Depletion risks of essential trace metals in a transboundary drain and its surrounding soil using GIS techniques

Hudiara drain, a big sewage water body originating from India, is an important tributary of river Ravi in Pakistan. In present study, role of the drain in build-up/depletion of metal micronutrients Cu, Fe, Mn and Zn in surrounding agricultural lands has been investigated. Soil samples, up to a vertical distance of 1200 m on both sides of the drain and drain water samples were collected and analysed for metal micronutrients. Soil analysis results were interpolated by using the best optimized interpolator to generate continuous variation of the selected metals. Further patterns have been identified using proximity stat with consecutive neighbouring zones of 100 m extent. Cu and Mn concentrations were higher in some drain water samples, whereas Fe and Zn were found below guidelines in all collected water samples. In adjacent agricultural land the metals did not show uniform dispersal pattern along the drain length. However, vertical pattern of distribution indicated that drain water was controlling Cu and Zn concentrations, positively, whereas it was causing a dilution effect on Fe and Mn build-up in the surrounding agricultural lands.

Impact of Zn Substitution on Fe(II)-induced Ferrihydrite 2 Transformation Pathways

Iron oxide minerals are ubiquitous in soils, sediments, and aquatic systems and influence the fate and availability of trace metals. Ferrihydrite is a common iron oxide of nanoparticulate size and poor crystallinity, serving as a thermodynamically unstable precursor to more crystalline phases. While aging induces such phase transformations, these are accelerated by the presence of dissolved Fe(II). However, the impact of trace metals on Fe(II)-catalyzed ferrihydrite phase transformations at ambient temperatures and the associated effects on trace metal speciation has seen limited study. In the present work, phase transformations of ferrihydrite that contains the trace metal zinc in its structure were investigated during aging at ambient temperature in the presence of two different Fe(II) concentrations at pH 7. X-ray diffraction reveals that low Fe(II) concentration (0.2 mM) generates hematite plus minor lepidocrocite, whereas high Fe(II) concentration (1.0 mM) promotes the production of a magnetite-lepidocrocite mixture. In both cases, a substantial fraction of ferrihydrite remains after 12 days. In contrast, Zn-free ferrihydrite forms primarily lepidocrocite and goethite in the presence of 0.2 mM Fe(II), with minor hematite and a trace of ferrihydrite remaining. For 1.0 mM Fe(II), magnetite, goethite, and lepidocrocite form when Zn is absent, leaving no residual ferrihydrite. Transformations of Zn-ferrihydrite produce a transient release of zinc to solution, but this is nearly quantitatively removed into the mineral products after 1 hour. Extended X-ray absorption fine structure spectroscopy suggests that zinc partitions into the newly formed phases, with a shift from tetrahedral to a mixture of tetrahedral and octahedral coordination in the 0.2 mM Fe(II) system and taking on a spinel-like local structure in the 1.0 mM Fe(II) reaction products. This work indicates that substituting elements in ferrihydrite may play a key role in promoting the formation of hematite in low temperature systems, such as soils or sediments. In addition, the retention of zinc in the products of ferrihydrite phase transformation shows that trace metal micronutrients and contaminants may not be mobilized under circumneutral conditions despite the formation of more crystalline iron oxides. Furthermore, mass balance requires that the abundance and isotopic composition of iron oxide-associated zinc, and possibly other trace metals, in the rock record may be retained during diagenetic phase transformations of ferrihydrite if catalyzed by dissolved Fe(II).

Abnormal Levels of Metal Micronutrients and Autism Spectrum Disorder: A Perspective Review

The aim of the present review is to summarize the prevalence of abnormal levels of various metal micronutrients including copper (Cu), iron (Fe), magnesium (Mg), zinc (Zn), and selenium (Se) in Autism Spectrum Disorder (ASD) using hair, nail and serum samples. A correlation of selected abnormal metal ions with known neurodevelopmental processes using Gene Ontology (GO) term was also conducted. Data included in this review are derived from ASD clinical studies performed globally. Metal ion disparity data is also analyzed and discussed based on gender (Male/Female) to establish any gender dependent correlation. Finally, a rational perspective and possible path to better understand the role of metal micronutrients in ASD is suggested.

Metal-dependent hormone function: the emerging interdisciplinary field of metalloendocrinology

Advances in understanding of hormones and metal micronutrients show critical interactions between the two in a newly-termed field of metalloendocrinology.