Status index of optimal water variables for biodiversity conservation in the Lagoon of Sonso in Colombia

In order to determine an index of the status of optimal water variables for biodiversity conservation in the Sonso Lagoon, the data obtained from 2004 to 2018 were used. To determine the index, a methodology based on a multivariate analysis of the physical-chemical water variables was used, as well as a correlation analysis for their delimitation. Subsequently, the definition of weights and the parameterization of the variables for the final construction of the index were made. As a result, it was found that the lagoon is in an adequate state with a value index of 0.65, with a highly vulnerable tendency to be in an acceptable state and go to a critical state, depending on the anthropic pressure it has. As a conclusion, it was obtained that variables such as dissolved oxygen, total phosphorus and electrical conductivity are determining factors in establishing the index.

Distribution and abundance of planktonic mollusks along a longitudinal gradient in the Southeastern Pacific off Chile

The objectives of this research were to estimate the abundance of the main groups of planktonic mollusks (meroplanktonic larvae, holoplanktonic gastropods and cephalopod paralarvae), and relate these groups to the physical-chemical water properties along a longitudinal gradient between Caldera, on the coast of mainland Chile, and the Easter Island ecoregion (Rapa Nui Island and Salas y Gómez Island), in the Southeast Pacific Ocean. Plankton samples were collected over the course of the CIMAR 21-Islas Cruise, from October to November 2015, at 33 oceanographic stations via vertical hauls of a WP2 net (180-µm mesh size) from a maximum depth of 300 m to the sea surface. Mollusks were sorted, counted and initially assigned to Class rank, later being identified to lower taxonomic ranks. Planktonic mollusks were obtained at all stations, and were composed of 92.7% of Gastropoda and 7.3% of Bivalvia. The total abundance of mollusks varied between 55 and 4,922 individuals 100 m-3.Euthecosomate gastropods exhibited the highest occurrence within the oceanic area. Meanwhile, no paralarvae were captured. Differences in the composition of planktonic mollusks between the continental and oceanic zones were evident. Bivalve larvae increased their abundance in warmer, salty and vertically mixed waters. These results are the first record of meroplanktonic mollusks in waters near the Chilean oceanic islands, and suggest that planktonic mollusks display spatial variation at the scale of the South Pacific Basin, which could be related to the hydrographic conditions and the water column structure.

Strategies to Mitigate the Challenges of Short Circuiting in Waterflood Reservoirs with Tracers: A Case Study

Water short circuiting leading to early, sudden and massive water breakthroughs in producer wells has been a lingering concern to oil operators for many years. Unfavorable mobility ratio leading to viscous fingering, horizontal wells exhibiting ‘the heel-toe effect’ and fields with fracture-fault activities are more prone to these kinds of unwanted water breakthroughs, suffering from oil production losses and higher operational cost for management of the excessive produced water. A brown field in the south of the Sultanate of Oman was experiencing massive water short circuiting within two of its patterns. [MJO1]While conformance was well established and dynamically confirmed through production performance and artificial lift parameters in most patterns within the field, the complicated inverted nine spot injector-producer pattern scenario[MJO2] was making it difficult to ascertain the offending injectors or unexpected flow paths leading to the condition within the study area. The lower API oil and slightly fractured and faulted geology was exhibiting conditions for injection imbalance and the challenge was to bring the high water-cut wells back to full potential and increase oil output whilst reducing water flow. To investigate the breakthrough occurrences and mitigate the challenge, chemical water tracers were introduced in the reservoir as a part of Integrated Reservoir Management framework to identify flow directions and offending injectors. The Phase-1 of the two-phase study, discussed in this paper, was carried out to determine reservoir conformance that was contributing to short circuiting and once the cause was identified and treated, Phase-2 was carried out post well intervention to validate the success of the treatment. Phase-1 of the tracer study was initiated in October 2019 where two injectors and nineteen producers across two adjacent patterns were traced with two unique chemical water tracers. Massive tracer responses were obtained within the first few days in few wells, directly pointing out towards the offending injector(s). Sampling and analysis for Phase-1 was continued for about six months, after which, a zonal isolation was carried out in one the identified injectors in August 2020. Cement was pumped across all the perforation intervals and a new perforation was performed across the top and bottom of the reservoir avoiding the middle intervals that were taking about 70% of injection as per production logging. Phase-2 of the study was initiated in March 2021 and continued sampling and analyses are still being carried out. With about 15% reduction in water cut and a three-fold increase in oil rate at the target producer, the study validated that an integrated knowledge of reservoir geology and production behavior coupled with tracer studies was a very successful strategy for managing short circuiting in waterflood reservoirs. The study showed that this sequence and combination of methods can be useful in effective treatment for wells experiencing high water cut across the world.

Environmental and Epidemiological Aspects of V. cholerae O1 Contamination of Water Bodies in the Republic of Kalmykia

Background: Within the framework of cholera surveillance in the Russian Federation, annual isolation of nontoxigenic V. cholerae O1 strains from water bodies is registered in the Republic of Kalmykia. This fact is the rationale for the present study and analysis of data on contamination of water bodies with V. cholerae O1 with account for some environmental and quality indicators of water bodies used for recreational purposes. Objective: To study contamination of water bodies with V. cholerae O1 as a component of cholera control surveillance in the Republic of Kalmykia. Materials and methods: We used notifications issued by Offices of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing (Rospotrebnadzor) in the constituent entities of the Russian Federation, passports for V. cholerae O1 strains, and information from “Cholera vibrios. Russia” database for 1991–2019. Results: In the 1970s, 1980s and 1990s, several outbreaks, sporadic and single imported cases of cholera were registered in the republic. The total of 446 strains of V. cholerae O1 El Tor were isolated during the analyzed period. The PCR analysis identified them as V. cholerae O1 ctxA–tcpA– and V. cholerae O1 ctxA– tcpA+. We observed an increasing trend in the number of isolated strains with the approximation coefficient of 0.374 against its general decrease in the country in 1991–2019. Strains were isolated annually, mainly from the Elista River, Zayachy Pond and other water bodies with poor microbiological and chemical water quality parameters. V. cholerae O1 ctxA– tcpA+ were isolated mainly at the wastewater discharge sites, which indicated their imported origin, along with V. cholerae O1 ctxA– tcpA– with InDel and PCR genotypes not previously found in this region. We consider the contamination of water bodies with V. cholerae O1 ctxA– tcpA– and V. cholerae O1 ctxA– tcpA+ as prerequisites for possible deterioration of the local epidemiological situation due to cholera importation from endemic areas. Conclusion: When analyzing the pollution of water bodies in the Republic of Kalmykia with V. cholerae O1, we established a long-term annual isolation of cholera vibrios from some water bodies in the city of Elista, including Elistinka river, Zayachy and Kolonsky ponds, notorious for poor microbiological and chemical water quality indicators. The contamination was mainly attributed to domestic wastewater discharge and poorly treated effluents of sewage treatment plants into the Elistinka river within the city boundaries, as well as watercourses from hollows. This proves the imported origin of the bacterium confirmed by isolation of V. cholerae O1 ctxA– tcpA– with InDel- and PCR-genotypes not previously found in this region.

ANALYSIS OF POTENTIAL PHYSICO CHEMICAL WATER QUALITY PARAMETERS OF ELENGENA BEEL, JAGIROAD, MORIGAON, ASSAM

The study was made to investigate the potential physico-chemical water quality of Elengena beel. In this study 40 nos water samples were collected from 4 sampling sites (10 from each) of Elengena beel and had been analyzed for some water quality parameters and ranges of results were found as - water temperature, transperancy, depth, pH, dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), total solids (TS), total alkalinity (TA), total hardness (TH), chloride (Cl-) and fluoride (F-). silicates (SiO2), free carbondioxide (FCO2), nitrate (NO3-), phosphate (PO43-), colour and odour. Nutrients were determined by following the standard procedures outlined in the American Public Health Association (APHA). The result showed that water temperature, transperancy, depth, pH, DO, BOD, COD, TA, TH, TS, TDS, SiO2 , F-CO2 , Cl- , NO3- , and PO43-were 19.9 ±0.28; 21.5 ± 0.71; 1.0 ± 0.23; 6.8 ± 0.15; 4.1 ± 0.34; 51.8 ± 2.32; 58.61 ± 3.22; 156.2 ± 1.2; 210.5 ± 0.2; 153.8 ±0.90; 170.2 ±0.60; 49.2 ± 0.85; 2.87 ± 0.02; 10.91 ± 1.32; 0.20 ± 0.01 and 0.10 ± 0.1 mg/L respectively. All the measured parameters were within the standard values of WHO. In general the present investigation found that the maximum parameters were not at a level of pollution. In order to stop further deterioration of Elengena beel water quality and to eventually restore the beneficial uses of the beel, management of effluents of Nagaon paper mill in the beel watershed should be given urgent priority.

Assessment of Groundwater Quality in Areas Surrounding Thundulu Phosphate Mine, Phalombe District, Malawi

Water is one of the renewable resources essential for sustaining all forms of life and quality of drinking water is very fundamental for human health. Human activities such as mining act as sources of water contamination which consequently lead to ecological, environmental and health problems. To the best of our knowledge, no study has been conducted around the Thundulu Phosphate Mine to establish the quality of drinking water. In this regard, this study was carried out to evaluate the physico-chemical water quality parameters of areas surrounding the Thundulu Phosphate Mine in Phalombe District. Groundwater samples from the villages surrounding the Phosphate Mine were collected both during the wet and dry seasons for analysis of physico-chemical water quality parameters (pH, electrical conductivity, turbidity, nitrate, chloride, sulphate, fluoride, iron, calcium and magnesium). The study also investigated microbiological water characteristics mainly Escherichia coli and faecal coliforms. Results showed that pH, electrical conductivity, turbidity, nitrate, chloride, sulphate, phosphate, calcium and magnesium complied with the national and international standards set by Malawi Bureau of Standards (MBS) and World Health Organization (WHO). As regards to microbiological characteristics, it was revealed that water from three sources (B2, B3 and B4) was contaminated with Escherichia coli and faecal coliforms. Keywords: Physico-chemical; Groundwater; Phalombe; Borehole; Electrical Conductivity; Turbidity; Phosphate;