Metals
Frank A. Barile in Barile’s Clinical Toxicology, 2019
Two major sources of Hg deposition in the environment are the natural degassing of the earth’s crust and the leaching of sediment. This natural source of contamination is estimated at 25,000 to 150,000 tons of Hg per year, which binds to organic or inorganic particles and to sediment that has a high sulfur content. Although discharges of Hg have been strictly regulated, some industrial activities still release substantial quantities of the metal. For example, fossil fuel contains as much as l.0 ppm. Since 1973, approximately 5000–10,000 tons of Hg per year has been discharged from burning coal, natural gas, and the refining of petroleum products, with one-third of the atmospheric Hg due to industrial releases. The element is used in a number of products, including thermometers, barometers, electrical apparatus, paints, and pharmaceuticals.
Sediments
Michael J. Kennish in Ecology of Estuaries Physical and Chemical Aspects, 2019
Within an estuary, most sediments are derived from the weathering and erosion of preexisting rock or sediment, with a minor fraction supplied by biologically and chemically precipitated materials. Wind, water, or ice transport sedimentary particles to sites of deposition. Once deposited, it is possible to describe sediments by means of physical properties, that is, fundamental and mass properties. The fundamental properties of sediments fall into four categories: (1) mineral composition, (2) grain size, (3) grain shape, and (4) fabric. Among mass properties, much applied ecology is concerned with the porosity (pore volume) and permeability (ease of fluid movement) of sediments. The physical properties of particles are of obvious importance in assessing the abundance and distribution of benthic organisms and the chemistry of pore waters.
Impact of Sulphur Dioxide Deposition on Medicinal Plants' Growth and Production of Active Constituents
Azamal Husen in Environmental Pollution and Medicinal Plants, 2022
Industries, thermal power plants, and automobiles are the sources of atmospheric pollution, creating various pollutants by reacting with temperature, light and humidity (Husen 1997, 2021). The chemicals present in the air travel far away from their origin point and affect the ecosystems and broad regional locations (Figure 4.1). Sulphur dioxide (SO2) and nitrogen oxides (NOx) are the major chemical precursors leading to acidic conditions in the atmosphere by reacting with oxygen, water, and sunlight. The wet (acidic rain, fog, snow) and dry (acidic gas, particles) parts of acid deposition in the atmosphere fall onto plants. Acid deposition is an example of the accumulation of acids and oxides from the atmosphere in the form of gas, rain, snow, or particulates that begin mainly from human activities (Abbasi et al. 2013). As a result, sulphuric acid (H2SO4) and nitric acids (HNO3) are deposited on vegetation. About 60–70 per cent of the acid deposition found throughout the world is SO2. Only 10 per cent of sulphur in the atmosphere is from natural sources, the remaining 90 per cent being anthropogenic (Ramadan 2004).
Nicotine forms: why and how do they matter in nicotine delivery from electronic cigarettes?
Published in Expert Opinion on Drug Delivery, 2020
Vinit V Gholap, Leon Kosmider, Laleh Golshahi, Matthew S Halquist
Although this method can provide a valuable characterization of e-liquids in terms of the free base nicotine yield, the method should be used with caution considering some concerns. After dilution, a solvent system is a mixture of water, nicotine, PG, VG, and flavoring chemicals. Such mixture, especially PG and VG, can affect the autoprotolysis constant of water and change the pKa of nicotine [74]. As per the mathematical model of inhaled e-cigarette aerosol presented by Asgharian et al. [56], the vapor concentration of each constituent of the e-cigarette aerosol in the oral cavity plays an important role in droplet formation by condensation. Among all the constituents, water vapor has the highest concentration considering the highly humid oral cavity. Thus, water content predominates in particle condensation (growth) as well as deposition process. Considering such high content of water vapor, it is important to study the dilution factor under the dilution approach such that it will negate the effect of PG and VG on the autoprotolysis constant of water. As described by Gholap et al. [65], a fixed dilution, for example 10X or higher, can smooth out the effect of PG, VG, and flavoring chemicals on autoprotolysis constant of water and pKa of nicotine. Having said that, the dilution factor remains an arbitrary number since the actual fraction of water in the condensation process may not be determined.
Surface Modification of lactose carrier particles using a fluid bed coater to improve fine particle fraction for dry powder inhalers
Published in Pharmaceutical Development and Technology, 2023
Qin Qin Gong, Justin Yong Soon Tay, Natalia Veronica, Jian Xu, Paul Wan Sia Heng, Yong Ping Zhang, Celine Valeria Liew
In the case of the dispersion with 5 µm particles, the spray droplet would likely have lesser liquid due to the larger particles. This resulted in the deposited particles being more exposed as protuberances on the surfaces when the impinged droplet was dried, yielding rougher LC5 carrier particles, which also happened to be the roughest among the spray-coated carrier particles prepared (Figure 1). In contrast, with 8 µm particles, as discussed earlier, due to the large size of the dispersion particles, they may either be deposited as surface slabs or be spray-dried without deposition. The deposits may even act to smooth the carrier surface by affixing smooth crystal fronts on the larger lactose carrier particles. With a thicker coat, the increased deposition thickness caused increased surface roughness due to the random addition of coarse deposits (Figure 1). For the coarser micronized particles, particularly the 8 µm particles, the proportion of liquid in the droplet decreases, hence increasing the probability of the micronized particle being spray-dried without being deposited onto the carrier surface. This meant that the efficiency of surface coating with micronized particles decreased with the size of the particles as the larger particles were more liable to be spray-dried.
Evaluation of trace elements concentration in surface sediments of Parishan International Wetland (Fars Province, SW Iran) by using geochemical and sedimentological analysis
Published in Toxin Reviews, 2021
Amir Karimian Torghabeh, Sayed Fakhreddin Afzali, Ashkan Jahandari, Mohamad Hosein Mahmudy Gharaie, Omar Ali Al-Khashman
In terrestrial environments, lake sediments are considered a valuable repository to the assess the behavior of heavy metals and their source, because they frequently act as ultimate sinks for anthropogenic emissions, such as those resulting from the use of fertilizers, mining, burning of fossil fuels, vehicle transport, etc. (Eby 2016). Many of these emissions include heavy metals released as particulate matter to air and deposited on land surface and water bodies incorporates pond and lakes too (Liang et al.2018, Karimian Torghabeh et al.2019a,b, Patel et al.2018). Raining and anthropic runoff (agricultural, industrial, and household) transport heavy metals, which eventually end up in water bodies and sediments (e.g. Ambedkar et al. 2017, Yazidi et al.2017). Different studies have been done to show the different origins of trace elements. For example, sediments of the Maharlou hyper saline lake in Iran, show extremely high enrichment of Sr and high enrichment of Ni, both related to the sedimentary bed rock, and high enrichments of As and Cd due to agricultural waste water leaching into the lake (Karimian Torghabeh et al.2018). Two other examples from China show atmospheric deposition as the main source for Cd, Cu, Hg, Pb, and Zn input to Erhai Lake surface sediments (Lin et al.2016), and industrial activities, agricultural and domestic wastewater as the main sources of Cd, Cu, Zn, and Pb pollution in Poyang Lake (Dai et al.2018).
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