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Author(s):  
Tuyet Nam Thi Nguyen ◽  
Quang Tran Vuong ◽  
Sang-Jin Lee ◽  
Hang Xiao ◽  
Sung-Deuk Choi

This study identifies the emission source areas for the atmospheric polycyclic aromatic hydrocarbons (PAHs) detected in Ulsan, South Korea. To achieve this, in addition to a conditional bivariate probability function...


2021 ◽  
Author(s):  
Ling Xie ◽  
Hongwei Wang ◽  
Suhong Liu ◽  
Yudong Li

Abstract The sustainable development of ecological environments is the basis of the sustainable development of inland river basins in arid areas with fragile ecological environments. The aim of our study is to diagnose the ecological problems of the Aksu River basin (ARB) and explore the ecological security pattern (ESP) and the layout and implementation path of ecological protection projects for mountains, rivers, forests, farmland, lakes, grasslands and deserts (MRFFLGD) in arid areas under different security levels. The Aksu River, the largest source of the Tarim River, was selected as the case study. The equivalent factor evaluation method (EFEM) was used to estimate the ecological service value (ESV), and the InVEST model was employed to quantify the ecological function indicators. By constructing the richness index, the ESV of the study area was measured spatially, and the ecological problems in the ARB were identified and diagnosed. Using cold/hot spot detection analysis and the minimum cumulative resistance (MCR) model, the ESPs at three security levels were constructed. The layout of ecological protection measures and the implementation path for MRFFLGD were studied. The results showed that the ESV of ARB showed an upwards trend from 1990 to 2018, and the three services of water conservation, waste treatment and soil formation and retention grew fastest. The value of ecosystem services in the study area in 2018 ranged from 5,390 yuan to 131,080 yuan/hm2. The high-value areas were mainly located in the oasis and the northern mountainous area, and the low-value areas were mainly located in the desert area. The ecological source areas of high, medium and low safety levels were 1806.3 km2, 3416.8 km2 and 4804.32 km2, respectively. Based on the spatial distribution of ESV in the ARB and the preliminary diagnosis of the basic ecological problems in the study area, three kinds of ecological protection engineering models, namely, conservation, natural restoration and assisted regeneration, were proposed for the four types of ecological protection zones. To provide a decision-making basis for ecological environmental management and regional sustainable development in the ARB, the optimization patterns of points (6 key ecological protection projects), lines (ecological corridors) and polygons (ecological source areas) were constructed. The results of this study can also serve as a reference for ecological environmental protection in other arid inland river basins.


2021 ◽  
Vol 9 (12) ◽  
pp. 1335
Author(s):  
Hiroshi Kuroda ◽  
Tomonori Azumaya ◽  
Takashi Setou ◽  
Natsuki Hasegawa

Unprecedented large-scale harmful algae blooms (HABs) were reported in coastal waters off the south-eastern coast of Hokkaido, Japan, in mid-to-late September 2021, about a month after very intense and extensive marine heatwaves subsided. To understand the physical–biological processes associated with development of the HABs, we conducted analyses via a combination of realistic ocean circulation models, particle-tracking simulations, and satellite measurements. The satellite-derived chlorophyll concentrations (SCCs) and areal extent of the high SCCs associated with the HABs were the highest recorded since 1998. More specifically, the extent of SCCs exceeding 5 or 10 mg m−3 started to slowly increase after 20 August, when the marine heatwaves subsided, intermittently exceeded the climatological daily maximum after late August, and reached record-breaking extremes in mid-to-late September. About 70% of the SCCs that exceeded 10 mg m−3 occurred in places where water depths were <300 m, i.e., coastal shelf waters. The high SCCs were also tightly linked with low-salinity water (e.g., subarctic Oyashio and river-influenced waters). High-salinity subtropical water (e.g., Soya Warm Current water) appeared to suppress the occurrence of HABs. The expansion of the area of high SCCs seemed to be synchronized with the deepening of surface mixed layer depths in subarctic waters on the Pacific shelves. That deepening began around 10 August, when the marine heatwaves weakened abruptly. However, another mechanism was needed to explain the intensification of the SCCs in very nearshore waters off southeast Hokkaido. Particle-tracking simulations based on ocean circulation models identified three potential source areas of the HABs: the Pacific Ocean east of the Kamchatka Peninsula, the Sea of Japan, and the Sea of Okhotsk east of the Sakhalin Island. Different processes of HAB development were proposed because distance, time, and probability for transport of harmful algae from the potential source areas to the study region differed greatly between the three source areas.


Author(s):  
Sofia Laskari ◽  
Konstantinos Soukis ◽  
Stylianos Lozios ◽  
Daniel F. Stockli ◽  
Eirini M. Poulaki ◽  
...  

Detailed mapping and structural observations on the Cycladic Blueschist Unit (CBU) of Iraklia island integrated by detrital zircon (DZ) U-Pb ages elucidate the Mesozoic pre-subduction evolution and the Cenozoic orogenic events. Field data reveal that the Iraklia tectonostratigraphy includes a heterogeneous Lower Schist Unit juxtaposed against a Variegated Marble Unit and an overlying Upper Schist Unit. The contact is an extensional ductile-to-brittle-ductile, top-to-N shear zone, associated with the Oligo-Miocene exhumation. The DZ spectrum of the Lower Schist Unit characterized by Gondwanan/peri-Gondwanan provenance signatures points to Late Triassic maximum depositional ages (MDAs). A quartz-rich schist layer yielded Precambrian DZ ages exclusively, considered part of the pre-Variscan metasedimentary Cycladic Basement, equivalent to those observed on Ios island. A significant change occurred during the deposition of the Upper Schist Unit, revealing Late Cretaceous MDAs and a high amount of Late Paleozoic DZ ages, attesting to more internal Pelagonian source areas. The imprint of Paleotethyan vs. Neotethyan geodynamic events is revealed in the DZ U-Pb ages record. The Triassic DZ input demonstrates eroded volcanic material related to the final Paleotethys closure and the Pindos/CBU rift basin opening. Late Cretaceous metamorphic/magmatic zircons and ~48-56 Ma zircon rims constrain the onset of subduction and high-pressure metamorphism.


2021 ◽  
Vol 9 ◽  
Author(s):  
Qin Hu ◽  
Yong Zhao ◽  
Anning Huang ◽  
Pan Ma ◽  
Jing Ming

Based on the output data from the Lagrangian flexible particle dispersion model (FLEXPART), we analyze the pathways of moisture to identify the moisture source areas for extreme precipitation in the summer half-year (April–September) over northern and southern Xinjiang, respectively. For both northern and southern Xinjiang, the local evaporation plays a decisive role for extreme precipitation in the summer half-year, of which contribution ratio accounts for 24.5% to northern Xinjiang and 30.2% to southern Xinjiang of all identified source areas. In addition, central Asia and northwestern Asia are the major moisture source areas as well and contribute similarly to extreme precipitation relative to local evaporation. For northern Xinjiang, central Asia surpasses northwestern Asia, and each of them contributes 24.1 and 18.8%, whereas northwestern Asia is somewhat more crucial than central Asia for southern Xinjiang, accounting 22.1 and 19.1%, respectively. Note that the three top-ranked moisture source areas make up a large proportion of total sources. Regarding the remaining source areas that also provide moisture, the contributions are entirely different for southern and northern Xinjiang. Originating from the North Atlantic Ocean, Europe, and the Mediterranean Sea, some water vapor enters northern Xinjiang and converge to precipitate, while this process is barely detectable for extreme precipitation over southern Xinjiang, which is affected by the westerly flow. On the contrary, the Arabian Sea, the Arabian Peninsula, and the Indian Peninsula contribute, even though slightly, to extreme precipitation over southern Xinjiang, which indicates that the meridional transport pathways from the Arabian Sea can carry moisture to this inland region.


Quaternary ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 39
Author(s):  
Jean-Daniel Stanley ◽  
Tobias Ullmann ◽  
Eva Lange-Athinodorou

Geoarchaeological information presented here pertains to a subsidiary Nile channel that once flowed west of the main Sebennitic distributary and discharged its water and sediments at Egypt’s then north-central deltaic coast. Periodical paleoclimatic episodes during the later Middle and Upper Holocene included decreased rainfall and increased aridity that reduced the Nile’s flow levels and thus likely disrupted nautical transport and anthropogenic activity along this channel. Such changes in this deltaic sector, positioned adjacent to the Levantine Basin in the Eastern Mediterranean, can be attributed to climatic shifts triggered as far as the North Atlantic to the west, and African highland source areas of the Egyptian Nile to the south. Of special interest in a study core recovered along the channel are several sediment sequences without anthropogenic material that are interbedded between strata comprising numerous potsherds. The former are interpreted here as markers of increased regional aridity and reduced Nile flow which could have periodically disrupted the regional distribution of goods and nautical activities. Such times occurred ~5000 years B.P., ~4200–4000 years B.P., ~3200–2800 years B.P., ~2300–2200 years B.P., and more recently. Periods comparable to these are also identified by altered proportions of pollen, isotopic and compositional components in different radiocarbon-dated Holocene cores recovered elsewhere in the Nile delta, the Levantine region to the east and north of Egypt, and in the Faiyum depression south of the delta.


2021 ◽  
Author(s):  
Lixia Chen ◽  
Yu Zhao ◽  
Yuanyao Li ◽  
Lei Gui ◽  
Kunlong Yin ◽  
...  

Abstract. Rockfall hazard is frequent along the national road (G318) in west Hubei, China. To understand the distribution and potential hazard probability, this study combines the result of a 3-years engineering geological investigation, statistical modeling, and kinemics-based method to identify risky road sections. Rockfall hazard probability is calculated by integrating spatial, temporal, size probability, and reaching probabilities of source areas. Rockfall source areas are preliminarily identified first by slope angle threshold (SAT) analysis. Random Forest model (RFM) and multivariate logistic regression model (MLRM) are then applied and compared to get the final susceptible source areas, considering eight factors, including slope, aspect, elevation, lithology, joint density, slope structure, land-use type, distance to the road. Temporal and size probability of source areas are separately obtained by Poisson distribution and power-law distribution theory. An important parameter (reach angle) for rockfall trajectory simulation was determined by back analysis in Flow-R and validated by field investigation. The results show good fitness with the measurements by field investigation. In the conditions of 5, 20, and 50 years return period, potential risky road sections are found out under two size scenarios (larger than 1 000 m3, 10 000 m3). This research helps the local government to completely understand the rock falls from source area existence and potential risk to roads.


Fire ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 83
Author(s):  
Christopher D. Elvidge ◽  
Mikhail Zhizhin ◽  
Feng Chi Hsu ◽  
Tamara Sparks ◽  
Tilottama Ghosh

Biomass burning is a coupled exothermic/endothermic system that transfers carbon in several forms to the atmosphere, ultimately leaving mineral ash. The exothermic phases include flaming and smoldering, which produce the heat that drives the endothermic processes. The endothermic components include pre-heating and pyrolysis, which produce the fuel consumed by flaming and smoldering. These components can be broadly distinguished from each other based on temperature. For several years, we have researched the subpixel analysis of two temperature phases present in fire pixels detected in nighttime VIIRS data. Here, we present the flaming subtractive method, with which we have successfully derived temperatures and source areas for two infrared (IR) emitters and a cooler background. This is developed as an add-on to the existing VIIRS nightfire algorithm version 3 (VNF v.3) which uses Planck curve fitting to calculate temperatures and source areas for a single IR emitter and background. The flaming subtractive method works with data collected in four spectral ranges: near-infrared (NIR), short-wave infrared (SWIR), mid-wave infrared (MWIR) and long-wave infrared (LWIR). With sunlight eliminated, the NIR and SWIR radiances can be fully attributed to the primary IR emitter. The analysis begins with Planck curve modeling for the primary emitter based on the NIR and SWIR radiances, yielding temperature, source area and primary emitter radiances in all spectral bands. The primary emitter radiances are subtracted from each spectral band and then the residual radiance is analyzed for a secondary IR emitter and the background. Spurious results are obtained in pixels lacking a discernable secondary emitter. These misfit pixels revert back to the single IR emitter analysis of VNF v.3. In tests run for two California megafires, we found that the primary emitters straddle the temperature ranges for flaming and smoldering, the exothermic portions of biomass burning, which are apparently commingled on the ground. The secondary emitter temperatures span 350–750 K, corresponding to pre-heating and slow pyrolysis. The natural gas flare test case had few numbers of successful secondary emitter retrievals and a wide range of secondary emitter temperatures. The flaming subtractive analysis is the key addition to VNF version 4, which will commence production later in 2021. In 2022, we will seek validation of the VNF v.4 from nighttime Landsat and other data sources.


2021 ◽  
Vol 74 (3) ◽  
pp. 253-271
Author(s):  
Tomislav Kurečić ◽  
◽  
Marijan Kovačić ◽  
Anita Grizelj ◽  
◽  
...  

Viviparus beds are sediments deposited in lacustrine and fluvial freshwater environments (Lake Slavonia) during the Pliocene and the earliest Pleistocene. A detailed field study and mineralogical, petrographic and chemical analyses were carried out to determine their composition and origin in the area of Vukomeričke Gorice, Central Croatia. Viviparus beds are characterized by the vertical and lateral exchange of mineralogically and chemically mature pelites and sands. Pelitic sediments consist mainly of detrital quartz, calcite, dolomite and feldspar grains, with smectite as the most common clay mineral. Quartz and the most resistant lithic fragments dominate the sandy detritus. The composition of the sediments indicates their origin from the recycled orogen, while their textural immaturity suggests a short transport distance. Most of the material was re-deposited from the underlying Upper Miocene sediments, originally of Alpine provenance. A lesser proportion originated from Palaeogene sediments, Triassic carbonate rocks, basic or acidic magmatic rocks and metamorphites. The Medvednica and Žumberak Mts. were the most important source areas, while a smaller proportion of the material could have come from the Moslavačka gora Mt. and Banovina region. The uniform composition of the Viviparus beds over the entire vertical distribution of the sediments clearly indicates that the source areas did not change during their deposition. A significant change from the texturally and compositionally mature Upper Miocene clastic detritus of alpine origin, to the texturally immature material of the Viviparus beds of local origin is a consequence of compression and inversion of the previously extensional basin resulting in the uplifting and erosion of the mountains within the SW part of the Pannonian Basin System.


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