scholarly journals Mercury Methylation in paddy soil: Source and distribution of mercury species at a Hg mining area, Guizhou Province, China

2016 ◽  
Author(s):  
L. Zhao ◽  
C. W. N. Anderson ◽  
G. L. Qiu ◽  
B. Meng ◽  
D. Y. Wang ◽  
...  
Keyword(s):  
Atmospheric Deposition ◽  
Paddy Soil ◽  
Soil Layer ◽  
Ambient Air ◽  
Rice Paddy ◽  
Mercury Species ◽  
Low Concentration ◽  
Paddy Water ◽  
Hg Mining

Abstract. Rice paddy plantation for human consumption is dominant land uses throughout Asia. Rice paddy fields have been identified as important sites for methylmerucry (MeHg) production in the terrestrial ecosystem, and a primary pathway of MeHg exposure to human in mercury (Hg) mining areas. We compared the source and distribution of Hg species in different compartments of the rice paddy during a complete rice-growing season at two different typical Hg-contaminated mining sites: an abandoned site with high Hg concentration in soil but low concentration in atmosphere, and a current-day artisanal site with low concentration in soil but high concentration in atmosphere. The contribution of new Hg to the ecosystem from irrigation and atmospheric deposition was insignificant relative to the pool of old Hg; the dominant source of MeHg to paddy soil is in situ methylation of inorganic Hg. Elevated MeHg concentrations jointly with the high proportion of Hg as MeHg in paddy water and the surface soil layer at the artisanal s ite demonstrated active Hg methylation at this site only. We propose that the in situ production of MeHg is dependent on elevated IHg in the atmosphere, and the deposition of new Hg into a low pH anoxic geochemical system. In contrast, the absence of depth-dependent variability in the MeHg concentration in soil cores collected from abandoned Hg mining site, consistent with the low concentration of Hg in atmospheric deposition and high pH of the paddy water/irrigation water, suggested that the net production of MeHg was limited. We also propose that the concentration of Hg in ambient air is an indicator for the risk of MeHg accumulation in paddy rice.

scholarly journals Mercury methylation in paddy soil: source and distribution of mercury species at a Hg mining area, Guizhou Province, China

2016 ◽  
Vol 13 (8) ◽  
pp. 2429-2440 ◽  
Author(s):  
Lei Zhao ◽  
Christopher W. N Anderson ◽  
Guangle Qiu ◽  
Bo Meng ◽  
Dingyong Wang ◽  
...  
Keyword(s):  
Paddy Soil ◽  
Surface Soil ◽  
Ambient Air ◽  
Rice Paddy ◽  
Guizhou Province ◽  
Mercury Species ◽  
Low Concentration ◽  
Paddy Water ◽  
Hg Mining

Abstract. Rice paddy plantation is the dominant agricultural land use throughout Asia. Rice paddy fields have been identified as important sites for methylmercury (MeHg) production in the terrestrial ecosystem and a primary pathway of MeHg exposure to humans in mercury (Hg) mining areas. We compared the source and distribution of Hg species in different compartments of the rice paddy during a complete rice-growing season at two different typical Hg-contaminated mining sites in Guizhou province, China: an abandoned site with a high Hg concentration in soil but a low concentration in the atmosphere and a current-day artisanal site with a low concentration in soil but a high concentration in the atmosphere. Our results showed that the flux of new Hg to the ecosystem from irrigation and atmospheric deposition was insignificant relative to the pool of old Hg in soil; the dominant source of MeHg to paddy soil is in situ methylation of inorganic Hg (IHg). Elevated MeHg concentrations and the high proportion of Hg as MeHg in paddy water and the surface soil layer at the artisanal site demonstrated active Hg methylation at this site only. We propose that the in situ production of MeHg in paddy water and surface soil is dependent on elevated Hg in the atmosphere and the consequential deposition of new Hg into a low-pH anoxic geochemical system. The absence of depth-dependent variability in the MeHg concentration in soil cores collected from the abandoned Hg mining site, consistent with the low concentration of Hg in the atmosphere and high pH of the paddy water and irrigation water, suggested that net production of MeHg at this site was limited. We propose that the concentration of Hg in ambient air is an indicator for the risk of MeHg accumulation in paddy rice.

scholarly journals Novel Euryarchaeotal Lineages Detected on Rice Roots and in the Anoxic Bulk Soil of Flooded Rice Microcosms

1998 ◽  
Vol 64 (12) ◽  
pp. 4983-4989 ◽  
Author(s):  
Regine Großkopf ◽  
Stephan Stubner ◽  
Werner Liesack
Keyword(s):  
Paddy Soil ◽  
Rice Paddy ◽  
Small Subunit ◽  
Small Subunit Rrna ◽  
Domain Specific ◽  
Rice Roots ◽  
Specific Oligonucleotide Probe ◽  
Culture Independent ◽  
Environmental Sequences

ABSTRACT Because excised, washed roots of rice (Oryza sativa) immediately produce CH4 when they are incubated under anoxic conditions (P. Frenzel and U. Bosse, FEMS Microbiol. Ecol. 21:25–36, 1996), we employed a culture-independent molecular approach to identify the methanogenic microbial community present on roots of rice plants. Archaeal small-subunit rRNA-encoding genes were amplified directly from total root DNA by PCR and then cloned. Thirty-two archaeal rice root (ARR) gene clones were randomly selected, and the amplified primary structures of ca. 750 nucleotide sequence positions were compared. Only 10 of the environmental sequences were affiliated with known methanogens; 5 were affiliated withMethanosarcina spp., and 5 were affiliated withMethanobacterium spp. The remaining 22 ARR gene clones formed four distinct lineages (rice clusters I through IV) which were not closely related to any known cultured member of theArchaea. Rice clusters I and II formed distinct clades within the phylogenetic radiation of the orders “Methanosarcinales” and Methanomicrobiales. Rice cluster I was novel, and rice cluster II was closely affiliated with environmental sequences obtained from bog peat in northern England. Rice cluster III occurred on the same branch asThermoplasma acidophilum and marine group II but was only distantly related to these taxa. Rice cluster IV was a deep-branching crenarchaeotal assemblage that was closely related to clone pGrfC26, an environmental sequence recovered from a temperate marsh environment. The use of a domain-specific oligonucleotide probe in a fluorescent in situ hybridization analysis revealed that viable members of theArchaea were present on the surfaces of rice roots. In addition, we describe a novel euryarchaeotal main line of descent, designated rice cluster V, which was detected in anoxic rice paddy soil. These results indicate that there is an astonishing richness of archaeal diversity present on rice roots and in the surrounding paddy soil.

scholarly journals Rice paddyNitrospiraeencode and express genes related to sulfate respiration: proposal of the new genusCandidatusSulfobium

2017 ◽  
Author(s):  
Sarah Zecchin ◽  
Ralf C. Mueller ◽  
Jana Seifert ◽  
Ulrich Stingl ◽  
Karthik Anantharaman ◽  
...  
Keyword(s):  
Sulfate Reduction ◽  
Paddy Soil ◽  
Rice Paddy ◽  
Bulk Soil ◽  
Sulfur Cycling ◽  
Dissimilatory Sulfate Reduction ◽  
Rice Paddy Soil ◽  
Novel Genus ◽  
Environmental Surveys

AbstractNitrospiraespp. distantly related to thermophilic, sulfate-reducingThermodesulfovibriospecies are regularly observed in environmental surveys of anoxic marine and freshwater habitats. However, little is known about their genetic make-up and physiology. Here, we present the draft genome ofNitrospiraebacterium Nbg-4 as a representative of this clade and analyzed itsin situprotein expression under sulfate-enriched and sulfate-depleted conditions in rice paddy soil. The genome of Nbg-4 was assembled from replicated metagenomes of rice paddy soil that was used to grow rice plants in the presence and absence of gypsum (CaSO4×2H2O). Nbg-4 encoded the full pathway of dissimilatory sulfate reduction and showed expression thereof in gypsum-amended anoxic bulk soil as revealed by parallel metaproteomics. In addition, Nbg-4 encoded the full pathway of dissimilatory nitrate reduction to ammonia, which was expressed in bulk soil without gypsum amendment. The relative abundance of Nbg-4-related metagenome reads was similar under both treatments indicating that it maintained stable populations while shifting its energy metabolism. Further genome reconstruction revealed the potential to utilize butyrate, formate, H2, or acetate as electron donor, with the Wood-Ljungdahl pathway being expressed under both conditions. Comparison to publicly availableNitrospiraegenome bins confirmed that the pathway for dissimilatory sulfate reduction is also present in relatedNitrospiraerecovered from groundwater. Subsequent phylogenomics showed that such microorganisms form a novel genus within the phylumNitrospirae, with Nbg-4 as a representative species. Based on the widespread occurrence of this novel genus, we propose for Nbg-4 the nameCandidatusSulfobium mesophilum, gen. nov., spec. nov.ImportanceRice paddies are indispensable for food supply but are a major source of the greenhouse gas methane. If not counterbalanced by cryptic sulfur cycling, methane emission from rice paddy fields would be even higher. However, the microorganisms involved in this sulfur cycling are little understood. By using an environmental systems biology approach of Italian rice paddy soil, we could retrieve the population genome of a novel member of the phylumNitrospirae. This microorganism encoded the full pathway of dissimilatory sulfate reduction and expressed itin situunder sulfate-enriched and anoxic conditions. Phylogenomics and comparison to environmental surveys showed that such microorganisms are actually widespread in freshwater and marine environments. At the same time, they represent a yet undiscovered genus within the little exploredNitrospirae. Our results will be important to design enrichment strategies and postgenomic studies to fully understand the contribution of these novelNitrospiraeto the global sulfur cycle.

scholarly journals Monitoring of pesticide residues in rice paddy soil and paddy water

2012 ◽  
Vol 16 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Hyun-Ho Noh ◽  
Jae-Yun Lee ◽  
So-Hyun Park ◽  
Oh-Seok Jeong ◽  
Seo-Hong Kim ◽  
...  
Keyword(s):  
Paddy Soil ◽  
Pesticide Residues ◽  
Rice Paddy ◽  
Rice Paddy Soil ◽  
Paddy Water

scholarly journals The influence of chemical parameters on the in-situ metal carbonyl complex formation studied with the fast on-line reaction apparatus (FORA)

2021 ◽  
Vol 109 (4) ◽  
pp. 243-260 ◽  
Author(s):  
Yves Wittwer ◽  
Robert Eichler ◽  
Dominik Herrmann ◽  
Andreas Türler
Keyword(s):  
Metal Carbonyl ◽  
Ambient Air ◽  
Single Atom ◽  
Carbonyl Complex ◽  
Carbonyl Complexes ◽  
On Line ◽  
Carrier Gases ◽  
And Performance ◽  
Atom Chemistry

Abstract A new setup named Fast On-line Reaction Apparatus (FORA) is presented which allows for the efficient investigation and optimization of metal carbonyl complex (MCC) formation reactions under various reaction conditions. The setup contains a 252Cf-source producing short-lived Mo, Tc, Ru and Rh isotopes at a rate of a few atoms per second by its 3% spontaneous fission decay branch. Those atoms are transformed within FORA in-situ into volatile metal carbonyl complexes (MCCs) by using CO-containing carrier gases. Here, the design, operation and performance of FORA is discussed, revealing it as a suitable setup for performing single-atom chemistry studies. The influence of various gas-additives, such as CO2, CH4, H2, Ar, O2, H2O and ambient air, on the formation and transport of MCCs was investigated. O2, H2O and air were found to harm the formation and transport of MCCs in FORA, with H2O being the most severe. An exception is Tc, for which about 130 ppmv of H2O caused an increased production and transport of volatile compounds. The other gas-additives were not influencing the formation and transport efficiency of MCCs. Using an older setup called Miss Piggy based on a similar working principle as FORA, it was additionally investigated if gas-additives are mostly affecting the formation or only the transport stability of MCCs. It was found that mostly formation is impacted, as MCCs appear to be much less sensitive to reacting with gas-additives in comparison to the bare Mo, Tc, Ru and Rh atoms.

scholarly journals Air Concentrations of Gaseous Elemental Mercury and Vegetation–Air Fluxes within Saltmarshes of the Tagus Estuary, Portugal

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 228
Author(s):  
Rute Cesário ◽  
Nelson J. O’Driscoll ◽  
Sara Justino ◽  
Claire E. Wilson ◽  
Carlos E. Monteiro ◽  
...  
Keyword(s):  
Leaf Area ◽  
Elemental Mercury ◽  
Ambient Air ◽  
Tagus Estuary ◽  
Contaminated Site ◽  
Gaseous Elemental Mercury ◽  
Mercury Flux ◽  
Sarcocornia Fruticosa ◽  
Air Concentrations

In situ air concentrations of gaseous elemental mercury (Hg(0)) and vegetation–atmosphere fluxes were quantified in both high (Cala Norte, CN) and low-to-moderate (Alcochete, ALC) Hg-contaminated saltmarsh areas of the Tagus estuary colonized by plant species Halimione portulacoides (Hp) and Sarcocornia fruticosa (Sf). Atmospheric Hg(0) ranged between 1.08–18.15 ng m−3 in CN and 1.18–3.53 ng m−3 in ALC. In CN, most of the high Hg(0) levels occurred during nighttime, while the opposite was observed at ALC, suggesting that photoreduction was not driving the air Hg(0) concentrations at the contaminated site. Vegetation–air Hg(0) fluxes were low in ALC and ranged from −0.76 to 1.52 ng m−2 (leaf area) h−1 for Hp and from −0.40 to 1.28 ng m−2 (leaf area) h−1 for Sf. In CN, higher Hg fluxes were observed for both plants, ranging from −9.90 to 15.45 ng m−2 (leaf area) h−1 for Hp and from −8.93 to 12.58 ng m−2 (leaf area) h−1 for Sf. Mercury flux results at CN were considered less reliable due to large and fast variations in the ambient air concentrations of Hg(0), which may have been influenced by emissions from the nearby chlor-alkali plant, or historical contamination. Improved experimental setup, the influence of high local Hg concentrations and the seasonal activity of the plants must be considered when assessing vegetation–air Hg(0) fluxes in Hg-contaminated areas.

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