From biomass to fossil fuels: A contemporaneous transition to anthropogenic driven environmental changes recorded in a Central Himalayan Lake

Long-Range Transport of Polycyclic Aromatic Hydrocarbons and Metals in High Altitude Lacustrine Environments of the Eastern Himalayas: Speciation, and Source Apportionment Perspectives

“…1,2 Although, the Himalayan range is a remote region with a cold and harsh climate, high altitude, and minimal anthropogenic emissions, imprints of long-range atmospheric transport of pollutants have been the focus in the recent times. 2−6 The concern becomes more prominent since the Himalayas are connected by some of the most densely populated countries that are undergoing rapid industrialization, urbanization, and land use change 7,8 generating large amounts of pollutants. Atmospheric aerosols, which impact the global climate, transport these pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs), over great distances, which is strongly influenced by the monsoon.…”

“…Pollutant build-up degrades the aquatic environments by causing nutrient enrichment, chemical pollution, and hydro-morphological changes. 8 High-altitude lakes (HALs) comprise the most remote and least perturbed aquatic systems since they are untouched by anthropogenic influences. 11−14 They are capable of mirroring any change in the local and global climate and have proven to be ideal ecosystems for assessing long-range transport of atmospheric pollutants (LRTAP) over isolated high-altitude regions for the following reasons: prevent the entry of pollutants into surface waters and sediments, making them particularly vulnerable to pollutants, and (c) the oligotrophic nature of these lakes and their lowtemperature conditions contribute to their restricted ability for post-depositional sediment mixing and buffering, which reduces any potential for the neutralization or uptake of contaminants.…”

“…7,27 In aquatic environments, they exhibit strong affinities for lake sediments; they bind with particulate matter and accumulate in sediments due to their low solubility, semi-volatility, and high partition coefficient values. 8,26 PAHs have the inherent property to exist in both vapor and particulate phases, thus exhibiting semivolatility. When released into the atmosphere, some PAHs undergo volatilization, resulting in the formation of vaporphase PAHs.…”

“…In addition, PAHs are also up taken by various benthic organisms, resulting in bioaccumulation and biomagnification in the trophic chain. 2,8 The primary sources of low molecular weight PAHs (LMWPAHs) are petrogenic and low-temperature biomass burning. In contrast, the origins of high molecular weight PAHs (HMWPAHs) are pyrogenic, including incomplete combustion of organic compounds and fossil fuels, industrial coal combustion, and incineration.…”

“…In contrast, the origins of high molecular weight PAHs (HMWPAHs) are pyrogenic, including incomplete combustion of organic compounds and fossil fuels, industrial coal combustion, and incineration. 8,9 The most abundant and stable PAHs (Phen, Fla, Pyr, BaA, and Chry) are important tracers for the source identification of PAHs. 10 Likewise, HMs are naturally occurring components often found in low amounts in the earth's crust.…”