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Abstract Background Global warming caused by greenhouse gas emissions affects sustainable human development. Agricultural practices are important source of greenhouse gases (GHG). Nitrous oxide (N2O) contributes greatly to farming GHG. It is important to find a potential and practical biological technique that mitigate N2O emissions in an environment friendly way. Methods N2O-inhibiting fungi were isolated and identified in the lab. The fungi were added into the soil and placed in the incubator and interval gas sampling was analyzed by gas chromatograph. Results Fungus coding Z17 was identified molecularly with the same evolutionary branch on the phylogenetic tree with Trichoderma asperellum by BLAST comparison on NCBI GenBank. In the lab simulation, the N2O emission flux was decreased by 28.18–47.16% by inoculating Trichoderma asperellum with 106 cfu·g−1, 5 × 106 cfu·g−1 and 107 cfu·g−1 fungal spores in the soil compared to the control. Conclusions The N2O-inhibiting fungus Z17 was identified as Trichoderma asperellum, capable of suppressing N2O emissions from soil with at least 106 CFU·g−1 soil. The best N2O-inhibiting effect was on day 9 of inoculation into soil because most of the fungal numbers were present in soil. Graphical Abstract

Air quality data from city clusters in the fast developing Yangtze River Delta (YRD) region of China during 1996-2003 were analyzed, with a cross-border transport study using the Regional Acid Deposition Model System (RegADMS). Investigations show that the annual average concentrations of SO2, NO2, PM10 are 12 to 64 /m3, 13~57 /m3, 79~184 /m3, respectively. As the primary air pollutants in the target area, surface NO2 levels increased by 13% while PM10 levels decreased by 39% from 1996 to 2003. The surface SO2 concentration showed fluctuations during the study period, reaching a minimum in 1999 and rising again in 2003. Acid rain still remains an important atmospheric environmental issue. The frequency of acid rain was about 23.5~36.7%, and the pH value of precipitation ranged from 5.09 to 5.48, with little change in these years. Modeling studies indicated that sulfur deposition and nitrogen deposition were in the ranges 0.5-10 g/m2/yr and 0.2-5 g/m2/yr, respectively; these levels exceed the critical load in some regions. The trans-boundary transport of sulfur deposition and nitrogen deposition due to SO2 and NOx emission among city clusters (Shanghai and the other 8 cities in Jiangsu Province, including Nanjing, Wuxi, Changzhou, Suzhou, Nantong, Yangzhou, Zhenjiang, Taizhou) in the YRD region was significant. The emission from Shanghai contributes 5%~29% of sulfur deposition and 3%~30% of nitrogen deposition in the 8 cities, while the 8 cities contribute 27.5% of sulfur deposition and 20.2% of nitrogen deposition in Shanghai.

Atmospheric sulfur deposition in East China was studied using the Regional Acid Deposition Modeling System (RegADMS) with a horizontal resolution of 75 km. A one-year run was performed for the year 2000. As a result, the annually averaged Vd for SO2 and SO4 2- are 0.34 and 0.27 cm s -1, respectively. The calculated Vd for SO2 and SO4

Atmospheric dry deposition is an important nitrogen (N) input to farmland ecosystems. The main nitrogen compounds in the atmosphere include gaseous N (NH3, NO2, HNO3) and aerosol N (NH4 +/NO3 −). With the knowledge of increasing agricultural effects by dry deposition of nitrogen, researchers have paid great attention to this topic. Based on the big-leaf resistance dry deposition model, dry N deposition velocities ( Vd) in a typical red soil agro-ecosystem, Yingtan, Jiangxi, Southeastern China, were estimated with the data from an Auto-Meteorological Experiment Station during 2004–2007. The results show that hourly deposition velocities ( Vdh) were in the range of 0.17–0.34, 0.05–0.24, 0.57–1.27, and 0.05–0.41 cm/s for NH3, NO2, HNO3, and aerosol N, respectively, and the Vdh were much higher in daytime than in nighttime and had a peak value around noon. Monthly dry deposition velocities ( Vdm) were in the range of 0.14–0.36, 0.06–0.18, and 0.07–0.25 cm/s for NH3, NO2, and aerosol N, respectively. Their minimum values appeared from June to August, while their maximum values occurred from February to March each year. The maximum value for HNO3 deposition velocities appeared in July each year, and Vdm(HNO3) ranged from 0.58 to 1.31 cm/s during the 4 years. As for seasonal deposition velocities ( Vds), Vds(NH3), Vds(NO2), and Vds(aerosol N) in winter or spring were significantly higher than those in summer or autumn, while Vds(HNO3) in summer were higher than that in winter. In addition, there is no significant difference among all the annual means for deposition velocities ( Vda). The average values for NH3, NO2, HNO3, and aerosol N deposition velocities in the 4 years were 0.26, 0.12, 0.81, and 0.16 cm/s, respectively. The model is convenient and feasible to estimate dry deposition velocity of atmospheric nitrogen in the typical red soil agro-ecosystem. [ABSTRACT FROM AUTHOR]

A 2-year monitoring study was conducted to estimate nitrogen deposition to a typical red soil forestland in southeastern China. The dry deposition velocities ( Vd) were estimated using big leaf resistance analogy model. Atmospheric nitrogen dry deposition was estimated by combing Vd and nitrogen compounds concentrations, and the wet deposition was calculated via rainfall and nitrogen concentrations in rainwater. The total inorganic nitrogen deposition was 83.7 kg ha − 1 a − 1 in 2004 and 81.3 kg ha − 1 a − 1 in 2005, respectively. The dry deposition contributed 78.6% to total nitrogen deposition, in which ammonia was the predominant contributor that accounted for 86.1%. Reduced nitrogen compounds were the predominant contributors, accounting for 78.3% of total nitrogen deposition. The results suggested that atmospheric inorganic nitrogen could be attributed to intensive agricultural practices such as excessive nitrogen fertilization and livestock production. Therefore, impacts of atmospheric nitrogen originated from agriculture practices on nearby forest ecosystems should be evaluated. [ABSTRACT FROM AUTHOR]

Regional climate model (RegCM2) and sulfur transport model (NJUADMS) were combined to simulate the distribution of anthropogenic sulfate aerosol burden over China, where a "look up table" method was applied to illustrate sulfate formation from S02-oxidation. Direct radiative forcing of sulfate aerosol was further estimated using the scheme suggested by Charlson et al (1991). Investigations show that the annual average total sulfate column over mainland China is 2.01 mg/m2 with high value in East and Central areas (more than 7 mg/m2). The annual average direct radiative forcing of China is about - 0.85 W/m2. The forcing can reach -7 W/m2 in Central and East China during the winter season. Total sulfate column shows significant seasonal variations with winter maximum-summer minimum in the Southern part of China and spring maximum-autumn minimum in the northern part of China. Strong seasonal cycles of direct radiative forcing are also found due to the influence of total sulfate column, cloud, relative humidity and the reflectivity of underlying surface. [ABSTRACT FROM AUTHOR]