Crab bioturbation drives coupled iron-phosphate-sulfide cycling in mangrove and salt marsh soils

Xiao，Kai1,2; Pan，Feng3; Santos，Isaac R.4; Zheng，Yan1,2; Zheng，Chunmiao1,2; Chen，Nengwang3; Lu，Zeyang3; Wang，Fenfang3; Li，Zhenyang1; Li，Hailong1,2

2022-10-15

10.1016/j.geoderma.2022.115990

GEODERMA   Impact Factor & Quartile

0016-7061

1872-6259

Coastal wetlands sequestering abundant blue carbon in soils are biogeochemical hotspots and critical habitats for benthic animals like invertebrate fiddler crabs. Here, we reveal how crab bioturbation (i.e., burrowing activity) drives the redox geochemistry of ferrous iron (Fe(II)), phosphate (PO43-), and sulfide (S(-II)) under contrasting vegetation types and hydrological conditions. We used in-situ approaches of diffusive gradients in thin films to perform detailed mm-scale burrow observations in two subtropical wetlands with a vegetation gradient of mudflat-salt marsh-mangrove. Burrow flushing caused a top-down hydrologic connectivity through the crab burrows and thus created a deep depth for the occurrence of Fe(III) reduction and sulfate reduction which were accompanied by P mobilization. The burrow oxidation zone, indicated by lower concentrations of Fe(II), PO43- and S(-II), were shallower in mudflats and salt marshes than in mangroves due to the unique respiratory roots of mangrove plants. The redox of Fe(II), PO(4)(3-)and S(-II) in crab burrow was insensitive to the convection flow induced input of dissolved oxygen through the surrounding soil matrix, indicating the burrow soil is an independent microenvironment. Crab burrowing activities favored Fe-S coupling which is conductive the formation of pyrite and alkalinity generation. Overall, our in-situ high-resolution observations and porewater hydraulic dynamics revealed spatially variable soil geochemistry, active coupled cycling of Fe-P-S in crab burrows, and mm-scale hotspots of redox cycling within burrows.

Bioturbation Blue carbon system Soil-water interfere Benthic flux Coastal biogeochemistry

SCI ; EI

English

First ; Corresponding

National Natural Science Foun-dation of China["42177046","41972260"] ; Science, Technology and Innovation Commission of Shenzhen["JSGG20210802153535002","20200925174525002"]

Agriculture

Soil Science

WOS:000822975600011

ELSEVIER

20222612279278

Carbon ; Dissolved oxygen ; Pyrites ; Redox reactions ; Soil moisture ; Sulfur compounds ; Vegetation ; Wetlands

Geochemistry:481.2 ; Soils and Soil Mechanics:483.1 ; Biochemistry:801.2 ; Chemical Reactions:802.2 ; Chemical Products Generally:804

AGRICULTURAL SCIENCES

2-s2.0-85132748727

Web of Science

1.State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control,School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,Guangdong,518055,China
2.Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control,Southern University of Science and Technology,Shenzhen,Guangdong,518055,China
3.College of the Environment & Ecology,Xiamen University,Xiamen,361102,China
4.Department of Marine Sciences,University of Gothenburg,Gothenburg,Sweden

Xiao，Kai,Pan，Feng,Santos，Isaac R.,et al. Crab bioturbation drives coupled iron-phosphate-sulfide cycling in mangrove and salt marsh soils[J]. GEODERMA,2022,424.

Xiao，Kai.,Pan，Feng.,Santos，Isaac R..,Zheng，Yan.,Zheng，Chunmiao.,...&Li，Hailong.(2022).Crab bioturbation drives coupled iron-phosphate-sulfide cycling in mangrove and salt marsh soils.GEODERMA,424.

Xiao，Kai,et al."Crab bioturbation drives coupled iron-phosphate-sulfide cycling in mangrove and salt marsh soils".GEODERMA 424(2022).