Mercury distribution in the surface soil of China is potentially driven by precipitation, vegetation cover and organic matter

Zhang, Zhaoyang; Li, Gang; Yang, Lei; Xin-jun, Wang; Sun, Guoxin

doi:10.1186/s12302-020-00370-1

Cited by 11 publications

(2 citation statements)

References 66 publications

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“…The spectrum of soil can be determined by a variety of factors, such as soil color, organic matter content, and SMC (Zhang et al, 2020). However, if other influencing factors remain unchanged, the reflectance of soil may decrease with increasing SMC.…”

Section: Discussionmentioning

confidence: 99%

Remote sensing‐based retrieval of soil moisture content using stacking ensemble learning models

Wang

et al. 2022

Land Degrad Dev

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Machine learning combined with multisource remote sensing data to assess soil moisture content (SMC) has attracted considerable attention in SMC studies, but the retrieval results still remain uncertain. The purpose of this study is to combine multiple single machine learning models with integrated learning algorithms and propose an SMC retrieval method based on multiple differentiated models under a stacking integrated learning architecture. First, 19 factors, including: radar backscattering coefficient, vegetation index, and drought index, that affect SMC were extracted from SENTINEL-1, LANDSAT, and terrain factors. Those with the highest importance scores were selected as retrieval factors using the Boruta algorithm combined with four single machine learning methods-classified regression tree, random forest, gradient boosting decision tree (GBDT), and extreme random tree. In addition, the two stacking ensemble models using least absolute shrinkage and selection operator (LASSO) and the generalized boosted regression model (GBM) were tested and applied to build the most reliable and accurate estimation model. The results showed that radar backscattering coefficient, temperature, vegetation drought index, land surface temperature, enhanced vegetation index, and solar local incident angle were the most important environmental variables for soil moisture retrieval. A comparison of the four machine learning methods in April and August showed that the GBDT model revealed the highest SMC retrieval accuracy, with root mean square error values of 1.87% and 1.64%, respectively. The stacking models were more accurate than the optimal single machine learning model, especially when using GBM. The multifactor integrated model constructed using spectral indices, radar backscatter coefficients, and topographic data exhibited high accuracy in soil surface moisture retrieval in an arid zone, providing a reference for land desertification studies and ecological environment management in the study region.

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Section: Discussionmentioning

confidence: 99%

Remote sensing‐based retrieval of soil moisture content using stacking ensemble learning models

Wang

et al. 2022

Land Degrad Dev

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“…Contrary to Cd, Hg was not detected in leachate, while the distribution ratio in surface residues was significantly higher than the other seven elements. Studies have shown that the majority of the added Hg tended to be bound by soil organic matter on the surface and precipitation input had a slight influence on its mobility [52][53][54]. This may explain the large distribution ratio of Hg in surface residues and the reason for its obvious growth with the increased adding of sludge.…”

Section: Discussionmentioning

confidence: 99%

Woodland for Sludge Disposal in Beijing: Sustainable?

Shi

et al. 2022

Sustainability

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The sludge products of urban sewage treatment plants in Beijing are increasing year by year, and there is a large amount of stagnation, which requires scientific and reasonable disposal strategies. Currently, the woodland in the mountainous area of Beijing is considered the main means for sludge disposal; however, because the heavy metals in the sludge may cause potential pollution to the soil and groundwater, it is unclear how much sludge can be applied per unit area. To ensure the sustainable disposal of sludge, it is necessary to measure the risk of heavy metals on soil and groundwater under different sludge application rates to determine the most scientific disposal plan. In this study, the undisturbed soil columns obtained from the field were used to clarify the migration behaviors and accumulation of eight hazardous heavy metals under simulated rainfall conditions, and three sets of tests (the application rates of sludge products were 30 t·ha−1·a−1, 60 t·ha−1·a−1 and 120 t·ha−1·a−1 respectively) were set based on the supply–demand relationship between Beijing’s annual sludge output and the woodland area available for sludge disposal. The results showed that there were significant differences in the migration rules of heavy metals under different application rates, which were mainly reflected in the differences in accumulation in each layer of the soil. In terms of the leaching efficiency of heavy metals, except for Cadmium, the leaching rates of other heavy metals did not exceed 0.1%, indicating that most heavy metals accumulated in the soil. During the application process of sludge products, Arsenic and Cadmium posed a greater potential risk to groundwater than other heavy metals, to which should be paid sufficient attention. Based on the accumulation of heavy metals in soil, Arsenic was the main factor limiting the amount and frequency of sludge product application. The application rate of 60 t·ha−1·a−1 was preferred compared with the other two tests because it presented minimal risk to groundwater and soil in the short term, while the total amount of sludge disposal can be maximized.

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Methylmercury Concentrations More Strongly Associated With Trait Variation Than Food Web Position in Plethodontid Salamanders

Tennant,

Cosentino,

Cleckner

et al. 2024

Enviro Toxic and Chemistry

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Salamanders serve as bioindicators of mercury (Hg) in both terrestrial and aquatic habitats and are an important link in the food web between low‐trophic prey and higher‐trophic predators. We investigated the drivers of methylmercury (MeHg) exposure in three common plethodontid salamander species in New York State, USA, including comparisons among regions, habitat types (terrestrial and semiaquatic), and color morphs of Plethodon cinereus (striped and unstriped). Nonlethal tail samples were collected from one terrestrial species (P. cinereus) and two semiaquatic species (Eurycea bislineata and Desmognathus spp.) in the Adirondack Mountains (ADK) and the Finger Lakes National Forest (FLNF) regions. Samples were analyzed for MeHg and stable isotopes, including δ15N and δ13C which are proxies of trophic position and diet, respectively. Despite elevated biota Hg concentrations typically found in the ADK, salamander MeHg concentrations did not differ by region in the terrestrial species and one of the semiaquatic species. In addition, diet and trophic level did not explain MeHg exposure in salamanders. Semiaquatic salamanders exhibited higher MeHg concentrations than terrestrial salamanders in the FLNF only. Within species, only snout–vent length predicted MeHg concentrations in E. bislineata with few other variables significant as predictors of MeHg concentrations in path models. Among P. cinereus individuals in the FLNF, the striped morph had greater MeHg concentrations than the unstriped morph, and food web tracers were not different between morphs. Overall, New York State salamander Hg concentrations were elevated compared to other locations where these species are present. The present study establishes baseline Hg data in salamanders for future assessments of changes in Hg bioavailability to forests of New York State. Environ Toxicol Chem 2024;00:1–13. © 2024 SETAC

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Mercury distribution in the surface soil of China is potentially driven by precipitation, vegetation cover and organic matter

Cited by 11 publications

References 66 publications

Remote sensing‐based retrieval of soil moisture content using stacking ensemble learning models

Remote sensing‐based retrieval of soil moisture content using stacking ensemble learning models

Woodland for Sludge Disposal in Beijing: Sustainable?

Methylmercury Concentrations More Strongly Associated With Trait Variation Than Food Web Position in Plethodontid Salamanders

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