Purpose To study the corrosion behavior of pipeline steel in coastal areas, a tidal seawater macro-cell corrosion device was built using a cycle soaking tank and a macro-cell corrosion facility to simulate the corrosion behavior of pipeline steel in a simulated coastal environment (dry and wet alternations during seawater-soil corrosion macro-cell processes). Design/methodology/approach The corrosion behaviors were studied via the weight loss method, electrochemical methods and morphological observations on corrosion. Findings The results show that during the initial stage of tidal seawater/soil macro-cell corrosion process of the X65 steel, the working electrode on the seawater side is the anode of the macro-battery. As corrosion progresses, the anode and the cathode of the macro-battery become inverted. As the area ratio and the dry – wet ratio increase, the time of anode and cathode inversion shortens. Galvanic current density decreases as the dry – wet ratio increases and increases as the area ratio increases. The corrosion process of macro-cell is affected by the reversal of anode and cathode. After the reversal of anode and cathode, the corrosion rate is mainly controlled by dry – wet alternating corrosion. Originality/value The corrosion behavior of a pipeline steel in a coastal environment was studied using a tidal seawater macro-cell corrosion device. The synergism effect between the tidal seawater and seawater-soil macro-cell on corrosion behavior was clarified.

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Unlike traditional phosphorus fertilizers, a new fertilization concept which is based on the complexation effect of β-cyclodextrin (β-CD) has been developed in this paper. For this purpose, the UV−vis absorption spectrum was applied to study the inclusion behavior of monoammonium phosphate (MAP) with β-CD. The results revealed that MAP with β-CD can form a 1:1 stoichiometry inclusion compound; the applicable inclusion time was 10 h, and the formation process of the inclusion compound was an exothermic process. The 1:1 β-CD-MAP inclusion compound was further characterized by FT-IR, 1 H NMR, and 31 P NMR. The adsorption−desorption processes of MAP without and with β-CD in the soil solution was studied. It was found that the K f value of MAP with β-CD was 3.293 and was lower than the K f value of MAP without β-CD; the n value of MAP with β-CD was 0.8050 and was higher than the n value of MAP without β-CD. Furthermore, the total percentages of MAP desorbed (η) at the different employed MAP initial concentrations in the presence of β-CD were 9.3%, 15.7%, and 18.6%, and were higher than the η in the absence of β-CD, respectively. The results showed that the effectiveness of MAP has been improved in soil and the presence of β-CD can play an important role in the adsorption of MAP on soil surfaces. In addition, the morphologies of soil particles in the presence of MAP and the β-CD-MAP inclusion compound were observed by SEM. SEM observations revealed that the β-CD-MAP inclusion compound fertilizer system could over soil hardening.

Abstract. The soil quality status of three typical land-use types (grassland, forestland and cultivated land) in Shiqu County is surveyed, including soil pH, soil calcium carbonate, cation exchange capacity, organic matter, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus, available potassium and microelements levels. The soil quality of different land-use types is evaluated by the soil quality index. The investigation results indicate the different land-use types display significant differences in soil fertility, and the Shiqu County soil is serious lack of microelements. In addition, the soil quality index of different land-use types is in order of grassland (73.2%) > forestland (62.2%) > cultivated land (27.1%).

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