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China is the biggest emitter of greenhouse gases (GHGs) in the world, and agricultural GHG emission accounts for nearly a fifth of the total emission in China. To understand the carbon absorption and emission characteristics of agricultural production systems in those arid oasis areas, a typical representative city in northwestern China, Zhangye City, was selected for study.The emission factor method was used to analyze and calculate the characteristics of changing carbon emission dynamics in the whole agricultural production system in Zhangye city region (38,592 km2) from 2010 to 2021.The results revealed that carbon emissions during agricultural planting mainly come from fertilizers, which account for the highest proportion (47.9%) of total carbon emissions in agricultural planting. Animal enteric fermentation emissions from local livestock farming are the main contributor (86%) to GHG emissions. The annual average carbon absorption intensity is 4.4 t C-eq ha−1 for crop and 2.6 t C-eq ha−1 for the agricultural production system. The ratio of total carbon emissions from agricultural production to carbon sequestration of crops is 1:1.7. We find that the total carbon sequestration slightly exceeds its total carbon emissions in the study region, with an annual average of 41% for its sustainable development index. Carbon emissions of the agricultural production system in this oasis area are mainly driven by the livestock industry, mostly CH4 emissions from cattle raising.Reducing the local carbon emissions from the livestock industry, typically the cattle raising, will play a crucial role in reducing carbon emissions from this local agricultural production system and maintaining its net positive carbon balance. [ABSTRACT FROM AUTHOR]

Atmospheric nitrogen (N) deposition has increased dramatically due to increased human activities since the industrial revolution. However, it is still unclear what the responses of soil nitrous oxide (N2O) is to long-term elevated N deposition in a temperate grassland. Here, we conducted an in situ field experiment to investigate these responses to long-term high N addition on a temperate steppe in Inner Mongolia, China, from April 2017 to October 2018. Soil N2O emissions significantly increased by long-term N addition, use of structural equation modeling (SEM) showed that topsoil (0-5 cm) NH4+-N content was the most important limiting factor for N2O emission. Our results indicate that long-term high N addition showed a significantly increase in N2O emission in this temperate grassland.

The present work was aimed to study the effect of melatonin pre-treatments on oxidative stress modulation, cadmium (Cd) accumulation, and tolerance in Abutilon theophrasti Medicus under the hydroponic system. Application of substances that can modulate the harmful effects of Cd on plant yield and reduce its accumulation in the edible parts is of particular importance. Therefore, the Abutilon pre-treated with 0.1mM melatonin were exposed to 200μM, 400μM, 800μM Cd. Our results showed that 0.1mM melatonin led to positive effects on 200μM and 400μM Cd tolerance, including a significant increase in root activity andperoxidase (POD) activity and a significant decrease in malondialdehyde (MDA) content. Withthe help of melatonin, the enrichment factor (BCF) significantly decreased, reducing the content in the ground and roots. At least in our experiment conditions, this information appears to be useful for healthy food production.

Phenol is widely used in China, it not only pollutes the environment, but also accumulates toxic substances in the human body through the food chain, further harming humans. In this experiment, a strain of high-efficiency low-temperature degradation phenol bacteria B5 was selected from the soil contaminated by organic matter of Lanzhou. Through research methods such as Gram staining observation, DNA extraction, PCR amplification, sequencing and comparison, it was found that this strain was Pantoea agglomerans. Through the subsequent optimization of degradation conditions, it was found that the B5 strain can degrade 500mg/L of phenol to 24.8mg/L in 36h. The ability to degrade phenol is stronger between pH5.5-pH6.0, and the ability to degrade phenol is higher in a medium containing 4-8g/L sodium chloride. This research can provide certain theoretical guidance for phenol degradation.

Along with the rapid advance of urbanization, urban disease appear. For detection city disease earlier, the ecological city is put in this article. The ecological city is regarded as the human body to plan, construct and manage city with the thought of “law in the human body”. The city’s population, land, water, air, transportation, culture, are considered as the body’s nerves, muscles, blood, breath, limbs and the vigor, respectively. And a quantitative standard is determined for each object of study. If the quantitative value is abnormally large or small, it indicates that the city is unhealthy, the early warning system for city will put forward, the causes will lookup and the treatment will give.

Soil desertification is an important factor leading to soil degradation and environmental problems such as atmospheric or water pollution. Conservation agriculture, such as crop rotation and conservation tillage, can reduce soil erosion and nutrient loss caused by wind in semi-arid regions. However, the relationships between the loss of soil and nutrients and surface vegetation characteristics are frequently obtained according to a short-term simulation experiment, which makes the application of the conclusions limited. In this study, we conducted a 4-year field experiment continuously with three crop rotations, i.e., spring wheat (Triticum aestivum L.) cropping, alfalfa (Medicago sativa L.) cropping, and fallow when previous rapeseed crops (Brassica napus L.) were being harvested; measured the surface vegetation characteristics, soil nutrients, and loss of soil and nutrients caused by wind; and analyzed their variations and quantitative relations. The findings of this study indicated that the coverage, height, and biomass of the aboveground vegetation in three rotations in the spring and autumn had significant differences, and the rank order was fallow field < wheat field < alfalfa field. With the extension of growing years, the soil organic carbon (SOC) and total nitrogen (TN) of a 0–5 cm soil layer all increased to varying degrees and had significant differences among the rotations during the late stages of the experiment (p < 0.05), while the changes in the total phosphorus (TP) and total potassium (TK) were small, and their values had decreasing trends. The available nitrogen (AN) and available phosphorus (AP) decreased first and then increased during the experimental period, while the available potassium (AK) had an increasing tendency. The increase in soil nutrients in the alfalfa field was the highest during the whole experiment period, while the loss of soil and nutrients (SOC, TN, TP, and TK) was the lowest, followed by the wheat and fallow fields. There were significant negative correlations between the surface vegetation characteristics and the loss of soil and nutrients (p < 0.01), while the correlations between soil loss and the loss of soil nutrients were significantly positive. In summary, alfalfa crop rotation can obviously reduce the loss of soil and nutrients in semi-arid areas, which is conducive to the sustainability of agroecosystems. [ABSTRACT FROM AUTHOR]