1
|
Tesoriero AJ, Robertson DM, Green CT, Böhlke JK, Harvey JW, Qi SL. Prioritizing river basins for nutrient studies. ENVIRONMENTAL MONITORING AND ASSESSMENT 2024; 196:248. [PMID: 38332337 PMCID: PMC10853301 DOI: 10.1007/s10661-023-12266-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 12/18/2023] [Indexed: 02/10/2024]
Abstract
Increases in fluxes of nitrogen (N) and phosphorus (P) in the environment have led to negative impacts affecting drinking water, eutrophication, harmful algal blooms, climate change, and biodiversity loss. Because of the importance, scale, and complexity of these issues, it may be useful to consider methods for prioritizing nutrient research in representative drainage basins within a regional or national context. Two systematic, quantitative approaches were developed to (1) identify basins that geospatial data suggest are most impacted by nutrients and (2) identify basins that have the most variability in factors affecting nutrient sources and transport in order to prioritize basins for studies that seek to understand the key drivers of nutrient impacts. The "impact" approach relied on geospatial variables representing surface-water and groundwater nutrient concentrations, sources of N and P, and potential impacts on receptors (i.e., ecosystems and human health). The "variability" approach relied on geospatial variables representing surface-water nutrient concentrations, factors affecting sources and transport of nutrients, model accuracy, and potential receptor impacts. One hundred and sixty-three drainage basins throughout the contiguous United States were ranked nationally and within 18 hydrologic regions. Nationally, the top-ranked basins from the impact approach were concentrated in the Midwest, while those from the variability approach were dispersed across the nation. Regionally, the top-ranked basin selected by the two approaches differed in 15 of the 18 regions, with top-ranked basins selected by the variability approach having lower minimum concentrations and larger ranges in concentrations than top-ranked basins selected by the impact approach. The highest ranked basins identified using the variability approach may have advantages for exploring how landscape factors affect surface-water quality and how surface-water quality may affect ecosystems. In contrast, the impact approach prioritized basins in terms of human development and nutrient concentrations in both surface water and groundwater, thereby targeting areas where actions to reduce nutrient concentrations could have the largest effect on improving water availability and reducing ecosystem impacts.
Collapse
|
2
|
Chang CF, Astitha M, Yuan Y, Tang C, Vlahos P, Garcia V, Khaira U. A New Approach to Predict Tributary Phosphorus Loads Using Machine Learning- and Physics-Based Modeling Systems. ARTIFICIAL INTELLIGENCE FOR THE EARTH SYSTEMS 2023; 2:1-20. [PMID: 37841557 PMCID: PMC10569129 DOI: 10.1175/aies-d-22-0049.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
Tributary phosphorus (P) loads are one of the main drivers of eutrophication problems in freshwater lakes. Being able to predict P loads can aid in understanding subsequent load patterns and elucidate potential degraded water quality conditions in downstream surface waters. We demonstrate the development and performance of an integrated multimedia modeling system that uses machine learning (ML) to assess and predict monthly total P (TP) and dissolved reactive P (DRP) loads. Meteorological variables from the Weather Research and Forecasting (WRF) Model, hydrologic variables from the Variable Infiltration Capacity model, and agricultural management practice variables from the Environmental Policy Integrated Climate agroecosystem model are utilized to train the ML models to predict P loads. Our study presents a new modeling methodology using as testbeds the Maumee, Sandusky, Portage, and Raisin watersheds, which discharge into Lake Erie and contribute to significant P loads to the lake. Two models were built, one for TP loads using 10 environmental variables and one for DRP loads using nine environmental variables. Both models ranked streamflow as the most important predictive variable. In comparison with observations, TP and DRP loads were predicted very well temporally and spatially. Modeling results of TP loads are within the ranges of those obtained from other studies and on some occasions more accurate. Modeling results of DRP loads exceed performance measures from other studies. We explore the ability of both ML-based models to further improve as more data become available over time. This integrated multimedia approach is recommended for studying other freshwater systems and water quality variables using available decadal data from physics-based model simulations.
Collapse
Affiliation(s)
- Christina Feng Chang
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut
| | - Marina Astitha
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut
| | - Yongping Yuan
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Chunling Tang
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
| | - Penny Vlahos
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut
| | - Valerie Garcia
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut
| | - Ummul Khaira
- Department of Civil and Environmental Engineering, University of Connecticut, Storrs, Connecticut
| |
Collapse
|
3
|
Shan X, Zhu Z, Ma J, Fu D, Song Y, Li Q, Huang Z, Pei L, Zhao H. Modeling nutrient flows from land to rivers and seas - A review and synthesis. MARINE ENVIRONMENTAL RESEARCH 2023; 186:105928. [PMID: 36889172 DOI: 10.1016/j.marenvres.2023.105928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 02/19/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Water quality modeling facilitates management of nutrient flows from land to rivers and seas, in addition to environmental pollution management in watersheds. In the present paper, we review advances made in the development of seven water quality models and highlight their respective strengths and weaknesses. Afterward, we propose their future development directions, with distinct characteristics for different scenarios. We also discuss the practical problems that such models address in the same region, China, and summarize their different characteristics based on their performance. We focus on the temporal and geographical scales of the models, sources of pollution considered, and the main problems that can be addressed. Summary of such characteristics could facilitate the selection of appropriate models for resolving practical challenges on nutrient pollution in the corresponding scenarios globally by stakeholders. We also make recommendations for model enhancement to expand their capabilities.
Collapse
Affiliation(s)
- Xiaoyang Shan
- State Key Laboratory of Marine Resources Utilization in South China Sea, Hainan University, Haikou, 570228, China; Center for Eco-Environment Restoration of Hainan Province & Key Laboratory of A&F Environmental Processes and Ecological Regulation of Hainan Province, College of Environment and Ecology, Hainan University, Haikou, 570228, China; College of Tropical Crops, Hainan University, Haikou, 570228, China.
| | - Zhiqiang Zhu
- College of Tropical Crops, Hainan University, Haikou, 570228, China.
| | - Jiyong Ma
- State Key Laboratory of Marine Resources Utilization in South China Sea, Hainan University, Haikou, 570228, China; Center for Eco-Environment Restoration of Hainan Province & Key Laboratory of A&F Environmental Processes and Ecological Regulation of Hainan Province, College of Environment and Ecology, Hainan University, Haikou, 570228, China.
| | - Dinghui Fu
- Haikou Research Center for Marine Geology, China Geological Survey, Haikou, 570312, China.
| | - Yanwei Song
- Haikou Research Center for Marine Geology, China Geological Survey, Haikou, 570312, China.
| | - Qipei Li
- Center for Eco-Environment Restoration of Hainan Province & Key Laboratory of A&F Environmental Processes and Ecological Regulation of Hainan Province, College of Environment and Ecology, Hainan University, Haikou, 570228, China.
| | - Zanhui Huang
- Haikou Research Center for Marine Geology, China Geological Survey, Haikou, 570312, China.
| | - Lixin Pei
- Haikou Research Center for Marine Geology, China Geological Survey, Haikou, 570312, China.
| | - Hongwei Zhao
- State Key Laboratory of Marine Resources Utilization in South China Sea, Hainan University, Haikou, 570228, China; Center for Eco-Environment Restoration of Hainan Province & Key Laboratory of A&F Environmental Processes and Ecological Regulation of Hainan Province, College of Environment and Ecology, Hainan University, Haikou, 570228, China.
| |
Collapse
|
4
|
Chen H, Yin J, Song M, Ding H, Mo F, Ren Q, Li G, Song S, Wang Y. The evaluation of N/P fate using the SPARROW model: a case study in an arid and semi-arid region, northern China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:55662-55677. [PMID: 36897454 DOI: 10.1007/s11356-023-26240-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
The assessment of nutrients' fate from source to sink is critical to water quality control. As an important ecological reserve in the arid and semi-arid regions of China, the Luanhe River Basin (LRB) has suffered from the deterioration of water quality, thus leading to the urgent management and control. However, few studies have devoted to exploring the fate of N/P contaminations for the entire watershed, due possibly to the large drainage area and heterogeneous watershed composition. Here, we attempt to illustrate N/P contaminations delivery and retention processes using the SPAtially Referenced Regression On Watershed attributes (SPARROW) model. The model reveals 97% of the spatial variability in the TN load and 81% in the TP load, verifying its availability and credibility. The results indicate that anthropogenic sources are dominating the N/P load, which account for 68.5% of N and 74.6% of P inputs. The results highlight the significant retention effects of streams and reservoirs, with 16.4% of N and 13.4% of P removals by streams and 24.3% of N and 10.7% of P removals by reservoirs, respectively. Ultimately, only 49,045.2 t yr-1 (or 16.9%) of N and 1668.7 t yr-1 (or 17.1%) of P being transported to the Bohai Sea. In addition, the analysis of influencing factors showed that regional characteristics (e.g., topography, rainfall), stream size, and delivery distance are potential factors affecting the riverine transport, whereas flow rate and surface area are primarily affecting the reservoirs attenuation. In the future, the watershed water quality management should pay more attention to source management and pollution legacy risks to achieve sustainable and healthy watershed development.
Collapse
Affiliation(s)
- Haitao Chen
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Jincheng Yin
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Menglai Song
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Han Ding
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Fan Mo
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Qiuru Ren
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China
| | - Guoguang Li
- Shenzhen Qianming Technology Co., Ltd, Shenzhen, 518000, Guangdong, China
| | - Shuang Song
- Ecological Environment Monitoring and Scientific Research Center of Haihe River Basin and Beihai Sea Area, Ministry of Ecological Environment, Tianjin, 300061, China
| | - Yuqiu Wang
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
| |
Collapse
|
5
|
Xu Z, Ji Z, Liang B, Song D, Lin Y, Lin J. Estimate of nutrient sources and transport into Bohai Bay in China from a lower plain urban watershed using a SPARROW model. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:25733-25747. [PMID: 33474666 DOI: 10.1007/s11356-020-11932-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/01/2020] [Indexed: 06/12/2023]
Abstract
In the development of a land-sea coordination management strategy, it is necessary to analyze pollution sources and loads of pollutants entering the sea. This study estimated the sources and transport of total nitrogen (TN) and total phosphorus (TP) entering Bohai Bay in Tianjin, a lower plain urban watershed, using a SPAtially Referenced Regression On Watershed attributes (SPARROW) model. We calibrated the model using TN and TP data from 26 and 27 sites, respectively. The results demonstrated that the R2 values of TN and TP were both above 0.99. In 2013, the TN load delivered to Bohai Bay was 21,320 ton, which could be traced to various sources: upstream (39%), industrial discharge (10%), sewage discharge (34%), fertilizer application (3%), livestock breeding (7%), aquaculture (5%), and rural communities (2%). The TP load delivered to Bohai Bay was 1504 ton, which originated from upstream (33%), industrial discharge (5%), sewage discharge (21%), fertilizer application (5%), livestock breeding (12%), aquaculture (10%), and rural communities (14%). Rational management of the water resources in streams, enhancement of water circulation between rivers and wetlands, and making full use of the effect of both land and water on pollutant retention are the suitable strategies in watershed management, reducing marine pollution.
Collapse
Affiliation(s)
- Zizhou Xu
- Environmental Science and Engineering College, Dalian Maritime University, Dalian, 116026, China
- National Marine Environmental Monitoring Center, Dalian, 116023, China
| | - Zhixin Ji
- National Marine Environmental Monitoring Center, Dalian, 116023, China
| | - Bin Liang
- National Marine Environmental Monitoring Center, Dalian, 116023, China
| | - Derui Song
- National Marine Environmental Monitoring Center, Dalian, 116023, China
| | - Yong Lin
- National Marine Environmental Monitoring Center, Dalian, 116023, China
| | - Jianguo Lin
- Environmental Science and Engineering College, Dalian Maritime University, Dalian, 116026, China.
| |
Collapse
|
6
|
Evenson GR, Kalcic M, Wang YC, Robertson D, Scavia D, Martin J, Aloysius N, Apostel A, Boles C, Brooker M, Confesor R, Dagnew AT, Guo T, Kast J, Kujawa H, Muenich RL, Murumkar A, Redder T. Uncertainty in critical source area predictions from watershed-scale hydrologic models. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 279:111506. [PMID: 33168300 DOI: 10.1016/j.jenvman.2020.111506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 09/08/2020] [Accepted: 10/11/2020] [Indexed: 06/11/2023]
Abstract
Watershed-scale hydrologic models are frequently used to inform conservation and restoration efforts by identifying critical source areas (CSAs; alternatively 'hotspots'), defined as areas that export relatively greater quantities of nutrients and sediment. The CSAs can then be prioritized or 'targeted' for conservation and restoration to ensure efficient use of limited resources. However, CSA simulations from watershed-scale hydrologic models may be uncertain and it is critical that the extent and implications of this uncertainty be conveyed to stakeholders and decision makers. We used an ensemble of four independently developed Soil and Water Assessment Tool (SWAT) models and a SPAtially Referenced Regression On Watershed attributes (SPARROW) model to simulate CSA locations for flow, phosphorus, nitrogen, and sediment within the ~17,000-km2 Maumee River watershed at the HUC-12 scale. We then assessed uncertainty in CSA simulations determined as the variation in CSA locations across the models. Our application of an ensemble of models - differing with respect to inputs, structure, and parameterization - facilitated an improved accounting of CSA prediction uncertainty. We found that the models agreed on the location of a subset of CSAs, and that these locations may be targeted with relative confidence. However, models more often disagreed on CSA locations. On average, only 16%-46% of HUC-12 subwatersheds simulated as a CSA by one model were also simulated as a CSA by a different model. Our work shows that simulated CSA locations are highly uncertain and may vary substantially across models. Hence, while models may be useful in informing conservation and restoration planning, their application to identify CSA locations would benefit from comprehensive uncertainty analyses to avoid inefficient use of limited resources.
Collapse
Affiliation(s)
- Grey R Evenson
- Department of Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH, USA.
| | - Margaret Kalcic
- Department of Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH, USA; The Ohio State University Translational Data Analytics Institute, Columbus, OH, USA
| | - Yu-Chen Wang
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA
| | - Dale Robertson
- U.S. Geological Survey, Upper Midwest Water Science Center, Middleton, WI, USA
| | - Donald Scavia
- School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA
| | - Jay Martin
- Department of Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH, USA; The Ohio State University Sustainability Institute, Columbus, OH, USA
| | - Noel Aloysius
- Department of Biomedical, Biological and Chemical Engineering, and School of Natural Resources, University of Missouri, Columbia, MO, USA
| | - Anna Apostel
- Department of Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH, USA
| | | | - Michael Brooker
- Department of Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH, USA
| | | | | | - Tian Guo
- Heidelberg University, Tiffin, OH, USA
| | - Jeffrey Kast
- Department of Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH, USA
| | - Haley Kujawa
- Department of Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH, USA
| | - Rebecca Logsdon Muenich
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
| | - Asmita Murumkar
- Department of Food, Agricultural and Biological Engineering, The Ohio State University, Columbus, OH, USA
| | | |
Collapse
|
7
|
Application of the RSPARROW Modeling Tool to Estimate Total Nitrogen Sources to Streams and Evaluate Source Reduction Management Scenarios in the Grande River Basin, Brazil. WATER 2020. [DOI: 10.3390/w12102911] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Large-domain hydrological models are increasingly needed to support water-resource assessment and management in large river basins. Here, we describe results for the first Brazilian application of the SPAtially Referenced Regression On Watershed attributes (SPARROW) model using a new open-source modeling and interactive decision support system tool (RSPARROW) to quantify the origin, flux, and fate of total nitrogen (TN) in two sub-basins of the Grande River Basin (GRB; 43,000 km2). Land under cultivation for sugar cane, urban land, and point source inputs from wastewater treatment plants was estimated to each contribute approximately 30% of the TN load at the outlet, with pasture land contributing about 10% of the load. Hypothetical assessments of wastewater treatment plant upgrades and the building of new facilities that could treat currently untreated urban runoff suggest that these management actions could potentially reduce loading at the outlet by as much as 20–25%. This study highlights the ability of SPARROW and the RSPARROW mapping tool to assist with the development and evaluation of management actions aimed at reducing nutrient pollution and eutrophication. The freely available RSPARROW modeling tool provides new opportunities to improve understanding of the sources, delivery, and transport of water-quality contaminants in watersheds throughout the world.
Collapse
|
8
|
Statistical Analysis of Nutrient Loads from the Mississippi-Atchafalaya River Basin (MARB) to the Gulf of Mexico. ENVIRONMENTS 2020. [DOI: 10.3390/environments7010008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study investigated the annual and seasonal variations in nutrient loads (NO2− + NO3− and orthophosphate) delivered to the Gulf of Mexico from the Mississippi-Atchafalaya River Basin (MARB) and examined the water quality variations. The results indicate that (1) annually, the mean NO2− + NO3− and orthophosphate loads showed a steady increase during 1996–1999, a persistent level during 2000–2007, and a moderate increase during 2008–2016; (2) seasonally, NO2− + NO3− and orthophosphate in MARB in spring and summer were higher than those in autumn and winter. Analysis of variance (ANOVA) identified highly significant differences among seasonal loads; and (3) the median value of NO2− + NO3− in normal weather conditions were higher than that during and right after the hurricanes, while the median value of orthophosphate loads in normal weather conditions was higher than that during the hurricanes, but higher than that right after hurricanes. The two-sample t-test indicates a significant difference (p < 0.046) in orthophosphate loads before and after Hurricane Katrina. Moreover, it is found that there is a significant (p < 0.01) increase in nutrient loads during normal weather conditions. The results indicate that hurricane seasons can significantly influence the nutrient loads from the MARB to the Gulf of Mexico.
Collapse
|
9
|
Ha M, Zhang Z, Wu M. Biomass production in the Lower Mississippi River Basin: Mitigating associated nutrient and sediment discharge to the Gulf of Mexico. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 635:1585-1599. [PMID: 29703598 DOI: 10.1016/j.scitotenv.2018.03.184] [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] [Received: 12/05/2017] [Revised: 03/09/2018] [Accepted: 03/16/2018] [Indexed: 05/22/2023]
Abstract
A watershed model was developed using the Soil and Water Assessment Tool (SWAT) that simulates nitrogen, phosphorus, and sediment loadings in the Lower Mississippi River Basin (LMRB). The LMRB SWAT model was calibrated and validated using 21 years of observed flow, sediment, and water-quality data. The baseline model results indicate that agricultural lands within the Lower Mississippi River Basin (LMRB) are the dominant sources of nitrogen and phosphorus discharging into the Gulf of Mexico. The model was further used to evaluate the impact of biomass production, in the presence of riparian buffers in the LMRB, on suspended-sediment and nutrient loading discharge from the Mississippi River into the Gulf of Mexico. The interplay among land use, riparian buffers, crop type, land slope, water quality, and hydrology were anlyzed at various scales. Implementing a riparian buffer in the dominant agricultural region within the LMRB could reduce suspended sediment, nitrogen, and phosphorus loadings at the regional scale by up to 65%, 38%, and 39%, respectively. Implementation of this land management practice can reduce the suspended-sediment content and improve the water quality of the discharge from the LMRB into the Gulf of Mexico and support the potential production of bioenergy and bio-products within the Mississippi River Basin.
Collapse
Affiliation(s)
- Miae Ha
- Energy Systems Division, Argonne National Laboratory, Lemont, IL 60439, USA.
| | - Zhonglong Zhang
- Limno Tech, Environmental Laboratory, U.S. Army Engineer R&D Center, USA
| | - May Wu
- Energy Systems Division, Argonne National Laboratory, Lemont, IL 60439, USA
| |
Collapse
|
10
|
Schilling KE, Kim SW, Jones CS, Wolter CF. Orthophosphorus Contributions to Total Phosphorus Concentrations and Loads in Iowa Agricultural Watersheds. JOURNAL OF ENVIRONMENTAL QUALITY 2017; 46:828-835. [PMID: 28783777 DOI: 10.2134/jeq2017.01.0015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Phosphorus (P) is delivered to streams as episodic particulate P and more continuous soluble P (orthophosphorus [OP]), and it is important to determine the proportion of each P form in river water to more effectively design remedial measures. In this study, we evaluated the annual mean ratios of OP to total P (TP) concentrations and loads in 12 Iowa rivers and found systematic variation in the ratios. The OP/TP ratios were >60% in two tile-drained watersheds of the Des Moines Lobe and in a shallow fractured bedrock watershed in northeast Iowa, whereas in southern and western Iowa, OP contributions to TP were <30%. Higher OP/TP ratios were associated with greater row crop intensity in the watershed and a greater proportion of baseflow in the river. Orthophosphorus contributions from croplands would be greater in watersheds characterized by widespread tile drainage and well-drained soils, whereas cropland TP export would be dominated by particulate P in dissected till plains with poorly drained soils. Understanding the dominant form and transport pathway of P from agricultural areas in a watershed is seen as an important first step in determining appropriate conservation practices to reduce P loads.
Collapse
|
11
|
Horvath EK, Christensen JR, Mehaffey MH, Neale AC. Building a potential wetland restoration indicator for the contiguous United States. ECOLOGICAL INDICATORS 2017; 83:462-473. [PMID: 29706804 PMCID: PMC5920525 DOI: 10.1016/j.ecolind.2017.07.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Wetlands provide key functions in the landscape from improving water quality, to regulating flows, to providing wildlife habitat. Over half of the wetlands in the contiguous United States (CONUS) have been converted to agricultural and urban land uses. However, over the last several decades, research has shown the benefits of wetlands to hydrologic, chemical, biological processes, spurring the creation of government programs and private initiatives to restore wetlands. Initiatives tend to focus on individual wetland creation, yet the greatest benefits are achieved when strategic restoration planning occurs across a watershed or multiple watersheds. For watershed-level wetland restoration planning to occur, informative data layers on potential wetland areas are needed. We created an indicator of potential wetland areas (PWA), using nationally available datasets to identify characteristics that could support wetland ecosystems, including: poorly drained soils and low-relief landscape positions as indicated by a derived topographic data layer. We compared our PWA with the National Wetlands Inventory (NWI) from 11 states throughout the CONUS to evaluate their alignment. The state-level percentage of NWI-designated wetlands directly overlapping the PWA ranged from 39 to 95%. When we included NWI that was immediately adjacent to the overlapping NWI, our range of correspondence to NWI ranged from 60 to 99%. Wetland restoration is more likely on certain landscapes (e.g., agriculture) than others due to the lack of substantive infrastructure and the potential for the restoration of hydrology; therefore, we combined the National Land Cover Dataset (NLCD) with the PWA to identify potentially restorable wetlands on agricultural land (PRW-Ag). The PRW-Ag identified a total of over 46 million ha with the potential to support wetlands. The largest concentrations of PRW-Ag occurred in the glaciated corn belt of the upper Mississippi River from Ohio to the Dakotas and in the Mississippi Alluvial Valley. The PRW-Ag layer could assist land managers in identifying sites that may qualify for enrollment in conservation programs, where planners can coordinate restoration efforts, or where decision makers can target resources to optimize the services provided across a watershed or multiple watersheds.
Collapse
Affiliation(s)
- Elena K Horvath
- US EPA, Office of Research and Development, Oak Ridge Institute for Science and Education, Research Triangle Park, Durham, NC, USA
| | - Jay R Christensen
- US EPA, Office of Research and Development, National Exposure Research Laboratory, Las Vegas, NV, USA
| | - Megan H Mehaffey
- US EPA, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park, Durham, NC, USA
| | - Anne C Neale
- US EPA, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park, Durham, NC, USA
| |
Collapse
|
12
|
Van Metre PC, Frey JW, Musgrove M, Nakagaki N, Qi S, Mahler BJ, Wieczorek ME, Button DT. High Nitrate Concentrations in Some Midwest United States Streams in 2013 after the 2012 Drought. JOURNAL OF ENVIRONMENTAL QUALITY 2016; 45:1696-1704. [PMID: 27695770 DOI: 10.2134/jeq2015.12.0591] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Nitrogen sources in the Mississippi River basin have been linked to degradation of stream ecology and to Gulf of Mexico hypoxia. In 2013, the USGS and the USEPA characterized water quality stressors and ecological conditions in 100 wadeable streams across the midwestern United States. Wet conditions in 2013 followed a severe drought in 2012, a weather pattern associated with elevated nitrogen concentrations and loads in streams. Nitrate concentrations during the May to August 2013 sampling period ranged from <0.04 to 41.8 mg L as N (mean, 5.31 mg L). Observed mean May to June nitrate concentrations at the 100 sites were compared with May to June concentrations predicted from a regression model developed using historical nitrate data. Observed concentrations for 17 sites, centered on Iowa and southern Minnesota, were outside the 95% confidence interval of the regression-predicted mean, indicating that they were anomalously high. The sites with a nitrate anomaly had significantly higher May to June nitrate concentrations than sites without an anomaly (means, 19.8 and 3.6 mg L, respectively) and had higher antecedent precipitation indices, a measure of the departure from normal precipitation, in 2012 and 2013. Correlations between nitrate concentrations and watershed characteristics and nitrogen and oxygen isotopes of nitrate indicated that fertilizer and manure used in crop production, principally corn, were the dominant sources of nitrate. The anomalously high nitrate levels in parts of the Midwest in 2013 coincide with reported higher-than-normal nitrate loads in the Mississippi River.
Collapse
|
13
|
Koontz M, Lundberg C, Lane R, Day J, Pezeshki R. Aboveground Net Primary Productivity in a Riparian Wetland Following Restoration of Hydrology. BIOLOGY 2016; 5:biology5010010. [PMID: 26861409 PMCID: PMC4810167 DOI: 10.3390/biology5010010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 01/15/2016] [Accepted: 01/18/2016] [Indexed: 11/16/2022]
Abstract
This research presents the initial results of the effects of hydrological restoration on forested wetlands in the Mississippi alluvial plain near Memphis, Tennessee. Measurements were carried out in a secondary channel, the Loosahatchie Chute, in which rock dikes were constructed in the 1960s to keep most flow in the main navigation channel. In 2008–2009, the dikes were notched to allow more flow into the secondary channel. Study sites were established based on relative distance downstream of the notched dikes. Additionally, a reference site was established north of the Loosahatchie Chute where the dikes remained unnotched. We compared various components of vegetation composition and productivity at sites in the riparian wetlands for two years. Salix nigra had the highest Importance Value at every site. Species with minor Importance Values were Celtis laevigata, Acer rubrum, and Plantanus occidentalis. Productivity increased more following the introduction of river water in affected sites compared to the reference. Aboveground net primary productivity was highest at the reference site (2926 ± 458.1 g·m−2·year−1), the intact site; however, there were greater increase at the sites in the Loosahatchie Chute, where measurements ranged from 1197.7 ± 160.0 g m−2·year−1·to 2874.2 ± 794.0 g·m−2·year−1. The site furthest from the notching was the most affected. Pulsed inputs into these wetlands may enhance forested wetland productivity. Continued monitoring will quantify impacts of restored channel hydrology along the Mississippi River.
Collapse
Affiliation(s)
- Melissa Koontz
- Department of Biological Sciences, The University of Memphis, Memphis, TN 38152, USA.
| | - Christopher Lundberg
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Robert Lane
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - John Day
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Reza Pezeshki
- Department of Biological Sciences, The University of Memphis, Memphis, TN 38152, USA.
| |
Collapse
|
14
|
|
15
|
Li X, Wellen C, Liu G, Wang Y, Wang ZL. Estimation of nutrient sources and transport using Spatially Referenced Regressions on Watershed Attributes: a case study in Songhuajiang River Basin, China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:6989-7001. [PMID: 25483972 DOI: 10.1007/s11356-014-3903-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/23/2014] [Indexed: 06/04/2023]
Abstract
We report here the first application of the Spatially Referenced Regressions on Watershed Attributes (SPARROW) model to China, a country naturally and culturally distinct from previous SPARROW applications. The Songhuajiang River Basin (556,700 km(2)) empties into the Tongjiang monitoring section, a shared water resource of great import for both Chinese and Russian citizens. The model was calibrated to annual loads of total nitrogen (TN) at 102 sites and total phosphorus (TP) at 65 sites. We assessed the rates of delivery and loss of nutrients from diffuse sources and also provided reach-level predictions of the percentage of nutrient loads delivered from upstream subbasins to Tongjiang monitoring section. The results indicated that farmland and pasture land were responsible for about 70 % of nutrient inputs to the Tongjiang monitoring section. Point source inputs were not statistically significant sources of TN or TP. We presented evidence that rice paddies delivered less TN to streams per area than other types of cropland. The locations responsible for the highest TN and TP inputs to the Tongjiang monitoring section tended to be located near the mainstream, though the areas of highest TN delivered yield did not correspond to the areas of highest TP delivered yield. This suggests that different management priorities may be needed in different parts of the Songhuajiang River Basin.
Collapse
Affiliation(s)
- Xue Li
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China
| | | | | | | | | |
Collapse
|
16
|
Robertson DM, Saad DA. SPARROW Models Used to Understand Nutrient Sources in the Mississippi/Atchafalaya River Basin. JOURNAL OF ENVIRONMENTAL QUALITY 2013; 42:1422-40. [PMID: 24216420 DOI: 10.2134/jeq2013.02.0066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nitrogen (N) and phosphorus (P) loading from the Mississippi/Atchafalaya River Basin (MARB) has been linked to hypoxia in the Gulf of Mexico. To describe where and from what sources those loads originate, SPAtially Referenced Regression On Watershed attributes (SPARROW) models were constructed for the MARB using geospatial datasets for 2002, including inputs from wastewater treatment plants (WWTPs), and calibration sites throughout the MARB. Previous studies found that highest N and P yields were from the north-central part of the MARB (Corn Belt). Based on the MARB SPARROW models, highest N yields were still from the Corn Belt but centered over Iowa and Indiana, and highest P yields were widely distributed throughout the center of the MARB. Similar to that found in other studies, agricultural inputs were found to be the largest N and P sources throughout most of the MARB: farm fertilizers were the largest N source, whereas farm fertilizers, manure, and urban inputs were dominant P sources. The MARB models enable individual N and P sources to be defined at scales ranging from SPARROW catchments (∼50 km) to the entire area of the MARB. Inputs of P from WWTPs and urban areas were more important than found in most other studies. Information from this study will help to reduce nutrient loading from the MARB by providing managers with a description of where each of the sources of N and P are most important, thus providing a basis for prioritizing management actions and ultimately reducing the extent of Gulf hypoxia.
Collapse
|
17
|
Wu Y, Liu S. Modeling of land use and reservoir effects on nonpoint source pollution in a highly agricultural basin. ACTA ACUST UNITED AC 2012; 14:2350-61. [DOI: 10.1039/c2em30278k] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
18
|
Brown JB, Sprague LA, Dupree JA. Nutrient Sources and Transport in the Missouri River Basin, with Emphasis on the Effects of Irrigation and Reservoirs. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 2011; 47:1034-1060. [PMID: 22457581 PMCID: PMC3307633 DOI: 10.1111/j.1752-1688.2011.00584.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 05/02/2011] [Indexed: 05/29/2023]
Abstract
SPAtially Referenced Regressions On Watershed attributes (SPARROW) models were used to relate instream nutrient loads to sources and factors influencing the transport of nutrients in the Missouri River Basin. Agricultural inputs from fertilizer and manure were the largest nutrient sources throughout a large part of the basin, although atmospheric and urban inputs were important sources in some areas. Sediment mobilized from stream channels was a source of phosphorus in medium and larger streams. Irrigation on agricultural land was estimated to decrease the nitrogen load reaching the Mississippi River by as much as 17%, likely as a result of increased anoxia and denitrification in the soil zone. Approximately 16% of the nitrogen load and 33% of the phosphorus load that would have otherwise reached the Mississippi River was retained in reservoirs and lakes throughout the basin. Nearly half of the total attenuation occurred in the eight largest water bodies. Unlike the other major tributary basins, nearly the entire instream nutrient load leaving the outlet of the Platte and Kansas River subbasins reached the Mississippi River. Most of the larger reservoirs and lakes in the Platte River subbasin are upstream of the major sources, whereas in the Kansas River subbasin, most of the source inputs are in the southeast part of the subbasin where characteristics of the area and proximity to the Missouri River facilitate delivery of nutrients to the Mississippi River.
Collapse
|
19
|
Robertson DM, Saad DA. Nutrient Inputs to the Laurentian Great Lakes by Source and Watershed Estimated Using SPARROW Watershed Models. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 2011; 47:1011-1033. [PMID: 22457580 PMCID: PMC3307632 DOI: 10.1111/j.1752-1688.2011.00574.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 03/22/2011] [Indexed: 05/19/2023]
Abstract
Nutrient input to the Laurentian Great Lakes continues to cause problems with eutrophication. To reduce the extent and severity of these problems, target nutrient loads were established and Total Maximum Daily Loads are being developed for many tributaries. Without detailed loading information it is difficult to determine if the targets are being met and how to prioritize rehabilitation efforts. To help address these issues, SPAtially Referenced Regressions On Watershed attributes (SPARROW) models were developed for estimating loads and sources of phosphorus (P) and nitrogen (N) from the United States (U.S.) portion of the Great Lakes, Upper Mississippi, Ohio, and Red River Basins. Results indicated that recent U.S. loadings to Lakes Michigan and Ontario are similar to those in the 1980s, whereas loadings to Lakes Superior, Huron, and Erie decreased. Highest loads were from tributaries with the largest watersheds, whereas highest yields were from areas with intense agriculture and large point sources of nutrients. Tributaries were ranked based on their relative loads and yields to each lake. Input from agricultural areas was a significant source of nutrients, contributing ∼33-44% of the P and ∼33-58% of the N, except for areas around Superior with little agriculture. Point sources were also significant, contributing ∼14-44% of the P and 13-34% of the N. Watersheds around Lake Erie contributed nutrients at the highest rate (similar to intensively farmed areas in the Midwest) because they have the largest nutrient inputs and highest delivery ratio.
Collapse
|
20
|
Rebich RA, Houston NA, Mize SV, Pearson DK, Ging PB, Evan Hornig C. Sources and Delivery of Nutrients to the Northwestern Gulf of Mexico from Streams in the South-Central United States. JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION 2011; 47:1061-1086. [PMID: 22457582 PMCID: PMC3307634 DOI: 10.1111/j.1752-1688.2011.00583.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 05/02/2011] [Indexed: 05/29/2023]
Abstract
SPAtially Referenced Regressions On Watershed attributes (SPARROW) models were developed to estimate nutrient inputs [total nitrogen (TN) and total phosphorus (TP)] to the northwestern part of the Gulf of Mexico from streams in the South-Central United States (U.S.). This area included drainages of the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf hydrologic regions. The models were standardized to reflect nutrient sources and stream conditions during 2002. Model predictions of nutrient loads (mass per time) and yields (mass per area per time) generally were greatest in streams in the eastern part of the region and along reaches near the Texas and Louisiana shoreline. The Mississippi River and Atchafalaya River watersheds, which drain nearly two-thirds of the conterminous U.S., delivered the largest nutrient loads to the Gulf of Mexico, as expected. However, the three largest delivered TN yields were from the Trinity River/Galveston Bay, Calcasieu River, and Aransas River watersheds, while the three largest delivered TP yields were from the Calcasieu River, Mermentau River, and Trinity River/Galveston Bay watersheds. Model output indicated that the three largest sources of nitrogen from the region were atmospheric deposition (42%), commercial fertilizer (20%), and livestock manure (unconfined, 17%). The three largest sources of phosphorus were commercial fertilizer (28%), urban runoff (23%), and livestock manure (confined and unconfined, 23%).
Collapse
|
21
|
|
22
|
Jacobson LM, David MB, Drinkwater LE. A spatial analysis of phosphorus in the Mississippi river basin. JOURNAL OF ENVIRONMENTAL QUALITY 2011; 40:931-941. [PMID: 21546679 DOI: 10.2134/jeq2010.0386] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Phosphorus (P) in rivers in the Mississippi River basin (MRB) contributes to hypoxia in the Gulf of Mexico and impairs local water quality. We analyzed the spatial pattern of P in the MRB to determine the counties with the greatest January to June P riverine yields and the most critical factors related to this P loss. Using a database of P inputs and landscape characteristics from 1997 through 2006 for each county in the MRB, we created regression models relating riverine total P (TP), dissolved reactive P (DRP), and particulate P (PP) yields for watersheds within the MRB to these factors. Riverine yields of P were estimated from the average concentration of each form of P during January to June for the 10-yr period, multiplied by the average daily flow, and then summed for the 6-mo period. The fraction of land planted in crops, human consumption of P, and precipitation were found to best predict TP yields with a spatial error regression model ( = 0.48, = 101). Dissolved reactive P yields were predicted by fertilizer P inputs, human consumption of P, and precipitation in a multiple regression model ( = 0.42, = 73), whereas PP yields were explained by crop fraction, human consumption of P, and soil bulk density in a spatial error regression model ( = 0.49, = 61). Overall, the Upper Midwest's Cornbelt region and lower Mississippi basin had the counties with the greatest P yields. These results help to point out specific areas where agricultural conservation practices that reduce losses to streams and rivers and point source P removal might limit the intensity or spatial occurrence of Gulf of Mexico hypoxia and improve local water quality.
Collapse
Affiliation(s)
- Linda M Jacobson
- Dep. of Natural Resources and Environmental Sciences, Univ of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | | |
Collapse
|
23
|
Hubbard L, Kolpin DW, Kalkhoff SJ, Robertson DM. Nutrient and sediment concentrations and corresponding loads during the historic June 2008 flooding in eastern Iowa. JOURNAL OF ENVIRONMENTAL QUALITY 2011; 40:166-175. [PMID: 21488505 DOI: 10.2134/jeq2010.0257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A combination of above-normal precipitation during the winter and spring of 2007-2008 and extensive rainfall during June 2008 led to severe flooding in many parts of the midwestern United States. This resulted in transport of substantial amounts of nutrients and sediment from Iowa basins into the Mississippi River. Water samples were collected from 31 sites on six large Iowa tributaries to the Mississippi River to characterize water quality and to quantify nutrient and sediment loads during this extreme discharge event. Each sample was analyzed for total nitrogen, dissolved nitrate plus nitrite nitrogen, dissolved ammonia as nitrogen, total phosphorus, orthophosphate, and suspended sediment. Concentrations measured near peak flow in June 2008 were compared with the corresponding mean concentrations from June 1979 to 2007 using a paired t test. While there was no consistent pattern in concentrations between historical samples and those from the 2008 flood, increased flow during the flood resulted in near-peak June 2008 flood daily loads that were statistically greater (p < 0.05) than the median June 1979 to 2007 daily loads for all constituents. Estimates of loads for the 16-d period during the flood were calculated for four major tributaries and totaled 4.95 x 10(7) kg of nitrogen (N) and 2.9 x 10(6) kg of phosphorus (P) leaving Iowa, which accounted for about 22 and 46% of the total average annual nutrient yield, respectively. This study demonstrates the importance of large flood events to the total annual nutrient load in both small streams and large rivers.
Collapse
Affiliation(s)
- L Hubbard
- U.S. Geological Survey, 400 S. Clinton St., Rm. 269, Iowa City, IA 52240, USA.
| | | | | | | |
Collapse
|
24
|
David MB, Drinkwater LE, McIsaac GF. Sources of nitrate yields in the Mississippi River Basin. JOURNAL OF ENVIRONMENTAL QUALITY 2010; 39:1657-1667. [PMID: 21043271 DOI: 10.2134/jeq2010.0115] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Riverine nitrate N in the Mississippi River leads to hypoxia in the Gulf of Mexico. Several recent modeling studies estimated major N inputs and suggested source areas that could be targeted for conservation programs. We conducted a similar analysis with more recent and extensive data that demonstrates the importance of hydrology in controlling the percentage of net N inputs (NNI) exported by rivers. The average fraction of annual riverine nitrate N export/NNI ranged from 0.05 for the lower Mississippi subbasin to 0.3 for the upper Mississippi River basin and as high as 1.4 (4.2 in a wet year) for the Embarras River watershed, a mostly tile-drained basin. Intensive corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] watersheds on Mollisols had low NNI values and when combined with riverine N losses suggest a net depletion of soil organic N. We used county-level data to develop a nonlinear model ofN inputs and landscape factors that were related to winter-spring riverine nitrate yields for 153 watersheds within the basin. We found that river runoff times fertilizer N input was the major predictive term, explaining 76% of the variation in the model. Fertilizer inputs were highly correlated with fraction of land area in row crops. Tile drainage explained 17% of the spatial variation in winter-spring nitrate yield, whereas human consumption of N (i.e., sewage effluent) accounted for 7%. Net N inputs were not a good predictor of riverine nitrate N yields, nor were other N balances. We used this model to predict the expected nitrate N yield from each county in the Mississippi River basin; the greatest nitrate N yields corresponded to the highly productive, tile-drained cornbelt from southwest Minnesota across Iowa, Illinois, Indiana, and Ohio. This analysis can be used to guide decisions about where efforts to reduce nitrate N losses can be most effectively targeted to improve local water quality and reduce export to the Gulf of Mexico.
Collapse
Affiliation(s)
- Mark B David
- Univ. of Illinois, Dep. of Natural Resources and Environmental Sciences, W-503 Turner Hall, 1102 S. Goodwin Ave., Urbana, IL 61801, USA.
| | | | | |
Collapse
|