生态环境 2004, 13(1): 40-42
Ecology and Environment
http://www.eco-environment.com
E-mail: editor@eco-environment.com
Carbon Mineralization and the Related Enzyme Activity of Soil in Wetland
XU Xiao-feng1, SONG Chang-chun1, SONG Xia2, SONG Xin-shan3
1. Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Sciences, Changchun 130012, China;
2. Institute of Geographical Science and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;
3. Department of Environmental Science and Engineering, Donghua University, Shanghai 20051, China
Abstract: The enzyme activity and carbon mineralization in the Calamagrostis angustifolia rhizosphere of soil in Sanjiang Plain,
China, were investigated in order to understand the microbial effect on carbon mineralization in wetland soil. The results suggest that
the β -Glucosidase, amylase and cellulase activities should be nice indicators for carbon cycling. The activities are high in the topsoil and low in the subsoil, decrease from rhizoplane soil to root-free soil for all three enzymes. Carbon is mineralized rapidly once
separated from field, then decrease in a short term, and stable after 2.5 h. The enzymes in microorganism are real catalysts for carbon
cycling.
Key words: carbon mineralizaion; basal respiration; enzyme activity; Sanjinag Plain
CLC number: X144；X172
Document code: A
Article ID: 1672-2175（2004）01-0040-03
Enzymes play a key role in soil nutrient transformation including carbon cycling. Plant residues, which usually make the
wetland types in Sanjiang Plain, and the most natural wetland
in China. So the spatial dynamic of enzyme related to carbon in
largest contribution of organic material to soils, contain both
labile and more recalcitrant compounds. The labile compounds
Calamagrostis angustifolia wetland is very important for carbon cycling research in China. However, there are only few
are usually soluble and easily degraded, such as simple sugars
just like glucose and amino acids[1]. The more recalcitrant
studies on this field[5] with none report about enzyme activity in
this area.
components are typically structural biopolymers such as starch,
cellulose and lignin [2, 3]. Since extracellular soil enzymes are
The objectives of this work were (1) analysis the Spatial
dynamics of enzyme activity related to carbon cycling and (2)
directly responsible for the initial processing of detrital carbon
and organic-bound nutrients[4]. Just like what showed in figure
carbon mineralization in Calamagrostis angustifolia rhizosphere soil in Sanjiang Plain, China, and (3) determine the
1, β -Glucosidase, amylase and cellulase are the major drives
relationship between the enzyme activity and carbon mineralization.
1
Plant residue input
Cellulose
Cellulase
Starch
Amylase
Celluobiose/triose
β-glucosidase
Maltose
Glucose
Figure 1 Decomposition of plant residue to macromolecular and
the related enzymes
for carbon decomposition and mineralization. β -Glucosidase
is the digestive enzyme for celluobiose/triose mineralization,
amylase is the digestive enzyme needed to digest carbohydrates
which is one of the three major food groups needed for proper
nutrition and cellulase is the digestive enzyme for cellulase
decomposition.
The Calamagrostis angustifolia wetland is one of main
Materials and methods
1.1
Site description
The study site is located in the Sanjiang Plain, the cross
zone of the Nongjiang river and Bielahong river which belongs
to a seasonal frozen zone, with the altitude 55.4~57.9 m, annual
mean temperature 1.9 ℃, non-frost period 125 d, and the annual
precipitation is 550~600 mm, concentrated in July and August,
and accounting for more than 65% of annual precipitation[6].
Soil samples were derived from the Calamagrostis angustifolia
wetland, located at the site (4735N, 13331E), the mire experimental station, CAS, in Sanjiang Plain. There are many
types of herbage swamp and dismal meadow in the area. Soil
types include meadow soil and peat soil.
1.2
Soil samples
Four soil cores were derived from Calamagrostis angusti-
folia wetland. We divided the soil cores into three layers, i.e.,
topsoil layer, root layer and subsoil layer, respectively. They
were air-dried in a controlled temperature room at 22 ℃ for
one day to make the wetland easily homogenized. Then the
plant debris, root and stone were removed, the samples were
Foundation item: The Knowledge Innovation Program of Chinese Academy of Sciences (KZCX1-SW-01; KZCX1-SW-19; KZCX1-SW-332)
Biography: XU Xiao-feng (1979-), male, B.S., major in carbon biogeochemistry and soil microorganism in wetland. E-mail: xuxiaofeng055@yahoo.com.cn
Received date: 2003-10-31
徐小锋等：湿地根际土壤碳矿化及相关酶活性分异特征
22
Soil organic matter (SOM) of the soil sub-sample was determined by potassium dichromate oxidation[7] revised as
K2Cr2O7-voluming outer-heating method[8, 9]. Results were
expressed as mass fraction ‘%’ (carbon mass divided by dry
soil mass). The physical-chemical characteristics of the soils
were showed in table 1.
Table 1 Physical-chemical features of the soil
Items
pH
Topsoil
Rhizoplane Rhizosphere
soil
soil
Bulk-soil
Root-free
soil
-1
-1
Carbon mineralizaion (mg CKg dry soil h )
stored at 4 ℃ before assay.
1.3 Assay in laboratory
41
topsoil
rhizoplane
rhizosphere
bulk
root-free
subsoil
20
18
16
14
12
10
8
6
4
2
0
0
Subsoil
1
2
3
6
5
4
7
8
9
TIME (hour)
5.85
6.32
6.02
5.87
5.55
5.54
w(SOM)/% 72.14
57.79
45.11
40.95
33.12
7.85
Figure 2 Variation of carbon mineralization with the incubation time
reach stable after 2.5 h incubation. It was disturbance from
Carbon mineralization was determined by CO2 evolution
through incubation in sealed mason jars at room temperature
sampling that leaded to carbon mineralization decreased rapidly
within the first 2.5 h. The carbon mineralization at topsoil was
(22±5) ℃. Evolving CO2 was measured with gas chromatography (Agilent 4 890) equipped with FID, CO2 was separated
highest during incubation period, initially C 20.82 mg/(kg·h),
then decreased to C 6.46 mg/(kg·h) after 2.5 h incubation. The
with 2 m column with inner diameter 2 mm 60~80 order
Porapak Q column，the detector works at 200 ℃，and the
carbon mineralization in subsoil was less active during incubation period, which maybe resulted from the low carbon content
carrier gas was high-pure nitrogen, with flow speed 30 ml/min.
For each sample, two 3 g (dry weight) portions were incubated
and low enzyme activity.
2.2 The enzymatic activity
in separate 300 ml of jar. Basal respiration rates were quantified
as CO2 accumulation in the headspace of jars with water hold
The spatial distribution of β -glucosidase, amylase and
cellucose were similar to each other (Figure 3). They were
capacity about 40%.
Enzyme activity (EC 3.2.1.21 β -glucosidase, EC 3.2.1.1
100
amylase, EC 3.2.1.4 cellulase) were assayed followed the revised method described by Guan Song-yin as the following
For measuring β -glucosidase and amylase
activity, excessive saccharose and starch were added with
90
80
descriptions[10].
after 24 h incubation for β -glucosidase and 96 h incubation
for amylase to get the enzyme activity. The method for cellulase measurement was similar to that for β -glucosidase and
amylase exception substrate and the investigation for reducing
sugar, here we take cellulose as the substrate, take acetic acid
buffer instead of PAB, and measured released reducing sugar
using absorbance at 551 nm for sugar and anthrone with the
absorbance was calibrated against standard solutions of glucose.
1.4 Data processing
70
Enzyme Activity
phosphor acid buffer (PAB, pH5.5), then the released reducing
sugar was determined using Somogyi[11] and Nelson[12] reagents
glucosidase
amylase
cellulase
60
50
40
30
20
10
0
topsoil rhizoplane soil
rhizosphere soil bulk soil
root-free soil
subsoil
soils
The units for β-glucosidase, amylase and cellulase were: ml (Na2S2O3 0.05
mol·L-1) ·24 h-1·g-1 dry soil, ml (Na2S2O3 0.05 mol·L-1)·96 h-1·g-1 dry soil,
and mg glucose·72 h-1·10 g-1 dry soil, respectively.
Figure 3 Spatial distribution of enzyme activities
related to carbon cycling
Carbon mineralization was computed as mineralizing
speed and the total mineralized carbon during incubation period.
decreased from topsoil to subsoil, from rhizoplane soil to
root-free soil. Topsoil contained more carbon for plant residue
We used the Origin 7.0 for windows and Excel 2000 for windows to deal with the data of the experiment.
input, and more intensive aerobic leaded to more microorganisms, thus more enzyme active. And the subsoil had less active
2
enzyme for its low carbon content and intensive anaerobic condition. The main reasons maybe lie on the fact that the three
2.1
Results and discussion
Carbon mineralization
Figure 2 showed the varied trends of carbon mineralization for all soil samples separated from field. Initially carbon
enzymes all were induced catalyst, topsoil and rhizoplane soil
contained more carbon induced to more amylase and cellucose,
was mineralized rapidly, which decreased in a short term, and
then leaded to moreβ -glucosidase showed as Figure 1.
生态环境 第 13 卷第 1 期（2004 年 2 月）
42
2.3 Relationship between enzyme activity and carbon
mineralization
Acknowledge:
We thank the staff of Sanjiang station, CAS for their
The correlation matrix showed a significant and positive
relationship between β -Glucosidase, amylase and cellulase
kindness on sampling.
activities and organic carbon content (Table 2), as already
References:
[1]
Table 2 The coefficient matrix of analysis items
Items
SOM
SOM
β -glucosidase
Amylase
Cellulase
Total carbon
mineralization
1
0.945 1
0.948 1
0.966 4
0.909 9
β
-glucosidase
1
0.986 2
0.986 4
0.986 6
Amylase Cellulase
Total carbon
mineralization
[2]
0.968 0
SWIFT M J, HEAL O W, ANDERSON J M. Decomposition in terrestrial ecosystems[M]. Oxford: Blackwell, 1979: 10-39.
[3]
1
0.960 6
MARSTORP H. Interactions in the microbial use of soluble plant
components in soil[J]. Biol Fertil Soils, 1996, 22, 45-52.
WEBSTER E A, CHUDEK J A, HOPKINS D W. Carbon transformations during decomposition of different components of plant leaves
in soil[J]. Soil Bio Biochemistry, 2000, 32: 301-314.
1
0.962 8
1
[4]
SOLLINS P, HOMANN P, CALDWELL B A. Stabilization and destabilization of soil organic matter mechanisms and controls[J]. Geoderma, 1996, 74: 65-105.
Tabatabai[13],
pointed out by Eivazi and
and their positive relationship with total carbon mineralization was also been inves-
[5]
with Enzyme Activity and Physical, Chemical Property of Shelter
tigated. However, our study was conducted on a wetland soil.
The total carbon mineralization was strongly correlated to enzyme activities, but a little weaker correlated to soil organic
carbon, which suggests that the effect of enzyme on carbon
mineralization should be significant and direct, and high enzyme activity should lead to high carbon mineralization, but the
HU HAI-BO, ZHANG JIN-CHI, GAO ZHI-HUI, et al. Study on
Quantitative Distribution of Soil Microorganism and Relationship
forest in Rocky Coastal Area[J]. Forest Research, 2001, 15(1): 88-95.
[6]
CHENG GANG-QI. Study on the mire in Sanjinag Plain[M]. Beijing:
Chinese science press, 1996: 1-3.
[7]
WALKEY A. Anexamination of methods for determination organic
carbon and nitrogen in soils[J]. J Agric Sci, 1935, 25: 598-609.
[8]
LIU GUANG-SONG. Soil physical and chemical analysis & descrip-
high soil organic carbon content could lead high carbon mineralization without necessity, which means that enzymes in mi-
tion of soil profiles: standard methods for observation and analysis in
croorganism were real catalysts, with soil organic carbon being
substrates for the process.
China, 1996.
3
Chinese ecosystem research network[M]. Beijing: Standard press of
[9]
Conclusions
LU RU-KUN. Agricultural and chemical analysis method for soil[M].
Beijing: Chinese science technology press, 1998.
The β -Glucosidase, amylase and cellulase activities,
[10] GUAN SONG-YIN. Soil enzyme and its research method[M]. Beijing:
which were nice indicators for carbon cycling, were spatial
varied in Calamagrostis angustifolia soil, they were decreased
[11] SOMOGYI M. Determination of blood sugar[J]. J Biol. Biochem,
from topsoil to subsoil, from rhizoplane soil to root-free soil, so
was the carbon mineralization. Carbon was mineralized rapidly
[12] NELSON N. A photometric adaptation of the Somogyi method for the
once separated from field, then decreased in a short term, and
stable after 2.5 h. Enzymes in microorganism were real catalyst
[13] EIVAZI F, TABATABAI M A. Factors affecting glucosidase and
Agriculture press, 1983.
1945, 160: 61-68.
determination of glucose[J]. J Biol Chem, 1944, 153: 375-380.
galactosidase activities in soils[J]. Soil Biol Biochem, 1990, 22:
for carbon cycling, with soil organic carbon’s being substrates
for the process.
891-897.
湿地根际土壤碳矿化及相关酶活性分异特征
徐小锋1，宋长春1，宋
霞2, 宋新山3
1. 中国科学院东北地理与农业生态研究所，吉林 长春 130012；2. 中国科学院地理科学与自然资源研究所，北京 101001；
3. 东华大学环境科学与工程系，上海 20051
摘要：研究了中国三江平原小叶章湿地根际土壤基础呼吸速率及相关酶活性，以了解碳矿化及其相关酶活性空间分异特征。
结果表明，β -葡萄糖苷酶、淀粉酶、纤维素酶均为碳循环的良好指示酶，它们均存在着显著的空间分异。从表层土向下，
由根表土向外，碳矿化速率及其相关的各种酶活性均呈下降趋势。当从田间取出土壤样品时，土壤样品在取出后的最初阶段
碳矿化速率较高，2.5 h 以后达到一个较为平稳的水平，然后呈平缓降低的趋势。β -葡萄糖苷酶、淀粉酶、纤维素酶是碳循
环的真正催化剂，而土壤有机碳则是此反应的低物。
关键词：碳矿化；基础呼吸速率；酶活性；三江平原
中图分类号：X144；X172
文献标识码：A
文章编号：1672-2175（2004）01-0040-03