Effects of plastic film mulch biodegradability on nitrogen in the plant-soil system

The application of biodegradable film mulching (BFM) instead of non-biodegradable film mulching (NBFM) is a promising way to mitigate the negative impacts of residual film in agricultural mulching systems. But the effects of BFM on soil mineral nitrogen (N) are not known. To investigate the effects of BFM on N mineralization, nitrate (NO₃^-) accumulation and leaching, and plant N uptake, we conducted two-year field experiment with five treatments: no-mulching (No-M), white non-biodegradable film mulching (White-NotBioM), black non-biodegradable film mulching (Black-NotBioM), white biodegradable film mulching (White-BioM), and black biodegradable film mulching (Black-BioM). The net N mineralization in NBFM was greater than that in BFM due to the disintegration of biodegradable films in the middle and late stages of maize growth, resulting in a decrease in soil water content under BFM. Higher net N mineralization caused a higher NO₃^- accumulation in the topsoil (0-20 cm) under NBFM. The NO₃^- accumulation in the topsoil in Black-NotBioM was 23-88% higher than that in Black-BioM; while in White-NotBioM it was 16-63% higher than that in White-BioM. After two years of cropping, the NO₃^- accumulation in 100-180 cm (defined as N leaching in deep layers, NLD) in NBFM was 52-63% higher than that in BFM, implying that the higher NO₃^- accumulation in the topsoil in NBFM caused more N leaching. The yields and plant N uptake were similar between NBFM and BFM, but BFM had higher N harvest index values. Compared with NBFM, BFM showed less NO₃^- accumulation in the topsoil and less NLD, whereas yield, plant N uptake and net economic benefits were not reduced. Therefore, BFM, especially Black-BioM, could be an alternative to NBFM in maize production on the Loess Plateau. However, the higher N accumulation in root soil layer (0-100 cm) under Black-BioM should be accounted for in N fertilizer management.

Urban heat islands in the Arctic cities: an updated compilation of in situ and remote-sensing estimations

Abstract. Persistent warm urban temperature anomalies – urban heat islands (UHIs) – significantly enhance already amplified climate warming in the Arctic. Vulnerability of urban infrastructure in the Arctic cities urges a region-wide study of the UHI intensity and its attribution to UHI drivers. This study presents an overview of the surface and atmospheric UHIs in all circum-Arctic settlements (118 in total) with the population larger than 3000 inhabitants. The surface UHI (SUHI) is obtained from the land surface temperature (LST) data products of the Moderate Resolution Imaging Spectroradiometer (MODIS) archive over 2000–2016. The atmospheric UHI is obtained from screen-level temperature provided by the Urban Heat Island Arctic Research Campaign (UHIARC) observational network over 2015–2018. Several other UHI studies are included for comparisons. The analysis reveals strong and persistent UHI during both summer and winter seasons. The annual mean surface UHI magnitudes vary from −0.6 ∘C (Hammerfest) to 4.3 ∘C (Murmansk). Thus, the observed UHI is likely an important climatic factor that must be included in future adjustment of urban construction, safety, and environmental quality codes.

Improving dialogue among researchers, local and indigenous peoples and decision-makers to address issues of climate change in the North

The Circumpolar North has been changing rapidly within the last decades, and the socioeconomic systems of the Eurasian Arctic and Siberia in particular have displayed the most dramatic changes. Here, anthropogenic drivers of environmental change such as migration and industrialization are added to climate-induced changes in the natural environment such as permafrost thawing and increased frequency of extreme events. Understanding and adapting to both types of changes are important to local and indigenous peoples in the Arctic and for the wider global community due to transboundary connectivity. As local and indigenous peoples, decision-makers and scientists perceive changes and impacts differently and often fail to communicate efficiently to respond to changes adequately, we convened a meeting of the three groups in Salekhard in 2017. The outcomes of the meeting include perceptions of how the three groups each perceive the main issues affecting health and well-being and recommendations for working together better.

Trace elements composition of surface snow in the polar zone of northwestern Siberia: the impact of urban and industrial emissions

In order to evaluate the level of atmospheric pollution in the north of Western Siberia, we studied the composition of urban snow in the vicinity of the Tazovsky settlement as well as in the area of Zapolyarnoye-the largest natural gas field in Russia in terms of a total extraction volume. Our results indicate that anthropogenic activities have caused an increase in electric conductivity and pH values of meltwaters. Concentrations of dissolved and particulate forms of trace elements (Fe, Mn, Ni, Cr, Cu, Pb, Zn, and Cd) were determined using atomic absorption spectroscopy. Dissolved forms of Cd, Zn, and Mn and particulate forms of Cu, Fe, and Ni prevailed in meltwaters of background territories. Human-affected territories were characterized by a predominance of particulate forms of trace elements (except Cd), which indicated increased dust deposition rates. For Cu, Mn, and Fe, mean values of contamination factor (CF) exceeded background levels by 4.4, 4.7, and 6.6 times, respectively. At some sampling sites, concentrations of trace elements exceeded background levels by 10-111 times. The concentration of Zn in our study area was higher than those in other oil and gas fields located in polar and boreal regions. The Cd concentration in the vicinity of the Tazovsky settlement was higher than those in other cities of Western Siberia. The data obtained in the present study on concentrations of soluble and particulate forms of trace elements in snow will be valuable for environmental protection in Russia's Arctic territory.