scholarly journals Changing nitrogen deposition with low δ15N−NH4 + and δ15N−NO3 − values at the Experimental Lakes Area, northwestern Ontario, Canada

FACETS ◽  
2017 ◽  
Vol 2 (1) ◽  
pp. 249-266 ◽  
Author(s):  
J.J. Venkiteswaran ◽  
S.L. Schiff ◽  
M.J. Paterson ◽  
N.A.P. Flinn ◽  
H. Shao ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
N Deposition ◽  
International Institute ◽  
Experimental Lakes Area ◽  
Total N ◽  
Global Trends ◽  
Northwestern Ontario ◽  
Wide Range ◽  
Sampling Regime ◽  
Ammonium Deposition

Ammonium deposition at the International Institute for Sustainable Development Experimental Lakes Area (IISD–ELA), in northwestern Ontario, Canada, has doubled in the last 45 years and thus is no longer among the low nitrogen (N) deposition sites in North America. This may be related to the concurrent intensification of Manitoba agriculture to the west and upwind of the ELA. Large increases in ammonium deposition at the ELA were important in driving the observed trend and increased the NH4 + to NO3 − ratio of input to aquatic and terrestrial systems. Stable isotope analyses of two years of bulk (wet and dry) atmospheric deposition revealed very large ranges in δ15N−NH4 + (22‰ range), δ15N−NO3 − (18‰), and δ18O–NO3 − (19‰). Few other δ15N−NH4 +, δ15N−NO3 −, and δ18O–NO3 − values have been published for Canadian precipitation. Increases in δ15N of NH4 + and NO3 − in July occurred with increases in total N deposition. The wide range and seasonal trends of δ15N and δ18O values in ELA precipitation mean that studies characterizing N inputs to watersheds and lakes require an ongoing and comprehensive annual sampling regime. Global trends of declining δ15N of N deposition evident in lake sediment records may be a result of increases in NH4 + deposition with lower δ15N−NH4 + values. Similarly, the relationship in Lake Superior between increasing NO3 − and lower δ15N−NO3 − values may be explained by increased atmospheric deposition of N with low δ15N values.

Aquaculture impacts on the algal and bacterial communities in a small boreal forest lakeThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.

2009 ◽  
Vol 66 (11) ◽  
pp. 1936-1948 ◽  
Author(s):  
David L. Findlay ◽  
Cheryl L. Podemski ◽  
Susan E.M. Kasian
Keyword(s):  
Water Quality ◽  
Nutrient Loading ◽  
Stocking Density ◽  
Freshwater Ecosystem ◽  
Experimental Lakes Area ◽  
Fish Food ◽  
Total N ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Northwestern Ontario ◽  
The Impact

A whole-lake experiment to examine the impacts of aquaculture on a freshwater ecosystem was conducted at the Experimental Lakes Area in northwestern Ontario, Canada. From 2003 to 2006, a 10 tonne fish capacity aquaculture cage stocked with rainbow trout ( Oncorhynchus mykiss ) was operated in Lake 375 and the impact of excess nutrients on the algal and bacteria communities was examined. The experiment was designed as a nutrient loading experiment with fish food and fish excretion the source of nutrients. Total N and P concentrations increased over the 4 years (15× and 4×, respectively). Phytoplankton biomass increased 4× annually following the start of aquaculture operation in 2003. The most dramatic responses occurred during spring and fall mixing, with blooms of chrysophytes and dinoflagellates increasing biomass by up to 12×. Bacteria biomass and densities were unaffected except for increases in late fall. Periphyton biomass was relatively unaffected except for an increase in biomass in the fourth year. The combination of a long water residence time in the lake coupled with an extremely high fish stocking density in Lake 375 resulted in an immediate impact on water quality. The results suggest that the impacts of aquaculture are accumulative and continual stocking will further impact water quality.

scholarly journals Wet and dry deposition of atmospheric nitrogen at ten sites in Northern China

2012 ◽  
Vol 12 (1) ◽  
pp. 753-785 ◽  
Author(s):  
Y. P. Pan ◽  
Y. S. Wang ◽  
G. Q. Tang ◽  
D. Wu
Keyword(s):  
Atmospheric Deposition ◽  
Dry Deposition ◽  
Northern China ◽  
N Deposition ◽  
Ecological Impacts ◽  
Total Flux ◽  
Spatial And Temporal Variation ◽  
Monitoring Networks ◽  
Atmospheric N Deposition ◽  
Total N

Abstract. Emissions of reactive nitrogen (N) species can affect surrounding ecosystems via atmospheric deposition. However, few long-term and multi-site measurements have focused on both the wet and the dry deposition of individual N species in large areas of Northern China. Thus, the magnitude of atmospheric deposition of various N species in Northern China remains uncertain. In this study, the wet and dry atmospheric deposition of different N species was investigated during a three-year observation campaign at ten selected sites in Northern China. The results indicate that N deposition levels in Northern China were high with a ten-site, three-year average of 60.6 kg N ha−1 yr−1. The deposition levels showed spatial and temporal variation in the range of 28.5–100.4 kg N ha−1 yr−1. Of the annual total deposition, 40% was deposited via precipitation, and the remaining 60% was comprised of dry-deposited forms. Compared with gaseous N species, particulate N species were not the major contributor of dry-deposited N; they contributed approximately 10% to the total flux. On an annual basis, oxidized species accounted for 21% of total N deposition, thereby implying that other forms of gaseous N, such as NH3, comprised a dominant portion of the total flux. The contribution of NO3− to N deposition was enhanced in certain urban and industrial areas. As expected, the total N deposition in Northern China was significantly larger than the values reported by national scale monitoring networks in Europe, North America and East Asia because of high rates of wet deposition and gaseous NH3 dry deposition. The results have three important implications. First, atmospheric N deposition in Northern China falls within the range of critical loads for temperate forests and grasslands, a threshold above which harmful ecological effects to specified parts of temperate ecosystems often occur. Second, the magnitude, patterns and forms of N deposition will help to inform simulated N addition experiments, which are used to evaluate ecological impacts on receiving ecosystems. Third, the field-based evidence in this unique deposition dataset validates emission inventories of reactive N species and will help policy-makers control atmospheric pollution. Taken together, these findings show that NH3 emissions should be abated to mitigate high N deposition and associated potential impacts on ecosystems in Northern China.

scholarly journals Wet and dry deposition of atmospheric nitrogen at ten sites in Northern China

2012 ◽  
Vol 12 (14) ◽  
pp. 6515-6535 ◽  
Author(s):  
Y. P. Pan ◽  
Y. S. Wang ◽  
G. Q. Tang ◽  
D. Wu
Keyword(s):  
Atmospheric Deposition ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Northern China ◽  
N Deposition ◽  
Total Flux ◽  
Spatial And Temporal Variation ◽  
Monitoring Networks ◽  
Total N ◽  
The Impact

Abstract. Emissions of reactive nitrogen (N) species can affect surrounding ecosystems via atmospheric deposition. However, few long-term and multi-site measurements have focused on both the wet and the dry deposition of individual N species in large areas of Northern China. Thus, the magnitude of atmospheric deposition of various N species in Northern China remains uncertain. In this study, the wet and dry atmospheric deposition of different N species was investigated during a three-year observation campaign at ten selected sites in Northern China. The results indicate that N deposition levels in Northern China were high with a ten-site, three-year average of 60.6 kg N ha−1 yr−1. The deposition levels showed spatial and temporal variation in the range of 28.5–100.4 kg N ha−1 yr−1. Of the annual total deposition, 40% was deposited via precipitation, and the remaining 60% was comprised of dry-deposited forms. Compared with gaseous N species, particulate N species were not the major contributor of dry-deposited N; they contributed approximately 10% to the total flux. On an annual basis, oxidized species accounted for 21% of total N deposition, thereby implying that other forms of gaseous N, such as NH3, comprised a dominant portion of the total flux. The contribution of NO3− to N deposition was enhanced in certain urban and industrial areas, possibly due to the fossil fuse combustion. As expected, the total N deposition in Northern China was significantly larger than the values reported by national scale monitoring networks in Europe, North America and East Asia because of high rates of wet deposition and gaseous NH3 dry deposition. Taken together, these findings show that NH3 emissions should be abated to mitigate high N deposition and associated potential impacts on ecosystems in Northern China. The present results improve our understanding of spatio-temporal variations of magnitudes, pathways and species of deposited N in the target areas, and are important not only to inform conservation and regulatory bodies but also to initiate further detailed studies. Uncertainties among current observations underscore the need to quantify the impact of vegetation on dry deposition and to refine the simulation of dry deposition velocity.

Land water linkages: influences of riparian deforestation on lake thermocline depth and possible consequences for cold stenotherms

1997 ◽  
Vol 54 (6) ◽  
pp. 1299-1305 ◽  
Author(s):  
Robert France
Keyword(s):  
Thermal Stratification ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Thermocline Depth ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Riparian Trees ◽  
Tree Removal ◽  
Riparian Tree ◽  
Land Water

The purpose of the present study was to determine if riparian deforestation would expose lake surfaces to stronger winds and therefore bring about deepening of thermoclines and resulting habitat losses for cold stenotherms such as lake trout (Salvelinus namaycush). Removal of protective riparian trees through wind blowdown and two wildfires was found to triple the overwater windspeeds and produce thermocline deepening in two lakes at the Experimental Lakes Area. A survey of thermal stratification patterns in 63 northwestern Ontario lakes showed that lakes around which riparian trees had been removed a decade before through either clearcutting or by a wildfire were found to have thermocline depths over 2 m deeper per unit fetch length compared with lakes surrounded by mature forests. Riparian tree removal will therefore exacerbate hypolimnion habitat losses for cold stenotherms that have already been documented to be occurring as a result of lake acidification, eutrophication, and climate warming.

scholarly journals Physicochemical Properties and Heavy Metal Concentration in Soil of Industrial Area, Zirani, Savar, Dhaka

2015 ◽  
Vol 8 (1) ◽  
pp. 65-68 ◽  
Author(s):  
MS Rahaman ◽  
F Nessa ◽  
MM Hoque ◽  
M Rehnuma ◽  
MS Islam
Keyword(s):  
Heavy Metals ◽  
Agricultural Production ◽  
Reference Value ◽  
Nutrient Status ◽  
Heavy Metal Concentration ◽  
Industrial Area ◽  
Total N ◽  
Maximum Value ◽  
Wide Range ◽  
Recommended Level

Zirani of Savar is an important industrial area of the country which provides wide range of potentiality for economic development. The purpose of the study was to observe the nutrient status and heavy metals concentration of the soil in Zirani, Savar, Dhaka. Nine soil samples were collected and analyzed through different methods for analyzing pH, OC, N, K, P, S and the heavy metals including Zn, Cd, Cu, and Pb, were investigated using Atomic Absorption Spectroscopy (AAS) technique. The analyzed result revealed the soil surrounding the dumping site was slightly acidic which is not harmful for agricultural production. The highest value of OC was recorded 2.14% at point 3 and the lowest value was 1.92% which was found in point 2 that is greater than the reference value. Except total N concentration, the amount of available P, K, and S were greater than their recommended level. In addition the result showed that the concentration of Cu and Pb were much higher than their recommended level and the maximum value of Cu was 0.09 ppm and 0.762 ppm was the maximum concentration of Pb. and the concentration of Zn and Cd were within tolerable limit. Zn at point 3 showed higher concentration which was 3.05 ppm. The maximum value of Cd was 0.09 ppm that was found at station 1 under point 3.J. Environ. Sci. & Natural Resources, 8(1): 65-68 2015

scholarly journals Simulation of nitrogen deposition in the North China Plain by the FRAME model

2011 ◽  
Vol 8 (11) ◽  
pp. 3319-3329 ◽  
Author(s):  
Y. Zhang ◽  
A. J. Dore ◽  
X. Liu ◽  
F. Zhang
Keyword(s):  
North China Plain ◽  
North China ◽  
Terrestrial Ecosystem ◽  
N Deposition ◽  
The Yellow Sea ◽  
Natural Ecosystems ◽  
Total N ◽  
Frame Model ◽  
The North ◽  
The North China Plain

Abstract. Simulation of atmospheric nitrogen (N) deposition in the North China Plain (NCP) at high resolution, 5 × 5 km2, was conducted for the first time by the Fine Resolution Atmospheric Multi-pollutant Exchange (FRAME) model. The total N deposition budget was 1481 Gg in this region, with 77 % from reduced N and 23 % from oxidized N, and the annual deposition rate (47 kg N ha−1) was much higher than previously reported values for other parts of the world such as the UK (13 kg N ha−1), Poland (7.3 kg N ha−1) and EU27 (8.6 kg N ha−1). The exported N component (1981 Gg) was much higher than the imported N component (584 Gg), suggesting that the NCP is an important net emission source of N pollutants. Contributions of N deposition budgets from the seven provinces in this region were proportional to their area ratios. The calculated spatial distributions of N deposition displayed high rates of reduced N deposition in the south and of oxidized N deposition in the eastern part. The N deposition exceeded an upper limit of 30 kg N ha−1 for natural ecosystems over more than 90 % of the region, resulting in terrestrial ecosystem deterioration, impaired air quality and coastal eutrophication not only in the NCP itself but also in surrounding areas including the Bohai Sea and the Yellow Sea.

Phosphorus Budgets and Stoichiometry during the Open-Water Season in Two Unmanipulated Lakes in the Experimental Lakes Area, Northwestern Ontario

1994 ◽  
Vol 51 (12) ◽  
pp. 2739-2755 ◽  
Author(s):  
P. Campbell
Keyword(s):  
Water Column ◽  
Bottom Sediments ◽  
Open Water ◽  
Short Term ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Phosphorus Budgets ◽  
Mass Balance Approach ◽  
Primary And Secondary Producers ◽  
Column Total

A comparative mass-balance approach is used to describe and quantify phosphorus (P) cycles during the open-water season in two unmanipulated Experimental Lakes Area (ELA) lakes. A bimodal cycle generally prevailed, in which water-column total phosphorus (TP = total dissolved P plus sestonic particulate P) peaked just after ice-out and again late in the summer. Changes in mass of water-column TP were often much larger than corresponding net external inputs. Shifts of P to and from either zooplankton or fish in the water column do not explain the P residuals. Rather, the bottom sediments must have been adding P to the water column. Short-term regeneration of P from the bottom sediments also probably occurs in artificially eutrophied ELA lakes. The mechanism of regeneration is probably biological. Other aspects of P cycling and P stoichiometry are discussed, particularly in relation to nutrient control of population structure and the function of primary and secondary producers.

scholarly journals Assessing land–ocean connectivity via submarine groundwater discharge (SGD) in the Ria Formosa Lagoon (Portugal): combining radon measurements and stable isotope hydrology

2016 ◽  
Vol 20 (8) ◽  
pp. 3077-3098 ◽  
Author(s):  
Carlos Rocha ◽  
Cristina Veiga-Pires ◽  
Jan Scholten ◽  
Kay Knoeller ◽  
Darren R. Gröcke ◽  
...  
Keyword(s):  
Submarine Groundwater Discharge ◽  
Large Fraction ◽  
Groundwater Discharge ◽  
Point Sources ◽  
Total N ◽  
Ria Formosa ◽  
Basin Scale ◽  
Wide Range ◽  
Dominant Feature ◽  
Submarine Groundwater

Abstract. Natural radioactive tracer-based assessments of basin-scale submarine groundwater discharge (SGD) are well developed. However, SGD takes place in different modes and the flow and discharge mechanisms involved occur over a wide range of spatial and temporal scales. Quantifying SGD while discriminating its source functions therefore remains a major challenge. However, correctly identifying both the fluid source and composition is critical. When multiple sources of the tracer of interest are present, failure to adequately discriminate between them leads to inaccurate attribution and the resulting uncertainties will affect the reliability of SGD solute loading estimates. This lack of reliability then extends to the closure of local biogeochemical budgets, confusing measures aiming to mitigate pollution.Here, we report a multi-tracer study to identify the sources of SGD, distinguish its component parts and elucidate the mechanisms of their dispersion throughout the Ria Formosa – a seasonally hypersaline lagoon in Portugal. We combine radon budgets that determine the total SGD (meteoric + recirculated seawater) in the system with stable isotopes in water (δ2H, δ18O), to specifically identify SGD source functions and characterize active hydrological pathways in the catchment. Using this approach, SGD in the Ria Formosa could be separated into two modes, a net meteoric water input and another involving no net water transfer, i.e., originating in lagoon water re-circulated through permeable sediments. The former SGD mode is present occasionally on a multi-annual timescale, while the latter is a dominant feature of the system. In the absence of meteoric SGD inputs, seawater recirculation through beach sediments occurs at a rate of  ∼  1.4  ×  106 m3 day−1. This implies that the entire tidal-averaged volume of the lagoon is filtered through local sandy sediments within 100 days ( ∼  3.5 times a year), driving an estimated nitrogen (N) load of  ∼  350 Ton N yr−1 into the system as NO3−. Land-borne SGD could add a further  ∼  61 Ton N yr−1 to the lagoon. The former source is autochthonous, continuous and responsible for a large fraction (59 %) of the estimated total N inputs into the system via non-point sources, while the latter is an occasional allochthonous source capable of driving new production in the system.

scholarly journals Global trends and growth dynamics in media industry

2021 ◽  
Vol 29 (2) ◽  
pp. 324-337
Author(s):  
Elena S. Pinchuk
Keyword(s):  
Growth Dynamics ◽  
Media Industry ◽  
Global Media ◽  
Global Trends ◽  
Expert Opinions ◽  
Current Period ◽  
Wide Range ◽  
Rapid Transition ◽  
The Media ◽  
Key Aspects

The article reviews the trends in the media industry landscape formation based on content as a source of economic processes taking place in the industry. A wide range of expert opinions, reflecting the current changes was collected and analyzed. The life cycle of content is examined and the key trends in its production, packaging, distribution and consumption are highlighted. The attention is focused on the economic and technological factors that determine each of the trends, for instance, a change in the model of media consumption, the development and distribution of OTT platforms as a new way of delivering content, as well as a rapid transition to a new technological level. The latest statistical data from Russian and foreign sources support the reviewed trends. There is a separate description of the coronavirus pandemic impact consequences on the global media and the Russian industry in particular, and the key aspects of the development of the industry are identified in the current period on its basis.

scholarly journals Exchange of reactive nitrogen compounds: concentrations and fluxes of total ammonium and total nitrate above a spruce forest canopy

2009 ◽  
Vol 6 (6) ◽  
pp. 10663-10706
Author(s):  
V. Wolff ◽  
I. Trebs ◽  
T. Foken ◽  
F. X. Meixner
Keyword(s):  
Forest Canopy ◽  
N Deposition ◽  
Reactive Nitrogen ◽  
Nitrogen Compounds ◽  
Spruce Forest ◽  
Gaseous Species ◽  
Total N ◽  
Fog Water ◽  
Dry Conditions ◽  
Total Ammonium

Abstract. Total ammonium (tot-NH4+) and total nitrate (tot-NO3−) provide a chemically conservative quantity in the measurement of exchange processes of reactive nitrogen compounds ammonia (NH3), particulate ammonium (NH4+), nitric acid (HNO3), and particulate nitrate (NO3−), using the aerodynamic gradient method. Total fluxes were derived from concentration differences of total ammonium (NH3 and NH4+) and total nitrate (HNO3 and NO3−) measured at two levels. Gaseous species and related particulate compounds were measured selectively, simultaneously and continuously above a spruce forest canopy in south-eastern Germany in summer 2007. Measurements were performed using a wet-chemical two-point gradient instrument, the GRAEGOR. Median concentrations of NH3, HNO3, NH4−, and NO3− were 0.57, 0.12, 0.76, and 0.48 μg m−3, respectively. Total ammonium and total nitrate fluxes showed large variations depending on meteorological conditions, with concentrations close to zero under humid and cool conditions and higher concentrations under dry conditions. Mean fluxes of total ammonium and total nitrate in September 2007 were directed towards the forest canopy and were −65.77 ng m−2 s−1 and −41.02 ng m−2 s−1 (in terms of nitrogen), respectively. Their deposition was controlled by aerodynamic resistances only, with very little influence of surface resistances. Including measurements of wet deposition and findings of former studies at the study site on occult deposition (fog water interception), the total N deposition in September 2007 was estimated to 5.86 kg ha−1.

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