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Mei K, Liu J, Xue L, Xu J, Jiang W, Tan Z, Li A, Qu J, Yan C. Stimulation of oxalate root exudate in arsenic speciation and fluctuation with phosphate and iron in anoxic mangrove sediment. MARINE POLLUTION BULLETIN 2023; 189:114823. [PMID: 36931154 DOI: 10.1016/j.marpolbul.2023.114823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 03/04/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
Mutual transformations of rhizospheric arsenic (As) in pollution-prone mangrove sediments affected by root exudate oxalate were simulated. This study focuses on the effect of oxalate on As release, mobilization, and phase speciation associated with P and Fe was examined under anoxic conditions in time-dependent changes. Results showed that oxalate addition significantly facilitated As-Fe-P release from As-contaminated mangrove sediments. Sediment As formed the adsorptive and the carbonate-binding fractionations, facilitating the re-adsorption processes. Solution As and As5+ correlated with NaOH-P positively but with NaHCO3-P and HCl-P negatively. Dominant Fe3+ (>84 %) from the amorphous Fe regulated suspension changes and then time-dependent co-precipitation with As and P. Sediment P formed strong complexes with Fe oxides and could be substituted for As via STEM analysis. Oxalate ligand exchange, competitive adsorption of oxalate, and Fe-reduced dissolution are confirmed to involve, allowing for an insight As/P/Fe mobilization and fate in mangrove wetland.
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Affiliation(s)
- Kang Mei
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
| | - Jingchun Liu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Liyang Xue
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Jicong Xu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
| | - Wanlin Jiang
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Zhiwen Tan
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Anran Li
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Jinyi Qu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Chongling Yan
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
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Zhao P, Sanganyado E, Wang T, Sun Z, Jiang Z, Zeng M, Huang Z, Li Y, Li P, Bi R, Liu W. Accumulation of nutrients and potentially toxic elements in plants and fishes in restored mangrove ecosystems in South China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:155964. [PMID: 35588846 DOI: 10.1016/j.scitotenv.2022.155964] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 05/10/2022] [Accepted: 05/11/2022] [Indexed: 06/15/2023]
Abstract
Mangroves are highly dynamic ecosystems that offer important services such as maintaining biodiversity, filtering pollutants, and providing habitats for fishes. We investigated the uptake and accumulation of nutrients and potentially toxic elements in mangrove plants and fish to better understand the role of mangrove restoration in maintaining mangrove biota quality. In mangrove plants, the average bioconcentration factors of nutrients and potentially toxic elements were in the order P > Pb > Mn > Mg > Se > Zn > Hg > Cu > Cd > As > Co > Cr > Ni > Fe > V > Sb, where only P (all plant species) and Pb (Sonneratia apetala Buchanan-Hamilton) had a BCF > 1.0 in mangrove plants. In general, Sonneratia spp. had better performances than Kandelia candel (Linn.) Druce, Aegiceras corniculatum (Linn.) Blanco and Acanthus ilicifolius L. Sp. in terms of nutrient uptake and toxic metal(loid)s accumulation, and the best uptake capacity was found in S. apetala. Fast growth and easy adaptation make S. apetala suitable for a restored mangrove ecosystem, but continual management is needed to prevent its suppression of mangrove species diversity. The concentration of As, Cd, Hg, Cu, Cr and Pb in the mangrove sediment were 30-220% higher than the Chinese National Standard of Marine Sediment Quality Class I limits, suggesting that the sediments were unsuitable for aquaculture and nature reserves. Although a higher toxic metal(loid)s concentration in the sediment was found, the target hazard quotient (THQ) of this toxic metal(loid)s in 5 mangrove habitat fishes was <1.0, except THQ of Pb in Boleophthalmus pectinirostris Linnaeus was 1.17, and THQ of Cr in Bostrychus sinensis Lacépède was 1.12. The low THQ (less than 1.0) of mangrove habitat fishes suggested that the restored mangrove system could alleviate the bioaccumulation of toxic metal(loid)s in mangrove fish.
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Affiliation(s)
- Puhui Zhao
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Edmond Sanganyado
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Tieyu Wang
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Zewei Sun
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Ziyang Jiang
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Mingrui Zeng
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Zhangxun Huang
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Yifan Li
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Ping Li
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
| | - Ran Bi
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China.
| | - Wenhua Liu
- Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, Shantou University, Shantou 515063, China
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Differed Adaptive Strategies to Nutrient Status between Native and Exotic Mangrove Species. FORESTS 2022. [DOI: 10.3390/f13050804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To rapidly rehabilitate mangrove forests, exotic mangrove species characterized by high growth rates have been introduced in China, which would undoubtedly affect the nutrient status, nutrient acquisition and utilization strategies of mangrove plants, but the mechanism remains unclear. Qi’ao Island (a suburb of Zhuhai City) has the largest continuous exotic mangrove forests in China, where a mass collection of mangrove soils, plant tissues and tidewater was conducted. Ecological stoichiometric ratios and isotopic compositions were then analyzed to evaluate the ecosystem-scale nutrient status and compare the nutrient acquisition and utilization strategies of native Kandelia obovata (KO) and exotic Sonneratia apetala (SA) species. Soil and foliar C:N:P stoichiometries indicated that there is high P availability but N limitations, while further isotopic evidence indicated that native KO and exotic SA responded differently to the N limitation status. First, native KO seemed to prefer NO3−, while exotic SA preferred NH4+, according to the Δ15Nleaf–root (leaf–root δ15N difference) as well as the relationships between foliar δ15N and soil-extracted NH4+ δ15N, and between N and heavy metal contents. This suggested possible inter-specific competition between native KO and exotic SA, leading to different N species’ preferences to maximize resource utilization. Next, native KO likely adopted the “conservative” strategy to ensure survival with reduced investment in N-rich growth components but root systems leading to lower growth rates and higher N use efficiency (NUE) and intrinsic water use efficiency (iWUE), while exotic SA adopted the “aggressive” strategy to ensure fast growth with heavy investment in N-rich growth components, leading to rapid growth and lower NUE and iWUE, and showing signs of invasiveness. Further, native KO is more responsive to aggravated N limitation by enhancing NUE. This study will provide insights into the adaptation of different mangrove species to nutrient limitations and the risks associated with large-scale plantations of exotic mangrove species.
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Phytoextraction and Antioxidant Defense of Mangrove Seedling (Kandelia obovata) to Inorganic Arsenate Exposure. WATER 2022. [DOI: 10.3390/w14040643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Increasing arsenic (As) pollution is posing potential endangerment to mangrove wetland ecosystems. Mangrove phytoextraction, translocation, and responses to As exposure must be urgently addressed. In this study, the growth and physiological response of Kandelia obovata seedlings were examined after addition of 25−200 mg kg−1 As under sediment culture conditions. Results showed that the seedling morphological variations were not significant below 100 mg kg−1 compared to the control group, indicating superoxide dismutase, peroxidase, and catalase synergetic interaction to resist the As exposure. High As concentrations (150–200 mg kg−1) inhibited the seedling growth accompanied by a significant increase in malondialdehyde content and decrease in activities of antioxidant enzymes. Toxicity symptoms and mortality appeared in 200 mg kg−1 As, presumably because the plant reached the limit of As tolerance. Besides, As accumulated mainly in roots, accounting for 87.04–97.85% of the total As, and the bioaccumulation factor (BCF) was >100%. However, the BCF and translocation factor (TF) in stems and leaves were below unity, illustrating a weak capacity of transferring As to aerial parts of the seedlings. Overall, K. obovata is a potential remediated species in polluted coastal wetlands due to high phytoextraction capacity and high tolerance to As exposure.
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Yang D, Wu J, Yan L, Yu L, Liu J, Yan C. A comparative study of sediment-bound trace elements and iron-bearing minerals in S. alterniflora and mudflat regions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151220. [PMID: 34717993 DOI: 10.1016/j.scitotenv.2021.151220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 10/19/2021] [Accepted: 10/21/2021] [Indexed: 06/13/2023]
Abstract
Elevated sediment-bound trace elements and iron-bearing minerals in intertidal habitats have been drawing more attention, but there is rarely a comparative study assessing these features between halophyte plants habitat and mudflats. In this paper, sediment samples were collected in S. alterniflora and the corresponding mudflat at 7 typical intertidal habitats (Chongming, Xiapu, Yueqing, Yunxiao, Zhanjiang, Beihai, and Zhuhai) from north to south of China, respectively. Trace element concentrations, including arsenic (As), mercury (Hg), cadmium (Cd), antimony (Sb) and scandium (Sc), and magnetic characteristics were determined. Variations in sediment-bound As, Hg, Cd, Sb were associated with S. alterniflora. Accumulations of sediment-bound As, Hg, Sb, Cd and Sc in S. alterniflora in Beihai were much higher than those in the mudflat. Concentration of sediment-bound As, Hg, Sb, Cd and Sc in S. alterniflora and mudflat were comparable in Yueqing, Xiapu, Yunxiao and Zhanjiang, respectively. Variations in low-frequency susceptibility, susceptibility of anhysteretic remanence magnetization, saturation isothermal remanence magnetization and frequency dependent susceptibility can explain the site-dependent accumulation of magnetic minerals in intertidal habitats. S. alterniflora tend to deplete sediment magnetic concentration and enhance sediment-bound As, Hg, and Sb concentration. The results of our study further revealed the coexistence of trace elements and magnetic minerals between the sampling sites and vegetative in intertidal habitats.
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Affiliation(s)
- Dan Yang
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region, Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering, College of Life Sciences, Guizhou University, Guiyang 550025, China; State Key Laboratory of Marine Environmental Science, Key Laboratory of the Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
| | - Jiajia Wu
- State Key Laboratory of Marine Environmental Science, Key Laboratory of the Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
| | - Lingbin Yan
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region, Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering, College of Life Sciences, Guizhou University, Guiyang 550025, China
| | - Lifei Yu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region, Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering, College of Life Sciences, Guizhou University, Guiyang 550025, China
| | - Jingchun Liu
- State Key Laboratory of Marine Environmental Science, Key Laboratory of the Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
| | - Chongling Yan
- State Key Laboratory of Marine Environmental Science, Key Laboratory of the Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China.
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Mei K, Wu G, Liu J, Hong H, Lu H, Yan C. Dynamics of low-molecular-weight organic acids for the extraction and sequestration of arsenic species and heavy metals using mangrove sediments. CHEMOSPHERE 2022; 286:131820. [PMID: 34416592 DOI: 10.1016/j.chemosphere.2021.131820] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 07/15/2021] [Accepted: 08/04/2021] [Indexed: 06/13/2023]
Abstract
Mangrove wetlands are subjected to pollution due to anthropogenic activities. Mangrove fitness is mainly determined by root exudates and microorganisms activities belowground, but the mechanisms are not yet well known. Rhizospheric interactions among mangrove sediments, microorganisms and root exudates were simulated. In particular, low-molecular-weight organic acids (LMWOA), were examined to explore the metal(loid)s rhizospheric dynamics via batch experiments. Using a combination of comparative sterilised and unsterilised sediments, LMWOA extracts and sediments constituents were examined. Factors such as the solution pH, dissolved organic carbon (DOC), arsenic and iron species and metal(loid)s in the aqueous phase were evaluated. The results show that on an average, the As decreased by 68.3 % and 42.1 % under citric and malic acid treatments, respectively, after sterilisation. In contrast, the As content increased by 29.6 % under oxalic acid treatment. Microorganisms probably facilitate sediment As release in the presence of citric and malic acids but suppress As mobilisation in the presence of oxalic acid. Fe, Mn and Al were significantly (p < 0.05) positively correlated with the trace metal(loid)s (Zn, Pb, Ni, Cu, Cr, Co, Ba, Cd and As). The solution pH was negatively correlated with the solution As. Both DOC and pH reach the peaks at the end of all treatments. The As absorption-desorption dynamics are closely linked to proton consumption, Fe-Mn-Al sedimentation of ageing performance and organic ligand complexation. The study provides an insight into the rhizospheric processes of microbial involvement and gives an enlightening understanding of the metal(loid)s redeployment for plant adaptation in mangrove wetlands.
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Affiliation(s)
- Kang Mei
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China
| | - Guirong Wu
- College of Food and Biological Engineering, Hezhou University, Hezhou, 542899, China
| | - Jingchun Liu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China.
| | - Hualong Hong
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China
| | - Haoliang Lu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China
| | - Chongling Yan
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, China
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Mei K, Liu J, Fan J, Guo X, Wu J, Zhou Y, Lu H, Yan C. Low-level arsenite boosts rhizospheric exudation of low-molecular-weight organic acids from mangrove seedlings (Avicennia marina): Arsenic phytoextraction, removal, and detoxification. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 775:145685. [PMID: 33631581 DOI: 10.1016/j.scitotenv.2021.145685] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 06/12/2023]
Abstract
Arsenic (As) contamination in mangrove wetlands has become a major concern. However, the impact of As on mangroves and the rhizospheric mechanism remains unclarified. In this study, various properties and responses of mangrove seedlings were investigated after exposure to arsenite (As3+). The results indicate that low-level As promoted the secretion of Low-molecular-weight organic acids (LMWOA, 4.5-6.59 mg/kg root in dry weight) and Fe plaque formation in their rhizospheres. Citric, oxalic, and malic acid were the three main components (84.3%-86.8%). Low-level As (5 and 10 μmol/L) also inhibited the rate of radial oxygen loss (ROL) but increased the accumulation of plant As (stem > leaf > root) and plaque As (0.23-1.13 mg/kg root in dry weight). We selected model LMWOAs to further examine As migration and speciation over time in As-enriched sediments (0, 20 and 40 mg/kg). The results reveal that LMWOAs promoted sediment As mobilisation and followed the order of citric acid > malic acid > oxalic acid. The hydrolysis and precipitation of Fe3+ and the complexation with organic ligand led to aqueous As and Fe sedimentation and, conversely, increased solution pH and re-translocated free As. The tolerance mechanisms include lowering ROL, translocating As and releasing LMWOAs to reduce its toxicity, and facilitating the fixation in sediment of oxidised As. The present study highlights the fact that mangroves are potentially favourable for As phytoextraction, removal and detoxification.
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Affiliation(s)
- Kang Mei
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China; College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Jingchun Liu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Jin Fan
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China; School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xin Guo
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Jiajia Wu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Yi Zhou
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Haoliang Lu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Chongling Yan
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
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Mei K, Liu J, Shi R, Guo X, Lu H, Yan C. The migrated behavior and bioavailability of arsenic in mangrove sediments affected by pH and organic acids. MARINE POLLUTION BULLETIN 2020; 159:111480. [PMID: 32738639 DOI: 10.1016/j.marpolbul.2020.111480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 07/12/2020] [Accepted: 07/12/2020] [Indexed: 06/11/2023]
Abstract
Batch experiments were conducted to study the migration behavior of arsenic (As) and iron (bivalent, trivalent, and total Fe) of the presence of the low molecular weight organic acids (LMWOAs) citric acid, malic acid, and oxalic acid in As-enriched mangrove sediments. The results for supernatant As/Fe species were significant according to each LMWOA treatment. Significant non-linear correlations were found among As level, pH, and acid dose based on our predictive model. The capacity of LMWOAs to mobilize As/Fe species followed the order of citric acid > malic acid/oxalic acid. The supernatant As correlated positively with the LMWOAs dose and negatively correlated with the pH. As migration was affected by acid strength, the number of carboxyl groups, the pH and levels of Fe compounds in the sediments. The results indicate that LMWOAs can potentially attenuate As contamination from mangrove sediment, allowing for a better understanding of As/Fe behavior in the rhizosphere.
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Affiliation(s)
- Kang Mei
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
| | - Jingchun Liu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Rongrong Shi
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Xin Guo
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Haoliang Lu
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Chongling Yan
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
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Remote Estimation of Mangrove Aboveground Carbon Stock at the Species Level Using a Low-Cost Unmanned Aerial Vehicle System. REMOTE SENSING 2019. [DOI: 10.3390/rs11091018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
There is ongoing interest in developing remote sensing technology to map and monitor the spatial distribution and carbon stock of mangrove forests. Previous research has demonstrated that the relationship between remote sensing derived parameters and aboveground carbon (AGC) stock varies for different species types. However, the coarse spatial resolution of satellite images has restricted the estimated AGC accuracy, especially at the individual species level. Recently, the availability of unmanned aerial vehicles (UAVs) has provided an operationally efficient approach to map the distribution of species and accurately estimate AGC stock at a fine scale in mangrove areas. In this study, we estimated mangrove AGC in the core area of northern Shenzhen Bay, South China, using four kinds of variables, including species type, canopy height metrics, vegetation indices, and texture features, derived from a low-cost UAV system. Three machine-learning algorithm models, including Random Forest (RF), Support Vector Regression (SVR), and Artificial Neural Network (ANN), were compared in this study, where a 10-fold cross-validation was used to evaluate each model’s effectiveness. The results showed that a model that used all four type of variables, which were based on the RF algorithm, provided better AGC estimates (R2 = 0.81, relative RMSE (rRMSE) = 0.20, relative MAE (rMAE) = 0.14). The average predicted AGC from this model was 93.0 ± 24.3 Mg C ha−1, and the total estimated AGC was 7903.2 Mg for the mangrove forests. The species-based model had better performance than the considered canopy-height-based model for AGC estimation, and mangrove species was the most important variable among all the considered input variables; the mean height (Hmean) the second most important variable. Additionally, the RF algorithms showed better performance in terms of mangrove AGC estimation than the SVR and ANN algorithms. Overall, a low-cost UAV system with a digital camera has the potential to enable satisfactory predictions of AGC in areas of homogenous mangrove forests.
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Chai M, Li R, Tam NFY, Zan Q. Effects of mangrove plant species on accumulation of heavy metals in sediment in a heavily polluted mangrove swamp in Pearl River Estuary, China. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2019; 41:175-189. [PMID: 29876676 DOI: 10.1007/s10653-018-0107-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/29/2018] [Indexed: 05/06/2023]
Abstract
The present study compared accumulation of heavy metals in a mangrove swamp dominated by Kandelia obovata with that by Sonneratia apetala in Pearl River Estuary, China. The results showed that the concentrations of heavy metals at all sediment depths in the S. apetala site were significantly higher than that in K. obovata. The geo-accumulation index and potential ecological risk index also showed that S. apetala sediment had a higher contamination of heavy metals, especially Cd. S. apetala significantly altered the biogeochemical cycles of Cd, lead (Pb), nickel (Ni) and chromium (Cr). In S. apetala sediment, TOC played an important role in sequestering heavy metals as reflected by its positive correlations with Zn and Pb. This study demonstrated the importance of plant species in altering soil quality and heavy metal accumulation, and S. apetala is more efficiently working as a pollution barrier than K. obovata.
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Affiliation(s)
- Minwei Chai
- School of Environment and Energy, Shenzhen Graduate School of Peking University, Shenzhen, 518055, China
| | - Ruili Li
- School of Environment and Energy, Shenzhen Graduate School of Peking University, Shenzhen, 518055, China.
| | - Nora Fung Yee Tam
- Department of Biology and Chemistry, City University of Hong Kong, Kowloon Tong, Hong Kong, China
| | - Qijie Zan
- Guangdong Neilingding Futian National Nature Reserve, Shenzhen, 518000, China
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Kulkarni R, Deobagkar D, Zinjarde S. Metals in mangrove ecosystems and associated biota: A global perspective. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2018; 153:215-228. [PMID: 29448175 DOI: 10.1016/j.ecoenv.2018.02.021] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 01/05/2018] [Accepted: 02/05/2018] [Indexed: 06/08/2023]
Abstract
Mangrove forests prevalent along the intertidal regions of tropical and sub-tropical coastlines are inimitable and dynamic ecosystems. They protect and stabilize coastal areas from deleterious consequences of natural disasters such as hurricanes and tsunamis. Although there are reviews on ecological aspects, industrial uses of mangrove-associated microorganisms and occurrence of pollutants in a region-specific manner, there is no exclusive review detailing the incidence of metals in mangrove sediments and associated biota in these ecosystems on a global level. In this review, mangrove forests have been classified in a continent-wise manner. Most of the investigations detail the distribution of metals such as zinc, chromium, arsenic, copper, cobalt, manganese, nickel, lead and mercury although in some cases levels of vanadium, strontium, zirconium and uranium have also been studied. Seasonal, tidal, marine, riverine, and terrestrial components are seen to influence occurrence, speciation, bioavailability and fate of metals in these ecosystems. In most of the cases, associated plants and animals also accumulate metals to different extents and are of ecotoxicological relevance. Levels of metals vary in a region specific manner and there is disparity in the pollution status of different mangrove areas. Protecting these vulnerable ecosystems from metal pollutants is important from environmental safety point of view.
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Affiliation(s)
- Rasika Kulkarni
- Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University, Pune 411007, India
| | - Deepti Deobagkar
- Indian Space Research Organization Cell, Savitribai Phule Pune University, Pune 411007, India
| | - Smita Zinjarde
- Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University, Pune 411007, India; Department of Microbiology, Savitribai Phule Pune University, Pune 411007, India.
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