No abstract

No abstract

Excessive nutrient input to surface water, including nitrate, exacerbates water eutrophication. Clarifying the proportions of different nitrate sources in the aquatic environment is critical for improving the polluted water. However, nitrate sources in river basins are very complex and not clearly understood. In this study, nitrogen concentrations and nitrate isotopic compositions were determined to estimate the spatiotemporal variation in nitrate sources in the Yuntaishan River basin, Nanjing, East China, from March 2019 to January 2020. The results showed that the concentrations of total nitrogen (TN), ammonium (NH4+-N), and nitrate (NO3−-N) changed in the ranges of 0.53–18.0 mg/L, 0.01–15.4 mg/L, and 0.06–9.3 mg/L, respectively, wherein NO3−-N was the main nitrogen form. Higher nitrogen concentrations appeared in winter and in the downstream parts of the river. In the entire river basin, the NO3−-N mainly originated from sewage (67%) and soil (26%), with clear spatial variations. NO3−-N in the Yunba sub-watershed was mainly derived from sewage (78%), which was higher than that in other tributaries, i.e., Shengli River (44%) and Yangshan River (49%). This was due to the fact that that Shengli and Yangshan sub-watersheds were covered by urban areas and were equipped with a complete sewage treatment system. In addition, the contributions of sewage to NO3−-N rose from 60% upstream to 86% downstream, suggesting the increasing influence of the point source of sewage. The results showed that 53% of NO3−-N in the basin outlet originated from the point source of sewage near the M4 site. Sewage contributed 75% of NO3−-N in the rainy season and 67% of NO3−-N in the dry season, suggesting the weakly temporal variation. Our results highlight the spatiotemporal variations in sources of NO3−-N. These results will aid in the development of measures needed to control nitrogen pollution in river basins.

Cold chain distribution is always well-known as the "Mount Everest" in international logistics industry, while the rapid development in recent years of domestic meat, frozen food, cold drinks industry and dairy industry brought a leapfrog growth of cold chain logistics, which respectively stimulated the need for logistics outsourcing service from Third Party Logistics. Those companies demanding for exploiting cold chain business on one hand requires a complete set of refrigerated logistics chains, on the other hand also requires enterprises to establish a good and professional transport system with refrigerated operation equipment, which are precisely the weakness of manufacturing enterprises. Thus, outsourcing of cold chain logistics to a third party is the best choice for companies to focus on its core business. By analyzing the bulletins of International Cold Chain Logistics Summits, this paper shows the problems of cold chain industry in China and points out the potentials for its future development. It further analyzes the feasibility of launching cold chain business of Deppon Logistics. The purpose is to offer some suggestions to work out the barriers and set up a modern operation system under the big data age in Deppon.

No abstract