Potential influence of rapid climate change on elemental geochemistry distributions in lacustrine sediments-A case study at a high Arctic site in Ny-Ålesund, Svalbard

Vertical distributions and potential contamination assessment of seldom monitored trace elements in three different land use types of Yellow River Delta

The Yellow River Delta (YRD) is the second largest petrochemical base in China and the impact of human activities has been continuously increasing in recent decades, however, the contamination status of seldom monitored trace elements (SMTEs) in YRD has rarely been reported. This study evaluated the levels, vertical distributions, contamination status and sources of SMTEs in soil samples of three different land use types in YRD. The results indicated that the vertical distributions of SMTEs contents showed a gradually upward increasing trend for the soil profiles of black locust forest, while the SMTEs contents displayed a gradually upward decreasing trend for the soil profiles of cotton field. However, the SMTEs contents in the oil field area showed no significant difference among different depths. The vertical distributions of SMTEs were very likely related to the anthropogenic disturbance in the later stage. The environmental pollution status assessment of SMTEs showed obvious enrichment of Cs, Sn, and U in the soils of YRD. Moreover, the potential source analysis based on multivariate statistical methods indicated that Ga, Rb, Cs, Sc, Sn, Tl, Be, Bi, Ca and Mo were clustered together and positively correlated with Al, Fe, Mg and K, and may be mainly associated with geochemical weathering process, while the Ce, La, Th, U, Nb, Ta, and Hf may be impacted by both natural process and human activities. Though the SMTEs pollution status was not very serious, our results highlighted the non-negligible influence of anthropogenic activities on vertical distributions of SMTEs in three different land use types from YRD. Our results provide valuable information for understanding the vertical distribution and pollution status of SMTEs in YRD.

Spatiotemporal profile and ecological impacts of major and trace elements in surface sediments of marginal seas of the Arctic and Northern Pacific Oceans

The status and ecological impacts of sedimentary elements of the marginal seas of Arctic and Northern Pacific Oceans was investigated during 2016 to 2018 by using inductively coupled plasma mass spectrometry. Industrial (0.006 mg kg-1-64.6 g kg-1), precious (0.003-43.8 mg kg-1), rare earth (0.006-112.9 mg kg-1), and heavy metal (0.009-398.9 mg kg-1) elements showed spatial variation, and temporal uniformity. The results indicated ΣREEs and light REEs enrichment compared to chondrite and heavy REEs, respectively, while nonsignificant positive and negative δCe and δEu anomalies existed, respectively. High contamination and extreme enrichment of priority control, industrial (As, Mo, Re, Sb), precious (Au, Ir, Pd, Pt, and Ru) and RE elements indicated potential moderate to high ecological and biological risks. The study highlighted the ecological importance and fragile nature of these ecosystems and calls for an urgent action to ensure sustainability of these ecosystems.

Sedimentary processes, metal enrichment and potential ecological risk of metals in lacustrine sediments of Svalbard, Arctic

The Svalbard archipelago is a glacial environment bestowed with various lakes that act as a natural archive for understanding environmental conditions. The accumulation of sediments in lake basins and their distribution are affected by different mechanisms. Therefore, to understand the distribution of sediments, factors controlling the transport and metal enrichment in the lake environment, core sediments were studied from four lakes (L-A, L-1, L-2 and L-3). Also, the potential ecological risk index (PERI) was computed to determine the impact of metal enrichment on the sediment-associated biota. The results obtained showed that the distribution of trace elements was mainly controlled by the major elements like Al, Ti, Fe, and Mn attributed to their lithogenic origin. Index of geoaccumulation (Igeo) of all four lakes showed a moderate level of enrichment of metals like Cr and Cd indicating an enhanced supply of these metals probably from the catchment rocks and anthropogenic activities. A comparison of metals with Arctic Sediment Quality Guidelines (ASQGs) showed that Cd, Cr and Cu were enriched in the sediments of all the cores indicating the occurrence of adverse biological effects. Furthermore, a potential ecological risk index (PERI) revealed high Cd indicating considerable potential ecological risk to the sediment-associated biota. Thus, trace element influx to the lakes needs to be monitored with due emphasis on Cd contamination.

Environmental implication of geochemical record in the Arctic Ny-Ålesund glacial sediment, Svalbard (Norway)

Glacial sediments as an important end member of the global dust system, could indicate changes in global climate, aerosols sources, ocean elements, and productivity. With global warming, ice caps shrinking and glaciers retreat at high latitudes have attracted concern. To understand the response of glacier to environment and climate in modern high latitude ice-marginal environments, this paper investigated glacial sediments in the Ny-Ålesund region of the Arctic and clarified the response of polar environmental to global changes through geochemical characteristics of glacial sediments. The results showed that: 1) main factors affecting the elements distribution of the Ny-Ålesund glacial sediments were thought as soil formation, bedrock and weathering, and biological activity; 2) variations of SiO₂/Al₂O₃ and SiO₂/Al₂O₃ + Fe₂O₃, indicating low weathering of the soil. The ratio of Na₂O/K₂O indicating a weak chemical weathering, was negatively correlated to the CIA. With the average CIA of Ny-Ålesund glacial sediments for main minerals of quartz, feldspar, and muscovite as well as dolomite and calcite 50.13, which implied glacial sediments at the early stage of chemical weathering and depletion of Ca and Na; 3) the separating effect of stones and soils by stone circle formation due to thermal conductivity and frost heave makes sediments in stone circle have lower chemical weathering with only two main minerals, albite and quartz; 4) changes of carbonate content in sediments with glacier front retreating in different period implied that weathering rate of calcite averagely reached an estimate of 0.0792%wt/year in glacier A. The succession of vegetation made biological weathering become an important driving force for carbonate leaching from glacial sediments. These results and data provide scientifically significant archive for future global change studies.

Spatial distribution, sources and risk assessment of potentially toxic elements contamination in surface soils of Yellow River Delta, China

The contamination status and ecological risk of soil potentially toxic elements (PTEs) in Yellow River Delta (YRD) are still poorly understood. Thirty surface soil samples were collected in YRD, determined for contents of PTEs, and assessed using four kinds of proxies. Results indicated that PTEs contents basically met the Environmental Quality Standard for Soils, and spatial heterogeneity of PTEs was not distinctive except for a few sampling sites. Results of geo-accumulation index (I_geo) and enrichment factor (EF) indicated significant enrichment of As and Sb in YRD. The multivariate analysis results distinguished the possible sources of these PTEs and demonstrated that sources of Ag, As, Cd, Cu, Pb, Sb and Zn could be influenced by anthropogenic activities (industrial and agricultural sources). Moreover, Ni, Cr and As had relatively high contributions to sum of toxicity units (ΣTUs). This study provides basic information for understanding soil PTEs contamination status of YRD.

Characteristics of sedimentary and dissolved heavy metals in the Chukchi plateau and adjacent waters

Heavy metals in sediments and waters in the Chukchi Plateau and adjacent waters were investigated in this study. The results showed that most metals (especially Ni, As and Co) have accumulated in sediments, and their levels followed the order of Zn > Ni > Co > Cr > Cu > As > Pb > Cd. Spatial variations of environmental variables and metal characteristics were revealed based on the transect research. Furthermore, heavy metal concentrations presented vertical variations in water column with the levels of Ni > As > Zn > Cu > Cr > Pb > Cd > Co, and they were inhomogeneous in different water masses. This paper will be helpful to the study of the pollution and distribution of the heavy metals in Arctic Ocean and its surrounding environment.