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Topic Review
Source Analysis of Heavy Metal Pollution in Soils
Eight types of heavy metals in the soil on the banks of Shuimo River in Urumqi were analysed via X-ray fluorescence spectrometry and national standard detection methods. The UNMIX and positive matrix factorisation (PMF) models were comprehensively used to analyse the sources and contribution rates of potential pollutants. The soil samples were collected from three layers: 0–20, 20–40, and 40–60 cm. Each sample point in each layer was located 5 m, 1 km, and 2 km from the riverbank. The results showed that only the average concentration of Mn in each layer of soil was lower than the background value, and the average concentrations of other heavy metals were higher than their background values. Among them, Ni concentration highly exceeded the background value in the 40–60 cm soil layer, reaching 1.92 times. The similarities and differences between the sources and contributions estimated by the UNMIX and PMF models were also clarified. The similarities of the two common sources (natural source and artificial source) for each soil layer were relatively large, and the analysis results of the two models were within model reliability range. By comparing the Pearson correlation coefficients and distribution maps of heavy metal concentrations in surface soil, Zn, Pb, Cr, and Cu were from human sources, and Mn, Ni, and V were from natural sources. In future studies, multiple models should be comprehensively used to determine the potential pollutant sources and estimate contribution rates.
  • 802
  • 23 Sep 2022
Topic Review
IAQ and Façade–Ventilation Systems
Poor indoor air quality affects the health of the occupants of a given structure or building. It reduces the effectiveness of learning and work efficiency. Among many pollutants, PM 2.5 and 10 dusts are extremely important. They can be eliminated using mechanical ventilation equipped with filters. Façade ventilation devices are used as a way to improve indoor air quality (IAQ) in existing buildings. For their analysis, researchers used carbon dioxide as a tracer gas. They have shown that façade ventilation devices are an effective way to improve IAQ, but require further analysis due to the sensitivity of façade ventilation devices to the effects of wind and outdoor temperature. In addition, legal regulations in some countries require verification in order to enable the use of this type of solution as a way to improve IAQ in an era characterised by the effort to transform buildings into passive houses (standard for energy efficiency in a building). 
  • 802
  • 04 Mar 2021
Topic Review
Machine Learning Model in HSI-AD
In the field of remote sensing, hyperspectral image (HSI) is a ground image collected by advanced sensor technology and imaging system mounted on satellites or other aircraft. Anomaly detection (AD) is a very important sub-branch in machine learning and has important applications in computer vision, data mining, and natural language processing (NLP). HSI-AD refers to the identification of pixels whose spectral characteristics in an image are significantly different from adjacent or global background pixels.
  • 801
  • 05 May 2022
Topic Review
Abundance of Mycoplankton and Its Ecological Role
Mycoplankton are saprophytic organisms in plankton communities in marine and freshwater ecosystems. They consist of filamentous free-living fungi and yeasts associated with planktonic particles or phytoplankton. Similar to planktonic bacteria, these aquatic fungi play important roles in heterotrophic mineralization and nutrient cycling. Planktonic bacteria can be up to 20 mm in diameter and over 50 mm in length
  • 799
  • 23 May 2022
Topic Review
Occurrence of Triclosan in the Water Environment
Triclosan (TCS), a kind of pharmaceuticals and personal care products (PPCPs), is widely used and has had a large production over years. It is an emerging pollutant in the water environment that has attracted global attention due to its toxic effects on organisms and aquatic ecosystems, and its concentrations in the water environment are expected to increase since the COVID-19 pandemic outbreak.
  • 799
  • 09 Sep 2022
Topic Review Peer Reviewed
Revisiting Lorenz’s Error Growth Models: Insights and Applications
This entry examines Lorenz’s error growth models with quadratic and cubic hypotheses, highlighting their mathematical connections to the non-dissipative Lorenz 1963 model. The quadratic error growth model is the logistic ordinary differential equation (ODE) with a quadratic nonlinear term, while the cubic model is derived by replacing the quadratic term with a cubic one. A variable transformation shows that the cubic model can be converted to the same form as the logistic ODE. The relationship between the continuous logistic ODE and its discrete version, the logistic map, illustrates chaotic behaviors, demonstrating computational chaos with large time steps. A variant of the logistic ODE is proposed to show how finite predictability horizons can be determined, emphasizing the continuous dependence on initial conditions (CDIC) related to stable and unstable asymptotic values. This review also presents the mathematical relationship between the logistic ODE and the non-dissipative Lorenz 1963 model.
  • 798
  • 15 Jul 2024
Topic Review
Outline of Geophysics
The following outline is provided as an overview of and topical guide to geophysics: Geophysics – the physics of the Earth and its environment in space; also the study of the Earth using quantitative physical methods. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and composition; its dynamics and their surface expression in plate tectonics, the generation of magmas, volcanism and rock formation. However, modern geophysics organizations have a broader definition that includes the hydrological cycle including snow and ice; fluid dynamics of the oceans and the atmosphere; electricity and magnetism in the ionosphere and magnetosphere and solar-terrestrial relations; and analogous problems associated with the Moon and other planets.
  • 798
  • 09 Nov 2022
Topic Review
Medium-Chain-Length Polyhydroxyalkanoates Production
Polyhydroxyalkanoates (PHAs) are a type of biopolymer developed as intracellular carbon/energy storage materials which have a wide range of material characteristics. PHAs are identified as granular inclusion bodies after extraction from cells, these are becoming popular as prospective replacements for traditional plastics in various applications, including food packaging industries, cultivational fields, scaffold preparation, and biomaterial implants.
  • 797
  • 27 May 2022
Topic Review
ESA Round Robin Exercise
Motivated by the experience acquired in the ESA promoted Round Robin exercise aimed at comparing cloud detection algorithms for PROBA-V sensor, we investigate specific issues related to cloud detection when remotely sensed images comprise only a few spectral bands in the visible and near-infrared by considering a bunch of well-known classification methods. First, we demonstrate the feasibility of using a training dataset semi-automatically obtained from other accurate algorithms. In addition, we investigate the effect of ancillary information, e.g., surface type or climate, on accuracy. Then we compare the different classification methods using the same training dataset under different configurations. We also perform a consensus analysis aimed at estimating the degree of mutual agreement among classification methods in detecting Clear or Cloudy sky conditions. Results are also compared on a high-quality test dataset of 1350 reflectances and Clear/Cloudy corresponding labels prepared by ESA for the mentioned exercise.
  • 797
  • 02 Feb 2021
Topic Review
Late Permian Coals
This study reports the mineralogy and geochemistry of the Late Permian C1 Coal from Bole and Laibin mines in eastern Yunnan, Southwestern China (C1 Coal in Laibin mine is composed of three layers termed B1, B2, and B3). The coals are characterized by medium-high ash yields and very low sulfur contents. Compared with average values of trace element concentrations in hard coals worldwide, the Bole and Laibin coals are enriched in V, Co, Cu, Zn, and Se, which were mainly derived from the sediment-source region of the Kangdian Upland. Major minerals in the coal samples and roof and floor strata include quartz, interstratified berthierine/chamosite (B/C), as well as kaolinite, mixed layer illite/smectite, calcite, pyrite, and anatase. Unlike a pure chamosite, the 7 Å peak of interstratified B/C is sharp and narrow, while the 14 Å peak is broad and weak, or absent in some coal samples. Interstratified B/C was largely precipitated from low-temperature Fe-rich and Mg-rich hydrothermal fluids or, in some cases, is an alteration product of kaolinite. Secondary phases of quartz, calcite, pyrite, kaolinite, chalcopyrite, gypsum, and REE-phosphates in the coal samples are the dominant authigenic minerals formed at syngenetic and early diagenetic stages. Four intra-seam partings in C1 Coal, B1, and B3 layers are identified as tonsteins derived from felsic volcanic ashes. These tonsteins consist mainly of cryptocrystalline kaolinite with graupen and vermicular textures, and minor amounts of high-temperature quartz, zircon, apatite, monazite, and anatase. The floor of the C1 Coal in the Bole mine is a tuffaceous claystone and consists of altered high-Ti basalt volcaniclastics, characterized by high concentrations of Zr, Nb, V, Co, Cu, and Zn, low Al2O3/TiO2 ratio (~4.62), high Ti/Y ratio (~900), enrichment of middle rare earth elements, and positive Eu anomalies.
  • 797
  • 19 Jan 2021
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