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Hydrochar obtained after hydrothermal carbonization (HTC) of Lepironia articulata (LA) was modified into biochar by reacting with a specific amount of KOH in a tubular reactor under slow pyrolysis. The physical and chemical properties of the hydrochar and modified biochar were characterized. The performance of modified biochar (LABC) was investigated through batch sorption experiments. Removal (%) and the maximum adsorption capacity (q max ) of Cr(VI) onto LABC increased up to 98.9% and 28.75 mg/g relative to 63.44% and 21.90 mg/g in unmodified hydrochar (LAHC) at pH 2.0, 313 K, and 200 mg/L, respectively. The sorption kinetics uptake data were best interpreted with pseudo-second-order model, and sorption isotherm was simulated with the Langmuir adsorption model. The thermodynamic parameters confirm the adsorption process to be an endothermic, spontaneous, and increased disorder. The overall results revealed that LABC can be utilized as an environmentally friendly, inexpensive, and effective adsorbent in Cr(VI) removal. • Practitioner points• Hydrochar and modified biochar prepared from a tropical biomass (Lepironia articulata) were successfully used for the removal of Cr(VI) from aqueous solution. • Increased specific surface was obtained by applying chemical modification with alkali treatment, contributing to effectiveness as adsorbent. • Dimensionless K c was estimated from the Langmuir fits and then used to estimate thermodynamics of adsorption. • The signs of ∆H°, ∆G°, and ∆S° indicate that the adsorption of Cr(VI) onto LABC was an endothermic, spontaneous, and increased disorder.

Altogether 209 species of algae and cyanobacteria has been revealed in 2014-2015 from four sites in the Kabul River that flow across the Peshawar Valley. Green algae, diatoms, and Charophyta filamentous algae were diverse and characterize regional feature in the river basin with high agricultural activity. Species richness and algal abundance were increase down the river. Index saprobity S varied between 1.55 and 1.59 (Class III of water quality) and reflects decreasing of water quality down the river as a result of pollutants impact, which brings mostly the Swat tributary. Bio-indication results show prevalence of benthic or plankto-benthic species, temperate temperature indicators, slow streaming middle oxygenated waters inhabitants, salinity-indifferents, eurysaprobes, mesotrophes, and autotrophic algae with tolerance to middle concentration of Nitrates that reflects middle polluted waters III-IV Class of Water 152 Sophia Barinova et al. Quality in the Kabul River. Our analysis shows that integral bio-indication in water quality assessment with using of algal communities can give relevant results of self-purification possibility, which can be employed in purpose of monitoring the regional water quality as economy and resultative method.

Drought variability analysis is of utmost concern for planning and efficiently managing water resources and food security in any specific area. In the current study, drought spell occurrence has been investigated in the Balochistan province of Pakistan during the past four decades (1981-2020) using standardized precipitation index (SPI), reconnaissance drought index (RDI), and precipitation deciles (PD) at an annual timescale. Precipitation and temperature data collected from 13 synoptic meteorological stations located in Balochistan were used to calculate the SPI, the RDI, and the PD for calculation of drought severity and duration. Based on these indices, temporal analysis shows adverse impacts of drought spells in Nokkundi during 1991-1993, in Barkhan, Dalbandin, Quetta stations during 1999-2000, whereas Barkhan, Dalbandin, Lasbella, Sibi during 2002-2003, Zhob during 2010-2011, Kalat and Khuzdar during 2014-2015, and Panjgur during 2017-2018. Also, the aridity index for each station was calculated based on the UNEP method shows that major part of Balochistan lies in the arid zone, followed by the hyper-arid in the southwestern part and the semi-arid zones in the northeastern part of the province. SPI and RDI results were found more localized than PD, as PD shows extensive events. Furthermore, principal component analysis shows a significant contribution from all the indices. For SPI, RDI, and PD, the first three principal components have more than 70% share, contributing 73.63%, 74.15%, and 72.30% respectively. By integrating drought patterns, long-term planning, and preparedness to mitigate drought impacts are only possible. The RDI was found more suitable and recommended in case of temperature data availability.