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Due to the difficulty of quantifying the temporal and spatial variations of the sewage sources of Taihu Lake, this paper collected water samples from Gonghu Bay and Meiliang Bay, in the northeast of Taihu Lake and from the inflow river of Wangyu River from January to December in 2012 and applied stable isotope techniques to trace the sources of the nitrogen pollutants. At the same time, a two-end-member mixing model of isotopes was used to determine the sources of domestic sewage. According to the results of nitrogen isotope values in the sampling points, the annual proportion of the sewage sources of the Meiliang Bay, Gonghu Bay and Wangyu River is 17.2%, 15.3% and 19.7%, respectively. More than 80% of the nitrogen pollution sources are from non-domestic sewage, which indicates that domestic sewage is not the primary source of nitrogen pollution in Taihu Lake. In addition, these three regions have demonstrated higher ratios of sewage sources during the winter season than during other seasons. Therefore, domestic sewage that flows into Taihu Lake during the winter season should be strictly limited. In the meantime, it is necessary to strengthen the treatment of nitrogen sources other than domestic sewage sources. [ABSTRACT FROM AUTHOR]

[Display omitted] • Grassland degradation is the main reason for the decline in carbon storage. • The carbon storage of farmland has increased significantly. • The risk of carbon storage reduction in the future is still high. The carbon storage of terrestrial ecosystems is closely related to global climate change. Therefore, assessing the impact of land-use changes on carbon storage is instructive to reduce global carbon emissions. Taking an arid region in northwest China as an example, this paper analyzed the land-use changes in arid region from 1980 to 2015. It used the CA-Markov model to predict the land-use pattern from 2020 to 2050, the carbon storage and sequestration module in Integrated Valuation of Ecosystem Services and Tradeoffs (Invest) mode to assess and predict ecosystem carbon storage over the past 35 years and in the next 30 years and discusses the impact of land-use changes on the carbon storage of terrestrial ecosystems. The results showed that: (1) The high-value areas of carbon storage in arid region were primarily concentrated in grassland, forests and farmland, and the low-value areas of carbon storage were mainly in desert areas. (2) The carbon storage in arid region showed a downward trend. From 1980 to 2015, the carbon reserves of terrestrial ecosystems in arid region decreased by 90.95 Tg, and the net loss of carbon reserves from 2020 to 2050 was 14.72 Tg. Grassland degradation was the main reason for the reduction of carbon storage in arid region. (3) The carbon storage of farmland had increased significantly, but the expansion of farmland dominated by high carbon density grassland, wetland and forest, had reduced the overall carbon storage of the arid region. [ABSTRACT FROM AUTHOR]