Freshwater salinization syndrome: from emerging global problem to managing risks

Freshwater salinization is an emerging global problem impacting safe drinking water, ecosystem health and biodiversity, infrastructure corrosion, and food production. Freshwater salinization originates from diverse anthropogenic and geologic sources including road salts, human-accelerated weathering, sewage, urban construction, fertilizer, mine drainage, resource extraction, water softeners, saltwater intrusion, and evaporative concentration of ions due to hydrologic alterations and climate change. The complex interrelationships between salt ions and chemical, biological, and geologic parameters and consequences on the natural, social, and built environment are called Freshwater Salinization Syndrome (FSS). Here, we provide a comprehensive overview of salinization issues (past, present, and future), and we investigate drivers and solutions. We analyze the expanding global magnitude and scope of FSS including its discovery in humid regions, connections to human-accelerated weathering and mobilization of ‘chemical cocktails.’ We also present data illustrating: (1) increasing trends in salt ion concentrations in some of the world’s major freshwaters, including critical drinking water supplies; (2) decreasing trends in nutrient concentrations in rivers due to regulations but increasing trends in salinization, which have been due to lack of adequate management and regulations; (3) regional trends in atmospheric deposition of salt ions and storage of salt ions in soils and groundwater, and (4) applications of specific conductance as a proxy for tracking sources and concentrations of groups of elements in freshwaters. We prioritize FSS research needs related to better understanding: (1) effects of saltwater intrusion on ecosystem processes, (2) potential health risks from groundwater contamination of home wells, (3) potential risks to clean and safe drinking water sources, (4) economic and safety impacts of infrastructure corrosion, (5) alteration of biodiversity and ecosystem functions, and (6) application of high-frequency sensors in state-of-the art monitoring and management. We evaluate management solutions using a watershed approach spanning air, land, and water to explore variations in sources, fate and transport of different salt ions (e.g. monitoring of atmospheric deposition of ions, stormwater management, groundwater remediation, and managing road runoff). We also identify tradeoffs in management approaches such as unanticipated retention and release of chemical cocktails from urban stormwater management best management practices (BMPs) and unintended consequences of alternative deicers on water quality. Overall, we show that FSS has direct and indirect effects on mobilization of diverse chemical cocktails of ions, metals, nutrients, organics, and radionuclides in freshwaters with mounting impacts. Our comprehensive review suggests what could happen if FSS were not managed into the future and evaluates strategies for reducing increasing risks to clean and safe drinking water, human health, costly infrastructure, biodiversity, and critical ecosystem services.

     

Brooding chicks with or without supplemental heat and light

The need for supplemental heat in brooding chicks in a hot humid tropical area where prevalent mean environmental temperature and relative humidity are 33°C and 60%, respectively, was tested in an experiment using 320 broiler chickens.The chicks were divided into four quadruplicate lots of 20 birds each and were brooded with or without supplemental heat and light for periods varying between zero and 28 days. Each treatment group of 80 birds was subjected to one of four heat and light treatments, namely: supplementation with heat and light for the 28-day brooding period (control), supplementation with heat and light for the first 14-days only, supplementation for the last 14-days only and non-supplementation with heat and light for the entire 28-day period. Final body weight, body weight gain, feed consumption, feed conversion efficiency and mortality were not significantly (P>0.05) affected by the treatments. However, chicks brooded with supplemental heat and light for 28 days consumed significantly more water than all others. Chicks brooded without supplemental heat and light for 28 days had significantly (P<0.05) higher haemoglobin and hematocrit values than all others.     

Genotyping of Chlamydia trachomatis directly from urogenital and conjunctiva samples using an ompA gene pyrosequencing-based assay

The aim of the present study was to develop and validate a multitarget pyrosequencing-based protocol for basic Chlamydia trachomatis genotyping directly from clinical samples and to characterize the distribution of genotypes among Slovenian sexually active population. The newly developed combination of assays that targets the variable domains VD-I and VD-IV of the C. trachomatis ompA gene, was optimized and validated with 11 reference C. trachomatis strains and by comparison to complete ompA conventional sequencing. In addition, 183 clinical specimens which were previously diagnosed as C. trachomatis positive were evaluated by pyrosequencing. The pyrosequencing products showed a 100% match to corresponding sections of the respective conventional ompA sequences. Based on our results the most frequent genotype in urogenital samples was E (51.1%) followed by F (21.4%), G and K (6.9%), D (6.1%), H (3.8%), J (2.3%) and Ia and Ja (0.8%). In conjunctiva samples the genotype distribution was E (63.3%), D and F (13.3%), K (6.7%) and G (3.3%). Pyrosequencing thus proved itself to be a rapid method for C. trachomatis typing, which is important for better understanding the pathogenesis and epidemiology of this pathogen.     

Response of chicks to two diets of differing energy levels under conditions of brooding with or without supplemental heat

A 2×2 factorial experiment was conducted to determine the performance and certain physiological parameters of 200 day-old chicks fed diets containing either 2600 or 3000 kcal metabolizable energy (ME) per kilogram for a period of 28 days under conditions of brooding with or without supplemental heat in a hot humid tropical area. The results indicated that within each dietary energy level, there was no significant difference in growth rates of chicks brooded with or without supplemental heat, however, the high energy diet significantly (P<0.01) promoted greater weight gains than the low energy diet. Brooding chicks with supplemental heat and with the high energy diet, decreased feed intake and improved feed conversion efficiency. Chicks brooded without supplemental heat consumed significantly (P<0.01) less water than those brooded with heat, irrespective of the dietary energy level. Mortality and blood glucose levels were not affected by the heat and dietary energy treatments. Thyroid weight expressed as percentage of body weight, haemoglobin and hematocrit values were significantly (P<0.01) higher for chicks brooded without supplemental heat. On the other hand, dietary energy levels did not exert any effect on these physiological parameters. No significant heat and dietary energy level interaction effects were noted on all the parameters considered under this trial.