Geochemical Characteristics of the Vertical Distribution of Heavy Metals in the Hummocky Peatlands of the Cryolithozone

Abstract

One of the main reservoirs depositing various classes of pollutants in high latitude regions are wetland ecosystems. Climate warming trends result in the degradation of permafrost in cryolitic peatlands, which exposes the hydrological network to risks of heavy metal (HM) ingress and its subsequent migration to the Arctic Ocean basin. The objectives included: (1) carrying out a quantitative analysis of the content of HMs and As across the profile of Histosols in background and technogenic landscapes of the Subarctic region, (2) evaluating the contribution of the anthropogenic impact to the accumulation of trace elements in the seasonally thawed layer (STL) of peat deposits, (3) discovering the effect of biogeochemical barriers on the vertical distribution of HMs and As. The analyses of elements were conducted by atom emission spectroscopy with inductively coupled plasma, atomic absorption spectroscopy and scanning electron microscopy with an energy-dispersive X-ray detecting. The study focused on the characteristics of the layer-by-layer accumulation of HMs and As in hummocky peatlands of the extreme northern taiga. It revealed the upper level of microelement accumulation to be associated with the STL as a result of aerogenic pollution. Specifically composed spheroidal microparticles found in the upper layer of peat may serve as indicators of the area polluted by power plants. The accumulation of water-soluble forms of most of the pollutants studied on the upper boundary of the permafrost layer (PL) is explained by the high mobility of elements in an acidic environment. In the STL, humic acids act as a significant sorption geochemical barrier for elements with a high stability constant value. In the PL, the accumulation of pollutants is associated with their sorption on aluminum-iron complexes and interaction with the sulfide barrier. A significant contribution of biogenic element accumulation was shown by statistical analysis.

The reaction of the urban soil-plant complex on abnormal weather conditions

“…Their content in the leaves significantly exceeds its content in the soil. This is due to the fact that during the period of stress caused by weather conditions abnormal 0 0.5 The coefficients of biological transition for other heavy metals (strontium, lead, nickel, chromium, vanadium) are less than one, that is, their accumulation undergoes less changes when barrier functions are violated [11,12]. The greatest increase in biological transition coefficients is observed in southern introducers -white poplar (Populus alba L.) and horse chestnut (Aesculus hippocastanum L.).…”

Yedoma Permafrost Releases Organic Matter with Lesser Affinity for Cu2+ and Ni2+ as Compared to Peat from the Non-Permafrost Area: Risk of Rising Toxicity of Potentially Toxic Elements in the Arctic Ocean

“…Such high levels of PTE emissions have a negative impact on the flora and fauna of the region. While the highest concentrations of PTEs are found in the vicinity of the emitting sources and accumulate in bottom sediments, peatlands and permafrost soils, their mobilization poses a potential threat to the global environment [ 7 , 13 , 14 , 15 ].…”

“…The mobility of metals in soil and water is regulated by hydrological parameters and soil regime (e.g., salinity, pH, temperature), redox conditions, chemical forms of the elements and organic matter (OM) [ 14 , 16 , 17 , 18 , 19 ]. Among the many factors that affect PTE mobility, the complexation of metals with organic matter and specifically with humic substances (HSs) is one of the most crucial [ 16 , 20 , 21 ].…”

The Molecular Composition of Peat Organic Matter and Prospects for Its Use in Agriculture

“…Lowland peatlands occur mainly in river valleys or near-terrace depressions of floodplains. Lowland peats are natural biogeochemical barriers against the migration of pollutants between soil and ground waters as follows: watershed → river valleys → rivers → seas and oceans [11]. Their reclamation and subsequent use for peat extraction will inevitably lead to a violation of the natural hydrological regime of rivers and water reservoirs and their large-scale pollution in emergency situations, accompanied by the entry into the environment of significant amounts of pollutants (oil and petroleum products, heavy metals, polycyclic aromatic hydrocarbons, etc.…”