Diatom Diversity and Organic Matter Sources in Water Bodies around Chennai, Tamil Nadu, India

Abstract

In the present study, sediment samples were collected from different locations and diverse environments around Chennai city to evaluate the environmental conditions and the health of the water bodies. The grain size analysis of the sediment samples reveals that sand is the dominant fraction deposited in highenergy coastal environments followed by silty sand, sandy silt, while as the sediment samples of Cooum River and fresh water lakes and Buckingham canal show the dominance of silty clay and clayey silt respectively. The C/N ratio of the sediment samples indicates in situ source of algal organic matter, except Cooum River, while the confluence of the Cooum River to the sea and the Buckingham canal exhibits dominant terrestrial source of organic matter. Significant positive correlation of clay with TOC, C/N ratio signifies strong binding of these elements with finer clay particles. Predominant occurrences of diatom species such as Cyclotella striata, Navicula and Nitzchia linearis in the water bodies of Chennai shows high organic pollution caused by anthropogenic influences.

Compositional characteristics and genetic affinity of the ferricrete deposit in Adi Kokeb district, northwestern Tigray, Ethiopia

“…This is in consistent to the case described by Abimbola et al (1999) where a ferruginous sandstone is the precursor material for a ferricrete. However, the higher values of SiO 2 in the meta-sandstone is due to the occurrence of quartz (Achyuthan 2004), whereas the lower values of silica in the ferricrete reflect the production of Secondary quartz through dissolution of original quartz grains (Bheemalingeswara et al 2013). Therefore, when compared to ferruginous sandstone or meta-sandstone in content of the major oxides, the ferricrete deposit has higher values of Fe 2 O 3 and lower values of SiO 2 and Al 2 O 3 (Table 1).…”

“…However, in some places, voids and fractures are filled by secondary quartz, suggesting variable environmental conditions within the ferricrete (Ramakrishnan and Tiwari 2006; Figure 6(C)). Achyuthan (2004) described the development of ferricretes found in different geological settings and reported that they consist of iron oxides and hydroxides (goethite), and quartz. We found a similar ferricrete deposit in our study area where finely crystalline hematite and goethite along with highly corroded quartz make up the matrix (Figure 5(A, B and D)).…”

Mineralogical and geochemical characteristics of the iron–duricrust deposit in Adi-Daero area, northwestern Tigray, Ethiopia: implication for the origin and controlling factors

“…Iron–duricrusts (ferricretes) have been used as morpho- and pedo-stratigraphic markers in landscape reconstruction (Bourman 2007) and as indicators of climatically controlled geomorphic and pedological processes (Achyuthan 2004). They have application in construction and industrial processes (McNally 2007; Ramanaidou and Morris 2010; Oyelami and Van Rooy 2016) and as raw materials for cement production (Emofurieta et al 1995; Gebresilassie et al 2012).…”