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Replacement
Published in Jay Ameratunga, Sivakugan Nagaratnam, M. Das Braja, Soft Clay Engineering and Ground Improvement, 2021
Even with a simple technique such as replacement, there could be serious environmental issues we have to deal with. They are mostly related to any earthworks construction site and could be summarized as follows:Presence of acid sulfate soils;Presence of contaminated soils;Noise;Vibration;Traffic; andQuarry operations.When acid sulfate soils and contaminated soils are present in the excavation, they need careful consideration prior to disposal. In the case of acid sulfate soils, space permitting, could be neutralized by the addition of lime. Then such material could be re-used in the project or disposed offsite.
Climate, Site, and Pond Design
Published in Hillary S. Egna, Claude E. Boyd, Dynamics of POND Aquaculture, 2017
Anita M. Kelly, Christopher C. Kohler
Soils may also contain other chemicals that are harmful to fish. Soils are comprised of various chemicals, some of which, such as phosphorous, when in contact with water are forced down into the lower soil layers, where they accumulate. Other chemicals, such as chlorides and sulfates, are less soluble and remain in the upper soil layers. When some of the chemicals are exposed to air, they may be oxidized, forming more soluble chemicals. Hence, the chemical composition of soils is dynamic. For example, when soil containing pyrites is moved during pond construction and the pyrites are exposed to air, oxidation of the pyrites results in acidic soils having pH values less than 4.0. These types of soils, called acid sulfate soils, are found throughout Southeast Asia.
Rivers and Lakes: Acidification
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Water Resources and Hydrological Systems, 2020
Agniezka Gałuszka, Zdzistaw M. Migaszewski
Acid sulfate soils are soils abundant in pyrite and other sulfide minerals. These soils, formed under waterlogged conditions, when exposed to the air (e.g., by draining, excavation, cultivation), undergo chemical reactions that are responsible for sulfuric acid generation and subsequent acidification. Pyrite-rich soils that are not exposed to weathering pose no hazard to the environment and are called “potential acid sulfate soils” or cat-clays.
Zebra rock and other Ediacaran paleosols from Western Australia
Published in Australian Journal of Earth Sciences, 2021
In contrast, zebra rock beds are thicker and more massive than associated shaley laminae (Figures 4b and 6b) as if each bed were deposited in one episode as an airfall crystal tuff, and in two cases as a biotite tuff (Figure 7). Once in place, profound chemical weathering (Figure 7) and paleomagnetic characters (Abrajevitch et al., 2018) are evidence that they were soils comparable with modern gleyed soils near Union, South Carolina (Figure 11a, b). This distinctive grey-red banding in soils within diffuse margins comparable with zebra rock (Figure 3) is considered the result of gleisation of a red soil by pockets of anaerobic bacteria active during waterlogging (Chen et al., 2019), like other examples of soil gleisation (Schulz et al., 2016). It is the opposite of conservation of total iron in red and grey areas of paleosols with closed-system burial gleisation (Retallack, 1991a). Loss of iron in white bands of zebra rock by open system reduction down to reduced lower horizons is compatible with groundwater rather than surface-water gleisation (Vepraskas & Sprecher, 1997). Soil lamellae are another comparable feature, but these ferruginised seams within soils are much more sandy than zebra rock (Bockheim & Hartemink, 2013; Rawling, 2000). An alternative view of Mattievich et al. (2003) is that zebra rock formed as a liquid crystal in which hematite grains in the tens of nanometre size range had sufficient magnetic moment to segregate within a colloidal bed under a normal intensity of Earth’s magnetic field. Evidence against this is the preservation of sand and silt grains in zebra rock (Figure 3), which were far from colloidal, with no more than 50% grains of clay or finer grainsize (Figure 7; Table S3). Among these grains are oxidised pyrite, supporting the idea of acid sulfate soil weathering to account for the localised intensity of weathering of thin zebra rock beds (Loughnan & Roberts, 1990).