scholarly journals The influence of landscape spatial configuration on nitrogen and phosphorus exports in agricultural catchments

2021 ◽  
Author(s):  
Antoine Casquin ◽  
Rémi Dupas ◽  
Sen Gu ◽  
Ewan Couic ◽  
Gérard Gruau ◽  
...  
Keyword(s):  
Spatial Configuration ◽  
Nitrogen And Phosphorus ◽  
Agricultural Catchments

scholarly journals Relationships between land use and nitrogen and phosphorus in New Zealand lakes

2011 ◽  
Vol 62 (2) ◽  
pp. 162 ◽  
Author(s):  
Jonathan M. Abell ◽  
Deniz Özkundakci ◽  
David P. Hamilton ◽  
Steven D. Miller
Keyword(s):  
Land Use ◽  
New Zealand ◽  
Nitrogen And Phosphorus ◽  
Nutrient Sources ◽  
Soil P ◽  
Agricultural Catchments ◽  
Relative Contribution ◽  
Naturally Occurring ◽  
Lake Catchment ◽  
The Relationship

Developing policies to address lake eutrophication requires an understanding of the relative contribution of different nutrient sources and of how lake and catchment characteristics interact to mediate the source–receptor pathway. We analysed total nitrogen (TN) and total phosphorus (TP) data for 101 New Zealand lakes and related these to land use and edaphic sources of phosphorus (P). We then analysed a sub-sample of lakes in agricultural catchments to investigate how lake and catchment variables influence the relationship between land use and in-lake nutrients. Following correction for the effect of co-variation amongst predictor variables, high producing grassland (intensive pasture) was the best predictor of TN and TP, accounting for 38.6% and 41.0% of variation, respectively. Exotic forestry and urban area accounted for a further 18.8% and 3.6% of variation in TP and TN, respectively. Soil P (representing naturally-occurring edaphic P) was negatively correlated with TP, owing to the confounding effect of pastoral land use. Lake and catchment morphology (zmax and lake : catchment area) and catchment connectivity (lake order) mediated the relationship between intensive pasture and in-lake nutrients. Mitigating eutrophication in New Zealand lakes requires action to reduce nutrient export from intensive pasture and quantifying P export from plantation forestry requires further consideration.

Seasonal Characterisation and Trends Study of Nutrient Concentrations in Surface Water from Catchments with Intensive Livestock Farming

2010 ◽  
Vol 5 (-1) ◽  
pp. 8-15 ◽  
Author(s):  
Laima Berzina ◽  
Ritvars Sudars
Keyword(s):  
Water Quality ◽  
Surface Water ◽  
Nutrient Concentrations ◽  
Water Protection ◽  
Nitrogen And Phosphorus ◽  
Livestock Farming ◽  
Protection Measures ◽  
Agricultural Catchments ◽  
Phosphorus Losses

Seasonal Characterisation and Trends Study of Nutrient Concentrations in Surface Water from Catchments with Intensive Livestock Farming Temporal changes in observed nitrogen and phosphorus losses to surface water were studied in 3 agricultural catchments in order to evaluate the achievement of water protection targets in Latvia. The aim of this study is to investigate the water quality measures in high density livestock farming catchments. Long-term monitoring data (years 1996-2008) of water quality used in the analysis show a high annual and monthly variability of nutrients. The results demonstrate little or no reduction of nutrient concentrations in surface water. The results suggest that water protection measures for agricultural production need to be further intensified.

The influence of landscape spatial arrangement on nitrogen and phosphorus export in agricultural catchments

2021 ◽  
Author(s):  
Rémi Dupas ◽  
Antoine Casquin ◽  
Sen Gu ◽  
Gérard Gruau ◽  
Patrick Durand
Keyword(s):  
Land Use ◽  
Agricultural Land ◽  
Spatial Configuration ◽  
Landscape Composition ◽  
Landscape Configuration ◽  
Agricultural Land Use ◽  
Nitrogen And Phosphorus ◽  
Nutrient Sources ◽  
Rural Landscapes ◽  
Flow Accumulation

<p>Nitrogen and Phosphorus losses from rural landscapes can cause eutrophication of inland and coastal waters. Here, we assessed the influence of the spatial configuration of nutrient sources on nitrate (NO<sub>3</sub><sup>-</sup>) and total phosphorus (TP) exports at the catchment scale. We analyzed NO<sub>3</sub><sup>-</sup> and TP in 19 headwater catchments (1 -14 km²) fortnightly during 17 months. The study catchments had similar soil type, climate, and farming systems but differed in their landscape composition (% agricultural land-use) and spatial configuration (field distance to streams & intersection with flow accumulation zones). We propose a landscape configuration index (LCI) that describes the spatial configuration of nutrient sources with regards to their hydrological distance to streams and flow accumulation zones. The LCI has two parameters that we calibrated to maximize rank correlation with median concentrations of TP and NO<sub>3</sub><sup>-</sup>. Results showed that NO<sub>3</sub><sup>-</sup> exports were correlated with %agricultural land-use whereas TP exports were better explained by the spatial configuration of agricultural fields. For a given landscape composition, landscape spatial configuration was highly heterogeneous at small scales (<10 km<sup>2</sup>) but became homogeneous at larger scales (>50 km<sup>2</sup>). This could explain why relationships between landscape composition and water quality parameters influenced by landscape spatial configuration break down below a certain size threshold.</p>

scholarly journals Nitrogen and phosphorus discharge from small agricultural catchments predicted from land use and hydroclimate

2018 ◽  
Vol 75 ◽  
pp. 260-268 ◽  
Author(s):  
Jaan Pärn ◽  
Hocine Henine ◽  
Kuno Kasak ◽  
Karin Kauer ◽  
Kristina Sohar ◽  
...  
Keyword(s):  
Land Use ◽  
Nitrogen And Phosphorus ◽  
Agricultural Catchments

The Effect of Nonlinear Amplitude Growth on the Speech Perception Benefits Provided by a Single-Sided Vocoder

2019 ◽  
Vol 62 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Jessica M. Wess ◽  
Joshua G. W. Bernstein
Keyword(s):  
Transfer Functions ◽  
Spatial Configuration ◽  
Free Field ◽  
Spatial Separation ◽  
Compression And Expansion ◽  
Interaural Difference ◽  
Interaural Differences ◽  
Single Sided Deafness ◽  
Perceptual Separation ◽  
Loudness Growth

PurposeFor listeners with single-sided deafness, a cochlear implant (CI) can improve speech understanding by giving the listener access to the ear with the better target-to-masker ratio (TMR; head shadow) or by providing interaural difference cues to facilitate the perceptual separation of concurrent talkers (squelch). CI simulations presented to listeners with normal hearing examined how these benefits could be affected by interaural differences in loudness growth in a speech-on-speech masking task.MethodExperiment 1 examined a target–masker spatial configuration where the vocoded ear had a poorer TMR than the nonvocoded ear. Experiment 2 examined the reverse configuration. Generic head-related transfer functions simulated free-field listening. Compression or expansion was applied independently to each vocoder channel (power-law exponents: 0.25, 0.5, 1, 1.5, or 2).ResultsCompression reduced the benefit provided by the vocoder ear in both experiments. There was some evidence that expansion increased squelch in Experiment 1 but reduced the benefit in Experiment 2 where the vocoder ear provided a combination of head-shadow and squelch benefits.ConclusionsThe effects of compression and expansion are interpreted in terms of envelope distortion and changes in the vocoded-ear TMR (for head shadow) or changes in perceived target–masker spatial separation (for squelch). The compression parameter is a candidate for clinical optimization to improve single-sided deafness CI outcomes.

Influence of increased nutrient supply on Microcystis aeruginosa at cellular and proteomic levels

2020 ◽  
Vol 85 ◽  
pp. 47-58
Author(s):  
Y Jiang ◽  
Y Liu
Keyword(s):  
Microcystis Aeruginosa ◽  
Regulatory Protein ◽  
Acid Synthesis ◽  
Nutrient Supply ◽  
Nitrogen Supply ◽  
Nitrogen And Phosphorus ◽  
Comprehensive Description ◽  
Amino Acid Synthesis ◽  
High Nutrient ◽  
Proteomic Responses

Various studies have observed that increased nutrient supply promotes the growth of bloom-forming cyanobacteria, but only a limited number of studies have investigated the influence of increased nutrient supply on bloom-forming cyanobacteria at the proteomic level. We investigated the cellular and proteomic responses of Microcystis aeruginosa to elevated nitrogen and phosphorus supply. Increased supply of both nutrients significantly promoted the growth of M. aeruginosa and the synthesis of chlorophyll a, protein, and microcystins. The release of microcystins and the synthesis of polysaccharides negatively correlated with the growth of M. aeruginosa under high nutrient levels. Overexpressed proteins related to photosynthesis, and amino acid synthesis, were responsible for the stimulatory effects of increased nutrient supply in M. aeruginosa. Increased nitrogen supply directly promoted cyanobacterial growth by inducing the overexpression of the cell division regulatory protein FtsZ. NtcA, that regulates gene transcription related to both nitrogen assimilation and microcystin synthesis, was overexpressed under the high nitrogen condition, which consequently induced overexpression of 2 microcystin synthetases (McyC and McyF) and promoted microcystin synthesis. Elevated nitrogen supply induced the overexpression of proteins involved in gas vesicle organization (GvpC and GvpW), which may increase the buoyancy of M. aeruginosa. Increased phosphorus level indirectly affected growth and the synthesis of cellular substances in M. aeruginosa through the mediation of differentially expressed proteins related to carbon and phosphorus metabolism. This study provides a comprehensive description of changes in the proteome of M. aeruginosa in response to an increased supply of 2 key nutrients.

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