Environmental Engineering Reference
In-Depth Information
In order to identify the character and influence factors of CO
2
and CH
4
emission in salt
marsh, we evaluated the GHGs fluxes and in-situ measured the environmental factors in the
coastal salt marsh of the Yellow River Delta in 2102. The objectives of this study were to: (i)
to study the variability of soil-atmosphere exchange of CO
2
and CH
4
in salt marsh of the
Yellow River Delta; (ii) to identify the driving environmental factors and processes so as to
aid the future development of process-based models of salt marsh biogeochemical function
and eco-restoration.
2.
M
ATERIAL AND
M
ETHODS
2.1. Study Site
The study was conducted at 1200 Station of National Nature Reserve of the Yellow River
delta (37ﾰ35′N~177 38ﾰ12′N, 118ﾰ33′E~119ﾰ20′E) in DongYing city, ShanDong province,
China. The reserve is the typical area of the coastal salt marshes, and the climate in this area
is the typical continent monsoon. The average temperature is 12.1°C, and the annual
precipitation is 551.6mm and from July to August is the rainy season. Soil physical and
chemical properties of the sample were shown in table 1.
2.2. Experiment Design
We measured the GHG emissions of bare land,
T. chinensis
community,
S. salsa
community and
P. australis
community by using opaque, static, manual stainless steel
chambers and gas chromatography techniques from April to December 2012. The static
chamber was made of stainless steel and consisted of two parts. Before observation, we
inserted a square box (without a top and bottom), which served as a collar for supporting
chamber the sampling chamber, directly into the soil with 5 cm exposed above the soil
surface and kept in the soil during the entire experiment. During observations, the chamber
(without bottom) was placed into the collar and filled water to prevent leakage, and the
vegetation was covered in the chamber. In order to reduce temperature variation within the
chamber, we wrapped the champers with a quilt. Inside the chamber, there was a thermometer
sensor to measure temperature and a fan to make turbulence. On the sampling date, Sampling
campaigns were undertaken at 8:00, 10:00, 12:00, 14:00, and 16:00. The air samples inside
the chamber were collected every 20 min over a 60 min period, and transported back to the
laboratory and analyzed within 36h using gas chromatography (Agilent 7890A). There were
correlations between the gas concentration and sampling interval. Only when the correlation
coefficient (R) of the gas greater than 0.95, can they be used. The gas flux was calculated
according to the following equation (Song et al., 2006):
dc
M
P
T
F
0
H
dt
V
P
T
0
0
