水面蒸发的盐度效应及其影响因子分析

The Effect of Salinity on Water Evaporation and the Associated Determinants

【目的】明确滨海盐碱地水面蒸发(E)的盐度效应及其主要影响因子。【方法】于2018年5-10月设置了盐分梯度为1、3、5、10 g/L和20 g/L的水面蒸发试验。通过自制的20 cm蒸发皿获取不同质量浓度咸水的水面蒸发量,利用灰度关联分析确定了气象因子与不同质量浓度咸水蒸发量的关联程度,分别于晴天和阴天,选取关联度前三的气象因子和质量浓度(S)对水面蒸发量进行通径分析。【结果】(1)咸水质量浓度的升高会增加液面的表面张力,导致水面蒸发量降低,观测期内1 g/L咸水的累积蒸发量相比于20 g/L增加了97.66 mm;(2)水面蒸发与辐射强度(R)、风速(W_(s))、饱和水汽压差(VPD)和空气温度(T_(a))呈正相关关系,与相对湿度(RH)、大气压力(P_(r))和质量浓度(S)呈负相关关系;(3)辐射强度是滨海盐碱地水面蒸发的主要影响因子,W;和VPD分别于晴天和阴天对水面蒸发起到间接作用。【结论】咸水质量浓度的升高增加了水面的表面张力,造成了质量浓度高的咸水蒸发量的降低;相比于质量浓度对水面蒸发的影响,气象因子的影响作用更为显著,其中,辐射强度是滨海盐碱地水面蒸发的主要影响因子。

【Objective】Water evaporation is influenced by many factors, besides meteorological factors, salinity also has an important effect on it. The aim of this paper is to study its impact on water evaporation in coastal saline-alkali land.【Method】The experiment was conducted by setting a salinity gradient ranging from 1 to 20 g/L from May to October in 2018. Evaporation from water with different salinity was measured using a in-house 20 cm evaporation pan, and the correlation between meteorological factors and the evaporation was determined by gray relational analysis.【Result】(1)Increasing water salinity increased water surface tension,thereby leading to a decrease in water evaporation. The cumulative evaporation with 1 g/L of saline water over the experimental period increased by 97.66 mm compared with that with 20 g/L of saline water.(2)Evaporation was positively correlated with radiation intensity(R), wind speed(W_(s)), vapor pressure deficit(VPD), and air temperature(T_(a)), while negatively correlated with relative humidity(RH), atmospheric pressure(P_(r)) and Salinity(S).(3)Among all factors we compared, R affected the evaporation from the coastal saline-alkali land more. We also found that W;and VPD affected the evaporation on sunny and cloudy days.【Conclusion】Increase in water salinity increased water surface tension, resulting in a decrease in water evaporation.Compared with water salinity, the meteorological factors affected the evaporation more, especially the radiation intensity.