The Total Environment
Reads 0
Downloads 0

Of increasing concern is pollution by volatile organic compounds, with particular reference to five aromatic hydrocarbons (benzene, toluene, ethyl benzene and two isomeric xylenes; BTEX). These pollutants are classified as hazardous air pollutants. Due to the potential health risks associated with these pollutants, BTEX concentrations were monitored at a bus diesel-refueling bay, in Johannesburg, South Africa, using gas chromatography, coupled with a photo-ionization detector. Results indicate that o-xylene (29-50%) and benzene (13-33%) were found to be the most abundant species of total BTEX at the site. Benzene was within South African occupational limits, but above international occupational exposure limits. On the other hand, occupational concentrations of toluene, ethyl-benzene and xylenes were within national and international occupational limits throughout the monitoring period, based on 8-hour workday weighted averages. Ethyl-benzene and p-xylene concentrations, during winter, correspond to activity at the site, and thus idling of buses during refueling may elevate results. Overall, occupational air quality at the refueling bay is a matter of health concern, especially with regards to benzene exposure, and future reduction strategies are crucial. Discrepancies between national and international limit values merit further investigation to determine whether South African guidelines for benzene are sufficiently precautionary.

ACS Style

Raeesa Moolla; Christopher J. Curtis; Jasper Knight. Assessment of occupational exposure to BTEX compounds at a bus diesel-refueling bay: A case study in Johannesburg, South Africa. Science of The Total Environment 2015, 537, 51 -57.

AMA Style

Raeesa Moolla, Christopher J. Curtis, Jasper Knight. Assessment of occupational exposure to BTEX compounds at a bus diesel-refueling bay: A case study in Johannesburg, South Africa. Science of The Total Environment. 2015; 537 ():51-57.

Chicago/Turabian Style

Raeesa Moolla; Christopher J. Curtis; Jasper Knight. 2015. "Assessment of occupational exposure to BTEX compounds at a bus diesel-refueling bay: A case study in Johannesburg, South Africa." Science of The Total Environment 537, no. : 51-57.

Book chapter
Published: 19 April 2015 in Climate Change Impacts on Water Resources
Reads 0
Downloads 0

Lake acidification in northern Europe provided some of the key impetus for the development of the critical loads approach during the 1980s. While major reductions in acidic deposition have been achieved during the last 20 years, through the application of this approach, regions with continued acidification and critical load exceedance persist around Europe. This chapter describes regional applications of the First-order Acidity Balance (FAB) model in five European countries, highlighting national approaches to lake surveys and regional representation, and how the model has been adapted in each of these countries. We discuss the implications of interpreting critical load exceedances, and provide an overall synthesis of freshwater exceedance in Europe using common European deposition data. Despite uncertainties within the FAB model, such as the parameterisation of nitrogen immobilisation and denitrification, a coherent picture of the spatial extent of acidification within European lakes is evident. The ongoing failure to meet critical loads by 2020 demonstrates that lake acidification is still a current, not a historical, problem in Europe, and under current legislation many lakes will remain more acidic than their pre-industrial reference condition.

ACS Style

Chris J. Curtis; Maximilian Posch; Julian Aherne; Jens Fölster; Martin Forsius; Thorjørn Larssen; Filip Moldan. Assessment of Critical Loads of Acidity and Their Exceedances for European Lakes. Climate Change Impacts on Water Resources 2015, 439 -462.

AMA Style

Chris J. Curtis, Maximilian Posch, Julian Aherne, Jens Fölster, Martin Forsius, Thorjørn Larssen, Filip Moldan. Assessment of Critical Loads of Acidity and Their Exceedances for European Lakes. Climate Change Impacts on Water Resources. 2015; ():439-462.

Chicago/Turabian Style

Chris J. Curtis; Maximilian Posch; Julian Aherne; Jens Fölster; Martin Forsius; Thorjørn Larssen; Filip Moldan. 2015. "Assessment of Critical Loads of Acidity and Their Exceedances for European Lakes." Climate Change Impacts on Water Resources , no. : 439-462.

Journal article
Published: 13 April 2015 in International Journal of Environmental Research and Public Health
Reads 0
Downloads 0

Diesel fuel is known to emit pollutants that have a negative impact on environmental and human health. In developing countries like South Africa, attendants are employed to pump fuel for customers at service stations. Attendants refuel vehicles with various octane unleaded fuel, lead-replacement petrol and diesel fuel, on a daily basis. Attendants are at risk to adverse health effects associated with the inhalation of volatile organic compounds released from these fuels. The pollutants released include benzene, toluene, ethylbenzene and xylenes (BTEX), which are significant due to their high level of toxicity. In this study, a risk assessment of BTEX was conducted at a diesel service station for public buses. Using Radiello passive samplers, it was found that benzene concentrations were above recommended international standards. Due to poor ventilation and high exposure duration, the average benzene concentration over the sampling campaign exceeded the US Environmental Protection Agency’s chronic inhalation exposure reference concentration. Lifetime cancer risk estimation showed that on average there is a 3.78 × 10−4 cancer risk, corresponding to an average chronic daily intake of 1.38 × 10−3 mg/kg/day of benzene exposure. Additionally, there were incidences where individuals were at potential hazard risk of benzene and toluene that may pose non-carcinogenic effects to employees.

ACS Style

Raeesa Moolla; Christopher J. Curtis; Jasper Knight. Occupational Exposure of Diesel Station Workers to BTEX Compounds at a Bus Depot. International Journal of Environmental Research and Public Health 2015, 12, 4101 -4115.

AMA Style

Raeesa Moolla, Christopher J. Curtis, Jasper Knight. Occupational Exposure of Diesel Station Workers to BTEX Compounds at a Bus Depot. International Journal of Environmental Research and Public Health. 2015; 12 (4):4101-4115.

Chicago/Turabian Style

Raeesa Moolla; Christopher J. Curtis; Jasper Knight. 2015. "Occupational Exposure of Diesel Station Workers to BTEX Compounds at a Bus Depot." International Journal of Environmental Research and Public Health 12, no. 4: 4101-4115.

Book chapter
Published: 11 April 2014 in Nitrogen Deposition, Critical Loads and Biodiversity
Reads 0
Downloads 0

It is now widely recognised that the deposition of nitrogen (N) compounds can lead to both acidification and eutrophication impacts in upland lakes. While major reductions in sulphur (S) emissions and deposition in the UK have been largely matched by chemical recovery from acidification in surface waters, reductions in emissions of N compounds have not been matched by corresponding reductions in deposition. Here we explore two related issues in the use of critical loads for N in upland waters:

ACS Style

Chris J. Curtis; Gavin L. Simpson; Rick W. Battarbee; Stephen Maberly. Challenges in Defining Critical Loads for Nitrogen in UK Lakes. Nitrogen Deposition, Critical Loads and Biodiversity 2014, 337 -344.

AMA Style

Chris J. Curtis, Gavin L. Simpson, Rick W. Battarbee, Stephen Maberly. Challenges in Defining Critical Loads for Nitrogen in UK Lakes. Nitrogen Deposition, Critical Loads and Biodiversity. 2014; ():337-344.

Chicago/Turabian Style

Chris J. Curtis; Gavin L. Simpson; Rick W. Battarbee; Stephen Maberly. 2014. "Challenges in Defining Critical Loads for Nitrogen in UK Lakes." Nitrogen Deposition, Critical Loads and Biodiversity , no. : 337-344.

Book chapter
Published: 11 April 2014 in Nitrogen Deposition, Critical Loads and Biodiversity
Reads 0
Downloads 0

This chapter reports the findings of a Working Group to review the critical loads (CLs) and levels approach for nitrogen (N). The three main approaches to estimating CLs are empirical, mass balance and dynamic modelling. Examples are given of recent developments in Europe, North America and Asia and it is concluded that other countries should be encouraged to develop basic assessments using soil, land cover, and deposition map overlays in order to determine what regions might exceed nitrogen CLs. There is a need for increasing the certainty of critical load (CL) estimates by focusing on empirical data needs, especially for understudied ecosystems such as tropical or Mediterranean, high elevation environments, and aquatic systems. There is also a need to improve steady-state mass balance parameters, especially soil solution terms, such as nitrate leaching, used to determine the CL, and denitrification, which is an equation parameter. Improved dynamic models are needed for predicting plant community changes, and work should continue on existing models to determine CL values. Dynamic models require more data and are more complex than simple calculated CLs but offer more information and allow the development of ‘what if?’ scenarios. Optimal use of CLs requires expert knowledge of ecosystem values to provide reference states so that safe deposition amounts can be determined. Increased interaction between CL and biodiversity specialists to identify critical biodiversity limits would help provide better CL assessments.

ACS Style

Thomas A. Clair; Tamara Blett; Julian Aherne; Marcos P. M. Aidar; Richard Artz; William J. Bealey; William Budd; J. Neil Cape; Chris J. Curtis; Lei Duan; Mark E. Fenn; Peter Groffman; Richard Haeuber; Jane R. Hall; Jean-Paul Hettelingh; Danilo López-Hernández; Scot Mathieson; Linda Pardo; Maximilian Posch; Richard V. Pouyat; Till Spranger; Harald Sverdrup; Hans Van Dobben; Arjan Van Hinsberg. The Critical Loads and Levels Approach for Nitrogen. Nitrogen Deposition, Critical Loads and Biodiversity 2014, 481 -491.

AMA Style

Thomas A. Clair, Tamara Blett, Julian Aherne, Marcos P. M. Aidar, Richard Artz, William J. Bealey, William Budd, J. Neil Cape, Chris J. Curtis, Lei Duan, Mark E. Fenn, Peter Groffman, Richard Haeuber, Jane R. Hall, Jean-Paul Hettelingh, Danilo López-Hernández, Scot Mathieson, Linda Pardo, Maximilian Posch, Richard V. Pouyat, Till Spranger, Harald Sverdrup, Hans Van Dobben, Arjan Van Hinsberg. The Critical Loads and Levels Approach for Nitrogen. Nitrogen Deposition, Critical Loads and Biodiversity. 2014; ():481-491.

Chicago/Turabian Style

Thomas A. Clair; Tamara Blett; Julian Aherne; Marcos P. M. Aidar; Richard Artz; William J. Bealey; William Budd; J. Neil Cape; Chris J. Curtis; Lei Duan; Mark E. Fenn; Peter Groffman; Richard Haeuber; Jane R. Hall; Jean-Paul Hettelingh; Danilo López-Hernández; Scot Mathieson; Linda Pardo; Maximilian Posch; Richard V. Pouyat; Till Spranger; Harald Sverdrup; Hans Van Dobben; Arjan Van Hinsberg. 2014. "The Critical Loads and Levels Approach for Nitrogen." Nitrogen Deposition, Critical Loads and Biodiversity , no. : 481-491.

Journal article
Published: 07 February 2014 in Water, Air, & Soil Pollution
Reads 0
Downloads 0

Acidification of lakes and rivers is still an environmental concern despite reduced emissions of acidifying compounds. We analysed trends in surface water chemistry of 173 acid-sensitive sites from 12 regions in Europe and North America. In 11 of 12 regions, non-marine sulphate (SO4*) declined significantly between 1990 and 2008 (−15 to −59 %). In contrast, regional and temporal trends in nitrate were smaller and less uniform. In 11 of 12 regions, chemical recovery was demonstrated in the form of positive trends in pH and/or alkalinity and/or acid neutralising capacity (ANC). The positive trends in these indicators of chemical recovery were regionally and temporally less distinct than the decline in SO4* and tended to flatten after 1999. From an ecological perspective, the chemical quality of surface waters in acid-sensitive areas in these regions has clearly improved as a consequence of emission abatement strategies, paving the way for some biological recovery.

ACS Style

Øyvind A. Garmo; Brit Lisa Skjelkvåle; Heleen A de Wit; Luca Colombo; Chris Curtis; Jens Fölster; Andreas Hoffmann; Jakub Hruška; Tore Høgåsen; Dean S. Jeffries; W. Bill Keller; Pavel Kram; Vladimir Majer; Don T. Monteith; Andrew M. Paterson; Michela Rogora; Dorota Rzychon; Sandra Martina Steingruber; John Stoddard; Jussi Vuorenmaa; Adam Worsztynowicz. Trends in Surface Water Chemistry in Acidified Areas in Europe and North America from 1990 to 2008. Water, Air, & Soil Pollution 2014, 225, 1 -14.

AMA Style

Øyvind A. Garmo, Brit Lisa Skjelkvåle, Heleen A de Wit, Luca Colombo, Chris Curtis, Jens Fölster, Andreas Hoffmann, Jakub Hruška, Tore Høgåsen, Dean S. Jeffries, W. Bill Keller, Pavel Kram, Vladimir Majer, Don T. Monteith, Andrew M. Paterson, Michela Rogora, Dorota Rzychon, Sandra Martina Steingruber, John Stoddard, Jussi Vuorenmaa, Adam Worsztynowicz. Trends in Surface Water Chemistry in Acidified Areas in Europe and North America from 1990 to 2008. Water, Air, & Soil Pollution. 2014; 225 (3):1-14.

Chicago/Turabian Style

Øyvind A. Garmo; Brit Lisa Skjelkvåle; Heleen A de Wit; Luca Colombo; Chris Curtis; Jens Fölster; Andreas Hoffmann; Jakub Hruška; Tore Høgåsen; Dean S. Jeffries; W. Bill Keller; Pavel Kram; Vladimir Majer; Don T. Monteith; Andrew M. Paterson; Michela Rogora; Dorota Rzychon; Sandra Martina Steingruber; John Stoddard; Jussi Vuorenmaa; Adam Worsztynowicz. 2014. "Trends in Surface Water Chemistry in Acidified Areas in Europe and North America from 1990 to 2008." Water, Air, & Soil Pollution 225, no. 3: 1-14.

Journal article
Published: 01 February 2014 in Ecological Indicators
Reads 0
Downloads 0
ACS Style

Chris Curtis; Gavin Simpson. Trends in bulk deposition of acidity in the UK, 1988–2007, assessed using additive models. Ecological Indicators 2014, 37, 274 -286.

AMA Style

Chris Curtis, Gavin Simpson. Trends in bulk deposition of acidity in the UK, 1988–2007, assessed using additive models. Ecological Indicators. 2014; 37 ():274-286.

Chicago/Turabian Style

Chris Curtis; Gavin Simpson. 2014. "Trends in bulk deposition of acidity in the UK, 1988–2007, assessed using additive models." Ecological Indicators 37, no. : 274-286.

Journal article
Published: 01 February 2014 in Ecological Indicators
Reads 0
Downloads 0

In this special issue we present papers based on data from the UK's Acid Waters Monitoring Network (UK AWMN) and other UK acid waters. The AWMN was set up in 1988. It was designed to monitor the chemical and biological response of acidified surface waters in the UK to the planned reduction in the emission of acidic sulphur and nitrogen gases as required by the UNECE Convention on Long Range Transboundary Air Pollution. Most papers in the volume are concerned with the changes that have taken place at the 22 AWMN sites during 20 years of monitoring from 1988 to 2008. They show that significant changes in deposition chemistry, in water chemistry and, to a lesser extent, in biology have taken place, consistent with a recovery from acidification. However, when compared with pre-acidification conditions inferred from lake sediment records, the extent of biological recovery so far is shown to be quite limited. The volume also contains papers on other aspects of surface water acidification in the UK. They include evidence for persistent highly acidic conditions of streams in the North York Moors, data from Scotland showing how afforestation is modifying recovery from acidification and the results of chemical speciation modelling in explaining the relationship between acidification and macroinvertebrate species richness at AWMN and other sites in the UK. The final papers are concerned with projections for the future and the extent to which acidified sites will continue to improve. They conclude that recovery will continue albeit slowly during this century but that other pressures principally from climate and land-use change are likely to alter the recovery pathways towards novel ecological endpoints potentially quite different from past baselines

ACS Style

Richard W. Battarbee; Ewan M. Shilland; Martin Kernan; Donald T. Monteith; Chris J. Curtis. Recovery of acidified surface waters from acidification in the United Kingdom after twenty years of chemical and biological monitoring (1988–2008). Ecological Indicators 2014, 37, 267 -273.

AMA Style

Richard W. Battarbee, Ewan M. Shilland, Martin Kernan, Donald T. Monteith, Chris J. Curtis. Recovery of acidified surface waters from acidification in the United Kingdom after twenty years of chemical and biological monitoring (1988–2008). Ecological Indicators. 2014; 37 ():267-273.

Chicago/Turabian Style

Richard W. Battarbee; Ewan M. Shilland; Martin Kernan; Donald T. Monteith; Chris J. Curtis. 2014. "Recovery of acidified surface waters from acidification in the United Kingdom after twenty years of chemical and biological monitoring (1988–2008)." Ecological Indicators 37, no. : 267-273.

Review article
Published: 09 November 2013 in Ecological Indicators
Reads 0
Downloads 0

Upland waters are located upstream of the areas of direct human disturbance and intensive land use through industry, agriculture and urbanisation and are valued particularly as sources of potable water and as biodiverse freshwater habitats. Nonetheless, the impact of human activity can be detected even in some of the most remote lakes on the planet due to the effects of long-range transport of air pollutants and global climate change. In the UK, upland waters are threatened by a range of pressures including not only atmospheric deposition of acidic compounds, trace metals and organic pollutants, but also climate change, nutrient enrichment by deposited nitrogen and changing land-use or land management regimes. The threat from acid deposition has declined sharply since the 1980s but its legacy remains a major concern; recovery is taking place but even assuming a complete chemical and biological recovery to a pre-industrial baseline were possible, dynamic models suggest that this could take another 100 years. However, current climate change projections suggest that by then, UK upland waters will become much warmer, with lower summer streamflows, higher winter streamflows and a much reduced or even absent influence of snowfall and lake ice-cover. Hence there is no rationale for aspiring to the return of pre-industrial “reference” conditions because climate change is likely to shift the climatic baseline at an unprecedented rate. Meanwhile, expansion of forest planting, changing grazing regimes and management measures for peatland restoration, among other land-use pressure, will affect upland catchments in the UK with potentially major repercussions for aquatic ecosystems, both positive and negative. The challenge for scientists, policymakers and other stakeholders in the uplands is to determine not only the trajectory of change in upland waters, but also to define the ecological endpoints needed to provide the optimum range of ecosystem services for society. Integrated monitoring of the kind exemplified by the papers in this volume is a fundamental prerequisite in this regard.

ACS Style

Chris J. Curtis; Richard W. Battarbee; Donald T. Monteith; Ewan Shilland. The future of upland water ecosystems of the UK in the 21st century: A synthesis. Ecological Indicators 2013, 37, 412 -430.

AMA Style

Chris J. Curtis, Richard W. Battarbee, Donald T. Monteith, Ewan Shilland. The future of upland water ecosystems of the UK in the 21st century: A synthesis. Ecological Indicators. 2013; 37 ():412-430.

Chicago/Turabian Style

Chris J. Curtis; Richard W. Battarbee; Donald T. Monteith; Ewan Shilland. 2013. "The future of upland water ecosystems of the UK in the 21st century: A synthesis." Ecological Indicators 37, no. : 412-430.