Specifications

Authors: Pan, Yanxin1 ; Luo, Wan1 ; Jia, Zhonghua1 ; Li, Jin1 ; Chen, Yuan1/潘延鑫;罗纨;贾忠华;
李进;陈远
Author affiliation: 1 Northwest Key Laboratory of Water Resource and Environment Ecology,
Minstry of Education, Xi'an University of Technology, Xi'an 710048, China
Corresponding author: Luo, W. ([e-mail])
Source title: Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural
Engineering
Abbreviated source title: Nongye Gongcheng Xuebao
Volume: 29
Issue: 2
Issue date: January 15, 2013
Publication year: 2013
Pages: 81-87
Language: Chinese
ISSN: 10026819
CODEN: NGOXEO
Document type: Journal article (JA)
Publisher: Chinese Society of Agricultural Engineering, Agricultural Exhibition Road South,
Beijing, 100026, China
Abstract: In arid and semi-arid agricultural regions, artificial drainage is provided to maintain
salt balance of the saline farmland. As a result of poor drainage outlet in some sites, salt
accumulation in the drainage ditches often leads to salinity rising to a critical level that threatens
ecological functions of the ditch system. Periodic flushing with fresh water has been suggested to
slow down the process of salinity growth in such ditch system. But the effect of the slow moving
freshwater in drainage ditches on salt balance is unclear. In order to investigate the internal
mechanism of salt release in saline drainage ditches when freshwater is added, and to examine
the relationship of salt exchange between sediment and the overlying water under hydrostatic
condition, we conducted a laboratory study to measure spatial and temporal variations of salinity
in sediment and water interface with two experimental plexiglass columns. Each column is 15 cm
in (inner) diameter and 100 cm high. The column has a top cover to prevent the evaporation loss
of water. Sediments were filled to 30 cm thick at the bottom and covered by a freshwater layer of
65 cm. Room temperature was kept at (15±1)°C during the experiment. The sediment salinity was
measured by extracting the pore water through four sampling holes on each column wall.
Electrical conductivity of the sediment pore water and the overlying water were measured every
24 hours during the monitoring period. The sediments were taken from a saline agricultural
drainage ditches in Lubotan reclamation area in Shaanxi, China, where salinity elevation in the
drainage ditches presents a problem to the ecological functions of the ditch system, and
freshwater is available for salt flushing in the end of the irrigation season. We measured salinity
variations in water and sediments in the experimental columns continuously for a period of 648
hours, then calculated salt fluxes in the water and sediment interface based on measured
sediment properties. The monitoring data showed that there existed a linear salinity variation
zone (or the diffusion boundary layer) within 10 cm of the sediment and water interface, salinity
of water remained stable above 10 cm. The results also showed that salt diffusion within the
boundary layer slowed the salt release from the sediment, and the slowing effect increased with