Yu Long Zhang

Growth, Cadmium Accumulation and Physiology of Marigold (Tagetes erecta L.) as Affected by Arbuscular Mycorrhizal Fungi

Abstract A pot experiment was carried out to study the effects of three arbuscular mycorrhizal fungi (AMF), including Glomus intraradices, Glomus constrictum and Glomus mosseae, on the growth, root colonization and Cd accumulation of marigold (Tagetes erecta L.) at Cd addition levels of 0, 5 and 50 mg kg −1 in soil. The physiological characteristics, such as chlorophyll content, soluble sugar content, soluble protein content and antioxidant enzyme activity, of Tagetes erecta L. were also investigated. The symbiotic relationship between the marigold plant and arbuscular mycorrhizal fungi was well established under Cd stress. The symbiotic relationship was reflected by the better physiobiochemical parameters of the marigold plants inoculated with the three AMF isolates where the colonization rates in the roots were between 34.3% and 88.8%. Compared with the non-inoculated marigold plants, the shoot and root biomass of the inoculated marigold plants increased by 15.2%-47.5% and 47.8%−130.1%, respectively, and the Cd concentration and accumulation decreased. The chlorophyll and soluble sugar contents in the mycorrhizal marigold plants increased with Cd addition, indicating that AMF inoculation helped the marigold plants to grow by resisting Cd stress. The antioxidant enzymes reacted differently with the three AMF under Cd stress. For plants inoculated with G. constrictum and G. mosseae, the activities of Superoxide dismutase (SOD) and catalase (CAT) increased with increasing Cd addition, but peroxidase (POD) activity decreased with increasing Cd addition. For plants inoculated with G. intraradices, three of the antioxidant enzyme activities were significantly decreased at high levels of Cd addition. Overall, the activities of the three antioxidant enzymes in the plants inoculated with AMF were higher than those of the plants without AMF inoculation under Cd stress. Our results support the view that antioxidant enzymes have a great influence on the biomass of plants, and AMF can improve the capability of reactive oxygen species (ROS) scavenging and reduce Cd concentration in plants to alleviate Tagetes erecta L. from Cd stress.

Effect of Silicon on Phosphorus Adsorption of Two Synthetic Iron Oxides

Iron oxides play an important role in controlling P activity and availability in environmental systems. Two iron oxides (goethite and ferrihydrite) were synthesized characterized by X-ray diffraction, transmission electron microscopy and N2 adsorption method. To investigate the effect of silicon on phosphorus adsorption of them, batch equilibration method was used. Attempts were made to explore the mechanisms involved by eliminating effects of pH and accompany ions. Results reveal that the ability of two kinds of iron oxides adsorbed phosphorus were as follows: ferrihydrite > goethite. Compared with the control, silicon inhibited the adsorption of phosphorus on two iron oxides, and this effect increased with the increasing of silicon content. Langmuir, Freundlich and Temkin equations could be used to describe the adsorption characteristics of phosphorus on iron oxides well, but the Langmuir model was optimal. With silicon addition, the adsorption equilibrium constants (K) decreased of the phosphorus absorbed on iron oxide, the free energy(ΔG)dropping degree increased, the maximum adsorption capacity(Xm)and maximum buffering capacity (MBC) reduced.

Construction of Ecological Function Evaluation Index System for Linghe Estuarine Wetland Natural Reserve

Based on the structural characteristics of the wetland ecological environment, we analyzed and evaluated the ecological functions of Linghe estuarine wetland quantitatively with methods of AHP and index judgment. The results showed, functions of regulating floods, biological products and soil conservation played relatively important role. The complex function of Ling estuarine wetland is in common level; the ecosystem is relatively stable to play fundamental ecological functions. AHP method made the ecological function indicators that are difficult to quantify more simple and intuitive. The article developed a new way of planning, management and conservation of the wetland with AHP method in sustainable development of Linghe Estuarine wetland.

Forecasting Analysis of Land Use Dynamic Change in Liaohe River Delta Wetlands

The paper supported by 3S technology, based on the remote sensing images in different periods within the 7 years from 1988 to 2009 in Liaohe River Delta wetlands, conducts the following researches :(1) establish single dynamic degree model and comprehensive dynamic degree model, extract the data of different types of land , and analyze the reason of the changes in this region. Results indicate that: the area of residential land use in this region is increasing remarkably, reed-swamp resources is deceasing slightly, and the comprehensive land use degree is increasing stably.(2)establish the Liaohe River Delta wetlands transition probability matrix, and forecast the land use area of Liaohe River Delta in 2030 using Markov model. The results indicate that: the area of forest, reed-swamp, shoals shows a downward trend, paddy field, glebe, river/channel, reservoir/pond/lake, residential land shows an upward trend in 2030 in Liaohe River Delta wetlands. It is obvious that the area of wetlands shrunk severely. Ecological balance and quality will face crisis seriously in Liaohe River Delta wetlands in the future.

Nitrogen and Phosphorus Removal from Simulated Wastewater with Aquatic Macrophytes

This study focused on the comparisons between nitrogen and phosphorus removal rates from the simulated wastewater using various kinds of aquatic plants (4 emergent and 3 floating plants). Results showed that aquatic plants has a significant effect on the removal of NO3--N and TP, but has a less effect on NH4+-N. Among the four emergent plants, the order of NO3--N removal capacities was: S. sagittifolia > S. tabernaemontani > T. latifolia > A. calamus. But for TP, the order was: T. latifolia > A. calamus > S. tabernaemontani > S. sagittifolia. To the floating plants, the order of NO3--N and TP removal capacities were: E. crassipes > P. stratiotes. The ANOVA analyses showed that there was a significant difference between planted treatments and unplanted treatment for the removal of NO3--N and TP. The study suggests that the treatment of simulated wastewater using the aquatic macrophytes was effective in the removal of nutrients.

Arbusular Mycorrhizal Fungi Effects of the Growth, Cd Uptake and Physiology of Solanum lycopersicum Seedlings under Cd Stress

The effects of three arbuscular mycorrhizal fungi (AMF) on the growth, Cd uptake and some physio-biochemical indexes of Solanum lycopersicum seedlings under different levels of Cd stress were investigated in a pot study. Generally, the symbiotic relationship between Solanum lycopersicum and AMF can be well established under Cd stress. This was reflected by the better physio-biochemical index of the plants inoculated with G. constrictum, G. mosseae and G. intraradices whose colonization rates were between 41.4% and 76.1%. Compared with the non-inoculated ones, G. constrictum inoculation enhanced the plant biomass at 50 mg kg-1 Cd addition level. AM colonization increased the Cd distribution to the roots in plants and alleviated shoots from high Cd stress, and thus increased the shoot biomass in the end. At the high Cd addition level, mycorrhizal plants reacted differently in the reduction of the contents of MDA, by influencing the soluble sugar, POD activity, SOD activity and so on. Our results showed that mycorrhizal colonization was beneficial to the Cd translocation in plants and reduced the membrane lipid peroxidation in plants under serious Cd stress. However, the mechanisms of mycorrhizal protection in plants were influenced by many factors and still need to be further studied.

Ecological Environment Evaluation of Liaohe Delta Wetland Based on PSR Model

Liaohe Delta estuarine wetland is the largest estuarine wetland in northeast China, the article proposed eco-environmental evaluation indicators system for the wetland based on PSR model. By selecting indicators of pressure, state and response, we analyzed dynamic variations of the ecological environment and fragmentation status of the wetland. The results showed that the main pressure of the wetland is from agricultural production and urban expansion since 1988, which resulted in large-scale land reclamation, expansion of rice planting area and reduction of tidal flat areas. The internal structure and status of the wetland had experienced significant variations and the trend of fragmentation was evident. With negative effects of dwindling wetland resources, human-being’s reasonable response to the variations of wetland status should be in three aspects: scientific classification of functional zones, conversion of appropriate economic model and adjustment of the industrial structure. Thus achieve the coordination of ecological protection and industrial economic development.

Monetary Value Evaluation of Liaohe River Estuarine Wetland’s Ecosystem Service Function

In order to achieve sustainable use of Liaohe River estuarine wetland ecosystems resources, this article calculated and analysed the monetary value of service functions for Liaohe River estuarine wetland. The wetland’s monetary value of service functions equals to direct use value plus indirect use value and non-use value. Using method of map data visual interpretation and the classification of functional zones, we identified nine main functions of wetland ecosystem services, classified the wetland’s functional zones. And the monetary value is calculated based on the functional zones with map data after visual interpretation. Conclusions can be made that the ecosystem service functions monetary value of Liaohe River estuarine wetland is a large amount, increasingly awareness on scientific conservation and development of resources should be taken into account.