Exploring the Relationship Between Hydrologic Parameters and Nutrient Loads Using Digital Elevation Model and GIS – A Case Study from Sugarcreek Headwaters, Ohio, U.S.A.

Ohio is typical among the Midwestern and Eastern United States with high levels of water pollutants, the main sources being from agriculture. In this study, we used a digital elevation model in conjunction with hydrological indices to determine the role of landscape complexity affecting the spatial and temporal variation in pollutant levels, in one of the most impaired headwater streams in Ohio. More than eighty five percent of the study area is dominated by agriculture. Spatial distribution of slope (S), altitude and wetness index along with other watershed parameters such as flow direction, flow accumulation, stream networks, flow stream orders and erosion index were used within a Geographic Information Systems framework to quantify variation in nitrate and phosphate loads to headwater streams. Stream monitoring data for nutrient loads were used to correlate the observed spatial and temporal patterns with hydrological parameters using multiple linear regressions. Results from the wetness index calculated from a digital elevation model suggested a range of 0.10–16.39, with more than 35% having values less than 4.0. A Revised Universal Soil Loss Equation (RUSLE) predicted soil loss in the range of 0.01–4.0 t/ha/yr. Nitrate nitrogen levels in the study area paralleled precipitation patterns over time, with higher nitrate levels corresponding to high precipitation. Atmospheric deposition through precipitation could explain approximately 35% of total nitrate levels observed in streams. Among the different topographic variables and hydrological indices, results from the step-wise multiple regression suggested the following best predictors, (1) elevation range and upstream flow length for nitrate, (2) flow direction and upstream flow length for ammonia-nitrogen and slope, and (3) elevation range for phosphate levels. Differences in the landscape models observed for nitrate, phosphate and ammonia-nitrogen in the surface waters were attributed partly to differences in the chemical activity and source strengths of the different forms of these nutrients through agricultural management practices. The results identify geomorphologic and landscape characteristics that influence pollutant levels in the study area.     

Simultaneous DOAS and mist-chamber IC measurements of HONO in Houston,TX

Nitrous acid is an important component of nighttime N-oxide chemistry, and provides a significant source of both OH and NO in polluted urban air masses shortly after sunrise. Several recent studies have called for new sources of HONO to account for daytime levels much higher than are consistent with current understanding. However, measurement of HONO is problematic, with most in-situ techniques reporting higher values than simultaneous optical measurements by long-path DOAS, especially during daytime. The discrepancy has been attributed to positive interference in the in-situ techniques, negative interference in DOAS retrievals, the difficulty of comparing the different air masses sampled by the methods, or combinations of these.During August and September 2006, HONO mixing ratios from collocated long-path DOAS and automated mist-chamber/ion chromatograph (MC/IC) systems ranged from several ppbv during morning rush hour to daytime minima near 100 pptv. Agreement between the two techniques was excellent across this entire range during many days, showing that both instruments accurately measured HONO during this campaign. A small bias towards higher LP-DOAS observations at night can be attributed to slow vertical mixing leading to pronounced HONO profiles. A positive daytime bias of the MC/IC instrument during several days in late August/early September was correlated with photochemically produced compounds such as ozone, HNO₃ and HCHO, but not with NO₂, NO_x, HO₂NO₂, or the NO₂ photolysis rate. While an interferant could not be identified organic nitrites appear a possible explanation for our observations.     

Atrazine removal in agricultural infiltrate by bioaugmented polyvinyl alcohol immobilized and free Agrobacterium radiobacter J14a: a sand column study

Bench-scale sand column breakthrough experiments were conducted to examine atrazine removal in agricultural infiltrate by Agrobacterium radiobacter J14a (J14a) immobilized in phosphorylated-polyvinyl alcohol compared to free J14a cells. The effects of cell loading and infiltration rate on atrazine degradation and the loss of J14a were investigated. Four sets of experiments, (i) tracers, (ii) immobilized dead cells, (iii) immobilized cells, and (iv) free cells, were performed. The atrazine biodegradation at the cell loadings of 300, 600, and 900 mg dry cells L(-1) and the infiltration rates of 1, 3, and 6 cm d(-1) were tested for 5 column pore volumes (PV). The atrazine breakthrough results indicated that the immobilized dead cells significantly retarded atrazine transport. The atrazine removal efficiencies at the infiltration rates of 1, 3, and 6 cm d(-1) were 100%, 80-97%, and 50-70%, respectively. Atrazine degradation capacity for the immobilized cells was not significantly different from the free cells. Both infiltration rate and cell loading significantly affected atrazine removal for both cell systems. The bacterial loss from the immobilized cell system was 10-100 times less than that from the free cell system. For long-term tests at 50 PV, the immobilized cell system provided consistent atrazine removal efficiency while the atrazine removal by the free cells declined gradually because of the cell loss.     

Developing a circumpolar programme for the monitoring of Arctic terrestrial biodiversity

The Arctic is undergoing biological and environmental changes, and a coordinated effort to monitor is critical to detect these changes. The Circumpolar Biodiversity Monitoring Programme (CBMP) of the Arctic Council biodiversity working group, Conservation of Arctic Flora and Fauna (CAFF), has developed pan-Arctic biodiversity monitoring plans that aims to improve the ability to detect and report on long-term changes. Whilst introducing this special issue, this paper also presents the making of the terrestrial monitoring plan and discusses how the plan follows the steps required for an adaptive and ecosystem-based monitoring programme. In this article, we discuss how data on key findings can be used to inform circumpolar and global assessments, including the State of the Arctic Terrestrial Biodiversity Report, which will be the first terrestrial assessment made by the CBMP. Key findings, advice for future monitoring and lessons learned will be used in planning next steps of pan-Arctic coordinated monitoring.     

Mounting Tensions: Materializing Strategies and Tactics on National Park “Social Trails”

This essay builds from Samantha Senda-Cook's 2013 article, “Materializing Tensions,” to explore the material rhetorics of the so-called “social trails” of the Apostle Islands National Lakeshore. These improvised, foot-worn pathways, diverging from and running alongside official Park Service trails, materialize a tension between what Michel de Certeau termed “strategies” and “tactics,” revealing how both are always at play in park and preserve trailspace and how the movements of the individual trail walker actualize and perpetuate a common concept of place. The study demonstrates and advocates close rhetorical attention to material aspects of the biophysical environment and the way that physical traces of many individuals over time can influence the subsequent actions and interpretations of others. The final discussion argues that as further tensions in trailspace rhetorics are identified rhetorical analysis must not fail to account for them.     

The geomorphology and ecosystem service economic value baselines of tributary watersheds in Malaysia

Environment, Development and Sustainability - This study presents how a cluster of tributary watersheds was evaluated for geomorphology and ecosystem service economic value baselines. Tributary...     

On the preconditions for large-scale collective action

Ambio - The phenomenon of collective action and the origin of collective action problems have been extensively and systematically studied in the social sciences. Yet, while we have substantial...     

Matching innovations with potential users, a case study of potato IPM practices

Through interviews and mail surveys, Ohio potato (Solanum tuberosum) growers were surveyed concerning their willingness to adopt three cultural controls being developed for management of the Colorado potato beetle, Leptinotarsa decemlineata (Say), which had become increasingly difficult to control. The principal objective of the research was to obtain a deeper understanding of how farmers make decisions to adopt or not adopt new techniques and how these decisions are related to farmers' educational backgrounds and the way they currently manage their farms. The three cultural management options emphasized ecological approaches to habitat management rather than ecologically disruptive chemical control: (1) using host plants in overwintering sites to slow the spring movement of the beetles to potato fields, (2) using larger potato plants at field borders than in the center of the field as a spring trap crop, and (3) concentrating beetles in relatively small undefoliated areas to be killed with heat in late summer. Most respondents would not adopt these alternative pest management strategies, mainly because they perceived an unsatisfactory trade-off between logistic difficulties and expenses and population suppression they would achieve compared with traditional chemical control measures. Education correlated positively and experience in farming negatively with the willingness to try new pest management techniques. Additionally, growers responding more negatively to questions regarding integrated pest management strategies were more willing to experiment with the alternative techniques, a result attributed to either the survey design or an indication of experience with the more intensive management effort required for integrated pest management. This profile of potential innovators should be used by researchers to establish partnerships with farmers that could assist with both the research and development of new farming techniques and the adoption of successful systems by other farmers.     

Differences in chloroplast ultrastructure of Phaeocystis antarctica in low and high light

Phaeocystis antarctica Karsten exhibits optical changes in pigment packaging during acclimation to drastically different light levels. Here, the three-dimensional morphological rearrangements are shown for two light conditions mimicking limiting and saturating conditions for photosynthesis. Cultures of P. antarctica were grown semi-continuously under light-limiting conditions for growth (14 μmol quanta m⁻² s⁻¹) and a light-saturating condition (259 μmol quanta m⁻² s⁻¹) for growth. Increased numbers of thylakoids were observed under the low light treatment. In contrast, there were less amounts of thylakoid stacking in each chloroplast under the high light treatment. Electron microscopic tomographic reconstructions illustrate the complexity of the chloroplast organelle where the thylakoids ‘interact’ with the pyrenoid and the chloroplast membrane. Highly complex characteristics, such as bi- and tri-furcations in the thylakoid stacks, were continuous throughout the chloroplast. Other organelles, such as the Golgi apparatus and dense vesicles that may potentially affect cellular scattering and absorption were also observed in both high and low light. These three dimensional thylakoid arrangements have profound implications for cellular photophysiology. They represent a new view of algal chloroplast structure, and provide a starting point for more accurate optical modeling studies.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.