Spatial variability in nutrient concentration and biofilm nutrient limitation in an urban watershed

Hoellein, Timothy J.; Arango, Clay P.; Zak, Yana

doi:10.1007/s10533-011-9631-x

Cited by 29 publications

(26 citation statements)

References 53 publications

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“…These findings are consistent with the urban stream syndrome and urban watershed concepts in that greater impervious surface leads to less infiltration, greater stormwater runoff, and higher nutrient concentrations flowing through the watershed (Walsh et al 2005;Kaushal & Belt 2012). Hoellein et al (2011) found a strong relationship between NO 3 ¡ ÀN instantaneous yield and percent impervious surface, while others found relationships between stream water NO 3 ¡ ÀN, a predictor of denitrification rates, and land use (Arango & Tank 2008). In contrast to our findings, Meyer et al (2005) found that NO 3 ¡ ÀN decreased with increasing urbanization.…”

Section: Discussionsupporting

confidence: 79%

Effects of seasonal variation and land cover on riparian denitrification along a mid-sized river

Hopfensperger

Schwarz

Kirtman

2014

Journal of Freshwater Ecology

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Urban areas contribute disproportional nitrogen (N) loads to downstream aquatic ecosystems resulting in potential hypoxic 'dead' zones. Riparian areas along streams and rivers reduce inorganic N concentrations through denitrification, an anaerobic microbial process. Our study objective was to investigate the denitrification potential of riparian areas with differing land cover composition along the Licking River in Kentucky, USA À a tributary of the Ohio River. For one year we collected monthly samples from four sites along a 60 km reach of the Licking River. We experienced substantial drought conditions in the first half of our study period followed by record precipitation and flooding in the second half of our study period. Land cover surrounding the sample sites was classified into distinct classes hypothesized to contribute to N loads. We found flooding increased denitrification potential, water nitrate concentration, and soil organic matter, while drought conditions increased soil ammonium concentrations. Our site with the greatest impervious surface had the highest denitrification potential, and soil and water ammonium concentrations. However, we determined that denitrification potential was mostly driven by soil organic matter content and only slightly by soil nitrate among all study sites. Our data demonstrate that riparian zones of mid-sized rivers in urban areas can be integral in removing excess N during flood events and can do so year-round provided sufficient N and carbon resources are present.

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Section: Discussionsupporting

confidence: 79%

Effects of seasonal variation and land cover on riparian denitrification along a mid-sized river

Hopfensperger

Schwarz

Kirtman

2014

Journal of Freshwater Ecology

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“…NH + 4 -N was the dominant form of TDN except at the Headwater and Estuary sites where NO − 2 + NO − 3 -N was predominant (Table 1). This finding differs from urban watershed studies in Japan and the USA, where elevated NO − 3 -N concentrations in stream water was the dominant response to urbanization (Wollheim et al 2005;Rosenzweig et al 2008;Ileva et al 2009;Hoellein et al 2011). However, the concentrations of NO − 2 + NO − 3 -N that we observed (Table 1) were in a similar range as the urbanized Baltimore watersheds, approximately 0-3 mg N L −1 (Kaushal et al 2011).…”

Section: Discussioncontrasting

confidence: 99%

“…Wollheim et al (2005) compared an urban catchment (79% urban) with a forested catchment (16% urban) and found that the urban catchment exported approximately 45% more NO − 3 -N in stream water. In the highly urbanized New York City metropolitan area, instantaneous NO − 3 -N yield was significantly correlated with impervious surface cover (%) in sub-watersheds of the Bronx River watershed (Hoellein et al 2011). The highest NO − 3 -N concentrations were delayed from the instream flow peak during rain events in a New Jersey urban catchment (Rosenzweig et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Preliminary results from monitoring of stream nitrogen concentrations, denitrification, and nitrification potentials in an urbanizing watershed in Xiamen, southeast China

Gao

et al. 2013

International Journal of Sustainable Development & World Ec

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As a part of the Long-term Urban Ecosystem Observation and Research Station in Xiamen (Xiamen LUEORS) with the Environmental Internet of Things (EIoT) as its technical support, southeast China by the Institute of Urban Environment, Chinese Academy of Sciences, long-term monitoring was established in an urbanizing watershed to understand the effects of urbanization on stream water quality. Six monitoring sites were established within forested headwater (Headwater), reservoir (Reservoir), agricultural (Agriculture, two locations), suburban residential (Residence), and estuarine (Estuary) locations within the Bantou reservoir watershed. Results from data collected in the whole year of 2012 show that in-stream total dissolved nitrogen (TDN) concentrations were significantly higher in the agricultural and residential sites and in the cool season. Although dissolved inorganic nitrogen (DIN) in stream water was dominated by NH + 4 -N rather than NO − 3 -N except in the headwater and estuary sites, NO − 3 -N concentrations were relatively greater in the residential and two agricultural sites than other sites. Dissolved organic nitrogen (DON) in stream water was high, comprising more than half of TDN in the forested headwater and estuary sites and nearly one third of TDN in other sites. Rain events (rainfall on or between the sampling dates) did not significantly influence nitrogen concentrations in stream water. Surface sediments from the different sites had similar denitrification enzyme activity (DEA), comparable to previous studies. Potential nitrification (potential ammonium oxidation, PAO) was significantly greater in the agricultural and residential sites (P < 0.05). These preliminary results suggest that land-use change has significant effects on watershed nitrogen dynamics in southeast China and that these effects differ somewhat from results observed in other parts of the world. The difference might be due to the 'real' urbanizing watershed in comparison with the stabilized watersheds with little development in the developed countries.

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“…run-off) inputs (Walsh et al, 2005). Johnson, Tank & Dodds, 2009;Hoellein, Arango & Zak, 2011). Differential enrichment of N and P may also change the identity of limiting nutrients with increasing urbanisation.…”

Section: Introductionmentioning

confidence: 99%

Urbanisation and earthquake disturbance influence microbial nutrient limitation in streams

2015

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Summary Nutrient loading as a consequence of urbanisation is a common phenomenon that can influence microbial nutrient limitation in streams. How nutrient loading and nutrient limitation relate to increasing urban intensity, and whether there is any coherence in patterns across cities, is not well known. Nutrient limitation may also be influenced by natural disturbances that alter urban infrastructure and processes in urban streams. To examine this, we measured microbial nutrient limitation across urbanisation gradients in two cities in New Zealand. We took advantage of recent large earthquakes in one of the cities to determine how natural disturbance influences processes in an urban system. Biofilm responses to nitrogen (N) and phosphorus (P) amendment were tested using nutrient diffusing substrata (NDS) in 24 streams, 12 in each of New Zealand's two largest cities (Auckland and Christchurch). Biofilm response was measured across a gradient of land‐use intensity in each city. Regression models were used to quantify the relationships among water chemistry, land use and degree of biofilm N and P limitation. Water column N:P (DIN:SRP) was a good predictor of response of community respiration on organic substrata, but not of response of chl a on inorganic substrata. Autotrophic response was often not nutrient‐limited and was not likely to have been limited by light, suggesting other factors governed the development of autotrophs. We found a switch in response of biofilm respiration on organic substrata from N to P limitation in Auckland, with N limitation increasing below a N:P ratio of 20.8 and P limitation increasing above a ratio of 14.5, roughly in line with the Redfield ratio. Similarly, in Christchurch microbes showed little response to nutrient enrichment at sites with elevated nutrient concentrations. In Auckland, increasing urban intensity was associated with increased nutrient concentrations, but N increased faster than P. This translated to a nonlinear response of biofilm nutrient limitation to increasing urbanisation indicated as population density. There was a breakpoint from N to P limitation at a relatively low population density of >97 people per km2. Patterns of limitation with urbanisation were not as strong in Christchurch; however, responses were similar within the range of overlapping population densities in the two cities. Earthquake disturbance had noticeable effects on streams, including sevenfold lower DIN concentrations and inhibition by both N and P of community respiration on organic substrata. Urbanisation is a key driver of microbial nutrient limitation. Between cities, nutrient loading associated with urbanisation consistently affected the capacity of biofilms to process excess nutrients. Earthquake effects further influenced microbial limitation patterns with natural disturbance dramatically altering how urbanisation effects are manifested.

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Spatial variability in nutrient concentration and biofilm nutrient limitation in an urban watershed

Cited by 29 publications

References 53 publications

Effects of seasonal variation and land cover on riparian denitrification along a mid-sized river

Effects of seasonal variation and land cover on riparian denitrification along a mid-sized river

Preliminary results from monitoring of stream nitrogen concentrations, denitrification, and nitrification potentials in an urbanizing watershed in Xiamen, southeast China

Urbanisation and earthquake disturbance influence microbial nutrient limitation in streams

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