Soil Chemical Analysis

Metal contamination issues are becoming increasingly common in India and elsewhere, with many documented cases of metal toxicity in mining industries, foundries, smelters, coal-burning power plants and agriculture. Heavy metals, such as cadmium, copper, lead, chromium and mercury are major environmental pollutants, particularly in areas with high anthropogenic pressure. Heavy metal accumulation in soils is of concern in agricultural production due to the adverse effects on food safety and marketability, crop growth due to phytotoxicity, and environmental health of soil organisms. The influence of plants and their metabolic activities affects the geological and biological redistribution of heavy metals through pollution of the air, water and soil. This article details the range of heavy metals, their occurrence and toxicity for plants. Metal toxicity has high impact and relevance to plants and consequently it affects the ecosystem, where the plants form an integral component. Plants growing in metal-polluted sites exhibit altered metabolism, growth reduction, lower biomass production and metal accumulation. Various physiological and biochemical processes in plants are affected by metals. The contemporary investigations into toxicity and tolerance in metal-stressed plants are prompted by the growing metal pollution in the environment. A few metals, including copper, manganese, cobalt, zinc and chromium are, however, essential to plant metabolism in trace amounts. It is only when metals are present in bioavailable forms and at excessive levels, they have the potential to become toxic to plants. This review focuses mainly on zinc, cadmium, copper, mercury, chromium, lead, arsenic, cobalt, nickel, manganese and iron.

Heavy metals, occurrence and toxicity for plants: a review

Preface.- Contributors.- List of Abbreviations.- Section 1: Basic Principles: Introduction.-Sources of Heavy Metals and Metalloids in Soils.- Chemistry of Heavy Metals and Metalloids in Soils.- Methods for the Determination of Heavy Metals and Metalloids in Soils.- Effects of Heavy Metals and Metalloids on Soil Organisms.- Soil-Plant Relationships of Heavy Metals and Metalloids.- Heavy Metals and Metalloids as Micronutrients for Plants and Animals.-Critical Loads of Heavy Metals for Soils.- Section 2: Key Heavy Metals And Metalloids: Arsenic.- Cadmium.- Chromium and Nickel.- Cobalt and Manganese.- Copper.-Lead.- Mercury.- Selenium.- Zinc.- Section 3: Other Heavy Metals And Metalloids Of Potential Environmental Significance: Antimony.- Barium.- Gold.- Molybdenum.- Silver.- Thallium.- Tin.- Tungsten.- Uranium.- Vanadium.- Glossary of Specialized Terms.- Index.

Heavy metals in soils : trace metals and metalloids in soils and their bioavailability

http://www.irrec.ifas.ufl.edu/IRSWS/History%20Publications/2/JTEMBHe2005.pdf

Trace elements in agroecosystems and impacts on the environment

https://cyberleninka.org/article/n/1104220.pdf

Heavy metals toxicity in plants: An overview on the role of glutathione and phytochelatins in heavy metal stress tolerance of plants

Heavy metals have been increasingly released into our environment. We present here, for the first time, the global industrial age production of Cd, Cu, Cr, Hg, Ni, Pb, and Zn, and their potential accumulation and environmental effects in the pedosphere. World soils have been seriously polluted by Pb and Cd and slightly by Zn. The potential industrial age anthropogenic Pb, Hg, and Cd inputs in the pedosphere are 9.6, 6.1, and 5.2 times those in the lithosphere, respectively. The potential anthropogenic heavy metal inputs in the pedosphere increased tremendously after the 1950s, especially for Cr and Ni. In 2000, the cumulative industrial age anthropogenic global production of Cd, Cr, Cu, Hg, Ni, Pb, and Zn was 1.1, 105, 451, 0.64, 36, 235, and 354 million tonnes, respectively. The global industrial age metal burdens per capita (in 2000) were 0.18, 17.3, 74.2, 0.10, 5.9, 38.6, and 58.2 kg for Cd, Cr, Cu, Hg, Ni, Pb, and Zn, respectively. Acidification may increase the bioavailability and toxicity of heavy metals in the pedosphere. The improvement of industrial processing technology reducing the metal dispersion rate, the recycling of metal-containing outdated products, by-products and wastes, and the development of new substitute materials for heavy metals are possible strategies to minimize the effects of heavy metals on our environment.

Industrial age anthropogenic inputs of heavy metals into the pedosphere

Summary
• Brassica juncea is a potential candidate plant for phytoremediation of a number of heavy metals, but little is known about the phytotoxicity of chromium (Cr) for this plant in Cr(III)- and Cr(VI)-contaminated soils.
• Chromium distribution and phytotoxicity at the whole plant and cellular levels were studied using chemical, light microscopy, scanning electron microscopy and transmission electron microscopy analyses.
• Bioavailability of Cr in soils was low, but the uptake significantly increased at phytotoxic levels. Chromium from Cr(VI)-contaminated soils was more phytotoxic than from Cr(III)-contaminated soils. Chromium causes growth retardation, reduces the number of palisade and spongy parenchyma cells in leaves, results in clotted depositions in the vascular bundles of stems and roots, and increases the number of vacuoles and electron dense materials along the walls of xylem and phloem vessels.
• Our results suggest that B. juncea is not a good candidate for phytoremediation of soils with lower Cr. However, it is able to accumulate significant amounts of Cr in both shoots and roots at higher soil-Cr concentrations despite severe phytotoxic symptoms.

Phytoavailability and toxicity of trivalent and hexavalent chromium to Brassica juncea

Large portions of Mars' surface are covered with deposits of fine, homogeneous, weathered dusty-soil material. Nanophase iron oxides, silicate mineraloids, and salts prevail in the soil. The mode of formation of this somewhat peculiar type of soil is still far from being clear. One scenario suggests that weathering took place during early epochs when Mars may have been “warm and wet”. The properties of the soil are not easily reconciled with this scenario. We propose another possible scenario that attributes, in part, the peculiar nature of the Martian dust and soil to a relatively “young” weathering product formed during the last few hundreds of millions of years in a process that involves acidic volatiles. We tested this hypothesis in an experimental study of the first step of acidolytic weathering of a partly palagonitized volcanic tephra of hawaiitic lava origin, using sulfuric, hydrochloric and nitric acids and their mixtures. The tephra effectively “neutralize” the added acidity. The protonic acidity added to the tephra attacks the primary minerals, releasing Fe, Al, and Mg, which control the pH, acting as Lewis-acid species of varying acid strengths. The full amount of acidity added to the tephra is stored in it, but only a very small fraction is preserved as the original protonic acidity. The majority of the added sulfate and chloride were present as salts and easily solubilized minerals. Well-crystallized sulfate salt minerals of aluminum and calcium were detected by powder X ray diffractometry, whereas secondary magnesium and iron minerals were not detected, due probably to lack of crystallinity. The presence of gypsum (CaSO4·2 H2O) and alunogen (Al2(SO4)3·17 H2O) is probably responsible for the observed increased hygroscopicity of the acidified tephra and their tendency to form hardened crusts. We suggest that if this mechanism is of importance on Mars, then the chemically weathered component of the Martian soil consists of a salt-rich mineral mixture containing the salts of the anionicligands SO4 and Cl resulting from volatiles emitted from volcanoes during more recent eruptions (up to 109 years B.P.). The lack of liquid water on Mars surface during that time slowed or halted mineralogical evolution into highly crystallized minerals having large mineral grains. The chemically weathered components are mixed with the products of physical weathering. The recently formed soil may cover and coat more evolved, hydrothermally modified, mineral deposits formed in earlier epochs of Mars.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/97JE01160

Acidic volatiles and the Mars soil

Dedication.- List of Figures.- List of Tables.- Preface.- SECTION I: Introduction on arid zone soil: Arid zone soils: Nature and properties. SECTION II: Biogeochemistry of trace elements in arid environments: Trace element distribution in arid zone soils.- Solution chemistry of trace elements in arid zone soils.- Selective sequential dissolution for trace elements in arid zone soils.- Binding and distribution of trace elements among solid-phase components in arid zone soils.- Transfer fluxes of trace elements in arid zone soils - a case study: Israeli arid soils.- Bioavailability of trace elements in arid zone soils.- Trace element pollution in arid zone soils.- Global perspectives of anthropogenic interferences in the natural trace element distribution: Industrial age inputs of trace elements into the pedosphere.- References.- Index.

Fengxiang X. Han

Papers

Industrial age anthropogenic inputs of heavy metals into the pedosphere

Phytoavailability and toxicity of trivalent and hexavalent chromium to Brassica juncea

Acidic volatiles and the Mars soil

Biogeochemistry of Trace Elements in Arid Environments

Binding, distribution, and plant uptake of mercury in a soil from Oak Ridge, Tennessee, USA.