Suaeda Heteroptera Research Articles

Vegetation degradation reduces aggregate associated carbon by reducing both labile and stable carbon fraction in Northeast China

Vegetation changes can affect soil organic carbon (SOC) content and storage by altering the inputs of plant biomass and the catabolism and anabolism of soil microorganisms. However, influence of vegetation degradation on aggregate associated carbon fractions and the contribution of different aggregates to total SOC in bulk soil remains poorly understood. In this study, undisturbed soil samples were collected from three types of grassland in Songnen grassland: an undegraded grassland (LEY, Leymus chinensis), a moderately degraded grassland (CHL, Chloris virgata), and a severely degraded grassland (SUA, Suaeda heteroptera). Three soil aggregates including macroaggregate (> 0.25 mm), microaggregate (0.053–0.25 mm) and silt and clay fraction (< 0.053 mm) were separated using wet sieving. Contents of total SOC, soil labile and stable carbon in bulk soil and different soil aggregates were measured. Compared with LEY, the mean weight diameter and geometric mean diameter under the degraded vegetation communities reduced by 39.42 % and 28.47 %, respectively. The reduction in SOC contents in bulk soil, macroaggregate, microaggregate and silt and clay fraction resulting from vegetation degradation was 49.81 %, 26.00 %, 76.17 % and 43.65 %, respectively. Under the degraded vegetation communities, contents of soil labile and stable carbon in bulk soil (45.73 % and 52.61 %, respectively), macroaggregate (17.38 % and 31.61 %, respectively), microaggregate (77.83 % and 74.18 %, respectively), and silt and clay fraction (21.20 % and 53.45 %, respectively) were significantly lower than those under LEY. The contribution of macroaggregate, microaggregate and silt and clay fraction to total SOC was 13.27 %, 23.61 % and 63.12 %, respectively. The contribution of soil aggregates to total SOC following vegetation degradation reduced by 53.63 % for microaggregate, but increased by 47.10 % for silt and clay fraction. These findings collectively indicate that vegetation degradation reduces the aggregate associated carbon content by reducing both labile and stable carbon fraction in Songnen grassland, and sustainable vegetation restoration strategies are need to enhance soil carbon storage in Northeast China.

β-Cyclodextrin enhanced bioavailability of petroleum hydrocarbons in industrially contaminated soil: A phytoremediation field study

Low remediation efficiency due to low bioavailability is a primary restrictive factor for phytoremediation applications. Specifically, this investigation examines whether Suaeda heteroptera Kitagawa (S. heteroptera) can be used in combination with β-cyclodextrin (β-CD) to remediate contaminated site. The study was conducted on the growth response of S. heteroptera, bioavailability and dissipation of petroleum hydrocarbons (PHs) in soil under the influence of β-CD Our preliminary studies confirmed that β-CD is effective in increasing the biomass and height of plants. The presence of β-CD could dramatically elevate polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in S. heteroptera. Moreover, a remarkable positive correlation between PHs levels in roots with the dosage of β-CD and a negative correlation between the PHs levels in roots with KOW of PHs have been observed. The dissipation of n-alkanes was estimated to be 38.73–62.27%, and the dissipation of PAHs was 36.59–60.10%. In addition, the dissipation behavior of n-alkanes and PAHs was well agreement with the first-order kinetic model. These results display that applying β-CD accelerated the desorption process of PHs from soil and promoted the absorption process of PHs onto the root epidermis. The enhancement of phytoremediation was achieved by increasing the bioavailability of PHs.

Mechanisms of cadmium absorption in Suaeda heteroptera roots

Heavy metal contaminated soil is a common environmental pollution problem, which has a negative impact. The potential for the phytoremediation has been widely recognized. This study investigated the mechanisms of cadmium (Cd) absorption in Suaeda heteroptera Kitag., a dominant wetland plant in northern China. A hydroponic experiment was carried out to determine the Cd content in S. heteroptera roots after adding ion channel inhibitors and metabolic inhibitors. Furthermore, subcellular distribution and chemical forms of Cd in S. heteroptera were investigated. The results showed that Cd was mainly absorbed by S. heteroptera roots through calcium ion channels. Cd absorption by S. heteroptera roots was closely associated with the P-type ATPase, suggesting that Cd was actively absorbed by S. heteroptera roots. Cell wall precipitation and vacuole compartmentalization were the major mechanisms underlying absorption and tolerance to Cd. Cd in S. heteroptera root system was predominantly bound to proteins, pectinate, and phosphates, thereby reducing its toxicity. However, Cd was transformed into a highly active form and became more toxic at high concentrations.

Numerical study on the influence of salt marsh plants on coastal wetland hydrodynamics and suspended sediment transport

Salt-marsh plants play important roles in the hydrodynamics and sediment transport and deposition processes in coastal regions. The Delft3D model was applied to quantify the influence of salt-marsh plants on the hydrodynamic characteristics and suspended sediment transport of a coastal wetland, and to reveal the contribution of plants in trapping sediment in the local area. Specifically, the spatial distributions of salt-marsh plants were acquired from remote sensing images and coupled with the Delft3D model. A comparison showed that the modeled results and observed data fit very well. The model results indicated that salt marsh plants had a negligible effect on tidal level, but they did significantly affect flow velocity and tidal flux, as indicated by the obvious slow-flow zones in vegetated belts. Phragmites australis attenuated the flow velocity more than Suaeda heteroptera. We also found that the suspended sediment concentration was lower in P. australis and S. heteroptera areas because the resistance created by vegetation prevented sediment from being resuspended and helped trap suspended sediment. Numerical experiments further confirmed that the suspended sediment flux was obviously different with and without vegetation. The interception of suspended sediment by salt marsh plants could reduce the suspended sediment by more than 60%.

Phytoremediation of crude oil-contaminated sediment using Suaeda heteroptera enhanced by Nereis succinea and oil-degrading bacteria

A 150-day experiment was performed to investigate the stimulatory effect of a promising phytoremediation strategy consisting of Suaeda heteroptera (S. heteroptera), Nereis succinea (N. succinea), and oil-degrading bacteria for cleaning up total petroleum hydrocarbons (TPHs) in spiked sediment. Inoculation with oil-degrading bacteria and/or N. succinea increased plant yield and TPH accumulation in S. heteroptera plants. The highest TPH dissipation (40.5%) was obtained in the combination treatment, i.e., S. heteroptera + oil-degrading bacteria + N. succinea, in which the sediment TPH concentration decreased from an initial value of 3955 to 2355 mg/kg in 150 days. BAF, BCF, and TF confirmed the role of N. succinea and oil-degrading bacteria in the amelioration and translocation of TPHs. In addition, TPH toxicity of S. heteroptera was alleviated by N. succinea and oil-degrading bacteria addition through the reduction of oxidative stress. Therefore, S. heteroptera could be used for cleaning up oil-contaminated sediment, particularly in the presence of oil-degrading bacteria + N. succinea. Field studies on oil-degrading bacteria + N. succinea may provide new insights on the rehabilitation and restoration of sediments contaminated by TPHs.

Remediation of Petroleum Contaminated Tidal Flat Sediments by Co-bioremediation System

ABSTRACT The remediation effects of oil-degrading bacteria, Nereis succinea and Suaeda heteroptera, on oil-contaminated sediments were studied by laboratory pot experiments under simulated conditions of intertidal zone. Three concentrations of oil-contaminated sediments (I: 500 mg/Kg, II: 1500 mg/Kg, III: 3000 mg/kg) and four bioremediation treatment groups (bacteria group, bacteria-N. succinea group, bacteria-S. heteroptera group, bacteria-N. succinea-S. heteroptera group) were set up, and the oil removal efficiency was measured after 15, 30, 45, 60, and 70 days of the experiment, respectively. The results showed that the percent removals of total petroleum content, linear hydrocarbons, and polycyclic aromatic hydrocarbons (PAHs) of each sediment under all bioremediation treatments were significantly higher than those of the control groups (P < .05). The bacteria – N. succinea – S. heteroptera synergistic model performed best, after 70 days of remediation tests, the percent removals of total petroleum content reached 51.9%, 47.8%, and 40.6% under I, II, and III oil concentration conditions, respectively, indicating the biological disturbance caused by N. succinea and the rhizosphere effect of S. heteroptera can effectively promote the oil removal of the bioremediation system. In addition, the oil degradation speed in each bioremediation combination showed an increasing trend in the began month, peaked during 15–30 d period, and then decreased obviously at 30–70 d in all bioremediation treatments. We also found that the synergistic bioremediation models promoted the removal of petroleum linear hydrocarbons and PAHs, and the percent removals of linear hydrocarbons were negatively related to their carbon chain length, and the removal rates of PAHs decreased significantly as the number of benzene rings increases. The above results demonstrated the feasibility of co-bioremediation technology in the remediation of petroleum contaminated tidal flat sediments.

Effects of Spartina alterniflora invasion on the community structure and diversity of wetland soil bacteria in the Yellow River Delta.

The exotic plant Spartina alterniflora is expanding rapidly along China's coast regions, seriously threatening native ecosystems. Soil bacteria are important for biogeochemical cycles, including those of carbon, nitrogen, and sulfur, in wetland ecosystems. There is growing evidence that microorganisms are important in case of plant invasion. In the present study, we studied the interlacing area of S. alterniflora and Suaeda heteroptera, selected soil of invaded and non‐invaded regions and explored the effect of the composition and diversity of bacterial communities in coastal wetlands. The bacterial community composition of invasive and noninvasive areas was subjected to high‐throughput sequencing. In the five areas tested, the main bacterial phyla were Proteobacteria, Bacteroides, and Acidobacteria; the richness of the bacterial community in the soil increased after S. alterniflora invasion, most changes occurred at the genus level. The relative abundances of Desulfobulbus and Sulfurovum were higher in invasive areas than in noninvaded areas. PCA, RDA, and LEfSe analyses found that the S. alterniflora invasion significantly influenced the bacterial community and physicochemical properties of wetland soil. In conclusion, soil microbial community composition was tightly associated with S. alterniflora invasion. This study provide an important scientific basis for further research on the invasion mechanism of S. alterniflora.

Vegetation Regulates Element Composition of Soils by Enhancing Organic Matter Accumulation in the Salt Marshes of Liao River Delta, China

The purpose of this study was to evaluate if vegetation regulates soil biogeochemistry in coastal salt marshes, here measured as element concentrations (43 elements) and organic matter content of the soils. We selected seven sampling sites in Liao River Delta, China, within each of which three areas existed in close proximity of each other, characterized as ‘bare, unvegetated sediments’, ‘Phragmites australis marsh’, and ‘Suaeda heteroptera marsh’. We recorded sampling locations and measured soil element concentrations, organic matter content, soil pH, soil salinity, soil water content, and soil electrical conductivity. All but four of element concentrations of soils varied by wetland type, and concentrations of 35 elements, and organic matter content increased from bare, unvegetated sites to Phragmites marshes to Suaeda marshes. Redundancy analysis (RDA) identified that organic matter content explained most variance. Organic matter content was positively related with most elements including nutrients and metals, negatively related with Sr, Ba and Na. However, further analysis of element concentrations revealed significant differences also between Phragmites-dominated and Suaeda-dominated sites, even though they did not differ significantly in organic matter content. This information highlights the importance of vegetation in regulating soil element composition and biogeochemical processes in coastal salt marshes.

The quantity and stability of soil organic carbon following vegetation degradation in a salt-affected region of Northeastern China

Understanding the influence of vegetation conversion induced by land degradation on soil organic carbon (SOC) dynamics provides a basis for the sustainable use of grasslands. While labile carbon fractions often vary with the type of vegetation, little is known about whether and how vegetation degradation affects the recalcitrant carbon fraction that is highly resistant to oxidation. Here, we studied the influence of vegetation degradation on changes in SOC and four oxidizable fractions with different stabilities in Northeastern China. The soil was collected from a vegetation degradation sequence, including Leymus chinensis (LEY, native grassland), Puccinellia tenuiflora(PUC, light degradation), Chloris virgata (CHL, moderate degradation), and Suaeda heteroptera (SUA, severe degradation). Contents of total SOC and four oxidizable SOC fractions extracted under a gradient of oxidation (F1, very labile; F2, labile; F3, less labile; F4, oxidizable resistant) were measured using a modified Walkley-Black method. Results showed that the contents of total SOC and oxidizable SOC fractions were significantly different under different vegetation types and soil depths. Under PUC, CHL, and SUA, contents of total SOC (29.0%, 34.3%, and 55.4%, respectively), F1 (22.5%, 20.8%, and 40.8%, respectively), F2 (28.2%, 53.8%, and 72.1%, respectively), F3 (52.0%, 40.6%, and 66.2%, respectively), and F4 (15.0%, 21.9%, and 42.8%, respectively) were lower than those under LEY. Vegetation degradation had a significant effect on the F4 fraction as well as the F1, F2, and F3 fractions. Regression coefficients of the relationship between oxidizable SOC fractions as a function of total SOC showed that these fractions, as a proportion of total SOC, were 22% for F1 and F2, 26% for F3, and 31% for F4. There were no significant differences in the percentages of active carbon fractions (F1 + F2) in total SOC and the lability of total SOC among the four vegetation types. These findings suggest that the recalcitrant carbon fraction can be affected by land degradation as well as the labile carbon fraction, and that shifts in land use affect the contents of total SOC and its fractions, but have no effect on the stability of SOC in semi-arid areas.

Continuous Change Mapping to Understand Wetland Quantity and Quality Evolution and Driving Forces: A Case Study in the Liao River Estuary from 1986 to 2018

Coastal wetland ecosystems, one of the most important ecosystems in the world, play an important role in regulating climate, sequestering blue carbon, and maintaining sustainable development of coastal zones. Wetland landscapes are notoriously difficult to map with satellite data, particularly in highly complex, dynamic coastal regions. The Liao River Estuary (LRE) wetland in Liaoning Province, China, has attracted major attention due to its status as Asia’s largest coastal wetland, with extensive Phragmites australis (reeds), Suaeda heteroptera (seepweed, red beach), and other natural resources that have been continuously encroached upon by anthropogenic land-use activities. Using the Continuous Change Detection and Classification (CCDC) algorithm and all available Landsat images, we mapped the spatial–temporal changes of LRE coastal wetlands (e.g., seepweed, reed, tidal flats, and shallow marine water) annually from 1986 to 2018 and analyzed the changes and driving forces. Results showed that the total area of coastal wetlands in the LRE shrank by 14.8% during the study period. The tidal flats were the most seriously affected type, with 45.7% of its total area lost. One of the main characteristics of wetland change was the concurrent disappearance and emergence of wetlands in different parts of the LRE, creating drastically different mixtures of wetland quality (e.g., wetland age composition) in addition to area change. The reduction and replacement/translocation of coastal wetlands were mainly caused by human activities related to urbanization, tourism, land reclamation, and expansion of aquaculture ponds. Our efforts in mapping annual changes of wetlands provide direct, specific, and spatially explicit information on rates, patterns, and causes of coastal wetland change, both in coverage and quality, so as to contribute to the effective plans and policies for coastal management, preservation, and restoration of coastal ecosystem services.

Soil phosphorus fractions and distributions in estuarine wetlands with different climax vegetation covers in the Yellow River Delta

To evaluate the relationship between phosphorus (P) fractions and physicochemical characteristics in soils of estuarine wetlands with different climax vegetation covers, surface 60-cm soil samples were collected in Suaeda heteroptera wetlands (SH), Tamarix chinensis wetlands (TC) and Phragmites australis wetlands (PA) in the Yellow River Delta during June 2017. Results showed that the inorganic phosphorus (Pi) in PA soils was significantly lower than that in TC and SH soils (p < 0.05), and the organic phosphorus (Po) showed the opposite pattern, with a rank of PA ≫ TC > SH. The available phosphorus (AP) had a high proportion at surface layer and decreased with increasing depth, with a rank of SH > TC > PA. D.HCl-Pi was the main component of the extracted Pi in all soil profiles, while C.HCl-Po, NaOH-Po and Bicarb-Po were the main components of the extracted Po in PA, TC and SH soils, respectively. Most of the Pi fractions were significantly positively correlated with Ca, Al and Fe in TC soils, whose correlations were better than those of SH and PA soils, and the Pi fractions were negatively correlated with the pH and sand contents. Our findings confirmed the complexity of the combination and unavailability of P fractions extracted by strong acids. Decreasing of sum of Po fractions (from14.72% in PA to 11.28% in SH) across a soil salinity gradient (1.0‰ to 12.0‰) provided valuable evidence of the mineralization of soil Po and that P. australis can enhance the biological functions of P. Although difference test revealed clear differences in soil physicochemical properties and slightly clear differences in P fractions, we did not extrapolate real correlations between soil P fractions and climax vegetation covers in this study. Research on the biological mechanism of climax vegetation covers and its influences on the plant absorption and utilization of P is our future direction.

Numerical Analysis of the Potential Effect of Wetlands on Reducing Tidal Currents in the Liao River Estuary, China

In this study, an explicit depth-averaged 2D flow model that considers vegetation effects was established to investigate the interactions between tidal currents and vegetation in coastal wetland waters. Roe’s approximate Riemann solver, coupled with the drying-wetting boundary technique, was proposed to evaluate the interface fluxes and track the moving shoreline. In addition, the vegetation-induced drag force was added to the momentum equations as an internal source. Model validation based on two laboratory experiments demonstrated that the model results were in good agreement with the measured results. The model was then applied to evaluate the interactions between vegetation and tidal currents in the Liao River Estuary, China. The simulation results showed that vegetation played a critical role in attenuating flow velocities in vegetated waters. In the Liao River wetland, the reductions in the amplitudes of the peak depth-averaged velocities in Phragmites austral (P. australis) wetlands were significantly higher than those of the Suaeda heteroptera (S. heteroptera) wetlands. Moreover, the flow velocity changes in the wetland waters also impacted the kinetic energy, creating a new flow field structure. The simulation results also indicated that higher vegetation densities resulted in a larger flow velocity attenuation rate in the vegetated areas.

Field study on bioaccumulation and translocation of polybrominated diphenyl ethers in the sediment-plant system of a national nature reserve, North China

Polybrominated diphenyl ethers (PBDEs) are the ubiquitous contaminants in the coastal wetlands, with high persistence and toxicity. Environmental behaviors of PBDEs in sediment-plant system is a hot research area, where much uncertainties still occurred in field environment. In this study, the sediments and Suaeda heteroptera were synchronously collected to investigate the bioaccumulation and translocation of PBDEs in Liaohe coastal wetland. Mean concentrations of PBDEs in sediments, roots, stems and leaves were 8.37, 6.64, 2.42 and 1.40 ng/g d.w., respectively. Tissue-specific accumulation of PBDEs were detected in Suaeda heteroptera, with predominant accumulation in roots. Congener patterns of PBDEs were similar between sediments and roots, demonstrating root uptake as the key pathway of PBDE bioaccumulation. The proportions of lower brominated congeners increased from roots to leaves, implying the congener-specific translocation. Meanwhile, the lower brominated congeners exhibited higher sediment-tissue bioaccumulation (AFs) and translocation factors (TFs) compared to higher brominated congeners in Suaeda heteroptera, further verifying their preferential translocation. AFs and TFs of PBDEs were both not correlated with their log Kow, which was inconsistent with those of laboratory studies, reflecting the complicated behaviors of PBDEs in field environment. This is the first comprehensive report on bioaccumulation and translocation of PBDEs within Suaeda heteroptera in Liaohe coastal wetland.

Total and Methylmercury of Suaeda heteroptera Wetland Soil Response to a Salinity Gradient Under Wetting and Drying Conditions.

Mercury (Hg) methylation could occur in freshwater ecosystems with low or high salinity. However, few studies are available about the effects of salinity change on mercury(Hg) release and methylation. In-situ experiments using Suaeda heteroptera wetland soil column from the Liaohe estuary were performed to decipher how total mercury (THg) and methylmercury (MeHg) contents change under fluctuant salinity and wet and dry soil conditions. Salinity gradients were set to 0.50% (S1), 1.00% (S2), 1.50% (S3) and 1.80% (S4), and pure deionized water was used as a blank control (CK). Wet and dry soil conditions were set to full inundation condition (WD1) and naturally dried treatment (WD2). Results indicated that the highest THg and MeHg contents were found in surface and bottom soil when water salinity treatment was CK under WD1. THg and MeHg decreased with salinity under WD1. THg contents in overlying water varied from 0.854 to 1.243µg L-1 under WD1 treatments and increased with salinity change. When under WD2 treatment, THg contents in both soil layers gradually decreased with rising salinity. Meanwhile, MeHg contents in both soil layers reached the lowest level at CK (1.666μg kg-1and 2.520μg kg-1) and increased gradually with the rising salinity. By comparison, THg content of the soil was much lower in WD1 than that in WD2. Under the WD1 condition, the MeHg contents and %MeHg decreased with rising salinity and showed significantly different in different salinity treatment, however, its showed an opposite trend with rising salinity under the WD2 condition.

The role of waterlogging stress on the distribution of salt marsh plants in the Liao River estuary wetland

The degradation of salt marsh plants due to human activities has accelerated in recent years, and this has decreased the ecological service functions of estuary wetlands and contributed to global climate change. In the threatened Red Beach area within the Liao River Estuary Wetland (LREW) of China, the factors that dominantly affect the distribution of salt marsh plants at large scale are unknown. Here, we used field observations and numerical simulation to identify factors influencing waterlogging stress and its role in the distribution of salt marsh plants (Suaeda heteroptera) in the LREW. Remote sensing image interpretation was then used to validate the results of the numerical simulation. Based on our field observations, the density of salt marsh plant communities may be highly sensitive to waterlogging. A hydrodynamic model was then used to reproduce the waterlogging distribution of the LREW. The distribution of the salt marsh plants was indirectly simulated by referencing the relationship between plant density responses to waterlogging. The simulation method proved consistent with remote sensing results. Our results show that the plant communities investigated here exhibited clear differences in density and inhabited environments based on waterlogging and soil salinity characteristics. S. heteroptera in the LREW can grow with 1.56–2.87 h/d of waterlogging. Our numerical model again confirmed this range and was consistent with field survey results. Based on these observations, drought tolerance and inundation tolerance determined the upper and lower boundaries of S. heteroptera distribution, respectively. Differences in waterlogging regimes that are suitable for growth resulted in a strip-shaped distribution of the salt marsh plants. Given the diverse threats posed by changing estuaries and coasts, our study provides a methodological framework for evaluating the distributions of salt marsh plants, in addition to baseline data to inform the protection and restoration of wetland plants.

In situ experiment on groundwater control of the ecological zonation of salt marsh macrophytes in an estuarine area

Tides and river water affect the groundwater vertical flow in the shallow soil in estuary areas, which in turn determines the ecological zonation of the salt marsh macrophytes. The groundwater vertical flow under the influence of the interaction of saltwater and freshwater is very complicated and includes upward porewater flow driven by evapotranspiration and downward groundwater drainage. In this study, in situ experiments were conducted to investigate the groundwater vertical flow direction and rate in four macrophytes zones of salt marsh macrophytes in the Yellow River Estuarine Nature Reserve. This study found that there are significant differences in groundwater vertical flow among these four macrophytes zones. (1) In the Bare flat zone, the downward drainage of groundwater and the upward porewater movement process frequently alternate. The processes of accumulation of and reduction in shallow soil salinity frequently alternate, and it is difficult for salt to accumulate continuously. (2) The Suaeda heteroptera Kitag. zone is mainly affected by tides. There are long periods of continuous porewater upward movement or groundwater downward drainage, and salinity in the shallow soils continues to accumulate or decrease during these periods. (3) In the Chinese tamarisk zone, the groundwater table is deep, and the moisture content of the shallow soil is low. The groundwater vertical flow is mainly an upward porewater process caused by evapotranspiration, and the shallow soil salinity accumulates gradually. (4) In the Staggered growth zone, the groundwater vertical flow characteristics of both the Bare flat zone and the Chinese tamarisk zone are evident. In general, in the salt marshes of the Yellow River Estuary, the tides and the Yellow River recharge affect the characteristics of the salt marsh groundwater. The salt marsh macrophytes are affected by the interactions of water and salt in the shallow soil, which form band-shaped macrophytes zones.

Analysis of Suaeda heteroptera cover change and its hydrology driving factors in the Liao River Estuary wetlands, China

Suaeda heteroptera (S. heteroptera) is the most common indicator plant of solonchak in coastal wetlands of the Liao River Estuary, the influence of meteorology, hydrology environment on vegetation distribution is of growing interest. With the help of satellite remote sensing (RS) technology and geographic information system (GIS), we investigated the spatial-temporal distribution and area change of S. heteroptera in the wetlands of the Liao River Estuary from 1997 to 2016, and the identification of the main driving mechanisms in the S. heteroptera evolution was analyzed in this coastal wetland. The SPSS Statistics 22 software was used to calculate the correlation coefficients between total area of S. heteroptera and each driving factor based on available long-term (1997-2016) and medium-term (2007-2016) data. Correlation analysis results indicated that the change in S. heteroptera coverage had insignificant correlations (correlation coefficients r=−0.241, r=−0.188 and r=−0.269) with annual mean temperature, precipitation, and sunshine duration, respectively. The results also showed that the growth of S. heteroptera was extremely relevant to runoff from the Liao River from April to June (r=0.889) over the last 10 years. This study revealed that some potential factors, such as river discharge may be related to the large-scale degeneration of S. heteroptera in Liao River Estuary wetlands.

Influence of Suaeda heteroptera – microorganisms – Nereis succinea on soil enzyme activities in oil-contaminated soil

ABSTRACT Oil is an important industrial raw material used as both a fuel and energy source and is the pillar of national economies. With the development of the petroleum industry, oil pollution is becoming increasingly serious and is one of the major pollutants. Bioremediation has become the main remediation method for the treatment of environmental pollutants owing to its advantages such as low resource consumption, high efficiency, absence of secondary pollution, environment-friendly, etc. The aim of this study was to determine the influence of Suaeda heteroptera–microorganisms–Nereis succinea on the activities of soil enzymes (including dehydrogenase, catalase, urease, and amylase) in petroleum-contaminated soil. A pot experiment was performed to determine the effects of Suaeda heteroptera, Suaeda heteroptera – microorganisms, and Suaeda heteroptera –microorganisms – Nereis succinea on oil pollution. While petroleum contamination decreased the soil dehydrogenase, catalase, urease, and amylase activities, Suaeda heteroptera –microorganisms – Nereis succinea improved the activities of these enzymes. Thus, Suaeda heteroptera – microorganisms – Nereis succinea could be employed to recover the soil polluted by oil.

Effects of Atrazine on the Growth of Suaeda Heteroptera

To explore the ecological degradation of Suaeda Heteroptera in Panjin Red Beach wetland, the effects of Atrazine on the growth and physiological effects of Suaeda Heteroptera seedlings were studied by indoor hydroponics. Experimental results show that the leaves and roots of the Suaeda Heteroptera seedlings are very sensitive to Atrazine. And the LD50 of the number of leaves of Suaeda Heteroptera seedlings were 34.2 μg/L. At low concentrations (3.8-11.4 μg/L), Atrazine promoted the growth of seedling leaves; at higher concentrations (22.8-34.8 μg/L), it inhibited leavse growth and had a significant dose-effect relationship Atrazine had different effects on height and root length of Suaeda Heteroptera, but had no effect on seedlings stem length. The formation of chlorophyll b in leaves of Suaeda Heteroptera treated by Atrazine was inhibited. Also, the main factor for the decrease of total chlorophyll consent is Atrazine.

The study on Suaeda heteroptera Kitag, Nereis succinea and bacteria's joint bioremediation of oil-contaminated soil

Petroleum, which is sometimes called “modern industrial blood”, is an important energy source. However, with the increased usage of oil and related products by industries, oil pollution is becoming increasingly serious. The methods used to remediate petroleum contaminated soil can be divided into physical, chemical, and biological remediation. In recent years, more attention has been paid to the bioremediation of soil and crude oil pollutants. In this study, a pot experiment investigated the use of N. succinea, S. heteroptera, and oil degrading bacteria as bioremediators. The changes in crude oil, petroleum hydrocarbons and the component degradation rate at different concentrations of crude oil were measured so that the removal effects of N. succinea, S. heteroptera, and oil degrading bacteria on soil crude oil contamination could be ascertained. The results show that the degradation rate for crude oil, normal hydrocarbons and PAHs in the S. heteroptera - N. succinea - oil degrading bacteria group was higher than in the S. heteroptera and S. heteroptera - oil degrading bacteria groups. The results showed that the biological disturbance caused by N. succinea can promote the growth of S. heteroptera, and that the root system of the plants provide a favorable breeding and growing environment for the oil degrading bacteria. The results also suggested that they synergistically promoted the degradation and removal of petroleum hydrocarbons and PAHs.