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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on LiHg2Os by Materials Project

LiOsHg2 crystallizes in the cubic F-43m space group. The structure is three-dimensional. Li is bonded in a body-centered cubic geometry to four equivalent Os and ten Hg atoms. All Li–Os bond lengths are 2.84 Å. There are four shorter (2.84 Å) and six longer (3.28 Å) Li–Hg bond lengths. Os is bonded in a distorted body-centered cubic geometry to four equivalent Li and four equivalent Hg atoms. All Os–Hg bond lengths are 2.84 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a 4-coordinate geometry to six equivalent Li, four equivalent Os, and four equivalent Hg atoms. All Hg–Hg bond lengths are 2.84 Å. In the second Hg site, Hg is bonded to four equivalent Li and four equivalent Hg atoms to form distorted edge-sharing HgLi4Hg4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ag2Hg5 by Materials Project

Ag2Hg5 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Ag is bonded to two equivalent Ag and ten Hg atoms to form a mixture of edge, face, and corner-sharing AgAg2Hg10 cuboctahedra. Both Ag–Ag bond lengths are 3.09 Å. There are a spread of Ag–Hg bond distances ranging from 3.05–3.18 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a distorted q6 geometry to four equivalent Ag and six Hg atoms. There are two shorter (3.09 Å) and four longer (3.13 Å) Hg–Hg bond lengths. In the second Hg site, Hg is bonded in a 9-coordinate geometry to four equivalent Ag and five Hg atoms. There are two shorter (3.06 Å) and two longer (3.09 Å) Hg–Hg bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr17(Li2Hg3)3 by Materials Project

Sr17(Li2Hg3)3 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Li is bonded in a bent 150 degrees geometry to one Sr and two equivalent Hg atoms. The Li–Sr bond length is 3.49 Å. Both Li–Hg bond lengths are 2.83 Å. There are four inequivalent Sr sites. In the first Sr site, Sr is bonded in a 12-coordinate geometry to twelve equivalent Li and six equivalent Hg atoms. All Sr–Hg bond lengths are 3.85 Å. In the second Sr site, Sr is bonded in a distorted rectangular see-saw-like geometry to one Sr and four Hg atoms. The Sr–Sr bond length is 4.32 Å. There are a spread of Sr–Hg bond distances ranging from 3.40–3.52 Å. In the third Sr site, Sr is bonded to twelve Sr atoms to form corner-sharing SrSr12 cuboctahedra. All Sr–Sr bond lengths are 4.17 Å. In the fourth Sr site, Sr is bonded in a distorted square co-planar geometry to two equivalent Sr and four equivalent Hg atoms. All Sr–Hg bond lengths are 3.49 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a 8-coordinate geometry to four equivalent Li and five Sr atoms. In the second Hg site, Hg is bonded in a 8-coordinate geometry to eight Sr atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgHg3 by Materials Project

MgHg3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Mg is bonded to twelve Hg atoms to form a mixture of edge, face, and corner-sharing MgHg12 cuboctahedra. There are four shorter (3.13 Å) and eight longer (3.31 Å) Mg–Hg bond lengths. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a square co-planar geometry to four equivalent Mg and eight equivalent Hg atoms. All Hg–Hg bond lengths are 3.31 Å. In the second Hg site, Hg is bonded in a 12-coordinate geometry to four equivalent Mg and eight Hg atoms. All Hg–Hg bond lengths are 3.13 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg3Pd8Se9 by Materials Project

Pd8Hg3Se9 crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. there are three inequivalent Pd sites. In the first Pd site, Pd is bonded to one Hg and five Se atoms to form distorted PdHgSe5 octahedra that share a cornercorner with one SeHgPd3 tetrahedra and edges with two equivalent PdHgSe5 octahedra. The Pd–Hg bond length is 2.89 Å. There are four shorter (2.55 Å) and one longer (2.65 Å) Pd–Se bond lengths. In the second Pd site, Pd is bonded in a 6-coordinate geometry to two Hg and four Se atoms. There are one shorter (2.85 Å) and one longer (2.98 Å) Pd–Hg bond lengths. There are a spread of Pd–Se bond distances ranging from 2.53–2.58 Å. In the third Pd site, Pd is bonded in a 6-coordinate geometry to one Hg and five Se atoms. The Pd–Hg bond length is 2.76 Å. There are a spread of Pd–Se bond distances ranging from 2.53–3.04 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a 5-coordinate geometry to four Pd and one Se atom. The Hg–Se bond length is 2.65 Å. In the second Hg site, Hg is bonded in a 4-coordinate geometry to four equivalent Pd atoms. There are four inequivalent Se sites. In the first Se site, Se is bonded in a 4-coordinate geometry to four Pd atoms. In the second Se site, Se is bonded in a 6-coordinate geometry to six Pd atoms. In the third Se site, Se is bonded to four Pd atoms to form distorted SePd4 trigonal pyramids that share corners with three equivalent SeHgPd3 tetrahedra, corners with three equivalent SePd4 trigonal pyramids, and edges with two equivalent SePd4 trigonal pyramids. In the fourth Se site, Se is bonded to three Pd and one Hg atom to form SeHgPd3 tetrahedra that share a cornercorner with one PdHgSe5 octahedra and corners with six equivalent SePd4 trigonal pyramids. The corner-sharing octahedral tilt angles are 76°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlHg by Materials Project

Hg(Tl) crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are three inequivalent Hg sites. In the first Hg site, Hg is bonded in a 6-coordinate geometry to six equivalent Tl atoms. All Hg–Tl bond lengths are 3.51 Å. In the second Hg site, Hg is bonded in a 6-coordinate geometry to six Tl atoms. All Hg–Tl bond lengths are 3.51 Å. In the third Hg site, Hg is bonded in a 6-coordinate geometry to six Tl atoms. All Hg–Tl bond lengths are 3.51 Å. There are two inequivalent Tl sites. In the first Tl site, Tl is bonded to six Hg and six equivalent Tl atoms to form a mixture of corner, edge, and face-sharing TlTl6Hg6 cuboctahedra. All Tl–Tl bond lengths are 3.45 Å. In the second Tl site, Tl is bonded to six Hg and ten equivalent Tl atoms to form TlTl10Hg6 cuboctahedra that share corners with twelve TlTl6Hg6 cuboctahedra, edges with sixteen TlTl6Hg6 cuboctahedra, and faces with sixteen equivalent TlTl10Hg6 cuboctahedra. There are a spread of Tl–Tl bond distances ranging from 3.45–6.91 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd2Hg13(As2Cl3)4 by Materials Project

Hg(Hg6Cd(As2Cl3)2)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional and consists of two mercury molecules and one Hg6Cd(As2Cl3)2 framework. In the Hg6Cd(As2Cl3)2 framework, there are six inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded to two As+2.25- and four Cl1- atoms to form distorted HgAs2Cl4 octahedra that share corners with eight HgAs2Cl4 octahedra, corners with two AsHg3As tetrahedra, edges with two CdCl6 octahedra, and edges with four HgAs2Cl4 octahedra. The corner-sharing octahedra tilt angles range from 18–89°. Both Hg–As bond lengths are 2.56 Å. There are a spread of Hg–Cl bond distances ranging from 3.03–3.41 Å. In the second Hg2+ site, Hg2+ is bonded to two As+2.25- and four Cl1- atoms to form distorted HgAs2Cl4 octahedra that share corners with eight HgAs2Cl4 octahedra, corners with two AsHg3As tetrahedra, edges with two CdCl6 octahedra, and edges with four HgAs2Cl4 octahedra. The corner-sharing octahedra tilt angles range from 18–89°. There are one shorter (2.56 Å) and one longer (2.57 Å) Hg–As bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.02–3.40 Å. In the third Hg2+ site, Hg2+ is bonded to two As+2.25- and four Cl1- atoms to form distorted HgAs2Cl4 octahedra that share corners with eight HgAs2Cl4 octahedra, corners with two AsHg3As tetrahedra, edges with two equivalent CdCl6 octahedra, and edges with four HgAs2Cl4 octahedra. The corner-sharing octahedra tilt angles range from 18–89°. There are one shorter (2.56 Å) and one longer (2.57 Å) Hg–As bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.02–3.41 Å. In the fourth Hg2+ site, Hg2+ is bonded to two As+2.25- and four Cl1- atoms to form distorted HgAs2Cl4 octahedra that share corners with eight HgAs2Cl4 octahedra, corners with two AsHg3As tetrahedra, edges with two equivalent CdCl6 octahedra, and edges with four HgAs2Cl4 octahedra. The corner-sharing octahedra tilt angles range from 18–89°. Both Hg–As bond lengths are 2.56 Å. There are a spread of Hg–Cl bond distances ranging from 3.02–3.41 Å. In the fifth Hg2+ site, Hg2+ is bonded to two As+2.25- and four Cl1- atoms to form distorted HgAs2Cl4 octahedra that share corners with eight HgAs2Cl4 octahedra, corners with two AsHg3As tetrahedra, edges with two CdCl6 octahedra, and edges with four HgAs2Cl4 octahedra. The corner-sharing octahedra tilt angles range from 18–89°. There are one shorter (2.56 Å) and one longer (2.57 Å) Hg–As bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.03–3.40 Å. In the sixth Hg2+ site, Hg2+ is bonded to two As+2.25- and four Cl1- atoms to form distorted HgAs2Cl4 octahedra that share corners with eight HgAs2Cl4 octahedra, corners with two AsHg3As tetrahedra, edges with two CdCl6 octahedra, and edges with four HgAs2Cl4 octahedra. The corner-sharing octahedra tilt angles range from 18–89°. There are one shorter (2.56 Å) and one longer (2.57 Å) Hg–As bond lengths. There are a spread of Hg–Cl bond distances ranging from 3.02–3.41 Å. There are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to six Cl1- atoms to form CdCl6 octahedra that share edges with twelve HgAs2Cl4 octahedra. All Cd–Cl bond lengths are 2.70 Å. In the second Cd2+ site, Cd2+ is bonded to six Cl1- atoms to form CdCl6 octahedra that share edges with twelve HgAs2Cl4 octahedra. There are two shorter (2.69 Å) and four longer (2.70 Å) Cd–Cl bond lengths. There are four inequivalent As+2.25- sites. In the first As+2.25- site, As+2.25- is bonded to three Hg2+ and one As+2.25- atom to form AsHg3As tetrahedra that share corners with three HgAs2Cl4 octahedra and corners with three AsHg3As tetrahedra. The corner-sharing octahedral tilt angles are 70°. The As–As bond length is 2.50 Å. In the second As+2.25- site, As+2.25- is bonded to three Hg2+ and one As+2.25- atom to form AsHg3As tetrahedra that share corners with three HgAs2Cl4 octahedra and corners with three AsHg3As tetrahedra. The corner-sharing octahedral tilt angles are 74°. The As–As bond length is 2.51 Å. In the third As+2.25- site, As+2.25- is bonded to three Hg2+ and one As+2.25- atom to form AsHg3As tetrahedra that share corners with three HgAs2Cl4 octahedra and corners with three AsHg3As tetrahedra. The corner-sharing octahedral tilt angles are 74°. In the fourth As+2.25- site, As+2.25- is bonded to three Hg2+ and one As+2.25- atom to form AsHg3As tetrahedra that share corners with three HgAs2Cl4 octahedra and corners with three AsHg3As tetrahedra. The corner-sharing octahedral tilt angles are 70°. There are six inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four Hg2+ and one Cd2+ atom. In the second Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four Hg2+ and one Cd2+ atom. In the third Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four Hg2+ and one Cd2+ atom. In the fourth Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four Hg2+ and one Cd2+ atom. In the fifth Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four Hg2+ and one Cd2+ atom. In the sixth Cl1- site, Cl1- is bonded in a 5-coordinate geometry to four Hg2+ and one Cd2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UHg3 by Materials Project

UHg3 is beta-derived structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. U is bonded to six equivalent U and six equivalent Hg atoms to form UU6Hg6 cuboctahedra that share corners with six equivalent UU6Hg6 cuboctahedra, corners with twelve equivalent HgHg12 cuboctahedra, edges with six equivalent UU6Hg6 cuboctahedra, edges with twelve equivalent HgU3Hg9 cuboctahedra, faces with six equivalent UU6Hg6 cuboctahedra, and faces with fourteen HgHg12 cuboctahedra. All U–U bond lengths are 3.18 Å. All U–Hg bond lengths are 3.30 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded to twelve Hg atoms to form HgHg12 cuboctahedra that share corners with six equivalent HgHg12 cuboctahedra, corners with twelve equivalent UU6Hg6 cuboctahedra, edges with eighteen HgHg12 cuboctahedra, faces with two equivalent UU6Hg6 cuboctahedra, and faces with eighteen HgHg12 cuboctahedra. There are six shorter (3.18 Å) and six longer (3.26 Å) Hg–Hg bond lengths. In the second Hg site, Hg is bonded to three equivalent U and nine Hg atoms to form distorted HgU3Hg9 cuboctahedra that share corners with eighteen equivalent HgU3Hg9 cuboctahedra, edges with six equivalent UU6Hg6 cuboctahedra, edges with twelve HgHg12 cuboctahedra, faces with six equivalent UU6Hg6 cuboctahedra, and faces with fourteen HgHg12 cuboctahedra. All Hg–Hg bond lengths are 3.18 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li6Yb17Hg9 by Materials Project

Li6Yb17Hg9 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Li is bonded in a 3-coordinate geometry to one Yb and three Hg atoms. The Li–Yb bond length is 3.34 Å. There are two shorter (2.76 Å) and one longer (3.10 Å) Li–Hg bond lengths. There are four inequivalent Yb sites. In the first Yb site, Yb is bonded in a 4-coordinate geometry to twelve Yb and two equivalent Hg atoms. There are four shorter (3.87 Å) and eight longer (3.98 Å) Yb–Yb bond lengths. Both Yb–Hg bond lengths are 3.95 Å. In the second Yb site, Yb is bonded in a distorted cuboctahedral geometry to twelve equivalent Li atoms. In the third Yb site, Yb is bonded in a distorted square co-planar geometry to two equivalent Yb and four equivalent Hg atoms. All Yb–Hg bond lengths are 3.27 Å. In the fourth Yb site, Yb is bonded in a 4-coordinate geometry to one Yb and four Hg atoms. There are a spread of Yb–Hg bond distances ranging from 3.13–3.27 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a 8-coordinate geometry to four equivalent Li and five Yb atoms. In the second Hg site, Hg is bonded in a 9-coordinate geometry to one Li and eight Yb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsHg by Materials Project

CsHg is delta Molybdenum Boride-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Cs sites. In the first Cs site, Cs is bonded in a 6-coordinate geometry to seven Hg atoms. There are a spread of Cs–Hg bond distances ranging from 4.02–4.44 Å. In the second Cs site, Cs is bonded in a 7-coordinate geometry to seven Hg atoms. There are a spread of Cs–Hg bond distances ranging from 3.95–4.37 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a 9-coordinate geometry to seven Cs and two equivalent Hg atoms. There are one shorter (3.09 Å) and one longer (3.14 Å) Hg–Hg bond lengths. In the second Hg site, Hg is bonded in a 9-coordinate geometry to seven Cs and two equivalent Hg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeHgPd by Materials Project

CePdHg crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent Ce sites. In the first Ce site, Ce is bonded in a 11-coordinate geometry to five Pd and six Hg atoms. There are four shorter (3.10 Å) and one longer (3.14 Å) Ce–Pd bond lengths. There are two shorter (3.28 Å) and four longer (3.38 Å) Ce–Hg bond lengths. In the second Ce site, Ce is bonded in a 11-coordinate geometry to five Pd and six Hg atoms. There are four shorter (3.09 Å) and one longer (3.13 Å) Ce–Pd bond lengths. There are two shorter (3.28 Å) and four longer (3.38 Å) Ce–Hg bond lengths. There are two inequivalent Pd sites. In the first Pd site, Pd is bonded in a 9-coordinate geometry to six Ce and three Hg atoms. All Pd–Hg bond lengths are 2.92 Å. In the second Pd site, Pd is bonded in a 9-coordinate geometry to three Ce and six Hg atoms. All Pd–Hg bond lengths are 2.85 Å. There are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a 10-coordinate geometry to six Ce and four Pd atoms. In the second Hg site, Hg is bonded in a distorted q6 geometry to six Ce and four Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on InHg3 by Materials Project

Hg3In crystallizes in the orthorhombic C222 space group. The structure is three-dimensional. there are two inequivalent Hg sites. In the first Hg site, Hg is bonded in a 8-coordinate geometry to eight Hg atoms. There are four shorter (3.27 Å) and four longer (3.29 Å) Hg–Hg bond lengths. In the second Hg site, Hg is bonded in a 8-coordinate geometry to six Hg and two equivalent In atoms. All Hg–Hg bond lengths are 3.27 Å. Both Hg–In bond lengths are 3.27 Å. In is bonded in a 8-coordinate geometry to four equivalent Hg and four equivalent In atoms. All In–In bond lengths are 3.27 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hg3S2BrCl by Materials Project

Hg3S2BrCl crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are five inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two S2-, one Br1-, and two Cl1- atoms. There are one shorter (2.46 Å) and one longer (2.47 Å) Hg–S bond lengths. The Hg–Br bond length is 3.44 Å. There are one shorter (2.81 Å) and one longer (3.06 Å) Hg–Cl bond lengths. In the second Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two equivalent S2-, one Br1-, and two equivalent Cl1- atoms. Both Hg–S bond lengths are 2.45 Å. The Hg–Br bond length is 3.33 Å. There are one shorter (2.87 Å) and one longer (3.08 Å) Hg–Cl bond lengths. In the third Hg2+ site, Hg2+ is bonded to two equivalent S2- and four Br1- atoms to form a mixture of edge and corner-sharing HgS2Br4 octahedra. The corner-sharing octahedra tilt angles range from 2–7°. Both Hg–S bond lengths are 2.45 Å. There are two shorter (3.29 Å) and two longer (3.30 Å) Hg–Br bond lengths. In the fourth Hg2+ site, Hg2+ is bonded in a 5-coordinate geometry to two equivalent S2-, one Br1-, and two Cl1- atoms. Both Hg–S bond lengths are 2.44 Å. The Hg–Br bond length is 3.49 Å. There are one shorter (2.85 Å) and one longer (3.29 Å) Hg–Cl bond lengths. In the fifth Hg2+ site, Hg2+ is bonded to two equivalent S2- and four Br1- atoms to form a mixture of edge and corner-sharing HgS2Br4 octahedra. The corner-sharing octahedra tilt angles range from 2–7°. Both Hg–S bond lengths are 2.44 Å. There are two shorter (3.27 Å) and two longer (3.33 Å) Hg–Br bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. In the second S2- site, S2- is bonded in a 3-coordinate geometry to three Hg2+ atoms. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 7-coordinate geometry to seven Hg2+ atoms. In the second Br1- site, Br1- is bonded in a 5-coordinate geometry to five Hg2+ atoms. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 5-coordinate geometry to five Hg2+ atoms. In the second Cl1- site, Cl1- is bonded in a distorted trigonal planar geometry to three Hg2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Mobilization of mercury from contaminated creekbank soils

The industrial use of mercury (Hg) led to the contamination of numerous watersheds worldwide, including the East Fork Poplar Creek (EFPC) in Tennessee, USA. Mercury can accumulate in creek banks and floodplain soils and is mobilized into downstream environments due to erosion from precipitation and flooding. Here, this study aimed to evaluate the geochemical conditions contributing to the release of Hg from contaminated soils in this watershed. Bank soil samples from the EFPC watershed with total Hg concentrations ranging from 27.2 to 1,425 mg·kg −1 were used in a series of batch experiments with artificial creek water at a solid-to-solution ratio of 1:30 to assess Hg release. Additional experiments examined Hg release across different soil size fractions and solid-to-solution ratios, as well as the effect of dissolved organic matter and time on Hg mobilization. Mercury release ranged from 0.011 to 0.17% of the total soil Hg and is correlated with total Hg concentrations. Variations in release among size fractions suggested heterogeneous distribution of labile Hg species. Results indicated two distinct solubility regimes depending on solid-to-solution ratios. Dissolved organic matter enhanced Hg release, and time-dependent experiments showed that changes in mercury speciation could decrease dissolved Hg concentrations over time. Identifying conditions that promote Hg mobilization from contaminated soils improves our understanding of Hg fluxes into downstream environments. Key factors influencing mercury release include soil characteristics, water chemistry, and temporal changes in mercury speciation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Brown watersnakes (Nerodia taxispilota) as bioindicators of mercury contamination in a riverine system

Herein, mercury (Hg) is a contaminant that enters the environment through natural or anthropogenic means. Ecological risk assessments have examined Hg bioaccumulation and effects in many taxa, but little is known about Hg dynamics in reptiles, or their potential use as bioindicator species for monitoring Hg in aquatic systems. Numerous snake species, like North American watersnakes (Nerodia spp.), are piscivorous and are exposed to Hg through their diet. The purpose of this study was to identify factors associated with Hg accumulation in a common watersnake species and compare Hg concentrations of the snakes to those in fish occupying the same habitats. To this end, we sampled brown watersnakes (Nerodia taxispilota) from the Savannah River, a major river system in the southeastern U.S., and compared N. taxispilota Hg accumulation trends to those of bass (Micropterus salmoides), catfish (Ictalurus and Ameiurus spp.), and panfish (Lepomis and Pomoxis spp.) collected from the same reach. Total Hg (THg) in N. taxispilota tail tips ranged from 0.020 to 0.431 mg/kg (wet weight; mean: 0.104 ± 0.008). Snake tail THg was significantly correlated with blood THg, which ranged from 0.003 to 1.140 mg/kg (0.154 ± 0.019). Snake size and site of capture were significantly associated with tail THg. Snake tail THg increased at sites along and downstream of the area of historic Hg pollution, consistent with fish THg. Snake muscle THg was predicted based on tail THg and ranged from 0.095 to 1.160 (0.352 ± 0.022). To gauge Hg biomagnification in N. taxispilota, we compared predicted snake muscle THg concentrations to THg in fish of consumable size. Average biomagnification factors for THg in N. taxispilota were 3.1 (panfish) and 5.4 (catfish), demonstrating N. taxispilota likely biomagnify Hg through their diet. These results reveal N. taxispilota to be an effective bioindicator species for monitoring Hg in aquatic environments.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Mercury Removal from Contaminated Water by Wood-Based Biochar Depends on Natural Organic Matter and Ionic Composition

Biochars can remove potentially toxic elements, such as inorganic mercury [Hg(II)] from contaminated waters. However, their performance in complex water matrices is rarely investigated, and the combined roles of natural organic matter (NOM) and ionic composition in the removal of Hg(II) by biochar remain unclear. Here, we investigate the influence of NOM and major ions such as chloride (Cl – ), nitrate (NO 3 – ), calcium (Ca 2+ ), and sodium (Na + ) on Hg(II) removal by a wood-based biochar (SWP700). Multiple sorption sites containing sulfur (S) were located within the porous SWP700. In the absence of NOM, Hg(II) removal was driven by these sites. Ca 2+ bridging was important in enhancing removal of negatively charged Hg(II)-chloro complexes. In the presence of NOM, formation of soluble Hg-NOM complexes (as seen from speciation calculations), which have limited access to biochar pores, suppressed Hg(II) removal, but Cl – and Ca 2+ could still facilitate it. The ability of Ca 2+ to aggregate NOM, including Hg-NOM complexes, promoted Hg(II) removal from the dissolved fraction (<0.45 μm). Hg(II) removal in the presence of Cl – followed a stepwise mechanism. Weakly bound oxygen functional groups in NOM were outcompeted by Cl – , forming smaller-sized Hg(II)-chloro complexes, which could access additional intraparticle sorption sites. Therein, Cl – was outcompeted by S, which finally immobilized Hg(II) in SWP700 as confirmed by extended X-ray absorption fine structure spectroscopy. We conclude that in NOM containing oxic waters, with relatively high molar ratios of Cl – : NOM and Ca 2+ : NOM, Hg(II) removal can still be effective with SWP700.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Conceptual Model Update of Mercury Sources and Flux at Y-12 and Upper East Fork Poplar Creek, Oak Ridge,Tennessee

The interactions between the key processes that control the fate and transport of mercury (Hg) in the sediments, groundwater, and stream water within the Y-12 National Security Complex (Y-12) in Oak Ridge, Tennessee are complex, and many aspects are not well understood. In contaminated environments such as Y-12, conceptual models are frequently developed to aid in visualizing and understanding the dynamic nature of the hydrologic, geochemical, and physical environment. These conceptual models integrate data in an internally consistent manner to understand processes that control the fate and transport of contaminants. Over the past few decades of environmental investigation at Y-12, a number of conceptual models have been developed to identify and define various technical processes at various scales. The main purpose of the activities described in this report is to update the 2011 conceptual model for Upper East Fork Poplar Creek using the most recent Hg concentration and flux data and informed scientific interpretation. Emphasis was placed on improving the previous model by implementing a more detailed spatial and temporal approach to visualize transport pathways in the watershed and trends in flux and concentration over time, and to compare baseflow and stormflow system dynamics. Detailed descriptions of historical and current Hg sources and transport pathways are also provided for the east and west ends of the facility. This conceptual model will allow the US Department of Energy to evaluate past and present remedial activities and provide a strong technical basis for prioritizing and optimizing remedial responses in a cost-effective and efficient manner. Twenty years ago, Hg flux from Outfall (OF) 200 at the headwaters of East Fork Poplar Creek represented approximately 20% of the overall flux leaving Y-12. By the time of the 2011 conceptual model report, that percentage had increased to 70%–80%. Flux estimates compiled for this report using data from 2009 to 2018 show that OF200 accounted for roughly 60% of the flux leaving Y-12. The relative role of the four storm drain conduits to OF200 appeared similar to 2011, with OF163 being the greatest contributor to downstream flux. An increase in Hg concentrations and flux occurred throughout and downstream of west end storm drains in 2011 in response to a storm drain cleanout. Leading up to the 2011 storm drain cleanout, annual baseflow flux was higher at OF200A6 than at Station 17. From 2011 to 2018, the trend reversed with concentrations and flux being higher at Station 17 than at OF200A6. A spike in concentrations occurred in July 2018, potentially due to a one-time influx of Hg that occurred during COLEX decontamination and decommissioning activities at Y-12. This report includes recommendations for improving our conceptual understanding of Hg sources, transport pathways, and flux at Y-12. Important recommendations include further evaluation of transport pathways, concurrent measurement of Hg concentration and flux under baseflow and stormflow conditions at multiple sites, and research to understand the connections among periphyton and methylmercury concentration, bioavailability, and bioaccumulation. Ongoing facility decontamination and decommissioning efforts, site characterization, remedial actions, and research are facilitating the collection of new Hg data at Y-12. The conceptual model update provided herein takes advantage of the extensive recent Hg sampling to provide an updated assessment of Hg mass balance and support a refined understanding of Hg behavior at or near Y-12. This assessment should assist in future environmental management decisions and in mitigating the impacts of Hg on the surrounding environment.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Materials Data on Hg6S4IBr2Cl by Materials Project

Hg6S4IBr2Cl crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are four inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two S2-, two equivalent I1-, and two Br1- atoms. Both Hg–S bond lengths are 2.45 Å. There are one shorter (3.43 Å) and one longer (3.64 Å) Hg–I bond lengths. There are one shorter (3.15 Å) and one longer (3.35 Å) Hg–Br bond lengths. In the second Hg2+ site, Hg2+ is bonded in a distorted trigonal bipyramidal geometry to two equivalent S2-, two Br1-, and one Cl1- atom. Both Hg–S bond lengths are 2.50 Å. There are one shorter (3.27 Å) and one longer (3.39 Å) Hg–Br bond lengths. The Hg–Cl bond length is 2.62 Å. In the third Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to two S2-, two equivalent I1-, and two Br1- atoms. Both Hg–S bond lengths are 2.45 Å. There are one shorter (3.40 Å) and one longer (3.71 Å) Hg–I bond lengths. There are one shorter (3.16 Å) and one longer (3.30 Å) Hg–Br bond lengths. In the fourth Hg2+ site, Hg2+ is bonded in a 4-coordinate geometry to two equivalent S2-, two equivalent Br1-, and one Cl1- atom. Both Hg–S bond lengths are 2.48 Å. There are one shorter (3.20 Å) and one longer (3.64 Å) Hg–Br bond lengths. The Hg–Cl bond length is 2.67 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three Hg2+ atoms. In the second S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three Hg2+ atoms. I1- is bonded in a distorted body-centered cubic geometry to eight Hg2+ atoms. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a 5-coordinate geometry to five Hg2+ atoms. In the second Br1- site, Br1- is bonded in a 7-coordinate geometry to seven Hg2+ atoms. Cl1- is bonded in a water-like geometry to two Hg2+ atoms.

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