Developing nations, such as Bangladesh, face an enormous crisis in maintaining natural sustainability due to heavy metal contamination by the peripheral rivers. Frequent heavy metals discharged from tanneries, dyeing, and potential anthropogenic activities in Savar city pollute the Dhaleshwari river, which is an important river of the capital city, Dhaka. The present study aimed to assess the heavy metals contamination in the Dhaleshwari river sediment and evaluate the subsequent ecological risk indices emerging from the deposits. The contamination levels of heavy metals such as lead (Pb), cadmium (Cd), chromium (Cr), and nickel (Ni) were analyzed in the Dhaleshwari River sediment. Various environmental indices, such as Potential Enrichment Risk (PER), Geo-accumulation Index (Igeo), Enrichment factor (EF), Toxic unit analysis (TUs), etc., were observed in various compartments. The concentration of heavy metals ranged as follows: Lead (Pb), 297.3-414.6 mg/L; Cadmium (Cd), 1.5-4.4 mg/L; chromium (Cr), 97.9 -282.4 mg/L; Nickle (Ni), 85.1-264.5 mg/L; Iron (Fe), 11800-14375 mg/L. The metal concentrations were higher than the threshold effect level (TEL) and probable effect level (PEL) standards. Based on the TUs, the probability of toxicity is about 76% (TU > 2.3) at the Dhaleshwari river. Comparative evaluation of different environmental indices between present and past studies indicated progressive deterioration of sediments by heavy metals. Linear correlations of heavy metals in sediment samples demonstrated toxic accumulation of heavy metals in the surrounding ecosystem. The study outcomes emphasize the necessity of systematic investigation in the Dhaleshwari river and warranting effective prioritization to ensure river health over industrial wastewater discharge.

Natural radioactivity levels in the eastern coastline of Lake Hawassa sediment samples of Ethiopia’s Sidama Region have been measured. Sediment samples were collected and analyzed using gamma-ray spectrometery (high purity germanium detector) to evaluate the radioisotopes of 238U (214Pb, 214Bi), 232Th (228Ac, 212Pb), and 40K and their ranges of activity concentrations were 11.70 to 29.73 Bq 〖kg〗^(-1), 19.01 to 58.61 Bq 〖kg〗^(-1), and BDL to 827.21 Bq 〖kg〗^(-1) ,with average values of 16.51 ± 1.20 Bq 〖kg〗^(-1) , 28.17 ± 2.27 Bq 〖kg〗^(-1) ,and 673.95 ± 29.92 Bq 〖kg〗^(-1) (dry mass), respectively. The radiological hazard indices average values (radium equivalent (R_eq) (108.69 Bq 〖kg〗^(-1) ); hazard index (H_ex (0.29); excess lifetime cancer risk (ELCR) (0.23 x 〖10〗^(-3) ); absorbed dose rate (D_R) (52.70 nGyh^(-1) ); annual effective dose equivalent (AEDE) (0.07 mSv〖yr〗^(-1)); and annual gonadal dose equivalent (AGDE) (0.38 mSv〖yr〗^(-1)) were also evaluated and compared to the worldwide-recommended values. All results of radiological hazard indices obtained in this study were lower than their worldwide-recommended values were 370 Bq 〖kg〗^(-1), ≤1, 59 nGyh^(-1), 0.07mSv〖yr〗^(-1), 0.29 × 〖10〗^(-3), and 0.3mSv〖yr〗^(-1) of radium equivalent activity, external hazard index, outdoor absorbed dose rate, outdoor annual effective dose equivalent, excess lifetime cancer risk, and annual gonadal dose equivalent, respectively. This suggests the eastern coastline of Lake Hawassa is safe from radioactive risk for aquatic species and various human activities, and appears as essential radiometric baseline information for further environmental monitoring programs.

International audience | Sediment cores from the central Algerian coast were collected to investigate the distribution, sources and risk oftrace metals. The local geochemical background of metals was defined from the core S collected in an uncontaminatedarea of the coast. The anthropogenic inputs in Algiers Bay elevated Ag, Cd, Pb and Zn concentrationsas their maximum were 3.1, 3, 2.1 and 1.8 times the background values, respectively. Meanwhile, increasedcontents of Arsenic (up to 21.1 mg/kg) were detected in all sites. Correlations and PCA suggest that lithogenicsources controlled metal deposition, while most sediment arsenic was agriculture-derived. Organic matter actedas a sink or source for some trace metals. According to EFs, the study area showed slight to moderate enrichmentwith respect to Ag, As, Pb, Cd, Zn and Cu, whereas they remained uncontaminated with Cr, V, Co and Ni. Thisstudy provides a needed baseline for future environmental investigations.

International audience | Fluoroquinolones and tetracyclines are frequently detected antibiotics in aquatic sediments. In this study, the transport of ciprofloxacin (CIP) and tetracycline (TET) was investigated in sediments from the Seine Estuary (France), under nitrate reducing conditions. Dynamic flow experiments showed that although TET and CIP strongly interacted with the sediment components through adsorption and (bio)-chemical transformation, they kept their antimicrobial activities. Less nitrate reduction was observed during the first period of breakthrough, while TET and CIP were absent in the column effluent. Batch experiments with freeze-dried vs fresh sediments showed that adsorption and abiotic degradation are the major removal processes, while microbe-driven transformation is of less importance. Whereas TET is to a large extent chemically transformed and little adsorbed in the sediment, CIP was less transformed and more adsorbed, most likely due to the great reactivity of TET with redox-active mineral surfaces. Our findings show the strong capacity of natural sediment to retain and transform antibiotics, while still maintaining their antimicrobial activity or inhibitory effect of nitrate reducing activity.

This research was conducted in the waters of Malili River, East Luwu Regency, with 4 observation points in Malili River East Luwu Regency, namely: (a) Southeast Sulawesi Sub Das (Point 1) namely Pongkeru village bridge, Coordinate point 12126.69’8°” E; (b) Larona Sub Das Karebbe basin bridge (Point 2), Coordinate point 12115.09’9°” E; (c) The meeting point of Larona sub-dash and Pongkeru sub-dash (Point 3), coordinate point 12159.64’8°” E; (d) Upper Malili River, Malili village, Malili bridge (Point 4), Coordinate point 12147.20’5°” E. Metal concentration and distribution were analyzed descriptively with the help of images (maps), graphs, and tables. Differences in Pb, Cd, and Hg metal concentrations in sediments between point locations were tested using analysis of variance (ANOVA) through the SPSS version 22 program. The relation between grain size, organic matter, and Pb, Cd, and Hg metal concentrations was tested using linear correlation. The results showed that the sediment content of Pb and Cd metal concentrations at each point location did not exceed NOAA (1999) quality standards. In the sediment, Hg metal concentration exceeds the quality standards of NOAA (1999) at each point, namely point 1. Pongkeru 0.590 μg.g-1, point 2. Karebbe 0.229 μg.g-1, point 3. Kawasule 0.514 μg.g-1 and point 4. Malili 0.358 μg.g-1. The relation between sediment size and Pb, Cd, and Hg metal concentrations at each point location has a weak correlation. The relation does not significantly affect the content of heavy metals in the sediment. It may be due to other factors, such as the source of heavy metal pollutants in each different point location. The relation between organic matter and the concentration of Pb, Cd, and Hg metals at each point location has a weak correlation. The relation does not significantly affect the content of heavy metals in the sediment because it may be due to other factors, such as different sources of heavy metal pollutants in each point location.