Geochemical ratios mediated understanding of estuarine dynamics in submarine groundwater discharge prevalent basaltic aquifer.

Submarine groundwater discharge (SGD) has been recognized as an integral pathway of hydrological cycle. The role of SGD as a mechanism for material transport from terrestrial to marine ecosystems has also been investigated, considering the large hydrological flux and a massive load of solutes is found to be carried as SGD to the coastal oceans. However, there are challenges in recognizing the process and delineating specific areas which are susceptible to SGD. Considering the unique geochemical signature of groundwaters found in varied lithology, this paper investigates the possibility of using geochemical ratios and their variability in coastal areas as a tracer for the identification of SGD. The Br-/Cl- ratio, prevalently used for identification of seawater-groundwater mixing is investigated. The study raises questions over the viability of Br-/Cl- as a tracer as Br- rich groundwater in the SGD prevalent area may be a cause of elevated Br-/Cl- ratio in the coastal oceans. Furthermore, the peculiar observation of Fe+2 enrichment in coastal seawater also indicated the influence of differential weathering on the subterranean estuarine (STE) sediments releasing Fe+2 as the groundwater in the area is not enriched in groundwater. This observation is very important in the context of rising sea levels as a larger STE due to rising sea levels can cause higher mobilization of Fe+2 in coastal oceans causing a direct influence on the coastal ecosystem.

Salinity and temperature profiling for the submarine groundwater discharge simulations: Quantification through heat and solute transport model.

Developed coastal regions are the hotspots for contaminated groundwater discharge, affecting sensitive marine ecosystems. The present study aims to identify submarine groundwater discharge (SGD) locations and quantify the contaminant load reaching to the western coast of India (Gujarat coast) using stable isotopes, seepage meter, heat and solute transport model. The coastal aquifers are highly enriched in trace metals due to various active natural processes and anthropogenic activities across the coast. Terrestrial and recirculated SGD was a significant contributor to flow and metal load, which ranged from 1.04 to 181.1 m3.year-1 and 0-77.41 kg.year-1, respectively. The highest estimated SGD in the Gujarat coast was relatively less than the SGD reported in the Bay of Bengal and comparable to the South Chennai coast. The order of metal flux found in the study was Zn > Fe > Cr > Pb > Ni > Cu > Mn, whereas the highest flux of Zn (77.41 kg. year-1) was reported at Fansa beach, which was 7x Fe-flux and 45 x Cr-flux, respectively. Higher micronutrients (Fe and Zn) load in the southern coast leads to increased vulnerability of eutrophication, algal blooms and biotic ligand formation in aquatic species. This enrichment of micronutrients in the coastal ecosystem was evident by the growth of seaweeds on the seabed at SGD identified locations.

Penetration of topically administered 0.5-percent caspofungin eye drops into human aqueous humor.

Ten participants attending elective anterior segment eye surgery received 0.5% caspofungin eye drops either 1 drop hourly for 4 h or 1 drop an hour before surgery. The eye drops were generally well tolerated. In the absence of inflammation or corneal abrasion, topical caspofungin does not achieve clinically relevant concentrations.

Rapid and sensitive liquid chromatography/mass spectrometry assay for caspofungin in human aqueous humor.

A rapid, precise, and sensitive liquid chromatography/mass spectrometry (LC/MS) method to quantify the caspofungin concentration in human aqueous humor was developed and validated. Sample preparation involved simple dilution of aqueous humor samples with acetonitrile. Azithromycin was the internal standard. Good linearity over 10 to 5,000 ng/ml was observed. The lower limit of quantification was 10 ng/ml. The intra- and interday accuracies (percent bias) were within 11%, while the intra- and interday precisions were within 6%.