Southeast Sichuan Geological Group

Chongqing, China

Southeast Sichuan Geological Group

Chongqing, China
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Chen J.P.,Southwest University | Chen J.P.,Guangxi Academy of Agricultural science | Zeng C.C.,Southwest University | Wei H.,Southwest University | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2017

The water level fluctuation zone of the Three Gorges Reservoir has been affected by a number of ecological problems, most importantly, the loss of previous vegetation. The revegetation of this region is just one example of a potential solution to this issue, and revegetation projects have been carried out in the region over recent years in an attempt to restore the riparian ecosystem within the Three Gorges Reservoir region. The riparian species Hemarthria altissima and Cynodon dactylon have been commonly used in this revegetation effort. Knowledge of the growth responses of plant species to different flood regimes and identifying a suitable planting pattern will lead to improvements in the design of wetland management strategies. Therefore, the aim of this study was to determine the optimal planting pattern for these two species under different flood conditions. Four flooding conditions were designed using an independent-group design and their results were evaluated. These groups were the Control Group (CK), the Flooding-Dry Alternating Group (FD), the Soil-Flooding Group (FL), and the Submergence Group (SM). These groups had four different planting densities, which were 1, 2, 4, or 12 plants per experimental pot. Single cropping strategies were applied to the pot with one plant, while both single and mixed cropping strategies were applied to the pots with, 2, 4, and 12 plants. The ratio of H. altissima to C. dactylon in the mixed intercropping groups was 1:1 in the pots with 2, 4, and 12 plants. The results indicated that the total and aboveground biomasses of H. altissima and C. dactylon were significantly influenced by water treatment, planting density, and planting pattern (P < 0.05). The total and aboveground biomasses of C. dactylon significantly decreased in the mixed intercropping pots with medium and high planting densities under the CK and FD conditions (P < 0.05). In contrast, the total and aboveground biomasses of H. altissima increased in the mixed intercropping pots for all planting densities, and increased significantly at the high planting density under the CK and FD conditions (P < 0.05). The total H. altissima and C. Dactylon biomasses increased in the mixed intercropping pots with low and medium planting density under the FL treatment. The total and aboveground C. dactylon biomasses also significantly increased in the mixed intercropping pots with low and medium planting density under the SM treatment (P < 0.05). However, the mixed intercropping pattern with low and medium planting density did not influence the H. altissima biomass under the SM treatment (P > 0.05). Furthermore, the mixed intercropping pattern with high planting density did not influence the H. altissima and C. Dactylon biomasses under the SM treatment (P > 0.05). The inhibition influence of the mixed intercropping pattern to C. Dactylon declined as flooding stress increased. The results suggested that the long-term coexistence of H. altissima and C. Dactylon would improve if a mixed intercropping pattern with low and medium planting densities was adopted in areas where flooding lasted for a long period. Therefore, in order to strengthen the soil retention functions of H. altissima and C. dactylon, and improve the species diversity and community stability of the vegetation restoration, mixed intercropping with a high H. altissima-to-C. dactylon planting density is the optimal choice in low-altitude areas that are completely flooded. © 2017, Ecological Society of China. All rights reserved.


Ma Y.,CAS Chongqing Institute of Green and Intelligent Technology | Jia Z.,Southwest University | Jia Z.,Southeast Sichuan Geological Group | Li S.,CAS Chongqing Institute of Green and Intelligent Technology
Environmental Science and Pollution Research | Year: 2017

Assessment of heavy metal (HM) pollution in soil is critical for human health, ecological remediation, and soil conservation. In this study, statistical analyses and geochemical approaches such as enrichment factor (EF), the index of geoaccumulation (Igeo), and potential ecological risk index (RI) were used for characterization and risk assessment of soil HMs through a high-spatial-resolution 385 samples from Tongnan District, an important agricultural practice area in Chongqing Municipality in Southwest China. Igeo and EF indicated that Hg and Cd could be considered as low and moderate polluted, respectively, and others HMs were not a major concern. Comprehensive ecological risk information further demonstrated that the HMs have caused a moderate risk. Principal component analysis (PCA) extracted two principal components (PCs) with eigenvalue >1 explaining about 66.1% of the total variance in the HM data sets, demonstrating major source of anthropogenic activity, phosphate fertilizers, vehicle, and pesticides. These multi-index methods have the capacity of HM assessment in soil, which are useful for soil conservation and ecological remediation. © 2017 Springer-Verlag GmbH Germany


Chen J.,Southwest University | Chen J.,Guangxi Academy of Agricultural science | Zeng C.,Southwest University | Ma W.,Southwest University | And 5 more authors.
Linye Kexue/Scientia Silvae Sinicae | Year: 2017

Objective: This study aimed at revealing variation in the phytoremediation ability of the cadmium-contaminated soil and providing theoretical basis on the adaptive management strategies of Salix variegata under flooding in the water-level-fluctuation zone of the Three Gorges Reservoir Region. For this end, the growth adaptability of S. variegata to flooding-and-Cd stress and its Cd accumulation characteristic under flooding were studied. Method: The biomass and cadmium concentrations in various parts of cuttings of S. variegata were determined. The plants were treated by four concentrations of cadmium (0, 0.5, 2 and 10 mg·kg-1 individually, achieved by adding CdCl2·2.5H2O to soil), interacted with two water conditions (Control group, CK; Flooding group, FL). Result: 1) The total biomass, aboveground, stem and leaf biomass of S. variegata were not significantly influenced by flooding-and-Cd stress treatments (P>0.05), while the root biomass under flooding was less than that of control at the same cadmium concentration. 2) The Cd contents in the aboveground parts of S. variegata were higher in the control groups than in the corresponding flooding groups. Under the concentration of 2 mg·kg-1 Cd, the Cd contents in branch, leaf, bark and xylem were 12.98, 10.08, 7.47 and 17.2 mg·kg-1, respectively. 3) Flooding significantly influenced the cadmium contents in various parts of S. variegata (P<0.05). The Cd contents in branch, leaf, bark and xylem were obviously decreased by flooding. With the increasing of Cd concentration (from 0, 0.5, 2 to 10 mg kg-1), the Cd contents in those tissues were 39.0%, 23.7%, 34.0% and 51.8% of the corresponding control treatment, respectively. However, the Cd contents of root increased significantly under flooding as compared to the controls, accounting for 133.0% to 390.0%. 4) Cd translocation ability from root to branch in flooding was decreased significantly compared to control (P<0.05). 5) Cd accumulations in the aboveground and whole plant of S. variegata were obviously reduced by flooding. For instance, with treatment of 2 mg·kg-1 Cd, the Cd accumulations of total plant and aboveground part under flooding accounted for 56.7% and 35.2% of the control, which were 146.40 μg·plant-1 and 125.35 μg·plant-1, respectively. Conclusion: S. variegata had a high growth adaptation under flooding-and-Cd stress. Cd contents of aboveground parts, Cd accumulations of aboveground parts and total plant of S. variegata were reduced under flooding. In order to enhance the efficiency of phytoremediation in Cd contaminated area of the Three Gorges Reservoir Region, and to prevent the secondary pollution caused by decayed litter, it is necessary to harvest the shoots of S. variegata before flooding every year. © 2017, Editorial Department of Scientia Silvae Sinicae. All right reserved.


Jia Z.,Southwest University | Jia Z.,Southeast Sichuan Geological Group | Wei H.,Southwest University | Sun X.,Southwest University | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Cadmium (Cd) is the most popular heavy metal element in the contaminated soil of Three Gorges Reservoir Region. Cadmium has significant negative effects on the health of soil-plant system in the research area due to its high concentration and biological activity. Thus, it is essential to study the tolerance and accumulative ability of plant species in cadmium contaminated soils in order to protect the ecological environment and plan the reasonable land use. Salix variegate and Pterocarya stenoptera are two native riparian plants which can be used widely in the vegetation restoration of the hydrofluctuation zone in Three Gorges Reservoir Region. In order to reveal the response of these two species to cadmium, five different kinds of cadmium treatment were applied to determine the growth, biomass and cadmium concentration in various parts of S. variegate and P. stenoptera seedlings. The cadmium treatments were 0(control), 10, 20, 50, and 100 mg/kg. The results showed that: (1) The root biomass, aerial biomass, changes of stem length and stem diameter of S. variegate and P. stenoptera seedlings decreased with Cd content raised. Tolerance index (Ti) based on the dry biomass and growth parameters of two species showed no significant difference in 10 mg/kg in contrast with a significant decrease in 20, 50, and 100 mg/kg (P < 0. 05), when compared to the control respectively. (2) The cadmium concentration reached up to 61.73, 163. 04, and 91. 05 mg/kg in stems, leaves, and roots of S. variegate in turn when treated with cadmium less than 20 mg/kg. However, in the same treated condition, the highest cadmium concentration was 7. 9,5. 25, and 190. 68 mg/kg in stems, leaves, and roots of P. stenoptera, respectively. (3) Cd accumulation in S. variegate was highest in leaves and lowest in stems except in the control, with the translocation factor (Tf) between 0. 789-1. 513. Very differently, Cd accumulation in P. stenoptera was highest in roots and lowest in stems also except in the control, with the translocation factor (Tf) between 0. 037- 0. 044. Thus, the translocation factor (Tf) o f P. stenoptera was far less than that of S. variegate. These characteristics indicated strategies of cadmium uptake and translocation by two plant species growing in Cdcontaminated soil were not totally different: Cd tended to be immobilised and held primarily in the roots of P. stenoptera, whereas it was more easily translocated to the aerial tissues of S. variegate. The tolerance of species to cadmium was demonstrated by these two strategies so that the plants were able to survive and had a high productivity. (4) The results indicated that S. variegate and P. stenoptera seedlings had a high capacity of growth adaptation and tolerance under 10 mg/ kg Cd stress, and also, the capacities of translocation and cadmium accumulation in aerial parts of S. variegate seedlings were higher than that of P. stenoptera seedlings, which verified that the differences in accumulation of cadmiumwere not correlated with tolerance ability of plants. Such a behavior in the seedlings of two species was further confirmed by the calculation of the bio-concentration factor (BCF). The study suggested that S. variegate had considerable potential application to those cadmium contaminated areas in the hydro-fluctuation zone of the Three Gorges Reservoir Region.


Yan M.-S.,Southeast Sichuan Geological Group | Yan M.-S.,Chengdu University of Technology | Li W.-B.,Southeast Sichuan Geological Group | Yang L.-C.,Southeast Sichuan Geological Group | And 2 more authors.
Research of Environmental Sciences | Year: 2014

Speciation characteristics, influencing factors and effectiveness of As, Cd, Cr and Pb in four main types of soils (purplish soil, limestone soil, yellow soil and paddy soil) were investigated through analyzing total contents and fractions of heavy metals in soils in Yubei District, Chongqing. The results showed that fractions of heavy metals significantly varied among different types of soils. Cr and Pb were the main components of the residual in all kinds of soils. Cd was mainly ion-exchangeable and residual speciated in yellow soils and purplish soils, which counted for 37.44% and 29.97% of the total Cd contents, respectively. The contents of available speciation of heavy metals in soils was as follows: w (available As) and w (available Cr) were 0.04 and 0.96 mg/kg in purplish soil respectively, w (available Cd) 0.13 and 0.09 mg/kg in paddy and purplish soil respectively, w (available Pb) was 1.94 mg/kg in yellow soil, which perhaps indicated a strong bio-effectiveness, when the bio-effectiveness of heavy metals in limestone-soil was lower. Available As and Cd significantly positively were correlated with total contents in main factors influencing on the chemical speciation and transformation process of heavy metals. However, there were significant negative correlations between available contents of Cd and Pb with pH, and between available Cr with soil organic matters. Available Cd, Cr, and Pb have a multivariate nonlinear logarithmic regressive relationship with total contents, pH and SOM in purplish soil. In conclusion, the equation can be used to effectively predict available contents of the heavy metals in the study area.

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