scholarly journals Speciation and dynamics of dissolved inorganic nitrogen export in the Danshui River, Taiwan

2014 ◽  
Vol 11 (2) ◽  
pp. 2497-2536
Author(s):  
T.-Y. Lee ◽  
Y.-T. Shih ◽  
J.-C. Huang ◽  
S.-J. Kao ◽  
F.-K. Shiah ◽  
...  
Keyword(s):  
Land Surface ◽  
Anthropogenic Activities ◽  
Inorganic Nitrogen ◽  
Monitoring Network ◽  
Population Increase ◽  
Dissolved Inorganic Nitrogen ◽  
Dense Population ◽  
Nitrate Export ◽  
The Individual ◽  
Danshui River

Abstract. Dissolved inorganic nitrogen (DIN, including ammonium, nitrite and nitrate) export from land to ocean is becoming dominated by anthropogenic activities and severely altering the aquatic ecosystem. However, rare observational analyses have been conducted in the Oceania, the hotspot of global DIN export. In this study a whole watershed monitoring network (20 stations) was conducted in 2003 to investigate the controlling factors of DIN export in the Danshui River of Taiwan. The results showed that DIN concentration ranged from ∼16 μM in the headwater and up to ∼430 μM in the estuary. However, the dominating DIN species transformed gradually from NO3− in the headwater (∼97%) to NH4+ in the estuary (∼70%), which well followed the descending dissolved oxygen (DO) distribution (from ∼8 mg L−1 to ∼1 mg L−1). NO2− was observed in the transition zone from high to low DO. DIN yield was increasing downstream, ranging from ∼160 to ∼6000 kg N km−2 yr−1 as population density increases toward the estuary, from ∼15 pop km−2 to ∼2600 pop km−2. Although the individual DIN export, ∼2.40 kg N person−1 yr−1, was comparable to the global average, the close-to-top DIN yield was observed owing to abundant rainfall, dense population, and the sensitive response to population increase. The Danshui River occupies 1.8 × 10−3% of the land surface area of the Earth but discharges disproportionately high percentage, ∼60 × 10−3% (∼14 000 t N yr−1) of the annual global DIN export to the ocean. Through this study, regulating factors and the significance of human population on DIN export were identified, and the regional databases were supplemented to promote the completeness of global models.

scholarly journals Speciation and dynamics of dissolved inorganic nitrogen export in the Danshui River, Taiwan

2014 ◽  
Vol 11 (19) ◽  
pp. 5307-5321 ◽  
Author(s):  
T.-Y. Lee ◽  
Y.-T. Shih ◽  
J.-C. Huang ◽  
S.-J. Kao ◽  
F.-K. Shiah ◽  
...  
Keyword(s):  
Land Surface ◽  
Urban Areas ◽  
Inorganic Nitrogen ◽  
Monitoring Network ◽  
Large River ◽  
Global Scale ◽  
Specific Response ◽  
Dissolved Inorganic Nitrogen ◽  
Density Control ◽  
Danshui River

Abstract. Human-induced excess nitrogen outflowing from land through rivers to oceans has resulted in serious impacts on terrestrial and coastal ecosystems. Oceania, which occupies < 2.5% of the global land surface, delivers 12% of the freshwater and dissolved materials to the ocean on a global scale. However, there are few empirical data sets on riverine dissolved inorganic nitrogen (DIN) fluxes in the region, and their dynamics are poorly understood. In this study, a river monitoring network covering different types of land uses and population densities was implemented to investigate the mechanism of DIN export. The results show that DIN concentration/yield varied from ∼20 μM/∼300 kg-N km−2 yr−1 to ∼378 μM/∼10 000 kg-N km−2 yr−1 from the relatively pristine headwaters to the populous estuary. Agriculture and population density control DIN export in less densely populated regions and urban areas, respectively, and runoff controls DIN at the watershed scale. Compared to documented estimates from global models, the observed DIN export from the Danshui River is 2.3 times larger, which results from the region-specific response of DIN yield to dense population and abundant runoff. The dominating DIN species change gradually from NO3− in the headwaters (∼97%) to NH4+ in the estuary (∼60%) following the urbanization gradient. The prominent existence of NH4+ is probably the result of the anaerobic water body and short residence time, unlike in large river basins. Given the analogous watershed characteristics of the Danshui River to the rivers in Oceania, our study could serve as a first example to examine riverine DIN fluxes in Oceania.

Stable nitrogen isotopes as indicators of anthropogenic activities in small freshwater systems

2001 ◽  
Vol 58 (5) ◽  
pp. 870-878 ◽  
Author(s):  
James L Lake ◽  
Richard A McKinney ◽  
Frank A Osterman ◽  
Richard J Pruell ◽  
John Kiddon ◽  
...  
Keyword(s):  
Largemouth Bass ◽  
Trophic Position ◽  
Anthropogenic Activities ◽  
Inorganic Nitrogen ◽  
Micropterus Salmoides ◽  
Anthropogenic Activity ◽  
Dissolved Inorganic Nitrogen ◽  
Shoreline Development ◽  
Freshwater Systems ◽  
Nitrogen Concentrations

Stable nitrogen isotope ratios (δ15N) were measured in fish, mussel, and sediment samples taken from 17 small freshwater sites to examine food chain length and trophic position across sites affected by differing levels of anthropogenic activity. Both shoreline development and fish species composition varied greatly among sites, and a range of up to 11.2‰ was found for the δ15N values of largemouth bass (Micropterus salmoides). Fish δ15N values were baseline corrected using unionid mussel (Elliptio complanata) δ15N values. Predators, such as largemouth bass and chain pickerel (Esox niger), exhibited normalized δ15N values that were less variable than those of benthic-feeding fishes. Relationships between δ15N and dissolved inorganic nitrogen concentrations indicated that δ15N was a valid descriptor of eutrophication at sites with low dissolved inorganic nitrogen concentrations. The fraction of residential land in buffer zones surrounding sites was correlated with fish δ15N, indicating that urban development, and presumably human wastewater, resulted in elevated δ15N values in these small freshwater systems.

Spatial Hotspot Analysis of Bucharest’s Urban Heat Island (UHI) Using Modis Data

2018 ◽  
Vol 18 (1) ◽  
pp. 14-22 ◽  
Author(s):  
Georgiana Grigoraș ◽  
Bogdan Urițescu
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Land Surface Temperature ◽  
Hot Spots ◽  
Land Surface ◽  
Hot Spot ◽  
Monitoring Network ◽  
Residential Areas ◽  
Hotspot Analysis ◽  
The City

Abstract The aim of the study is to find the relationship between the land surface temperature and air temperature and to determine the hot spots in the urban area of Bucharest, the capital of Romania. The analysis was based on images from both moderate-resolution imaging spectroradiometer (MODIS), located on both Terra and Aqua platforms, as well as on data recorded by the four automatic weather stations existing in the endowment of The National Air Quality Monitoring Network, from the summer of 2017. Correlation coefficients between land surface temperature and air temperature were higher at night (0.8-0.87) and slightly lower during the day (0.71-0.77). After the validation of satellite data with in-situ temperature measurements, the hot spots in the metropolitan area of Bucharest were identified using Getis-Ord spatial statistics analysis. It has been achieved that the “very hot” areas are grouped in the center of the city and along the main traffic streets and dense residential areas. During the day the "very hot spots” represent 33.2% of the city's surface, and during the night 31.6%. The area where the mentioned spots persist, falls into the "very hot spot" category both day and night, it represents 27.1% of the city’s surface and it is mainly represented by the city center.

scholarly journals A Review on Polymer Nanocomposites and Their Effective Applications in Membranes and Adsorbents for Water Treatment and Gas Separation

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 139
Author(s):  
Oluranti Agboola ◽  
Ojo Sunday Isaac Fayomi ◽  
Ayoola Ayodeji ◽  
Augustine Omoniyi Ayeni ◽  
Edith E. Alagbe ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Polymer Nanocomposites ◽  
Gas Separation ◽  
Rapid Growth ◽  
Dye Removal ◽  
Anthropogenic Activities ◽  
Polymer Nanocomposite ◽  
Population Increase ◽  
Nanocomposite Membranes

Globally, environmental challenges have been recognised as a matter of concern. Among these challenges are the reduced availability and quality of drinking water, and greenhouse gases that give rise to change in climate by entrapping heat, which result in respirational illness from smog and air pollution. Globally, the rate of demand for the use of freshwater has outgrown the rate of population increase; as the rapid growth in town and cities place a huge pressure on neighbouring water resources. Besides, the rapid growth in anthropogenic activities, such as the generation of energy and its conveyance, release carbon dioxide and other greenhouse gases, warming the planet. Polymer nanocomposite has played a significant role in finding solutions to current environmental problems. It has found interest due to its high potential for the reduction of gas emission, and elimination of pollutants, heavy metals, dyes, and oil in wastewater. The revolution of integrating developed novel nanomaterials such as nanoparticles, carbon nanotubes, nanofibers and activated carbon, in polymers, have instigated revitalizing and favourable inventive nanotechnologies for the treatment of wastewater and gas separation. This review discusses the effective employment of polymer nanocomposites for environmental utilizations. Polymer nanocomposite membranes for wastewater treatment and gas separation were reviewed together with their mechanisms. The use of polymer nanocomposites as an adsorbent for toxic metals ions removal and an adsorbent for dye removal were also discussed, together with the mechanism of the adsorption process. Patents in the utilization of innovative polymeric nanocomposite membranes for environmental utilizations were discussed.

Characteristics of Non-Point Source N Export via Surface Runoff from Sloping Croplands in Northeast China

2011 ◽  
Vol 347-353 ◽  
pp. 2302-2307 ◽  
Author(s):  
Hong Xiang Wang ◽  
Yi Shi ◽  
Jian Ma ◽  
Cai Yan Lu ◽  
Xin Chen
Keyword(s):  
Point Source ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Inorganic Nitrogen ◽  
Rainfall Amount ◽  
Organic N ◽  
Dissolved Inorganic Nitrogen ◽  
Slope Gradient ◽  
N Loss ◽  
Total N

A field experiment was conducted to study the characteristics of non-point source nitrogen (N) in the surface runoff from sloping croplands and the influences of rainfall and cropland slope gradient. The results showed that dissolved total N (DTN) was the major form of N in the runoff, and the proportion occupied by dissolved inorganic nitrogen (DIN) ranged from 45% to 85%. The level of NH4+-N was generally higher than the level of NO3--N, and averaged at 2.50 mg·L-1and 1.07 mg·L-1respectively. DIN was positively correlated with DTN (R2=0.962). Dissolved organic N (DON) presented a moderate seasonal change and averaged at 1.40 mg·L-1. Rainfall amount and rainfall intensity significantly affected the components of DTN in the runoff. With the increase of rainfall amount and rainfall intensity, the concentrations of DTN, NH4+-N and NO3--N presented a decreased trend, while the concentration of DON showed an increased trend. N loss went up with an increase in the gradient of sloping cropland, and was less when the duration was longer from the time of N fertilization.fertilization.

Variation in the instream dissolved inorganic nitrogen response between and within rainstorm events in an urban watershed

2008 ◽  
Vol 43 (11) ◽  
pp. 1223-1233 ◽  
Author(s):  
Bernice R. Rosenzweig ◽  
Hee Sun Moon ◽  
James A. Smith ◽  
Mary Lynn Baeck ◽  
Peter R. Jaffe
Keyword(s):  
Inorganic Nitrogen ◽  
Urban Watershed ◽  
Dissolved Inorganic Nitrogen ◽  
Nitrogen Response

Modelled estimates of dissolved inorganic nitrogen exported to the Great Barrier Reef lagoon

2021 ◽  
Vol 171 ◽  
pp. 112655
Author(s):  
G.L. McCloskey ◽  
R. Baheerathan ◽  
C. Dougall ◽  
R. Ellis ◽  
F.R. Bennett ◽  
...  
Keyword(s):  
Great Barrier Reef ◽  
Inorganic Nitrogen ◽  
Barrier Reef ◽  
Dissolved Inorganic Nitrogen ◽  
Reef Lagoon

Spatio-Temporal Gaussianization Flows for Extreme Event Detection

2021 ◽  
Author(s):  
Miguel-Ángel Fernández-Torres ◽  
J. Emmanuel Johnson ◽  
María Piles ◽  
Gustau Camps-Valls
Keyword(s):  
Event Detection ◽  
Land Surface ◽  
Extreme Event ◽  
Learning Approaches ◽  
Proposed Model ◽  
Individual Contributions ◽  
Current Context ◽  
Spatio Temporal ◽  
The Individual ◽  
Anomaly Score

&lt;p&gt;Automatic anticipation and detection of extreme events constitute a major challenge in the current context of climate change. Machine learning approaches have excelled in detection of extremes and anomalies in Earth data cubes recently, but are typically both computationally costly and supervised, which hamper their wide adoption. We alternatively present here an unsupervised, efficient, generative approach for extreme event detection, whose performance is illustrated for drought detection in Europe during the severe Russian heat wave in 2010. The core architecture of the model is generic and could naturally be extended to the detection of other kinds of anomalies. First, it computes hierarchical appearance (spatial) and motion (temporal) representations of several informative Essential Climate Variables (ECVs), including soil moisture, land surface temperature, as well as features describing vegetation health. Then, these representations are combined using Gaussianization Flows that yield a spatio-temporal anomaly score. This allows the proposed model not only to detect droughts areas, but also to explain why they were produced, monitoring the individual contributions of each of the ECVs to the indicator at its output.&lt;/p&gt;

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