萨拉乌苏河第四纪地层中化学元素的迁移和聚集与古气候的关系

过去半个多世纪中，国内外学者在萨拉乌苏河地区做了大量考察和研究工作，取得了一系列成果。但是，以往都把重点放在该区第四纪地层划分、考古、古人类、古生物和古地理环境等方面。对于在地层中化学元素的迁移和聚集与古气候的关系，探讨不多。

Distribution of heavy metals in the topsoil of the Jining mining area

The geochemical baseline is the fundamental reference for environmental change and assessment.In this article we describe cluster and regression analyses with a normalization procedure.The elements Sc and Ag were chosen to calculate the environmental geochemical baseline.The geoaccumulation index was calculated and mapped to indicate the environmental quality of the soil.The results show that the urban areas are barely polluted with Ni and Cr but the rural areas in the southern part of the city, and the western part of the lake,are polluted with Ni,Cr,and Cu at the second level.On the other hand,the rural areas in the southern part of the city,and the western part of the lake,are polluted with As at a moderate level.The other area is polluted at the second level.An increase in As pollution occurs in a direction from northeast to southwest.The Cd pollution follows a trend similar to As,with an additional smaller contaminated area polluted at levelⅢ.The Hg pollution typical of urban areas occurs in the main and northern parts of the city.The geochemical accumulation index decreases from the city center to the periphery.The highest pollution level reaches levelⅣ,which indicates that the soil is seriously polluted with Hg.The southern part of the city and the rural areas to the west of the lake are not contaminated with Hg.Geological factors and the disturbance from human activities are both possible major factors:further research is needed to identify them.

Temporal variation and its drivers in the elemental traits of four boreal plant species

Aims Intraspecific variation in plant traits has important consequences for individual fitness and herbivore foraging.For plants,trait variability across spatial dimensions is well documented.However,temporal dimensions of trait variability are less well known,and may be influenced by seasonal differences in growing degree days(GDD),temperature and precipitation.Here,we aim to quantify intraspecific temporal variation in traits and the underlying drivers for four commonly occurring boreal plant species.Methods We sampled the elemental and stoichiometric traits(%C,%N,%P,C:N,C:P,N:P)of four common browse species'foliage across 2 years.Using a two-step approach,we first fitted generalized linear models(GzLM,n=24)to the species'elemental and stoichiometric traits,and tested if they varied across years.When we observed evidence for temporal variability,we fitted a second set of GzLMs(n=8)with temperature,productivity and moisture as explanatory variables.Important Findings We found no evidence of temporal variation for most of the elemental and stoichiometric traits of our four boreal plants,with two exceptions.Year was an important predictor for percent carbon across all four species(R^(2)=0.47-0.67)and for multiple elemental and stoichiometric traits in balsam fir(5/8,R2=0.29-0.67).Thus,variation in percent carbon was related to interannual differences,more so than nitrogen and phosphorus,which are limiting nutrients in the boreal forest.These results also indicate that year may explain more variation in conifers'stoichiometry than for deciduous plants due to life history differences.GDD was the most frequently occurring variable in the second round of models(8/8 times,R^(2)=0.21-0.41),suggesting that temperature is an important driver of temporal variation in these traits.