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Carbon pollution of freshwater ecosystems causes predictable decreases in the depth of light penetration. Tests of dissolved organic carbon (DOC) enrichment on the fates of benthic light climate with concurrent effects on periphytic diatoms in the Ganga River is lacking. This study, conducted along a 37 km gradient of the Ganga River, indicated rising concentration of DOC downstream point sources and downstream Varanasi city. High turbidity and concentration of DOC with a concurrent decline in the depth of light penetration (Secchi depth) lead to a significant decline in the abundance of periphytic diatoms. Site with highest DOC showed lowest Secchi depth and poorest dominance of study species. This study shows that increasing concentration of DOC and turbidity over time, which is expected to rise due to tourism-driven increase in the frequency of boating, will alter the light climate and consequently the population of benthic diatoms. Because benthic diatoms oxygenate the bottom, the study has relevance for sediment P-driven eutrophy, waste assimilation capacity, resilience and fisheries in the Ganga River. [ABSTRACT FROM AUTHOR]

Background: Mold brachytherapy using high-energy β--emitting radioisotopes is a promising treatment modality for skin cancers and keloids. Simple methodologies for consistent and stable incorporation of radionuclides into the matrix are desired for preparation of therapeutic sources. Methods: The authors report a facile strategy for the stable incorporation of Yttrium-90 (90Y) into amidoxime-functionalized polyacrylonitrile-polyvinylidene fluoride (PAN-PVDF) membranes. The strategy consisted of surface modification of PAN-PVDF membranes by reaction with hydroxylamine, characterization of the functionalized membranes, and optimization of experimental variables for maximum loading of 90Y onto the membranes. Quality control tests essential for confirming the suitability of the 90Y therapeutic sources for human application, such as uniformity of activity distribution, absence of leaching of activity, and estimation of surface contamination, were performed. Theoretical calculations to estimate the dose imparted by the 90Y therapeutic sources at varying depths of tissue were also carried out to predict the possible therapeutic outcome of treatment. Results: A facile method for large-scale preparation of 90Y-based mold brachytherapy sources could be established. Conclusions: The source fabrication methodology standardized in this work could be tailored for fabrication of custom-made 90Y sources for individualized treatment of superficial tumors, Bowen's disease, and keloids. [ABSTRACT FROM AUTHOR]

Yttrium-90 used for therapy should be of very high radionuclidic (RN) purity (>99.998%) as the most probable contaminant, strontium-90, is a bone seeker with a maximum permissible body burden of 74 kBq (2 [micro]Ci) only. None of the current known methods of RN purity estimations is adequate to reliably measure the [sup.90]Sr RN impurity at such low levels. Our aim was to develop a reliable technique to accurately determine the amount of [sup.90]Sr in [sup.90]y used for therapy. This new technique combines chelate-based extraction with paper chromatography using paper impregnated with 2-ethylhexyl, 2-ethylhexylphosphonic acid (KSM-17), which is a [sup.90]y-specific chelator. A PC strip impregnated with KSM-17 at the point of spotting is used for chromatography. Upon development with normal saline, [sup.90]Sr moves to the solvent front leaving [sup.90]y completely chelated and retained at the point of spotting. The activity at the solvent front ([sup.90]Sr) is quantified by liquid scintillation counting, and the data are compared with the total applied activity to provide the RN purity of the test solution. The method has a sensitivity of [greater than or equal to] 74 kBq (2 [micro]Ci) of [sup.90]Sr per 37 GBq (1 Ci) of [sup.90]Y. This novel, innovative, and simple technique offers a reliable solution to the unanswered problem of estimation of [sup.90]Sr content in [sup.90]Y used for cancer therapy.

Moving beyond monitoring the state of water quality to understanding how the sensitive ecosystems "respond" to complex interplay of climatic and anthropogenic perturbations, and eventually the mechanisms that underpin alterations leading to transitional shifts is crucial for managing freshwater resources. The multiple disturbance dynamics—a single disturbance as opposed to multiple disturbances for recovery and other atrocities—alter aquatic ecosystem in multiple ways, yet the global models lack representation of key processes and feedbacks, impeding potential management decisions. Here, the procedure we have embarked for what is known about the biogeochemical and ecological functions in freshwaters in context of ecosystem resilience, feedbacks, stressors synergies, and compensatory dynamics, is highly relevant for process‐based ecosystem models and for developing a novel paradigm toward potential management decisions. This review advocates the need for a more aggressive approach with improved understanding of changes in key ecosystem processes and mechanistic links thereof, regulating resilience and compensatory dynamics concordant with climate and anthropogenic perturbations across a wide range of spatio‐temporal scales. This has relevance contexting climate change and anthropogenic pressures for developing proactive and adaptive management strategies for safeguarding freshwater resources and services they provide. [ABSTRACT FROM AUTHOR]