The in situ observation of modelled sea ice drift characteristics in the Bohai Sea

Sea ice drift is mainly controlled by ocean currents, local wind, and internal ice stress. Information on sea ice motion, especially in situ synchronous observation of an ice velocity, a current velocity, and a wind speed, is of great significance to identify ice drift characteristics. A sea ice substitute, the so-called "modelled ice", which is made by polypropylene material with a density similar to Bohai Sea ice, is used to complete a free drift experiment in the open sea. The trajectories of isolated modelled ice, currents and wind in the Bohai Sea during non-frozen and frozen periods are obtained. The results show that the currents play a major role while the wind plays a minor role in the free drift of isolated modelled ice when the wind is mild in the Bohai Sea. The modelled ice drift is significantly affected by the ocean current and wind based on the ice–current–wind relationship established by a multiple linear regression. The modelled ice velocity calculated by the multiple linear regression is close to that of the in situ observation, the magnitude of the error between the calculated and observed ice velocities is less than12.05%, and the velocity direction error is less than 6.21°. Thus, the ice velocity can be estimated based on the observed current velocity and wind speed when the in situ observed ice velocity is missing. And the modelled ice of same thickness with a smaller density is more sensitive to the current velocity and the wind speed changes. In addition, the modelled ice drift characteristics are shown to be close to those of the real sea ice, which indicates that the modelled ice can be used as a good substitute of real ice for in situ observation of the free ice drift in the open sea, which helps solve time availability, safety and logistics problems related to in situ observation on real ice.

Effect of Turbulence on Phosphorus Release from Estuarine Sediment

Phosphorus (P) is an essential element for growth in aquatic ecosystems but the dynamics of phosphorus cycling within catchments is poorly constrained. The aim of this study was therefore to develop analytical tools to investigate the release of inorganic and organic phosphorus species in rivers and estuaries during resuspension events such as storm, wind and tidal induced turbulence. To achieve this aim, laboratory simulations using a mini-annular flume coupled with segmented flow analyser detection were performed. To collect SPM (suspended particulate matter), a specially designed specimen box was deployed in the River Tamar (Devon, UK). Inorganic and total phosphorus were determined using segmented flow analyser methods adapted for use with acidified persulfate digests. The segmented flow analyser had a detection limit (3 s.d.) of 0.53 μg P L-1 for inorganic P and 1.5 μg P L-1 for total P. The mini-annular flume provides a suitable method for laboratory simulations, e.g. we managed to get low blanks and good experimental reproducibility, and are also able to see changes in P species within analytical precision. Results showed that increase of shear stress (or SPM) caused release of inorganic P from sediment. This could be used as a fact to build a model to study P dynamics during resuspension events in the river and estuaries environment.

Do Water Matrix and Particulate Buffering Capacity Affect the Rate and Extent of P Release?

The aim of this study was to investigate the release of inorganic and organic phosphorus species from particles in rivers and estuaries during resuspension events such as storm, wind and tidal induced turbulence. To achieve this aim, laboratory beaker experiments were designed with autoanalyzer 3 (AA3). The study first investigates phosphorus equilibration in ultra-pure water (UHP) water, biotic river water and abiotic river water under short term and long term conditions. Then, three typical organic and inorganic phosphorus compounds were selected (orthophosphate, phytic acid (PTA) and β-D-glucose-6-phosphate monosodium salt (G-6-P)) to simulate the effect of addition input to river and estuaries in the time period of 150 h. The results show that in a turbulent river, dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP) will reach equilibrium between the particulate matter and the water column within 24 h. Additional input of DIP or DOP to the river, has different effects to the river nutrients balance. The buffering capacity of the suspended particulate matter (SPM) plays an important role and behavior difference to the inorganic and various organic phosphorus compounds.

Consumers' Perception of Risks,Awareness of Products and Willingness to Pay: A Case Study of Organic Milk

Based on survey data from Ji'nan city and some other cities in Shandong province,this paper conducted a research on consumers' perception degree of the food safety risk,and the awareness degree about organic food. Then taking organic milk as an example,the factors affecting the customers' buy willingness to pay for organic milk were analyzed by binary logit model and the willingness to pay was also calculated. The results show that the consumers' food safety risk perception degree is high,and the awareness about organic food is low. The consumers' age,level of education,whether the family has children below 12 years old,whether the family has a man( woman) older than 60years,health situation self-evaluation,organic food cognition and food safety risk perception have significant effect on customers' willingness to pay organic food. According to the calculation,the consumers were willing to pay a price premium of 60% for organic milk above ordinary milk.

Effects of Water-Soluble Fertilizer on Yield and Quality of Asparagus in Greenhouse under Chemical Fertilizer Reduction

In order to understand the effects of water-soluble fertilizer on the yield and quality of asparagus in greenhouse,taking conventional fertilization as a control,in the case of a decrease in total nutrient of chemical fertilizer,the application effect of humic acid-contained watersoluble fertilizer in asparagus was studied by experiment. The results show that,under the condition that the conventional fertilizer was reduced by 30% and 50%,the application of humic acid-contained water-soluble fertilizer to asparagus in greenhouse can improve the shoot length,single shoot weight,shoot diameter and shoot growth( degree of scatter) of asparagus,improve effectively the quality of asparagus( e. g. increasing the content of vitamin C and decreasing the nitrate content in asparagus shoots),and increase the yield of asparagus shoots( by 2 583 and 4 218 kg/ha compared with the conventional fertilization,with growth rates of 10. 3% and 16. 8%,respectively).

The research of sea-land breeze (SLB) on the west coast of Bohai Bay based on field observation

Four automatic meteorological stations were set up in a line from beach to inland perpendicular to the west coast of Bohai Bay. Wind direction and velocity at altitudes of 2 m, 4 m and 12 m were surveyed with 10 minute intervals. On ＂Sea-Land Breeze＂ （SLB） days, the transition from sea breeze to land breeze was very evident in the study area. Direction of sea breeze was basically perpendicular to the coast and mainly from the ENE and E. Duration of sea breeze varied by the stations＇ distance to the coastline, and the near-coast wind velocity was larger than that of the inland and decreases as it reaches inland. There was increased development of SLB on sunny days than on overcast days. The term ＂Climatic Coastal Zone＂ can be defined for the area influenced by SLB, which reaches more than 74 km inland on a typical SLB day but less than 10 km on a non-typical SLB day.

Flash Flood Risk Assessment and Driving Factors:A Case Study of the Yantanxi River Basin,Southeastern China

In the context of climate change,the impact of extreme precipitation and its chain effects has intensified in the southeastern coastal region of China,posing a serious threat to the socioeconomic development in the region.This study took tropical cyclones–extreme precipitation–flash floods as an example to carry out a risk assessment of flash floods under climate change in the Yantanxi River Basin,southeastern China.To obtain the flash flood inundation characteristics through hydrologic–hydrodynamic modeling,the study combined representative concentration pathway(RCP)and shared socioeconomic pathway(SSP)scenarios to examine the change of flash flood risk and used the geographical detector to explore the driving factors behind the change.The results show that flash flood risk in the Yantanxi River Basin will significantly increase,and that socioeconomic factors and precipitation are the main driving forces.Under the RCP4.5-SSP2 and RCP8.5-SSP5 scenarios,the risk of flash floods is expected to increase by 88.79%and 95.57%,respectively.The main drivers in the case study area are GDP density(q=0.85),process rainfall(q=0.74),asset density(q=0.68),and population density(q=0.67).The study highlights the influence of socioeconomic factors on the change of flash flood disaster risk in small river basins.Our findings also provide a reference for regional planning and construction of flood control facilities in flash flood-prone areas,which may help to reduce the risk of flash floods.