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Lee LC, Weigelhofer G, Hein T, Chan SC, Liou YS, Liao CS, Shiah FK, Yu YL, Lee TY, Huang JC. Transition of carbon-nitrogen coupling under different anthropogenic disturbances in subtropical small mountainous rivers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 870:162017. [PMID: 36739020 DOI: 10.1016/j.scitotenv.2023.162017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 12/31/2022] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
The commonly observed inverse relationship between dissolved organic carbon (DOC) and nitrate (NO3-) concentrations in aquatic systems can be explained by stoichiometric and thermodynamic principles regulating microbial assimilation and dissimilation processes. However, the interactive effects of human activities and dissolved oxygen (DO) on the DOC and DIN (dissolved inorganic nitrogen, mainly composed of NO3--N and NH4+-N) relations are not well identified, particularly in subtropical small mountainous rivers (SMRs). Here, we investigated the exports and relations of DOC-DIN in 42 Taiwan SMRs under different anthropogenic disturbances. Results showed that the island-wide mean concentrations of the three solutes in streams are generally low, yet the abundant rainfall and persistent supply contrarily lead to disproportional high DOC and DIN yields. The inverse DOC-NO3--N relation does not appear under well‑oxygenated conditions, regardless of low or high human disturbance. However, a significant inverse relationship between DOC-NO3--N would emerge in highly-disturbed watersheds under low-oxygenated conditions (mean annual DO <6.5 mg L-1), where excess N accumulates as NH4+-N rather than NO3--N. The controlling mechanism of DOC-DIN relations would shift from energetic constraints to redox constraints in low-oxygenated conditions. Although riverine concentrations of DOC, NO3--N, and NH4+-N could be elevated by human activities, the transition of DOC-DIN relation pattern is directly linked to DO availability. Understanding the mechanism that drives CN coupling is critical for assessing the ecosystem function in the delivery and retention of DOC and DIN in aquatic ecosystems.
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Affiliation(s)
- Li-Chin Lee
- Department of Geography, National Taiwan University, Taipei, Taiwan; Department of Water, Atmosphere and Environment, Institute of Hydrobiology and Aquatic Ecosystem Management, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Gabriele Weigelhofer
- Department of Water, Atmosphere and Environment, Institute of Hydrobiology and Aquatic Ecosystem Management, University of Natural Resources and Life Sciences, Vienna, Austria; WasserCluster Lunz, Lunz am See, Austria
| | - Thomas Hein
- Department of Water, Atmosphere and Environment, Institute of Hydrobiology and Aquatic Ecosystem Management, University of Natural Resources and Life Sciences, Vienna, Austria; WasserCluster Lunz, Lunz am See, Austria; Christian Doppler Laboratory for Meta Ecosystem Dynamics in Riverine Landscapes, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Shin-Chien Chan
- Department of Geography, National Changhua University of Education, Changhua, Taiwan
| | - Ying-San Liou
- Department of Natural Resources and Environmental Studies, National Dong Hwa University, Hualien, Taiwan
| | - Chien-Sen Liao
- Department of Biological Science and Technology, I-Shou University, Kaohsiung, Taiwan
| | - Fuh-Kwo Shiah
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Yu-Lin Yu
- Department of Geography, National Taiwan University, Taipei, Taiwan
| | - Tsung-Yu Lee
- Department of Geography, National Taiwan Normal University, Taipei, Taiwan
| | - Jr-Chuan Huang
- Department of Geography, National Taiwan University, Taipei, Taiwan.
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2
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Burkholder JM, Kinder CA, Dickey DA, Reed RE, Arellano C, James JL, Mackenzie LM, Allen EH, Lindor NL, Mathis JG, Thomas ZT. Classic indicators and diel dissolved oxygen versus trend analysis in assessing eutrophication of potable-water reservoirs. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2541. [PMID: 35072953 DOI: 10.1002/eap.2541] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/19/2021] [Accepted: 09/15/2021] [Indexed: 06/14/2023]
Abstract
Potable source-water reservoirs are the main water supplies in many urbanizing regions, yet their long-term responses to cultural eutrophication are poorly documented in comparison with natural lakes, creating major management uncertainties. Here, long-term discrete data (June 2006-June 2018) for classical eutrophication water quality indicators, continuous depth-profile data for dissolved oxygen (DO), and an enhanced hybrid statistical trend analysis model were used to evaluate the eutrophication status of a potable source-water reservoir. Based on classical indicators (nitrogen, N and phosphorus, P concentrations and ratios; phytoplankton biomass as chlorophyll a, chl a; and trophic state indices), the reservoir was eutrophic to hypereutrophic and stoichiometrically imbalanced. Anoxia/hypoxia occurred for 7-8 months annually systemwide, even throughout the water column for days to weeks in some years; and elevated total ammonia (up to ~900 μg tNH3 L-1 ) in surface waters from late summer/fall through late winter/early spring suggested substantial internal legacy nutrient loading. These surprising DO and tNH3 phenomena may characterize many reservoirs in urbanizing areas, and the associated cascade of negative impacts may increasingly affect them under global warming. Total organic carbon (TOC), seasonally influenced by phytoplankton biomass, commonly exceeded 6 mg L-1 , which is problematic for potable-water treatment, and significantly trended up over time. Wet-year inflow dilution influenced an apparent decreasing trend in nutrients within the hypereutrophic upper reservoir, which receives most tributary inputs. Nevertheless, significant reservoirwide trends (increasing total phosphorus [TP], phytoplankton chl a, TOC) and mid- and/or lower region trends (increasing total nitrogen [TN], tNH3 , decreasing TN:TP ratios) suggest that water quality degradation from eutrophication has worsened over time. These findings support broadly applicable recommendations to strengthen protection of potable source-water reservoirs in urbanizing watersheds: (1) protective numeric water quality criteria are needed for TOC as well as TN, TP, and chl a; (2) continuous diel data capture more realistic DO conditions than traditional sampling, and can provide important insights for water treatment managers; and (3) assessment of reservoir eutrophication status to track management progress over time should emphasize classic indicators equally as statistical trends, which are highly sensitive to short-term meteorological forcing.
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Affiliation(s)
- JoAnn M Burkholder
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Carol A Kinder
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - David A Dickey
- Department of Statistics, North Carolina State University, Raleigh, North Carolina, USA
| | - Robert E Reed
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Consuelo Arellano
- Department of Statistics, North Carolina State University, Raleigh, North Carolina, USA
| | - Jennifer L James
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Linda M Mackenzie
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Elle H Allen
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Nicole L Lindor
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Joshua G Mathis
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
| | - Zachary T Thomas
- Center for Applied Aquatic Ecology, Department of Applied Ecology, North Carolina State University, Raleigh, North Carolina, USA
- Division of Water Resources, North Carolina Department of Water Quality, Raleigh, North Carolina, USA
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Gonçalves PHS, Gonçalves-Souza T, Albuquerque UP. Chronic anthropogenic disturbances in ecology: a bibliometric approach. Scientometrics 2020. [DOI: 10.1007/s11192-020-03403-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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4
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Xu H, Lin C, Shen Z, Gao L, Lin T, Tao H, Chen W, Luo J, Lu C. Molecular Characteristics of Dissolved Organic Nitrogen and Its Interaction with Microbial Communities in a Prechlorinated Raw Water Distribution System. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:1484-1492. [PMID: 31927953 DOI: 10.1021/acs.est.9b04589] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dissolved organic nitrogen (DON) represents a unique challenge in prechlorinated raw water distribution systems (PRWDSs) because of its contribution to the formation of harmful nitrogen-disinfection byproducts, influence upon biogeochemical processes, and unclear molecular characteristics. Here, Fourier transform ion cyclotron resonance mass spectrometry in combination with high-throughput sequencing was applied to elucidate the molecular changes of DON and biofilm microbial communities in a PRWDS in Yixing, China. Our study revealed that dynamic characteristics of DON are significantly correlated with the biofilm. The accumulation of refractory lignin-like compounds and CnHmOpN1 contributes to the higher recalcitrance molecular characteristics of DON in the effluent associated with Alphaproteobacteria, Planctomycetes, and Bacteroidetes. Additionally, with the help of prechlorination, the biofilm may change the DON characteristics and lead to higher oxygenation, higher m/z, and lower saturation during transportation. Despite the promotion of CnHmOpN1 and CnHmOpN3 at the early stage, we suggest that appropriate concentration of chlorine can add to the front end of raw water distribution pipes. Prechlorination may control the nitrification process and stabilize the rapid growth of diversity and concentration of low molecular weight DON, especially the refractory CnHmOpN1 in the effluent, which may help to improve treatment efficiency of drinking water treatment plants.
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Affiliation(s)
- Hang Xu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment , Hohai University , Nanjing 210098 , China
| | - Chenshuo Lin
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment , Hohai University , Nanjing 210098 , China
| | - Zhen Shen
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment , Hohai University , Nanjing 210098 , China
- Wanjiang University of Technology , Maanshan , China
| | - Li Gao
- Future Water Strategy Group , South East Water , P.O. Box 2268, Seaford , Victoria 3198 , Australia
| | - Tao Lin
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment , Hohai University , Nanjing 210098 , China
| | - Hui Tao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment , Hohai University , Nanjing 210098 , China
| | - Wei Chen
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment , Hohai University , Nanjing 210098 , China
| | - Jian Luo
- School of Civil and Environmental Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Chunhui Lu
- State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering , Hohai University , Nanjing 210098 , China
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Li Y, Xu H, He C, Shen Z, Chen W, Gao L, Lin C, Lin T, Lu C, Shi Q, Luo J, Wang W. Transformation and fate of dissolved organic nitrogen in drinking water supply system: A full scale case study from Yixing, China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 673:435-444. [PMID: 30991333 DOI: 10.1016/j.scitotenv.2019.03.309] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 03/19/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
The transformation of dissolved organic nitrogen (DON) in the drinking water treatment plants could be closely associated with nitrogenous disinfection by-product (N-DBP) formation. In this study, we have assessed the molecular transformation of DON and its impact on N-DBP formation in a full scale drinking water treatment plant. Based on the result of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis, DON compounds with low molecular weight (<1 kDa) were classified as CHON, CHON2 and CHON3 according to the number of nitrogen atoms. Via the analytical window of van Krevelen diagrams, we found that the molecular structural features of CHON, CHON2 and CHON3 were not altered before the chlorination process. In detail, the CHON2 and CHON3 compositions were concentrated on the regions assigned to a lignin-structure while CHON compositions were also distributed in other compounds including proteins, carbohydrates and tannin. Furthermore, CHON formation was more difficult to be removed before the V-filter process. For N-DBP, chlorine-containing DON (Cl-DON) composition was likely to be removed through flocculation and sedimentation processes, whereas N-nitrosamine compounds were removed in V-filter and biological activated carbon filter processes. The health risks of aromatic structure N-nitrosamines due to the pre-chlorination of the raw water should be further studied.
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Affiliation(s)
- Yang Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China
| | - Hang Xu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China.
| | - Chen He
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
| | - Zhen Shen
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China
| | - Wei Chen
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China
| | - Li Gao
- Future Water Strategy Group, South East Water, 101 Wells Street, Frankston, Melbourne, Victoria 3199, Australia
| | - Chenshuo Lin
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China
| | - Tao Lin
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, No. 1 Xikang Road, Nanjing 210098, China
| | - Chunhui Lu
- State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, China
| | - Quan Shi
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
| | - Jian Luo
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0355, USA
| | - Wei Wang
- State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China
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Bellmore RA, Compton JE, Brooks JR, Fox EW, Hill RA, Sobota DJ, Thornbrugh DJ, Weber MH. Nitrogen inputs drive nitrogen concentrations in U.S. streams and rivers during summer low flow conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 639:1349-1359. [PMID: 29929300 PMCID: PMC6361169 DOI: 10.1016/j.scitotenv.2018.05.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/28/2018] [Accepted: 05/01/2018] [Indexed: 05/26/2023]
Abstract
Ecological and human health impairments related to excess nitrogen (N) in streams and rivers remain widespread in the United States (U.S.) despite recent efforts to reduce N pollution. Many studies have quantified the relationship between N loads to streams in terms of N mass and N inputs to watersheds; however, N concentrations, rather than loads, are more closely related to impacts on human health and aquatic life. Additionally, concentrations, rather than loads, trigger regulatory responses. In this study, we examined how N concentrations are related to N inputs to watersheds (atmospheric deposition, synthetic fertilizer, manure applied to agricultural land, cultivated biological N fixation, and point sources), land cover characteristics, and stream network characteristics, including stream size and the extent of lakes and reservoirs. N concentration data were collected across the conterminous U.S. during the U.S. Environmental Protection Agency's 2008-09 National Rivers and Streams Assessment (n = 1966). Median watershed N inputs were 15.7 kg N ha-1 yr-1. Atmospheric deposition accounted for over half the N inputs in 49% of watersheds, but watersheds with the highest N input rates were dominated by agriculture-related sources. Total N input to watersheds explained 42% and 38% of the variability in total N and dissolved inorganic N concentrations, respectively. Land cover characteristics were also important predictors, with wetland cover muting the effect of agricultural N inputs on N concentrations and riparian disturbance exacerbating it. In contrast, stream variables showed little correlation with N concentrations. This suggests that terrestrial factors that can be managed, such as agricultural N use practices and wetland or riparian areas, control the spatial variability in stream N concentrations across the conterminous U.S.
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Affiliation(s)
- R A Bellmore
- National Research Council, in residence at the Environmental Protection Agency, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - J E Compton
- U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - J R Brooks
- U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - E W Fox
- U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - R A Hill
- Oak Ridge Institute for Science and Education Post-doctoral Participant c/o U.S. EPA, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - D J Sobota
- Water Quality Program, Oregon Department of Environmental Quality, 700 NE Multnomah Street, Suite 600, Portland, OR 97232, United States.
| | - D J Thornbrugh
- Oak Ridge Institute for Science and Education Post-doctoral Participant c/o U.S. EPA, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, United States.
| | - M H Weber
- U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Western Ecology Division, 200 SW 35th St., Corvallis, OR 97333, United States.
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Mallin MA, McIver MR. Season matters when sampling streams for swine CAFO waste pollution impacts. JOURNAL OF WATER AND HEALTH 2018; 16:78-86. [PMID: 29424721 DOI: 10.2166/wh.2017.194] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Concentrated (or confined) animal feed operations (CAFOs) are the principal means of livestock production in the United States, and such facilities pollute nearby waterways because of their waste management practices; CAFO waste is pumped from the confinement structure into a cesspit and sprayed on a field. Stocking Head Creek is located in eastern North Carolina, a state with >9,000,000 head of swine confined in CAFOs. This watershed contains 40 swine CAFOs; stream water quality was investigated at seven sites during 2016, with five sampling dates in early spring and five in summer. Geometric mean fecal coliform counts were in the thousands/100 mL at five sites in spring and all seven sites in summer. Excessive nitrate pollution was widespread with concentrations up to >11.0 mg N/L. Seasonality played an important role in pollutant concentrations. In North Carolina, spraying animal waste on adjoining fields is permissible from March 1 through September 30. Seasonal data showed significantly higher (p < 0.01) concentrations of conductivity, nitrate, total nitrogen, total organic carbon, and fecal bacteria in summer as opposed to early spring. Thus, sampling performed only in winter-early spring would significantly underestimate impacts from swine CAFO spray fields on nearby waterways.
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Affiliation(s)
- Michael A Mallin
- Center for Marine Sciences, University of North Carolina Wilmington, Wilmington, NC 28409, USA E-mail:
| | - Matthew R McIver
- Center for Marine Sciences, University of North Carolina Wilmington, Wilmington, NC 28409, USA E-mail:
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8
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Differences in Stream Water Nitrate Concentrations between a Nitrogen-Saturated Upland Forest and a Downstream Mixed Land Use River Basin. HYDROLOGY 2017. [DOI: 10.3390/hydrology4030043] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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9
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Palviainen M, Laurén A, Launiainen S, Piirainen S. Predicting the export and concentrations of organic carbon, nitrogen and phosphorus in boreal lakes by catchment characteristics and land use: A practical approach. AMBIO 2016; 45:933-945. [PMID: 27250098 PMCID: PMC5102966 DOI: 10.1007/s13280-016-0789-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 03/31/2016] [Accepted: 04/27/2016] [Indexed: 05/12/2023]
Abstract
The majority of C, N and P in boreal lakes are in organic form. Organically bound nutrients are released through biodegradation or photodegradation which affects the water quality, eutrophication and greenhouse gas emissions of lakes. We tested whether open land-use data combined with land-use-specific export coefficients can be used to predict total organic carbon (TOC), dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) loading and lake water concentrations. Using data from 12 lake catchments in eastern Finland, we found that land use and management of the catchment explained a substantial proportion of the variations in TOC (r 2 = 0.78), DON (r 2 = 0.55) and DOP (r 2 = 0.80) concentrations between lakes. The computation does not account for in-lake processes, which are reflected as mismatch between the predicted and observed concentrations. However, this simple practical approach is useful in ranking lakes according to their water quality. The results indicated that natural sources dominate TOC, DON and DOP exports; the background leachings accounted for 57-99 %, 48-96 % and 55-99 % of TOC, DON and DOP export, respectively. The proposed method has promise as a practical decision support tool for assessing the impacts of land use on water quality. The results showed that possibilities to control TOC, DON and DOP loading to surface waters are limited to catchments where the peatland proportion is low and anthropogenic sources significant.
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Affiliation(s)
- Marjo Palviainen
- Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland
| | - Ari Laurén
- Natural Resources Institute Finland (Luke), P.O. Box 68, 80101 Joensuu, Finland
| | - Samuli Launiainen
- Natural Resources Institute Finland (Luke), P.O. Box 18, 01301 Vantaa, Finland
| | - Sirpa Piirainen
- Natural Resources Institute Finland (Luke), P.O. Box 68, 80101 Joensuu, Finland
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Soucek DJ, Dickinson A. Influence of chloride on the chronic toxicity of sodium nitrate to Ceriodaphnia dubia and Hyalella azteca. ECOTOXICOLOGY (LONDON, ENGLAND) 2016; 25:1406-16. [PMID: 27386878 DOI: 10.1007/s10646-016-1691-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/27/2016] [Indexed: 05/25/2023]
Abstract
While it has been well established that increasing chloride concentration in water reduces the toxicity of nitrite to freshwater species, little work has been done to investigate the effect of chloride on nitrate toxicity. We conducted acute and chronic nitrate (as sodium nitrate) toxicity tests with the cladoceran Ceriodaphnia dubia and the amphipod Hyalella azteca (chronic tests only) over a range of chloride concentrations spanning natural chloride levels found in surface waters representative of watersheds of the Great Lakes Region. Chronic nitrate toxicity test results with both crustaceans were variable, with H. azteca appearing to be one of the more sensitive invertebrate species tested and C. dubia being less sensitive. While the variability in results for H. azteca were to an extent related to chloride concentration in test water that was distinctly not the case for C. dubia. We concluded that the chloride dependent toxicity of nitrate is not universal among freshwater crustaceans. An additional sodium chloride chronic toxicity test with the US Lab strain of H. azteca in the present study suggested that when present as predominantly sodium chloride and with relatively low concentrations of other ions, there is a narrow range of chloride concentrations over which this strain is most fit, and within which toxicity test data are reliable.
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Affiliation(s)
- David J Soucek
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, 1816 S. Oak St, Champaign, IL, 61820, USA.
| | - Amy Dickinson
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, 1816 S. Oak St, Champaign, IL, 61820, USA
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Crawford JT, Stanley EH. Controls on methane concentrations and fluxes in streams draining human-dominated landscapes. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:1581-1591. [PMID: 27755752 DOI: 10.1890/15-1330] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 11/04/2015] [Accepted: 11/06/2015] [Indexed: 06/06/2023]
Abstract
Streams and rivers are active processors of carbon, leading to significant emissions of CO2 and possibly CH4 to the atmosphere. Patterns and controls of CH4 in fluvial ecosystems remain relatively poorly understood. Furthermore, little is known regarding how major human impacts to fluvial ecosystems may be transforming their role as CH4 producers and emitters. Here, we examine the consequences of two distinct ecosystem changes as a result of human land use: increased nutrient loading (primarily as nitrate), and increased sediment loading and deposition of fine particles in the benthic zone. We did not find support for the hypothesis that enhanced nitrate loading down-regulates methane production via thermodynamic or toxic effects. We did find strong evidence that increased sedimentation and enhanced organic matter content of the benthos lead to greater methane production (diffusive + ebullitive flux) relative to pristine fluvial systems in northern Wisconsin (upper Midwest, USA). Overall, streams in a human-dominated landscape of southern Wisconsin were major regional sources of CH4 to the atmosphere, equivalent to ~20% of dairy cattle emissions, or ~50% of a landfill's annual emissions. We suggest that restoration of the benthic environment (reduced fine deposits) could lead to reduced CH4 emissions, while decreasing nutrient loading is likely to have limited impacts to this ecosystem process.
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Affiliation(s)
- John T Crawford
- U.S. Geological Survey, National Research Program, 3215 Marine Street, Boulder, Colorado, 80303, USA
| | - Emily H Stanley
- Center for Limnology, University of Wisconsin-Madison, 680 North Park Street, Madison, Wisconsin, 53706, USA
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12
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Lusk MG, Toor GS. Dissolved organic nitrogen in urban streams: Biodegradability and molecular composition studies. WATER RESEARCH 2016; 96:225-235. [PMID: 27058880 DOI: 10.1016/j.watres.2016.03.060] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 03/25/2016] [Accepted: 03/26/2016] [Indexed: 06/05/2023]
Abstract
A portion of the dissolved organic nitrogen (DON) is biodegradable in water bodies, yet our knowledge of the molecular composition and controls on biological reactivity of DON is limited. Our objective was to investigate the biodegradability and molecular composition of DON in streams that drain a gradient of 19-83% urban land use. Weekly sampling over 21 weeks suggested no significant relationship between urban land use and DON concentration. We then selected two streams that drain 28% and 83% urban land use to determine the biodegradability and molecular composition of the DON by coupling 5-day bioassay experiments with high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Both urban streams contained a wide range of N-bearing biomolecular formulas and had >80% DON in lignin-like compounds, with only 5-7% labile DON. The labile DON consisted mostly of lipid-and protein-like structures with high H/C and low O/C values. Comparison of reactive formulas and formed counterparts during the bioassay experiments indicated a shift toward more oxygenated and less saturated N-bearing DON formulas due to the microbial degradation. Although there was a little net removal (5-7%) of organic-bound N over the 5-day bioassay, there was some change to the carbon skeleton of DON compounds. These results suggest that DON in urban streams contains a complex mixture of compounds such as lipids, proteins, and lignins of variable chemical structures and biodegradability.
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Affiliation(s)
- Mary G Lusk
- Soil and Water Quality Laboratory, Gulf Coast Research and Education Center, University of Florida, Institute of Food and Agricultural Sciences, 14625 CR 672, Wimauma, FL, United States
| | - Gurpal S Toor
- Soil and Water Quality Laboratory, Gulf Coast Research and Education Center, University of Florida, Institute of Food and Agricultural Sciences, 14625 CR 672, Wimauma, FL, United States.
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Stanley EH, Casson NJ, Christel ST, Crawford JT, Loken LC, Oliver SK. The ecology of methane in streams and rivers: patterns, controls, and global significance. ECOL MONOGR 2016. [DOI: 10.1890/15-1027] [Citation(s) in RCA: 255] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Emily H. Stanley
- Center for Limnology University of Wisconsin 680 North Park Street Madison Wisconsin 53706 USA
| | - Nora J. Casson
- Center for Limnology University of Wisconsin 680 North Park Street Madison Wisconsin 53706 USA
| | - Samuel T. Christel
- Center for Limnology University of Wisconsin 680 North Park Street Madison Wisconsin 53706 USA
| | - John T. Crawford
- U.S. Geological Survey 3215 Marine Street Suite E127 Boulder Colorado 80303 USA
| | - Luke C. Loken
- Center for Limnology University of Wisconsin 680 North Park Street Madison Wisconsin 53706 USA
| | - Samantha K. Oliver
- Center for Limnology University of Wisconsin 680 North Park Street Madison Wisconsin 53706 USA
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Oviedo-Vargas D, Royer TV. The role of dissolved organic nitrogen in a nitrate-rich agricultural stream. JOURNAL OF ENVIRONMENTAL QUALITY 2015; 44:668-675. [PMID: 26023984 DOI: 10.2134/jeq2014.07.0314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Agricultural activities have heavily altered the nitrogen (N) cycle in stream ecosystems draining croplands, particularly in the midwestern United States. However, our knowledge about dissolved organic N (DON) biogeochemistry in agricultural ecosystems is limited. From January 2011 to June 2012, we investigated DON dynamics in an agricultural headwater stream in the midwestern United States. We quantified the contribution of DON to the total dissolved N (TDN) pool and examined the role of DON as a source of N for microbial metabolism. For this we measured N-acquiring enzyme activities (aminopeptidases) and whole-stream DON uptake through short-term releases of amino acids. To investigate potential coupling between the N and C cycles occurring via simultaneous uptake of these two elements during assimilation of amino acids, seven of the short-term releases were performed concurrently with acetate. We found minimal contribution of DON to the TDN pool in this stream as a result of high concentrations of nitrate. Acetate uptake suggested that C was a limiting factor for microbial metabolism in this stream. In contrast, we were not able to detect amino acid uptake during any of the 13 short-term releases we conducted, likely as a result of high availability of dissolved inorganic N. Aminopeptidase (AMP) activity did not reflect N demand. Large spatial variability in AMP was observed within and among sites, possibly as result of physicochemical characteristics of the sediments. In contrast to other human-dominated streams, DON appeared to play a minor role in microbial metabolic processes and contributed minimally to the N pool of the study stream.
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Heinz M, Graeber D, Zak D, Zwirnmann E, Gelbrecht J, Pusch MT. Comparison of organic matter composition in agricultural versus forest affected headwaters with special emphasis on organic nitrogen. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:2081-2090. [PMID: 25594834 DOI: 10.1021/es505146h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Agricultural management practices promote organic matter (OM) turnover and thus alter both the processing of dissolved organic matter (DOM) in soils and presumably also the export of DOM to headwater streams, which intimately connect the terrestrial with the aquatic environment. Size-exclusion chromatography, in combination with absorbance and emission matrix fluorometry, was applied to assess how agricultural land use alters the amount and composition of DOM, as well as dissolved organic nitrogen (DON) forms in headwater streams, including temporal variations, in a temperate region of NE Germany. By comparing six agriculturally and six forest-impacted headwater streams, we demonstrated that agriculture promotes increased DOC and DON concentrations, entailing an even more pronounced effect on DON. The major part of DOC and DON in agricultural and forest reference streams is exported in the form of humic-like material with high molecular weight, which indicates terrestrial, i.e., allochthonous sources. As an obvious difference in agricultural streams, the contribution of DOC and particularly DON occurring in the form of nonhumic high-molecular-weight, presumably proteinous material is clearly elevated. Altogether, DOM in agricultural headwaters is mainly complex-soil-derived and aromatic material with a low C:N ratio, which is more microbial processed than its counterpart from forest reference catchments. Our results emphasize the importance of agricultural land use on DOM loss from soils and identify agricultural soils as important DOC and particularly DON sources to headwater streams.
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Affiliation(s)
- Marlen Heinz
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries , Müggelseedamm 301, 12587 Berlin, Germany
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Divers MT, Elliott EM, Bain DJ. Quantification of nitrate sources to an urban stream using dual nitrate isotopes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:10580-10587. [PMID: 25134416 DOI: 10.1021/es404880j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Human-engineered landscapes and subsequent altered hydrology affect the fate and transport of reactive nitrogen, particularly in urban watersheds. In this study, we used dual-nitrate isotopes and mixing model analysis (δ(15)N and δ(18)O of NO3(-)) to quantify nitrogen inputs from two sources concentrated in urban systems, sewage and atmospheric deposition. Analysis was conducted on samples collected from Nine Mile Run (Pittsburgh, PA) including over two years of samples collected biweekly and samples collected through the hydrographs of four storm events. Mixing models incorporated uncertainties in the isotopic composition of potential nitrate sources and resolved the relative proportions of nitrate inputs from each source using Bayesian techniques. The results indicate that up to 94% of nitrate in streamwater originated from sewage sources during baseflow conditions. During storms, atmospheric deposition was a substantial nitrate source (∼ 34%) to total event-based nitrate loads, although sewage-derived nitrate remained the dominant source (66%). The potential influence of denitrification was considered by incorporating associated isotopic fractionations into mixing models; up to 19% of sewage-derived samples showed the isotopic effects of denitrification. This study quantitatively delineates proportions of nitrate from different sources to urban streamwater, while incorporating remaining uncertainties in source endmember compositions.
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Affiliation(s)
- Marion T Divers
- Department of Geology & Planetary Science, University of Pittsburgh , 4107 O'Hara Street, Pittsburgh, Pennsylvania 15260, United States
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17
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Arnold WA, Longnecker K, Kroeger KD, Kujawinski EB. Molecular signature of organic nitrogen in septic-impacted groundwater. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2014; 16:2400-2407. [PMID: 25142948 DOI: 10.1039/c4em00289j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Dissolved inorganic and organic nitrogen levels are elevated in aquatic systems due to anthropogenic activities. Dissolved organic nitrogen (DON) arises from various sources, and its impact could be more clearly constrained if specific sources were identified and if the molecular-level composition of DON were better understood. In this work, the pharmaceutical carbamazepine was used to identify septic-impacted groundwater in a coastal watershed. Using ultrahigh resolution mass spectrometry data, the nitrogen-containing features of the dissolved organic matter in septic-impacted and non-impacted samples were compared. The septic-impacted groundwater samples have a larger abundance of nitrogen-containing formulas. Impacted samples have additional DON features in the regions ascribed as 'protein-like' and 'lipid-like' in van Krevelen space and have more intense nitrogen-containing features in a specific region of a carbon versus mass plot. These features are potential indicators of dissolved organic nitrogen arising from septic effluents, and this work suggests that ultrahigh resolution mass spectrometry is a valuable tool to identify and characterize sources of DON.
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Affiliation(s)
- William A Arnold
- Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, 500 Pillsbury Dr SE, Minneapolis, MN 55455, USA.
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18
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Soucek DJ, Dickinson A. Acute toxicity of nitrate and nitrite to sensitive freshwater insects, mollusks, and a crustacean. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2012; 62:233-42. [PMID: 21877224 DOI: 10.1007/s00244-011-9705-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 08/16/2011] [Indexed: 05/25/2023]
Abstract
Both point- and nonpoint-sources of pollution have contributed to increased inorganic nitrogen concentrations in freshwater ecosystems. Although numerous studies have investigated the toxic effects of ammonia on freshwater species, relatively little work has been performed to characterize the acute toxicity of the other two common inorganic nitrogen species: nitrate and nitrite. In particular, to our knowledge, no published data exist on the toxicity of nitrate and nitrite to North American freshwater bivalves (Mollusca) or stoneflies (Insecta, Plecoptera). We conducted acute (96-h) nitrate and nitrite toxicity tests with two stonefly species (Allocapnia vivipara and Amphinemura delosa), an amphipod (Hyalella azteca), two freshwater unionid mussels (Lampsilis siliquoidea and Megalonaias nervosa), a fingernail clam (Sphaerium simile), and a pond snail (Lymnaea stagnalis). Overall, we did not observe a particularly wide degree of variation in sensitivity to nitrate, with median lethal concentrations ranging from 357 to 937 mg NO(3)-N/l; furthermore, no particular taxonomic group appeared to be more sensitive to nitrate than any other. In our nitrite tests, the two stoneflies tested were by far the most sensitive, and the three mollusks tested were the least sensitive. In contrast to what was observed in the nitrate tests, variation among species in sensitivity to nitrite spanned two orders of magnitude. Examination of the updated nitrite database, including previously published data, clearly showed that insects tended to be more sensitive than crustaceans, which were in turn more sensitive than mollusks. Although the toxic mechanism of nitrite is generally thought to be the conversion of oxygen-carrying pigments into forms that cannot carry oxygen, our observed trend in sensitivity of broad taxonomic groups, along with information on respiratory pigments in those groups, suggests that some other yet unknown mechanism may be even more important.
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Affiliation(s)
- D J Soucek
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, 1816 S. Oak St., Champaign, IL 61820, USA.
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19
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Roley SS, Tank JL, Stephen ML, Johnson LT, Beaulieu JJ, Witter JD. Floodplain restoration enhances denitrification and reach-scale nitrogen removal in an agricultural stream. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2012; 22:281-297. [PMID: 22471090 DOI: 10.1890/11-0381.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Streams of the agricultural Midwest, USA, export large quantities of nitrogen, which impairs downstream water quality, most notably in the Gulf of Mexico. The two-stage ditch is a novel restoration practice, in which floodplains are constructed alongside channelized ditches. During high flows, water flows across the floodplains, increasing benthic surface area and stream water residence time, as well as the potential for nitrogen removal via denitrification. To determine two-stage ditch nitrogen removal efficacy, we measured denitrification rates in the channel and on the floodplains of a two-stage ditch in north-central Indiana for one year before and two years after restoration. We found that instream rates were similar before and after the restoration, and they were influenced by surface water NO3- concentration and sediment organic matter content. Denitrification rates were lower on the constructed floodplains and were predicted by soil exchangeable NO3- concentration. Using storm flow simulations, we found that two-stage ditch restoration contributed significantly to NO3- removal during storm events, but because of the high NO3- loads at our study site, < 10% of the NO3- load was removed under all storm flow scenarios. The highest percentage of NO3- removal occurred at the lowest loads; therefore, the two-stage ditch's effectiveness at reducing downstream N loading will be maximized when the practice is coupled with efforts to reduce N inputs from adjacent fields.
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Affiliation(s)
- Sarah S Roley
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA.
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Chiwa M, Onikura N, Ide J, Kume A. Impact of N-Saturated Upland Forests on Downstream N Pollution in the Tatara River Basin, Japan. Ecosystems 2011. [DOI: 10.1007/s10021-011-9505-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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21
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Sobota DJ, Johnson SL, Gregory SV, Ashkenas LR. A Stable Isotope Tracer Study of the Influences of Adjacent Land Use and Riparian Condition on Fates of Nitrate in Streams. Ecosystems 2011. [DOI: 10.1007/s10021-011-9489-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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Withers PJA, Jarvie HP, Stoate C. Quantifying the impact of septic tank systems on eutrophication risk in rural headwaters. ENVIRONMENT INTERNATIONAL 2011; 37:644-653. [PMID: 21277632 DOI: 10.1016/j.envint.2011.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 12/22/2010] [Accepted: 01/04/2011] [Indexed: 05/30/2023]
Abstract
Septic tank systems (STS) are a potential source of nutrient emissions to surface waters but few data exist in the UK to quantify their significance for eutrophication. We monitored the impact of STS on nutrient concentrations in a stream network around a typical English village over a 1-year period. Septic tank effluent discharging via a pipe directly into one stream was highly concentrated in soluble N (8-63mgL(-1)) and P (<1-14mgL(-1)) and other nutrients (Na, K, Cl, B and Mn) typical of detergent and household inputs. Ammonium-N (NH(4)N) and soluble reactive P (SRP) fractions were dominant (70-85% of total) and average concentrations of nitrite-N (NO(2)N) were above levels considered harmful to fish (0.1mgL(-1)). Lower nutrient concentrations were recorded at a ditch and a stream site, but range and average values downstream of rural habitation were still 4 to 10-fold greater than those in upstream sections. At the ditch site, where flow volumes were low, annual flow-weighted concentrations of NH(4)N and SRP increased from 0.04 and 0.07mgL(-1), respectively upstream to 0.55 and 0.21mgL(-1) downstream. At the stream site, flow volumes were twice as large and flow-weighted concentrations increased much less; from 0.04 to 0.21mgL(-1) for NH(4)N and from 0.06 to 0.08mgL(-1) for SRP. At all sites, largest nutrient concentrations were recorded under low flow and stream discharge was the most important factor determining the eutrophication impact of septic tank systems. The very high concentrations, intercorrelation and dilution patterns of SRP, NH(4)-N and the effluent markers Na and B suggested that soakaways in the heavy clay catchment soils were not retaining and treating the septic tank effluents efficiently, with profound implications for stream biodiversity. Water companies, water regulators and rural communities therefore need to be made more aware of the potential impacts of STS on water quality so that their management can be optimised to reduce the risk of potential eutrophication and toxicity to aquatic ecosystems during summer low flow periods.
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Affiliation(s)
- P J A Withers
- School of Environment, Natural Resources and Geography, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
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Waiser MJ, Tumber V, Holm J. Effluent-dominated streams. Part 1: Presence and effects of excess nitrogen and phosphorus in Wascana Creek, Saskatchewan, Canada. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2011; 30:496-507. [PMID: 21072844 DOI: 10.1002/etc.399] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Regina, Saskatchewan, Canada (population 190,400) treats its sewage at a modern sewage treatment plant (STP) on Wascana Creek. In the winter, treated sewage effluent makes up almost 100% of stream flow. Four surveys conducted from 2005 to 2007, in differing seasons, indicated significantly higher nitrogen (N) and phosphorus (P) concentrations at sites downstream of the STP compared to an upstream control site. Downstream, Wascana Creek is N hypersaturated (total dissolved N >3 mg/L) and soluble reactive phosphorus (SRP) makes up a greater percentage of total P (TP). Diminished nutrient retention capacities for both N and P are directly attributable to STP effluent. Creek SRP concentrations are less than estimates of equilibrium P concentrations (EPC(o)), indicating that creek sediments may be a source of P, further exacerbating hypereutrophic ambient SRP concentrations. As well, NO(2) + NO(3)-N concentrations far surpass World Health Organization limits for drinking water (10 mg/L) and sensitive taxa, while NH(3)-N, NH(4)-N, and NO(2) + NO(3)-N exceed Canadian Water Quality Guidelines for Protection of Aquatic Life and those for the U.S. Environmental Protection Agency. High NH(4)-N concentrations may be responsible for depressions not only in algal biomass and production observed downstream but reductions in primary to bacterial production ratios (PP:BP). In spring and fall, these reductions push PP:BP from net autotrophy to heterotrophy. The Wascana Creek study highlights the considerable problems associated with excess nutrients in effluent-dominated ecosystems (EDS). It also underlines the need for better controls on NH(4)-N additions from STPs in such EDS, especially in a day and age when freshwater supplies are dwindling and negative effects of climate change are expected.
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Affiliation(s)
- Marley J Waiser
- Environment Canada, Water Science and Technology Directorate, Saskatoon, Saskatchewan, Canada.
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Affiliation(s)
- Martin W Doyle
- Department of Geography, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA.
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26
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Petrone KC. Catchment export of carbon, nitrogen, and phosphorus across an agro-urban land use gradient, Swan-Canning River system, southwestern Australia. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009jg001051] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Zambrano L, Contreras V, Mazari-Hiriart M, Zarco-Arista AE. Spatial heterogeneity of water quality in a highly degraded tropical freshwater ecosystem. ENVIRONMENTAL MANAGEMENT 2009; 43:249-263. [PMID: 18941831 DOI: 10.1007/s00267-008-9216-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 09/08/2008] [Accepted: 09/09/2008] [Indexed: 05/26/2023]
Abstract
Awareness of environmental heterogeneity in ecosystems is critical for management and conservation. We used the Xochimilco freshwater system to describe the relationship between heterogeneity and human activities. This tropical aquatic ecosystem south of Mexico City is comprised of a network of interconnected canals and lakes that are influenced by agricultural and urban activities. Environmental heterogeneity was characterized by spatially extensive surveys within four regions of Xochimilco during rainy and dry seasons over 2 years. These surveys revealed a heterogeneous system that was shallow (1.1 m, SD=0.4 ), warm (17 degrees C, SD=2.9), well oxygenated (5.0 mg l(-1), SD=3), turbid (45.7 NTU SD = 26.96), and extremely nutrient-rich (NO(3)-N=15.9 mg l(-1), SD=13.7; NH(4)-N=2.88 mg l(-1), SD=4.24; and PO(4)-P=8.3 mg l(-1), SD=2.4). Most of the variables were not significantly different between years, but did differ between seasons, suggesting a dynamic system within a span of a year but with a high resilience over longer periods of time. Maps were produced using interpolations to describe distributions of all variables. There was no correlation between individual variables and land use. Consequently, we searched for relationships using all variables together by generating a combined water quality index. Significant differences in the index were apparent among the four regions. Index values also differed within individual region and individual water bodies (e.g., within canals), indicating that Xochimilco has high local heterogeneity. Using this index on a map helped to relate water quality to human activities and provides a simple and clear tool for managers and policymakers.
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Affiliation(s)
- Luis Zambrano
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Tercer Circuito Exterior Ciudad Universitaria, Coyoacán, México, D.F. 04510, México.
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