The Characteristics of Lipid Biomarkers from the Abyssal and Hadal Sediments of the Yap Trench and the Influence of V-Shape Topography

Lipid biomarkers from deep-sea sediments have been observed in several studies, but little is known about their occurrence in trench system sediments. Here, we determined the concentrations of lipid biomarkers (fatty acids and neutral lipids) in sediments from the north Yap Trench. Our results showed that short-chain (C12–20) saturated fatty acids (SFAs) contributed more than (C12:1–23:1) monounsaturated fatty acids (MUFAs), and (C16:3–24:4) polyunsaturated fatty acids (PUFAs). Most fatty acids (FAs) suggest that bacteria and algae were the main contributors to marine organic matter. In contrast, terrestrial organic matter (OM) was a minor contributor to long carbon chain fatty acids greater than C20. On the other side, the observed neutral lipids such as alkanes (C14–C27), alkanols (C12–C20), alkenes (C17:1–C26:1), phytol and sterol (C27–29) indicate that phytoplankton and bacteria were the main contributors of organic materials in the sediments, and the carbon chain of neutral lipids C20–29 offering the sources of terrestrial organic matter. The extremely depleted δ13C values of fatty acids give the sources of organic carbon in the sediments from bacteria, algae, and methane-related microbes. This study is important for understanding the biogeochemical activities in deep-sea environments, particularly in the abyss and hadal zones. It will be helpful to understand the sources, transfer, and deposition of organic matter in marine trenches

Risk assessment of heavy metals and salts for human and irrigation consumption of groundwater in Qambar city: a case study

The study investigated the water quality of groundwater for consumption of human beings and irrigation of taluka Qamber district Qamber-Shahdadkot, Sindh, Pakistan. A total of 21 representative groundwater samples were collected mostly used for human consumption. According to the research work, 81% samples were not suitable for drinking purpose with TDS above the maximum permissible limit of WHO (1000 mg/L). The pH, total phosphate-P, orth ophosphate-P, nitrate-N, nitrite-N, and arsenic were within WHO limits. The concentrations of essential metals more than half samples were higher than WHO guideline. The concentrations of trace metals like Mn, Fe, Co, and Cu of all samples were within WHO limits, but the values of Cr and Ni 52.38%, Cd 57.14%, and Pb 28.57% were above the WHO limits. The concentrations of fluoride in 81% were higher than permissible limits of WHO. The high consumption of water with concentration of salts and fluoride above the permissible limits may be a leading factor of a number of diseases in the area. The water quality determined for irrigation based on Kelly index (KI), sodium percentage (Na%), chloride–sulfate ratio, sodium adsorption ratio (SAR), permeability index (PI), chloro alkaline indices1 (CAI-1), residual sodium carbonate (RSC), and chloride bicarbonate ratio indicated that 25–90% samples were suitable for irrigation purposes