The Sustainability of the World's Soils
Bill Pritchard, Rodomiro Ortiz, Meera Shekar in Routledge Handbook of Food and Nutrition Security, 2016
The age and rainfall regime are two important factors determining soil quality. The older and the more exposed to rainfall, the more weathered the soils. Excess rainfall leaches minerals and nutrients from the topsoil into deeper layers inaccessible to plant roots. West and Central African soils are predominantly old, up to 200 million years, and have been exposed to high rainfall for most of that development time. Accordingly, many soils are highly weathered and inherently nutrient poor, with a dominance of kaolinitic clay minerals, which have very low cation exchange capacity, thus lacking a major prerequisite to retain nutrients in the soil.
The kidneys
Martin Andrew Crook in Clinical Biochemistry & Metabolic Medicine, 2013
Therefore, during cation exchange there is insignificant net movement of anions or water. For example, Na+ may be reabsorbed in exchange for potassium (K+) or hydrogen (H+) ions. Na+ and H+ exchange also occurs proximally, but at that site it is more important for bicarbonate reclamation than for fine adjustment of solute reabsorption (see Chapter 4). In the cells lining the renal tubules, the intestine and many secretory organs, the pumps are located on the membrane on one side of the cell only and therefore solute flows in one direction.
Radionuclide Transport Processes and Modeling
Michael Pöschl, Leo M. L. Nollet in Radionuclide Concentrations in Food and the Environment, 2006
One key property of soil is its ability to adsorb ions and to immobilize them to different extents on the solid phase. Soil colloids (clay minerals and organic matter) contain a high specific density of negative charges acting as cation exchange sites. The ability of a soil to adsorb ions is proportional to the density of exchange sites and is expressed by its cation exchange capacity (CEC, in mEq/kg). Values reported for the CEC range from 0.3 to 1.5 mEq/kg for kaolinite, 1 to 4 mEq/kg for illite, 8 to 15 mEq/kg for montmorillonite, and 30 to 50 mEq/kg for organic compounds.
Hydrogeochemical characterization, multi-exposure deterministic and probabilistic health hazard evaluation in groundwater in parts of Northern India
Published in Toxin Reviews, 2023
Herojeet Rajkumar, Pradeep K. Naik, Gagandeep Singh, Madhuri Rishi
On the other hand, the plot Mg2+/Na+ vs. Ca2+/Na+ (Figure 5(h)) depicts majority of the groundwater samples are clustered within the silicate zone, and very few samples are scattered in the silicate-carbonate mixing region during the investigational period. This plot clearly shows that silicate mineral is not only the prime source of Na+, Mg2+, and Ca2+ in the study area. The dissolution of carbonate minerals and reverse ion exchange elevates the contents of alkaline earth elements in groundwater (as expressed in Equations (10–12), (17), and (18). Gao et al. (2022) reported that clay minerals, when rich in alluvial sediment, enhance cation exchange processes that affect the cation concentrations in groundwater. The following reactions explain the cation exchange for Ca2+ and Mg2+ with Na+ in the clay sediments as expressed in Equations (15–18) (Li et al.2018a, 2018b, Zhou et al.2020).
High-throughput tool to discriminate effects of NMs (Cu-NPs, Cu-nanowires, CuNO3, and Cu salt aged): transcriptomics in Enchytraeus crypticus
Published in Nanotoxicology, 2018
Susana I. L. Gomes, Carlos P. Roca, Natália Pegoraro, Tito Trindade, Janeck J. Scott-Fordsmand, Mónica J. B. Amorim
The test soil consisted of a natural soil collected at the Hygum site, Jutland, Denmark. In this site, the soil has been historically exposed to contamination with CuSO4 (due to activities of timber preservation, ceased more than 80 years ago), originating a well-known Cu gradient along the field, ranging from the natural background levels of 30 up to 2900 mg Cu/kg dry soil (Scott-Fordsmand, Weeks, and Hopkin 2000). Soil was sampled in the field to a depth of 20 cm, dried at 80 °C for 24 h in an oven (Memmert, Type UL40, Braunschweig, Germany) to exclude soil fauna, and then sieved through a 2 mm mesh to remove larger particles. The general physico-chemical characteristics of the soil are as follows: 20–32% coarse sand (>200 µm), 20–25% fine sand (63–200 µm), 11–20% coarse silt (20–63 µm), 12–20% silt (20–20 µm), 12–16% clay (<2 µm), 3.6–5.5% organic matter, Cation Exchange Capacity 6.8–10 (cmolc/kg dw), pH = 5, N 0.25–0.31% and P 0.10–0.12%. The clay mineralogy analyzed by X-ray diffraction was dominated by illite, kaolinite, chlorite, and vermiculite.
Assessment of trace element toxicity in surface water of a fish breeding river in Bangladesh: a novel approach for ecological and health risk evaluation
Published in Toxin Reviews, 2022
Md. Refat Jahan Rakib, Yeasmin Nahar Jolly, Bilkis Ara Begum, Tasrina Rabia Choudhury, Konika Jannat Fatema, Md. Saiful Islam, Mir Mohammad Ali, Abubakr M. Idris
Water samples were analyzed for common inorganic anions fluoride, chloride, nitrite, sulfate, and major cation sodium, ammonium, potassium, magnesium, and calcium by ion exchange chromatography. The concentration of anions in this study follows the decreasing order of chloride > sulfate > nitrate > fluoride. Fluoride was found in only five samples in which highest value is 0.29 ppm which is also below the safe limit set by WHO. The range of chloride, sulfate, and nitrite are 6.30–8.93, 3.475–4.255, 0.29–9.535, respectively (Table 1), and all the values are within the range of international standard and consider Halda river water is not significantly polluted by these anions. In cation test major cation like sodium, ammonium, potassium, magnesium, and calcium were analyzed in DIONEX. In all of the water samples, lithium was below its LOD value. Hardness of water is due to alkaline earth metals such as Mg and Ca ions (Abbasi 1998). Suitable hardness for fish growth is about 15 mg/L, less than 11 mg/L requires liming for higher fish production, so water having less than 5 mg/L CaCO3 cause pain, slow growth rate, and ultimately death of fish (Boyd 1981). In our study TDS value is between 18.74 and 20.30 mg/L which is within the safe range set by WHO. The highest and lowest value of ammonium ion recorded in 0.47 mg/L in station 4 and 0.28 mg/L in station 7, respectively. Sodium and potassium ions mean concentrations between the range of 8.40–10.8 ppm and 3.35–4.03 ppm was reported during the present study.
Related Knowledge Centers
- Chemical Structure
- Hydroxide
- Montmorillonite
- Polymer
- Ion-Exchange Resin
- Electrolyte
- Gel
- Zeolite
- Ion
- Amphoterism