The background concentrations of 13 soil trace elements and their relationships to parent materials and vegetation in Xizang (Tibet), China

Wang

Science of The Total Environment

et al. 2015

129

• Cr, Zn, Cu, As, Cd, and Pb in soils along the highway are related to the traffic.• There are three distribution patterns of the traffic-related metals in soils.• Regional differences had significant relationship with the enrichment levels.• Cd was the prior metal and the TTH was the key area for soil environment monitoring. The road transportation could affect roadside soils environment detrimentally, including heavy metal enrichment. In order to identify and evaluate the enrichment of heavy metals resulted from road transportation on the Tibetan Plateau, the 11 heavy metals (V, Cr, Co, Ni, Cu, Zn, As, Cd, Rb, Pb and Tl) in the topsoil (0-10 cm depth) from four sites along the Qinghai-Tibet highway were discussed in this study. Our results indicate that heavy metals such as Cr, Cu, Zn, As, Cd and Pb are related to road transportation. The content of most of these heavy metals in roadside soils decreased exponentially with the distance from the road, as did some of the Nemero Synthesis Indexes (PN values). The contamination factor for the traffic-related metals ranged from 0.56 (no pollution) to 5.67 (considerable pollution) and the Nemero Synthesis Indexes of these heavy metals ranged from 0.80 (no pollution) to 4.49 (severe pollution). Cd was of priority concern as it had the highest contamination factor. The highest PN value for these traffic-related heavy metals was found in soils at site TTH (alpine steppe). Although transportation contributed to the high contents of these traffic-related metals in roadside environments, regional differences such as wind and the terrain also had significant relationship with their enrichment in these roadside soils. The roadside distance at which there is a potential risk to livestock and wildlife from the contamination of soils by heavy metals should be determined scientifically along the Qinghai-Tibet highway, based on the different natural environments found in the region. a b s t r a c t a r t i c l e i n f o

Section: Tablesupporting

confidence: 85%

Section: Tablesupporting

confidence: 84%

Section: Discussionsupporting

confidence: 71%

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Identification of traffic-related metals and the effects of different environments on their enrichment in roadside soils along the Qinghai–Tibet highway

Wang

Science of The Total Environment

et al. 2015

129

“…), and much of the TP lies above the atmospheric boundary layer. 19 Soils in the TP have originated from various parent materials, mainly involving residue deposits, glacial deposits and other sediments of the quaternary, 20 and are associated with various vegetation types. The diverse origins of the resulting soils and the complicated geology in this region have resulted in a range of different contents of soil elements.…”

Section: Introductionmentioning

confidence: 99%

Variability of heavy metal content in soils of typical Tibetan grasslands

Liu

Yang

et al. 2016

RSC Adv.

Relatively high contents of heavy metals were recently reported in the high-altitude Tibetan Plateau (TP) environment, but the source and distribution characteristics of heavy metals in grassland environments of the TP remain unclear. Here, we report the contents of Hg, Cd, As, Pb, Ni, Cr, Cu, and Zn in soils of typical grasslands from the western to eastern parts of the TP, and the factors regulating accumulation of these heavy metals in the soil. Results show a large degree of variability of the eight heavy metals in the topsoil (0-20 cm) of different grasslands of the TP. Distribution characteristics of the heavy metals in the subsoil (20-40 cm) from the different grasslands were similar to those in the topsoil. Concentrations of As, Cd, Cu, and Zn in grassland soil tended to decrease as longitude increased, whereas Hg content displayed an increasing trend with increasing longitude after 88 E. These observations may be related to different sources of the heavy metals in the soils. Our results suggest that Cu, Zn, Cr, Cd, Ni, and As were mainly derived from natural sources, whereas anthropogenic activities could be responsible for the accumulation of Pb and Hg in the soil. Positive correlation between average annual rainfall amounts and soil Hg content may suggest the contribution of precipitation to soil Hg content. However, accumulation and distribution of heavy metals in the grasslands also depend on soil characteristics which could influence the mobility of heavy metals. These findings have important implications for an understanding of the occurrence and accumulation of soil heavy metals in grasslands of high-altitude environments.

“…It has been assumed that the behavior of elements in soils and in consequence their bioavailability differ as to their origin (Zhang et al, 2002). The element transfer from soil is a very complex process governed by several factors, both natural and affected by humans (Roivainen et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Spatial Distribution and Bioavailability of Some Essential Trace Elements in Southern Ondo State Nigeria

Tomori

Amoo²,

Aiyesanmi³

et al. 2015

The total elemental content of soil though may give abundance of element concentration but have been found not to be suitable for prediction of environmental bioavailability and toxicity by scientific community. Surface (0-30cm) and subsurface (60-90cm) soil profile in the Southern Ondo State Nigeria were investigated for spatial distribution, bioavailability and mobility of some essential trace elements (Cu, Fe, Mn, Zn). Their spatial distribution were very similar in both surface and subsurface soil environment indicating that similar geochemical factors may be responsible for their distribution. The North was composed of basement complex while the South was largely undifferentiated sedimentary rock. Higher concentrations of Cu, Fe, Mn and Zn were recorded in the North through the centre of study area to lower concentrations in the South. The spatial concentration of the trace elements may have been influenced by the nature of underlying bedrock type. Cu was potentially bioavailable in both surface and subsurface soil environment considering the fact that >50% of its total concentration were in the nonresidual fraction. Other trace elements were not bioavailable because >60% of their total concentrations were found in residual fractions. The relative risk assessment code of Cu (surface; subsurface) indicated progressive risk (MoF1, MoF2, MoF3) from low (2-10; 1-6) through medium (12-30; 10-21) to high risk (25-40; 21-35) in both surface and subsurface soil environment while Zn (surface) shows similar trend (1-5; 11-21; 22-35) only in the surface soil environment. Other elements show some level of risk to no risk. There is likelihood that Cu and/or Mn may be associated with anthropogenic sources.