Trihalomethanes and physicochemical quality of drinking water in Addis Ababa, Ethiopia.

Background: Trihalomethanes (THMs) are the most dominant fraction of all the byproducts formed during chlorination of water. Disinfection by product (DBP) formation in water is a function of numerous factors, including pH, temperature, residual chlorine, source water characteristics, and organic matter. No study has determined the THM level in the drinking water supply of Addis Ababa, Ethiopia. Methods: A cross-sectional design was conducted to collect water samples in the water supply distribution networks of Addis Ababa, Ethiopia. Twenty-one (21) sampling stations yielded a total of one hundred twenty (120) samples of drinking water. The sample handling and collection procedures were carried out in accordance with USEPA guidelines. A DB-5 capillary column was used to separate the THMs, which were detected using GC-ECD (gas chromatography-electron capture detector). Spectrophotometric and in situ methods were used for physicochemical parameters. Redundancy analysis (RDA) was used for data analysis of trihalomethanes and environmental variables using CANOCO 4.5. Results: The mean concentration of total trihalomethanes in drinking water in Addis Ababa was 76.3 µg/L. The concentration of chloroform in the drinking water supply in Addis Ababa, Ethiopia, ranged between 4.03 and 79.4 µg/L. The mean total THMs in the Legedadi and Gefersa water supply systems were 77.4 µg/L and 69.66 µg/L, respectively. The residual chlorine, phosphates, UV absorbance at 254 nm, and combined chlorine had positive correlations with THM formation. However, electron conductivity had a negative correlation with THM formation. Conclusions: Chloroform contributed the most to TTHMs in nearly all samples. The residual chlorine, UV absorbance, phosphate and hardness as calcium, and electron conductivity were found to be the main predictors determining the abundance and distribution of trihalomethanes. The monitoring and regulation of the THMs is required on a regular basis to analyse trends and guide the water treatment and distribution system.

Exposure and carcinogenic risk assessment of trihalomethanes (THMs) for water supply consumers in Addis Ababa, Ethiopia.

Background: Trihalomethanes (THMs), a class of DBPs (disinfection byproducts) that includes chloroform, bromodichloromethane (BDCM), chlorodibromomethane (CDBM), and bromoform. To the best of authors' knowledge, no study has addressed the relationship between the concentration of THMs and lifetime cancer risks (LCR) in drinking water supply system in Addis Ababa, Ethiopia. Therefore, this study aimed to determine the lifetime cancer risks of exposure to THMs in Addis Ababa, Ethiopia. Method: A total of 120 duplicate water samples were collected from 21 sampling points in Addis Ababa, Ethiopia. The THMs were separated by a DB-5 capillary column and detected by an electron capture detector (ECD). Cancer and non-cancer risk assessments were performed. Results: The average total THMs (TTHMs)concentration in Addis Ababa, Ethiopia, was 76.3 µg/L. Chloroform was the most dominant THM species identified. The total cancer risk for males was higher than that for females. The average LCR for TTHMs via ingestion in drinking water in this study was unacceptably high risk 93.4 × 10 - 2 . An average LCR through dermal routes was also of unacceptably high risk 4.3 × 10 - 2 . The LCR by chloroform contributes the highest (72%) of the total risk, followed by BDCM (14%), DBCM (10%) and bromoform (4%). Conclusions: The cancer risk of drinking water due to THMs in Addis Ababa was higher than the level recommended by the USEPA. The total LCR from the targeted THMs was higher via the three exposure routes. Males were at higher THM cancer risk than females. The hazard index (HI) indicated that the dermal route caused higher HI values than the ingestion route. It is essential to apply alternatives to chlorine, i.e., chlorine dioxide (ClO2), ozone and ultraviolet radiation, in Addis Ababa, Ethiopia. The monitoring and regulation of the THMs is required on a regular basis to analyse the trends and guide the water treatment and distribution system. Availability of data and materials: The datasets generated for this analysis are available from the corresponding author upon reasonable request.

In vivo appraisal of oxidative stress response, cell ultrastructural aberration and accumulation in Juvenile Scylla serrata exposed to uranium.

In vivo studies were performed to evaluate the organ specific tissue accumulation and cellular toxicity of uranium to mud crab Scylla serrata. The specimens were acclimated in natural seawater and the exposure to 50-250 µg/L uranium was investigated up to 60 days. The present study examined the effects of concentration and duration of uranium exposure in the tissue of S. serrata at cellular and subcellular level using scanning electron microscopy and bright field transmission electron microscopy in addition to histological analysis. The results indicated that accumulation of U in S. serrata was organ specific and followed the order gills > hepatopancreas > muscle. The response of key antioxidant enzyme activities such as SOD, GPx and CAT in different organs of crabs indicated oxidative stress due to U in the ambient medium and tissue. At 50 and 100 µg/L of U exposure, individuals were able to acclimate the oxidative stress and withstand the uranium exposure. This acclimation could not be sustained at higher concentrations (250 µg/L), affecting the production of CAT in the tissues. Cellular and subcellular changes were observed in the hemocytes with reduction in their number in consonance with the antioxidant enzymes. Histological aberrations like lamellar disruption of gill, necrosis of hepatopancreas, disruption and rupture of muscle bundles were observed at different concentrations and were severe at higher concentration (250 µg/L). Necrosis was observed in the electron micrographs of tissues shortly after 15 days of exposure. SEM micrograph clearly shows disrupted lamellae, folding of marginal canal and reduction of inter lamellar spaces in the gills of crab exposed to high concentration of uranium. Mitochondrial anomalies are reported for the first time in the present study in addition to the subcellular changes and vacuoles on exposure uranium in the cells of gill and hepatopancreas.

Influence of interstitial UO22+ doping on the valence control of Eu and energy transfer to substitutional Eu3+ and Sm3+ in SrBPO5.

Controlling the valence mixing of Eu3+/Eu2+ and energy transfer between activator ions in solid solution is an important process to improve the efficiency and specificity of phosphors. In this work, the structural and optical properties of stillwellite type SrBPO5 doped with uranium/europium/samarium, as prepared by conventional solid-state reaction synthesis, were investigated. PXRD studies and Rietveld analysis were carried out to determine the structure, phase purity, and coordination environment of the dopants in the host matrix. Samarium existed only as a trivalent cation in SrBPO5 synthesised in an air atmosphere, whereas europium exhibited abnormal reduction and Eu2+ co-existed with Eu3+. Unlike Eu and Sm, which replaced Sr at its sites, uranium gets stabilised as UO22+ in the interstitial vacant space in the SrBPO5 lattice. Uranium co-doping strongly influenced the Eu valence distribution by favouring the re-oxidation of Eu2+ to Eu3+. Possible mechanisms of Eu abnormal reduction in SrBPO5 and Eu valence control based on the electron transfer from substitutional Eu2+ to interstitial UO22+ are discussed. The photoluminescence and time-resolved photoluminescence properties of Eu/Sm/U doped SrBPO5 were investigated systematically. Uranium co-doping significantly enhanced the emission intensities of trivalent Eu and Sm through the exchange-type energy transfer. Besides, the Eu3+ luminescence intensity was further amplified in the presence of uranium due to the partial oxidation of Eu2+ to Eu3+. By controlling the uranium to Eu concentration ratio, the Eu-SrBPO5 phosphor could be tuned to different CIE coordinates.

SrBPO5: Ce3+, Dy3+ - A cold white-light emitting phosphor.

A single-component white-light emitting phosphor SrBPO5: Ce3+, Dy3+ with high color purity, good quantum efficiency and high thermal stability was prepared through the conventional high temperature solid state reaction. PXRD studies confirmed its phase purity. The suitability of Strontium borophosphate as a host for phosphor was confirmed through DFT calculations. The presence of Ce3+ along with Dy3+ in this host resulted in efficient energy transfer from Ce3+ to Dy3+ through a non-radiative multipole-multipole mechanism leading to the enhancement of Dy3+ luminescence towards white light emission. Lifetime decay and time-resolved emission studies confirmed the energy transfer along with multisite occupancy of Ce3+. In addition to energy transfer, the thermal stability of the phosphor was confirmed through temperature-dependent photoluminescence studies and the particle shape, size, uniformity of dopants of the phosphor was studied using the SEM and EDX spectroscopy.

Distribution and ecological- and health-risk assessment of heavy metals in the seawater of the southeast coast of India.

The objective of the present study was to conduct an ecological and health risk assessment of heavy metals in the seawater of the southeast coast of India. The distribution profile of heavy metals in the surface seawater was Fe (79.60 ± 21.57 µg/L) > Zn (9.31 ± 1.33 µg/L) > Cu (5.19 ± 2.00 µg/L) > Ni (2.45 ± 0.76 µg/L) > Mn (1.20 ± 1.00 µg/L) > U (0.44 ± 0.23 µg/L) > Pb (0.36 ± 0.06 µg/L) > Cr (0.31 ± 0.57 µg/L) > Cd (0.11 ± 0.05 µg/L) > Co (0.07 ± 0.20 µg/L). Cu level for most of the samples exceeded the USEPA criteria for acute CMC (criterion maximum concentration) and chronic CCC (criterion continuous concentration). Other studied metals, Cd, Cr, Pb, and Ni, remained below the acute CMC and chronic CCC guidelines. The seawater pollution index (Iwp) of Cr, Ni, Zn, Cd, and Pb complied with the category-I seawater (<1, unpolluted). The ERI values (0.46-3.99) of the seawater of the studied coast mostly fell under the ecologically low risk category with respect to heavy metals. Dermal Hazard index values were orders of magnitude lower than one, indicating no potential health concern due to dermal exposure.

Monitoring chlorine residual and trihalomethanes in the chlorinated seawater effluent of a nuclear power plant.

Periodic sampling of the discharged seawater effluent from Madras Atomic Power Station (Kalpakkam, Tamil Nadu, India) was carried out during 2013-2017 to assess the residual chlorine and trihalomethanes content in the outfall discharge water. The variations in dissolved oxygen, temperature, and pH were correlated with the residual chlorine and trihalomethanes content in the discharged effluent. The difference in temperature (ΔT) between influent and effluent seawater samples ranged from 1.95 to 11.0 °C (6.47 ± 1.87). More than 95% of the ΔT values were within the guideline value of 7 °C. The discharge water was associated with a marginal reduction in dissolved oxygen and a marginal increase in conductivity values. The total residual chlorine content in the discharged seawater at outfall ranged from 0.06 to 0.42 (0.16 ± 0.08) mg/L, which was within the stipulated values of 0.5 mg/L. Trihalomethanes values ranged from 0.04 to 65.03 (13.06 ± 14.38) µg/L. In addition to bromoform as the major constituent, occurrence of significant amount chloroform of was occasionally observed in the discharge water.

Trace metal distribution in crab organs and human health risk assessment on consumption of crabs collected from coastal water of South East coast of India.

The concentrations of nine heavy metals accumulated in different organs of two crab species collected from the South East coast of India were estimated. The order of trace metal concentration in different organs of Portunus pelagicus was Cu > Mn > Cd > Ni > Pb > Co > Hg = Cr = U in gills, Cu > Mn > Cd > Ni > Pb = Co > Hg > Cr = U in hepatopancreas, and Cu > Cr > Ni > Mn > Cd > Pb > Co > Hg > U in muscles, whereas that for Portunus sanguinolentus was Cu > Mn > Cd > Ni > Pb > Co > Hg > Cr = U in gills, Cu > Mn > Cd > Ni > Pb = Co > U > Cr = Hg in hepatopancreas, and Cr > Cu > Ni > Mn > Cd > Co > Pb > Hg = U in muscles. The order of trace metal uptake for different organs was gills > hepatopancreas > muscles. Individual mean bioaccumulation index (IMBI) values varied between 0.0 and 0.52, 0.0 and 0.28, and 0.06 and 0.30 for gills, hepatopancreas, and muscles, respectively. Cr in muscles of P. sanguinolentus and Cu and Cd in all organs of both the species were found to be higher than the maximum permitted concentration recommended by food safety guidelines. Target hazard quotient (THQ) results suggested that there is a potential risk due to Co, Cd, and Cr, particularly for children, if the crab consumption frequency is more than once a month.

Formation, distribution, and speciation of DBPs (THMs, HAAs, ClO2-,andClO3-) during treatment of different source water with chlorine and chlorine dioxide.

Formation potential and speciation characteristics of two important groups of disinfection byproducts (DBPs), namely, trihalomethanes (THMs) and haloacetic acids (HAAS), during Cl2 and ClO2 treatment of water samples collected from three different sources, namely, sea, river, and reservoir, were investigated with reference to key controlling parameters. Formation of inorganic DBPs such as chlorate and chlorite was evaluated. Dissolved organic carbon (DOC) and UV absorbance (UV254) of the sea, river, and reservoir samples were 3.35 ±â€¯0.05, 3.12 ±â€¯0.05, and 3.23 ±â€¯0.05 mg/L and 0.062 ±â€¯0.01, 0.074 ±â€¯0.01, and 0.055 ±â€¯0.01 cm-1, respectively. For Cl2 and ClO2 treatments, the respective formation potential of THMs and HAAs from the three water sources studied exhibited unidentical trend suggesting that higher THM formation was not necessarily associated with higher HAA formation. On chlorination, the concentrations of total HAAs formed were 9.8 µg/L (sea), 12.8 µg/L (river), and 20.6 µg/L (reservoir) and total THM yields were 38.3 µg/L (sea), 18.8 µg/L (river), and 21.5 µg/L (reservoir) for a Cl2 dose of 1 mg/L and 30 min reaction time. The trend of formation of THMs and HAAs for Cl2 treatment was similar to that for ClO2 treatment. However, the amount of HAAs (3.5 µg/L (sea), 1.8 µg/L (river), and 1.9 µg/L (reservoir)) and THMs (not detected) formed was much lower than that formed during chlorination. Regardless of source water type, di-HAAs were the most favored HAAs, followed by tri-HAAs with a small amount of mono-HAAs formed for both Cl2 and ClO2 treatment. Chlorination yielded more THMs than HAAs, whereas it was reverse for chlorine dioxide treatment. Irrespective of treatment with ClO2 or Cl2, seawater samples showed the highest bromine incorporation percentage (BIP) in both THMs and HAAs followed by that for river and reservoir water samples. HAAs were found to be always associated with lower amount of BIP than THMs.

Elemental distribution and trace metal contamination in the surface sediment of south east coast of India.

Spatial distribution and potential ecological risk of trace metals in the surface sediment of south east coast of India covering eight different ecosystems was studied. The concentration of major elements viz. Ca, Mg, K, Ti and trace metals viz. Cr, Mn, Co, Al, Fe, Ni, Cu, Zn, Cd and Pb were analysed by energy dispersive X-ray fluorescence technique. Contamination factor, geo-accumulation index, probable effect level, enrichment factor and pollution load index were calculated to evaluate the pollution status. Except cadmium, CF values for all the metals ranged between 1≤CF≤3 indicating moderate metal contaminations along the coast. Mean PEL quotient (Qm-PEL) indicated toxicity probability to be below 21%. Fe, Cu, Zn and Co showed significant positive correlation (p<0.01) with clay. Chromium was the only metal that demonstrated strong negative correlation with clay (p<0.01) and positive correlation (p<0.01) with sand content.

Impact of groundwater surface storage on chlorination and disinfection by-product formation.

The change in water quality arising from the open storage of groundwater (GW) and its impact on chlorination and chlorination by-product formation were investigated. Water quality descriptors, such as temperature, pH, chlorophyll, and dissolved oxygen contents of GW undergo substantial alteration when stored in a reservoir. Dissolved organic content (DOC) measured in the two water sources studied, i.e., GW and open reservoir water (RW), varied from 0.41 mg/L to 0.95 mg/L and 0.93 mg/L to 2.53 mg/L, respectively. Although DOC demonstrated wide variation, UV absorbance at 254 nm (UVA254) values for GW (0.022-0.067) and RW (0.037-0.077) did not display reciprocal variations. The chlorine demand (CD) of RW was always higher than that of GW for the corresponding sampling period. Average trihalomethane (THM) formation for RW was 50-80% higher compared to GW and thus poses an enhanced health risk. Appreciable amounts of bromide present in these water sources (0.15-0.26 mg/L in GW and 0.17-0.65 mg/L in RW) have resulted in the non-selective distribution of the four THM species. The formation of more toxic brominated THM due to chlorination of these near-coast drinking water sources must be regarded as a decisive factor for the choice of water disinfection regime.

Successful salvage of thrombosed arterio-venous fistula with thrombolytic therapy using tissue plasminogen activator.

A functioning vascular access is crucial to the wellbeing of patients on hemodialysis. Thrombosis is the most common complication of arteriovenous fistula (AVF) resulting in late fistula failure; Its treatment is difficult, and results are often suboptimal. Interventional treatment of AVF thrombosis may not be available all the time, and timely application of an available noninterventional treatment may salvage the fistula. We report the successful treatment of AVF thrombosis using local thrombolytic therapy using tissue plasminogen activator in a patient, for the first time in India.

Groundwater nitrate contamination and use of Cl/Br ratio for source appointment.

Source appointment for groundwater nitrate contamination is critical in prioritizing effective strategy for its mitigation. Here, we assessed the use of Cl/Br ratio and statistical correlation of hydro-chemical parameters to identify the nitrate source to the groundwater. A total of 228 samples from 19 domestic wells distributed throughout the study area were collected during June 2011-May 2012 and analyzed for various physicochemical parameters. Study area was divided into three spatial zones based on demographic features, viz., northern, southern, and central part. Nitrate concentration in 57 % of samples exceeded the prescribed safe limit for drinking stipulated by the World Health Organization (WHO) and Bureau of Indian standards (BIS). The central part of the study area showed elevated nitrate concentration ranging from below detection limit (BDL) to 263.5 mg/l as NO3 (-) and demonstrated high attenuation within the immediate vicinity thereby restricting diffusion of the nitrate to the adjacent parts. Resolution of correlation matrix as statistical indicator for nitrate contamination was poor. Seventy-seven percent of samples with high nitrate concentration (>45 mg/l as NO3 (-)) showed strong association with high Cl/Br mass ratio (350-900), indicating mixing of sewage and septic tank effluents with groundwater as a primary source for the nitrate in the studied area. Nitrate level during monsoon (BDL, 229.9 mg/l as NO3 (-)), post-monsoon (BDL, 263.5 mg/l as NO3 (-)), and pre-monsoon (0.5-223.1 mg/l as NO3 (-)) indicated additional contribution of surface leaching to groundwater.

Phosphorus speciation in the marine sediment of Kalpakkam coast, southeast coast of India.

A study was carried out at Kalpakkam coast to find out the distribution of various fractions of phosphorus (P) in the marine sediment during pre-northeast monsoon period. Samples were collected from ten locations covering ~80 km(2) of the inner-shelf region. Sedimentary parameters such as sand, silt, clay, and organic carbon percentage were analyzed in order to find out their relation with various P fractions. The sediment was found to be predominantly sandy in nature with low silt and clay content. Among all the fractions (loosely bound (LoP), calcium bound (CaP), iron bound (FeP), aluminum bound (AlP), and organic (OP)), CaP fraction constituted the largest portion (68.7%) followed by organic fraction (16.3%). The bioavailable P fractions ranged from 5 to 44% of the total P (TP) content. Relatively high LoP content was observed at the offshore locations with comparatively high mud percentage as compared with the near-shore locations. As FeP and AlP concentrations were directly proportional to the amount of fine-grain sediment, the low levels of these fractions found in this coastal area were therefore attributed to the sandy nature of the sediments. The order of abundance of the major forms of P in the surface sediments of Kalpakkam coast was as follows: CaP > OP > LoP > AlP > FeP.

Temporal distribution of dissolved trace metal in the coastal waters of Southwestern Bay of Bengal, India.

The objective of the present study was to characterize the concentrations of selected dissolved trace metals in the coastal waters (500 m from shore) of Kalpakkam, Tamil Nadu, India. The order of dissolved concentration of these metals was found to be as follows: Co (cobalt) < Cd (cadmium) < Cr (chromium) < Mn (manganese) < Cu (copper) < Ni (nickel) < Pb (lead) < Zn (zinc). The levels of these trace metals were found to be relatively low as compared to the reported values for other Indian coastal waters, which indicates negligible pollution at this location. Cadmium was the only metal found to increase its concentration during the monsoon period, suggesting its allochthonous input. Factor analysis indicated that chromium, nickel, zinc, cobalt, copper, manganese, and lead were of common origin, and external inputs through land runoff had nominal or little impact, typifying in-situ regeneration and remineralization linkage with their temporal variation. However, levels of zinc, cobalt, and copper remained relatively high during the summer period, and abrupt increases in their concentration during December (monsoon season) may be due to their dual (autochthonous as well as allochthonous) input.

Formation and speciation characteristics of brominated trihalomethanes in seawater chlorination.

Formation character of brominated-trihalomethanes (Br-THMs) in chlorinated seawater and its dependence on applied chlorine dose, reaction time, and temperature were investigated in the laboratory. Seawater was collected from the east coast of India and a chlorine dose of 1, 3, 5, and 10 ppm was each applied at a temperature of 20, 30, and 40 degrees C to investigate the yield and kinetics of Br-THMs formation. Qualitative and quantitative estimation of THM formation at various intervals of time ranging from 5 min to 168 h was determined by a gas chromatograph equipped with an electron capture detector (GC-ECD). Chlorine dose, chlorine contact time, and reaction temperature positively affected the load of THMs. The ratio of chlorine dose to halogen incorporation decreased from 12% to 5% with increasing applied chlorine dose from 1 to 10 ppm. Significant levels of THMs were found to be formed within 0.5 h of reaction, followed by a very slow rate of formation. Elevated temperature favored both increased rate of formation and overall THM yield. The formation order of different trihalomethane species at all studied temperatures was observed to be bromodichloromethane (CHCl2Br) < dibromochloromethane (CHClBr2) < bromoform (CHBr3). Formation of chloroform was not observed, and bromoform was the dominant (96% to 98%) among the three THM species formed.