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Research about Inner Mongolia

Source-linked reports with geographic coverage including Inner Mongolia.

3 recordsLinked to original sources
USGS2013

Evidence that acidification-induced declines in plant diversity and productivity are mediated by changes in below-ground communities and soil properties in a semi-arid steppe

Anthropogenic acid deposition–induced soil acidification is one of the major threats to biodiversity, ecosystem functioning and services. Few studies, however, have explored in detail how above-ground changes in plant species richness and productivity resulting from soil acidification are mediated by effects on below-ground biota and soil properties. To increase our understanding of this linkage, we collected data on below- and above-ground communities and soil properties in a 3-year field experiment with seven levels of acid addition rate to build-up broad intensities of soil acidification in the semi-arid Inner Mongolian grassland. Acid addition directly elevated concentrations of soil Al 3+ ions, decreased the base cations Ca 2+ , Mg 2+ and Na + , and increased soil moisture and available phosphorus. Acid addition also appears to have altered the soil microbial community via changes in H + and Al 3+ ions and altered the nematode community via changes in H + ions and soil moisture. The observed changes in soil N availability (i.e. net N mineralization, NO 3 - -N and NH 4 + -N) could be explained by mediating changes in the H + and Al 3+ ions, microbial community (i.e. community structure, bacteria and fungi/bacteria as indicated by phospholipid fatty acids analysis) and the nematode community (i.e. total abundance, taxa richness and maturity index). Declines in plant species richness and productivity were greater at high intensities of soil acidification in the second sampling year than in the first sampling year. The changes in plant community observed were mostly explained by soil nutrient pathways (e.g. N availability or base mineral cations), which were in turn regulated by the soil microbial or nematode communities as well as by the direct effects of the increase in H + or Al 3+ ions. Synthesis. Our results suggest that the below-ground microbial and nematode communities are more sensitive to soil acidification than the plant communities are, and further that soil acidification–induced changes in plants are mediated by changes in below-ground communities and soil nutrients. These findings improve our understanding of the links between below- and above-ground communities in the Inner Mongolia grassland, especially in the context of anthropogenic acid enrichment.

Inner Mongolia↗
USGS2013

Pathways of coupled arsenic and iron cycling in high arsenic groundwater of the Hetao basin, Inner Mongolia, China: an iron isotope approach

High As groundwater is widely distributed all over the world, which has posed a significant health impact on millions of people. Iron isotopes have recently been used to characterize Fe cycling in aqueous environments, but there is no information on Fe isotope characteristics in the groundwater. Since groundwater As behavior is closely associated with Fe cycling in the aquifers, Fe isotope signatures may help to characterize geochemical processes controlling As concentrations of shallow groundwaters. This study provides the first observation of Fe isotope fractionation in high As groundwater and evaluation of Fe cycling and As behaviors in shallow aquifers in terms of Fe isotope signatures. Thirty groundwater samples were taken for chemical and isotopic analysis in the Hetao basin, Inner Mongolia. Thirty-two sediments were sampled as well from shallow aquifers for Fe isotope analysis. Results showed that groundwater was normally enriched in isotopically light Fe with δ 56 Fe values between −3.40‰ and 0.58‰ and median of −1.14‰, while heavier δ 56 Fe values were observed in the sediments (between −1.10‰ and 0.75‰, median +0.36‰). In reducing conditions, groundwaters generally had higher δ 56 Fe values, in comparison with oxic conditions. High As groundwaters, generally occurring in reducing conditions, had high δ 56 Fe values, while low As groundwaters normally had low δ 56 Fe values. Although sediment δ 56 Fe values were generally independent of lithological conditions, a large variation in sediment δ 56 Fe values was observed in the oxidation–reduction transition zone. Three pathways were identified for Fe cycling in shallow groundwater, including dissimilatory reduction of Fe(III) oxides, re-adsorption of Fe(II), and precipitation of pyrite and siderite. Dissimilatory reduction of Fe(III) oxides resulted in light δ 56 Fe values (around −1.0‰) and high As concentration (>50 μg/L) in groundwater in anoxic conditions. Re-adsorption of isotopically heavy Fe(II) produced by microbially mediated reduction of Fe(III) oxides led to further enrichment of isotopically light Fe in groundwater (up to −3.4‰ of δ 56 Fe) in anoxic–suboxic conditions. Arsenic re-adsorption was expected to occur along with Fe(II) re-adsorption, decreasing groundwater As concentrations. In strongly reducing conditions, precipitation of isotopically light Fe-pyrite and/or siderite increased groundwater δ 56 Fe values, reaching +0.58‰ δ 56 Fe, with a subsequent decrease in As concentrations via co-precipitation. The mixed effect of those pathways would regulate As and Fe cycling in most groundwaters.

Inner Mongolia↗