Synthesis and application of graphene-based sensors in biology: a review

Environmental Chemistry Letters - Biosensors are gaining interest in biomedical and environmental sciences. In particular, graphene-based biosensors are promising due to the unique properties of...     

Lichens reveal air PAH fractionation in the Himalaya

This paper shows that gas/particulate phase partitioning of polycyclic aromatic hydrocarbons (PAHs) can be monitored using lichens. Anthropogenic sources are responsible for the release of PAHs, which are bioaccumulated in plants at various spatial scales based on their physicochemical properties. Atmospheric PAHs are distributed both in the gaseous and particulate states. Here, a lichen species, Dermatocarpon vellereum Zschacke, has been collected at different altitudes in and around the Rudraprayag valley, located in Central Himalayan region of India, in order to study the spatial distribution of PAHs in the valley. Results show that PAH concentration ranged from 0.136 to 4.96 μg g^?1. Findings reveal that the bioaccumulation of 2- and 3-ringed PAHs was higher in high-altitude samples, whereas bioaccumulation of fluoranthene, a 4-ringed PAH, showed higher concentration in samples from localities away from town centre. 5- and 6-ring PAHs were then confined to the lower altitude at the base of the valley, thus justifying their particulate-bound nature. This is the first report showing the utility of lichen to biomonitor PAHs in the Himalayan ecosystem.     

Effects of solar geometry and operation period on stability of solar desalination systems: a review

Environmental Science and Pollution Research - The sun is the primary source of life on the earth. The heating effect of the sun provides a more fruitful environment for mankind. In addition, solar...     

Lichens to distinguish urban from industrial PAHs

This paper shows that lichens can be used as biomonitors to distinguish urban from industrial polycyclic aromatic hydrocarbons (PAHs). PAHs are atmospheric pollutants originating mainly from incomplete combustion of fuels in vehicles and industry. The occurrence of PAHs in air is a serious health issue in urban areas and industrial areas because some PAHs are carcinogenic. Biomonitoring PAHs with lichens is generally applied for quantification of PAHs. However, the precise sources of PAHs are not well known. Here we use lichen to trace the source of PAHs. PAHs were analyzed in Pyxine subcinerea Stirton, a lichen species collected from twelve sites which vary from urban and industrial to periurban forest area of Haridwar, in the foothills of the Indian Himalayas. Total PAH concentration ranged between 1.25 and 187.3 μg g⁻¹. Results indicate a clear distinction between urban and industrial PAHs profile, using principal component analysis. Lichen sampled from industrial sites exhibited higher concentrations of two-, five-, and six-ringed PAHs, up to 60% of total PAHs, while samples from urban sites were dominated by four-ringed PAHs, predominantly fluoranthene and acenaphthylene. Molecular ratios indicate that combustion was the dominant source of origin of PAHs in industrial area, while urban sites showed mixed origin of PAHs, both pyro- and petrogenic.     

Tree species diversity and composition in logged and unlogged rainforest of Kudremukh National Park, South India

Species composition and diversity in logged and unlogged forests were assesed to understand the regeneration of the residual stand twenty years after logging in Kudremukh National Park, South India. Relative density, frequency and basal area were measured by Point Centered Quarter method to calculate the diversity and stand quality. The logged forest harbored lower stem density of mature trees (508 ha(-1)) than unlogged ones (630 ha(-1)). Indeed, logging operations increased the species diversity in the regenerative phase (seedling phase) due to the creation of larger canopy gaps. The extra radiation reaching the ground, facilitated the colonization of early and late secondary species. Ramakrishanan Index of Stand Quality (RISQ) values in logged forest was higher in comparison with unlogged forest, indicating the dominance of early and late secondary species, especially at sapling phase. The light demanding secondary forest species contribute higher percentage to the overall tree population in logged forest. It is observed from the study that a sufficient period of felling cycle should be practiced to reinstate the same set of species prevailed before logging.     

Targeting natural products against SARS-CoV-2

Environmental Science and Pollution Research - The human coronavirus disease (COVID-19) pandemic is caused by a novel coronavirus; the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2)....     

Spatial–temporal variation and comparative assessment of water qualities of urban river system: a case study of the river Bagmati (Nepal)

The study presents the assessment of variation of water qualities, classification of monitoring networks and detection of pollution sources along the Bagmati River and its tributaries in the Kathmandu valley of Nepal. Seventeen stations, monitored for 23 physical and chemical parameters in pre-monsoon, monsoon, post-monsoon and winter seasons, during the period 1999-2003, were selected for the purpose of this study. The study revealed that the upstream river water qualities in the rural areas were increasingly affected from human sewage and chemical fertilizers. In downstream urban areas, the river was heavily polluted with untreated municipal sewage. The contribution of industries to pollute the river was minimal. The higher ratio of COD to BOD (3.74 in the rural and 2.06 in the urban) confirmed the increased industrial activities in the rural areas. An increasing trend of nitrate was found in the rural areas. In the urban areas, increasing trend of phosphorus was detected. The water quality measurement in the study period showed that DO was below 4 mg/l and BOD, COD, TIN, TP and TSS above 39.1, 59.2, 10.1, 0.84 and 199 mg/l, respectively, in the urban areas. In the rural areas, DO was above 6.2 mg/l and BOD, COD, TIN, TP and TSS below 15.9, 31, 5.24, 0.41 and 134.5 mg/l, respectively. The analysis for data from 1988 to 2003 at a key station in the river revealed that BOD was increasing at a rate of 1.8 mg/l in the Bagmati River. A comparative study for the water quality variables in the urban areas showed that the main river and its tributaries were equally polluted. The other comparison showed the urban water qualities were significantly poor as compared with rural. The cluster analysis detected three distinct monitoring groups: (1) low water pollution region, (2) medium water pollution region, (3) heavy water pollution region. For rapid assessment of water qualities using the representative sites could serve to optimize cost and time without loosing any significance of the outcome. The factor analysis revealed distinct groups of sources and pollutions (organics, nutrients, solutes and physicochemical).     

Cyhalofop‐p‐butyl mobility and distribution of residues in soil at various depths

This study was conducted to evaluate cyhalofop‐p‐butyl mobility in a sandy loam soil and subsequent distribution of residues at various depths under field conditions. Soil samples were taken from 0 to 150 cm depths at 3–90 d after rains in lysemeter of 1 and 2 m depths. Cyhalofop‐p‐butyl application at two rates and subsequent precipitation had a significant impact on soil, physico‐chemical properties and herbicide mobility. Precipitation caused substantial mobility of cyhalofop‐p‐butyl in the soil and 1.1–7.6 μg L^?1 of cyhalofop‐p‐butyl was found in leachates. Cyhalofop‐p‐butyl residues in the leachates were probably due to preferential flow through the soil. Cyhalofop‐p‐butyl residues were detected in significant amounts from the soil up to 10 d, later, residues were found below the detection limit but its three transformation products viz., cyhalofop acid, diacid, and phenol were detected.     

Exposure profiles of mercury in human hair at a terai belt of North India

Human hair is frequently used as a bioindicator of mercury exposure. Mercury (Hg) has for centuries been a useful metal in a variety of applications. Unfortunately, this usefulness is counterbalanced by its neurotoxicological health impact. The US Environmental Protection Agency recommends keeping the hair Hg level <1.0 µg/g. Therefore, an investigation has been performed in order to ascertain the hair Hg levels among the people living at the terai belt of North India. Hair samples were collected from 111 individuals and were placed in an identified plastic bag, stapled to prevent the shift of the hair strand. Samples were analyzed by combustion, gold amalgamation, atomic absorption spectrometry (C-GA-AAS). The mean Hg level in hair was 0.28 µg/g for the whole group ranging from 0.0012 to 1.9091 µg/g. The mean hair Hg levels were 0.16 µg/g for men and 0.12 µg/g for women, indicating that men had higher hair Hg levels than women. Total hair Hg was found to be significantly associated with age, gender and fish consumption frequency. 98 % of the total sample had hair Hg concentrations less than 1.0 µg/g, i.e, within safe dose, whereas only 2 % had Hg concentrations greater than 1.0 µg/g, thereby exceeding the safe dose.