Underwater blasting technology has been widely used in inland waterway improvement projects. However, due to the particularity and complexity of underwater blasting, it is difficult to predict the transmission patterns of underwater blasting shock waves. Therefore, based on the Guoyuan Port Phase II project in Chongqing, the transmission patterns and influencing factors of underwater drilling blast shock wave pressure were investigated by field monitoring and numerical simulation. In this study, a total of 45 groups of shock wave pressures were measured, and the underwater shock wave pressure transmission formula obtained through data fitting was P = 27.39 × (Q1/3/R)1.25. Furthermore, the shock wave pressure transmission process in water was numerically simulated, and the simulation results were verified using field monitoring data. The results showed that the simulation and measured results were consistent. Finally, the influence of water depth, flow rate, and flow direction on the transmission pattern of shock wave pressure was analyzed, based on a numerical simulation method. The results showed that the more blastholes there are, the smaller the peak pressure of the shock wave. The lower the depth of blasting, the faster the decay of shock wave pressure. The flow rate has less effect on the shock wave pressure. At flow rates of 1, 2, 3, and 4 m/s in the range of 0 to 50 m, the shock wave pressure in the upstream flow decreased by 5.7%, 7.4%, 9.1%, and 10.2%, respectively, compared with that in the downstream flow. This study provides a theoretical basis for safety control of underwater drilling blasting engineering in inland waterways.

Due to the implementation of many regulation projects in the upper Yangtze River, the vessel transit capacity has been improved visibly. The trend of large-scale ships becomes more obvious, leading to an increase of the traffic flow and underwater noise density in the upper Yangtze River, which has significant influence on the habitat of many aquatic animals, especially for the endemic fish. Thus, it is crucial to accurately assess the ship underwater noise conditions for the ecological protection in the upper Yangtze River. In this study, the underwater noise from different types of ships under the normal operating conditions in the Chaotianmen-Fuling section has been monitored using the underwater noise tracking and monitoring system. The results indicate that the frequency of underwater radiation noise from ships is concentrated in the range of 200Hz~1300Hz, and the sound pressure level is distributed in the range of 148.50dB~172.86dB, and the underwater radiation noise energy is concentrated in the low frequency part. The sound pressure level of underwater radiation noise from ships is proportional to the ship speed and ship tonnage. The research results can provide theoretical support for the subsequent research on the underwater noise distribution in such waterways as well as the ecological route selection.

Aims The efficiency of fertilizer nitrogen (N) use strongly depends on soil pH and affects both agricultural production and environmental pollution control. However, the effect of soil pH on N use efficiency (NUE) remains unclear. Methods We compared crop yield, N uptake, NUE, and the N input-output balance in a Chinese cabbage-maize cropping system in a field experiment from 2011 to 2016 along a pH gradient (alkaline (pH 8.32), near-neutral (pH 6.56) and acidic soil (pH 5.91)). Results Mineral fertilization had the worst effect in acidic soils, because it significantly decreased soil pH, as well as decreased crop yield, N uptake, and NUE. Combined chicken manure-mineral fertilization was most favorable irrespective of soil pH because it increased soil quality (e.g., high total N and organic C contents) and maintained a neutral soil pH. Chicken manure treatment was most appropriate in acidic soils because it increased pH by 2.03 units, up to 13% crop yield, and increased N uptake and NUE than that in alkaline and near-neutral soils. Under manure treatments, the N surplus was the lowest in acidic soil. Under mineral fertilization, however, the N surplus in acidic soil was the highest. Conclusions We conclude that combined organic-mineral fertilization in alkaline, near-neutral, and acidic soils is a promising strategy that not only increases the crop yield, N uptake, and NUE but also decreases the N surplus. Manure fertilization is also recommended as an efficient strategy in acidic soils to increase crop yield and NUE by improving soil pH.

The inter-regional freight volume is a crucial factor for transportation infrastructure planning and investment decision-making. However, existing studies on freight volume estimation have mainly focused on the total freight volume within a specific region, without taking freight flow into consideration. In this research, a gravity model was employed to estimate the inter-regional trade coefficient matrix based on the input–output tables of the 31 provinces in China in 2017. The inter-regional freight volume was then determined by converting the value flow into freight flow. To determine the model parameters, we used information from 2017 and subsequently validated the results using dates from 2012 to 2020. We also studied the impact of industrial structure change on freight volume by simulating dates from the aforementioned model in 2017. The results indicated that the model can effectively simulate inter-regional freight volume while taking into account the influence of industrial restructuring.