Elucidation of the tidal influence on bacterial populations in a monsoon influenced estuary through simultaneous observations

The influence of tides on bacterial populations in a monsoon influenced tropical estuary was assessed through fine resolution sampling (1 to 3 h) during spring and neap tides from mouth to the freshwater end at four stations during pre-monsoon, monsoon and post-monsoon seasons. Higher abundance of total bacterial count (TBC) in surface water near the river mouth, compared to the upstream, during pre-monsoon was followed by an opposite scenario during the monsoon When seasonally compared, it was during the post-monsoon season when TBC in surface water was highest, with simultaneous decrease in their count in the river sediment. The total viable bacterial count (TVC) was influenced by the depth-wise stratification of salinity, which varied with tidal fluctuation, usually high and low during the neap and spring tides respectively. The abundance of both the autochthonous Vibrio spp. and allochthonous coliform bacteria was influenced by the concentrations of dissolved nutrients and suspended particulate matter (SPM). It is concluded that depending on the interplay of riverine discharge and tidal amplitude, sediment re-suspension mediated increase in SPM significantly regulates bacteria populations in the estuarine water, urging the need of systematic regular monitoring for better prediction of related hazards, including those associated with the rise in pathogenic Vibrio spp. in the changing climatic scenarios.     

A review on recent progress in observations,sources, classification and regulations of PM<Subscript>2.5</Subscript> in Asian environments

Natural and human activities generate a significant amount of PM_2.5 (particles ≤2.5 μm in aerodynamic diameter) into the surrounding atmospheric environments. Because of their small size, they can remain suspended for a relatively longer time in the air than coarse particles and thus can travel long distances in the atmosphere. PM_2.5 is one of the key indicators of pollution and known to cause numerous types of respiratory and lung-related diseases. Due to poor implementation of regulations and a time lag in introducing the vehicle technology, levels of PM_2.5 in most Asian cities are much worse than those in European environments. Dedicated reviews on understanding the characteristics of PM_2.5 in Asian urban environments are currently missing but much needed. In order to fill the existing gaps in the literature, the aim of this review article is to describe dominating sources and their classification, followed by current status and health impact of PM_2.5, in Asian countries. Further objectives include a critical synthesis of the topics such as secondary and tertiary aerosol formation, chemical composition, monitoring and modelling methods, source apportionment, emissions and exposure impacts. The review concludes with the synthesis of regulatory guidelines and future perspectives for PM_2.5 in Asian countries. A critical synthesis of literature suggests a lack of exposure and monitoring studies to inform personal exposure in the household and rural areas of Asian environments.     

Assessing the current practice and policy with recommendations for emission control strategy for coal‐fired thermal power plants under Indian regulatory framework emphasizing the roles of R&D

On December 7, 2015, the Ministry of Environment, Forest and Climate Change (MoEFCC), Government of India (GoI), promulgated stack emission standards for sulfur dioxide (SO₂), oxides of nitrogen (NO_x), and mercury (Hg) from coal‐fired thermal power plants (TPPs). These standards were promulgated in addition to tightening the emission standard for particulate matter. Thus far, the GoI and a non‐governmental organization (NGO) have recommended the use of limestone‐based flue‐gas desulfurization (FGD) technology for removing only SO₂ emissions, which would then require the application of additional technologies to remove the other regulated pollutants. A single technology, such as the Multi‐pollutants Control Technology (MPCT), which was recently developed elsewhere in the world and can remove all of the pollutants from the TPP, could be more economical than introducing separate technologies for the removal of each pollutant. Furthermore, unlike the limestone‐based FGD technology, which generates carbon dioxide (CO₂) during the desulfurization process, the MPCT does not increase power plant CO₂ emissions. Water consumption is also lower in MPCT than with the limestone‐based FGD technology. Thus, MPCT offers a lower carbon footprint as well as a lower water footprint than the limestone‐based FGD technology in accordance with the United Nations Environmental Programme's Sustainable Development Goals. In light of these observations, this article aims to assess current practices and policies and offers policy recommendations for Indian TPPs with the goal of providing a cogent technological solution that also strengthens the Decision Support System for the holistic protection of the Indian environment.     

Development of Zinc Oxide Sensors for Detecting Ammonia Gas in the Ambient Air: A Critical Short Review

Ammonia (NH₃) is emitted into the atmosphere by various industries and other sources and causes environmental pollution. Considering the hazards of ammonia, detecting leakage from vessels and pipes demands the use of sensors. Therefore, the development of NH₃ gas sensors assumes considerable importance to researchers and regulators and to industry, businesses, and facilities that make, store, or use ammonia. The use of metal oxide sensors (MOS) for detecting NH₃ gas, such as zinc oxide (ZnO), has been a topic of interest to researchers seeking methods to detect NH₃ gas, even at low concentrations. In this article, an attempt has been made to review the research thus far published on the synthesis of ZnO‐based NH₃ gas sensor materials, their characterization, and analyses of their performance. Finally, we make several recommendations regarding the scope of future research. For example, the kinetics of the sensor materials should be determined. Furthermore, extensive studies of gas–solid (NH₃–ZnO) adsorption are proposed to ascertain the exact adsorption mechanism in terms of isotherm, kinetics, and diffusive mass transport, and to determine “reversibility” and “recovery” of sensor materials so they can continue sensing and activating alarms when necessary for practical applications.     

The role of liquefied petroleum gas in decarbonizing India: fresh evidence from wavelet–partial wavelet coherence approach

Environmental Science and Pollution Research - India is predominantly a fossil fuel-intensive South Asian country that has traditionally settled for higher economic gains at the expense of lower...     

Phytoaccumulation of iron by callus tissue of Clerodendrum indicum (L)

Clerodendrum indicum (L.) is one of the important medicinal plants, originating in India. The plant is used as medicine for bronchitis, asthma and different immunological disease. Micro-propagation is a quick method, producing a huge number of plants. Apical leaf of Clerodendrum indicum (L.) was used as an explant for callogenesis. The combinations of different plant growth regulators (2,4-D, NAA, KN) in MS (Murashige and Skoog) medium produced two types of calli: one was friable and loose and the other was green, embryogenic and compact. Heavy metals cause pollution and health hazards. The plant absorbs heavy metals, which is very useful for controlling environmental pollution. Iron is a major nutrient for both plants and animals, but hyper accumulation of iron is injurious to health. Calli were used to study the optimum conditions of iron uptake in presence of different chemical environments. The different environments were created by using different chemical reagents such as (HCL, HNO₃, H₃PO₄ and KNO₃). Iron (III) was spiked with radioactive Fe-59 and dynamics of uptake was followed by measuring radioactivity by gamma-ray spectrometer. The best condition of iron uptake corresponded to 1 mol L^?1 KNO₃ after 4 hour of equilibration.     

Impact of salinity and pH on phytoplankton communities in a tropical freshwater system: An investigation with pigment analysis by HPLC

An in vitro study was carried out to understand the effects of salinity shock and variation in pH on phytoplankton communities in a tropical freshwater system of the Godavari River (a major peninsular river in India). The distributions of, and variations in, phytoplankton communities were assessed by quantitative determination of their class specific marker pigments, using HPLC. Subtle changes in salinity of the freshwater by one practical salinity unit (PSU) completely removed green algae from the system and allowed the cyanobacteria to come into dominance. The cyanobacteria were found to tolerate higher osmotic stress until the salinity reached a PSU of 16. The higher salinity tolerance range of the cyanobacteria was attributed to the enhanced synthesis of zeaxanthin as protective xanthophylls against the osmotic stress. However, the effects of changing pH were not as dramatic as salinity where the green algae and the cyanobacteria from the same freshwater system showed a considerable acclimation towards the fluctuating pH. These findings are environmentally relevant to understand the likely impact of salt water intrusion and pH variation on phytoplankton communities in a tropical freshwater system.