Anne L. Bates

Health impacts of coal and coal use: possible solutions

Abstract Coal will be a dominant energy source in both developed and developing countries for at least the first half of the 21st century. Environmental problems associated with coal, before mining, during mining, in storage, during combustion, and postcombustion waste products are well known and are being addressed by ongoing research. The connection between potential environmental problems with human health is a fairly new field and requires the cooperation of both the geoscience and medical disciplines. Three research programs that illustrate this collaboration are described and used to present a range of human health problems that are potentially caused by coal. Domestic combustion of coal in China has, in some cases, severely affected human health. Both on a local and regional scale, human health has been adversely affected by coals containing arsenic, fluorine, selenium, and possibly, mercury. Balkan endemic nephropathy (BEN), an irreversible kidney disease of unknown origin, has been related to the proximity of Pliocene lignite deposits. The working hypothesis is that groundwater is leaching toxic organic compounds as it passes through the lignites and that these organics are then ingested by the local population contributing to this health problem. Human disease associated with coal mining mainly results from inhalation of particulate matter during the mining process. The disease is Coal Workers Pneumoconiosis characterized by coal dust-induced lesions in the gas exchange regions of the lung; the coal workers “black lung disease”.

Solid-state 13C nuclear magnetic resonance studies of coalified gymnosperm xylem tissue from Australian brown coals

We report here on the use of solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to contrast the average chemical composition of modern degraded gymnosperm woods with fossil gymnosperm woods from Australian brown coals (Miocene). We first established the quantitative nature of the NMR techniques for these samples so that the conventional solid-state 13C NMR spectra and the dipolar dephasing NMR spectra could be used with a high degree of reliability to depict average chemical compositions. The NMR results provide some valuable insights about the early coalification of xylem tissue from gymnosperms. Though the cellulosic components of wood are degraded to varying degrees during peatification and ensuing coalification, it is unlikely that they play a major role in the formation of aromatic structures in coalified woods. The NMR data show that gynmosperm lignin, the primary aromatic contribution to the coal, is altered in part by demethylation of guaiacyl-units to catechol-like structures. The dipolar dephasing NMR data indicate that the lignin also becomes more cross-linked or condensed.

Speciation and isotopic composition of sedimentary sulfur in the Everglades, Florida, USA

Abstract We have studied the sulfur speciation and isotopic composition of two peat cores from Water Conservation Area 2A (WCA 2A) in the Florida Everglades. Core site E1 is affected by agricultural runoff from the Hillsboro Canal which drains the Everglades Agricultural Area; Core site U3 is distant from the canal and relatively unaffected by agricultural runoff. Depth profiles of the total sulfur content of both cores show fairly constant levels (∼0.7 wt.%) below about 25–30 cm depth in Core E1 and below 40–45 cm in Core U3. Above these depths, total sulfur increases to as much as 1.52 wt.% in Core E1 and 1.74 wt.% in Core U3, suggesting that more sulfur has entered the sediments and/or that more sulfur is being retained in recent times at both sampling sites. The changes in total sulfur content with depth in Core E1 correlate with changes in total phosphorus that have been observed in other studies at core sites near the Hillsboro Canal. This correlation of total sulfur with phosphorus with depth is not seen in Core U3 located away from the canal, possibly because phosphorus is more effectively retained than sulfur in the organic sediment near the canal. Organic-sulfur (OS) concentrations are at least twice as high as the disulfide-sulfur (DS) concentrations in the upper parts of both cores suggesting that iron is presently limiting the amount of disulfide minerals formed in these sediments. The degree of pyritization (DOP) in the upper parts of the cores suggest that sulfide mineralization is limited by the availability of highly reactive iron during the earliest stages of diagenesis. Positive δ 34 S values for reduced sulfur forms in both cores indicate a relatively restricted sulfate reservoir, consistent with nearly complete reduction of the sulfate available in the sediment at any given time. Differences between the two cores appear in the δ 34 S values for the near-surface sediments. The DS δ 34 S values in the upper 10.0 cm of sediment are more positive at site E1, with a mean δ 34 S value of +12.9 per mil, than at site U3, with a mean δ 34 S value of +2.9 per mil. These results may indicate that increased rates of organic deposition due to nutrient loading near the canal have increased the rate of sulfate reduction at the E1 site in recent times. Acid-volatile-sulfide (AVS) concentrations are lower than DS and OS concentrations by at least a factor of 10. Increasing δ 34 S values for AVS with increasing depth in both cores suggests ongoing reduction of a limited porewater sulfate reservoir after deposition. The disulfide and organic-sulfur δ 34 S values diverge from the δ 34 S values for AVS with depth, suggesting that most of the transformation of AVS into disulfide minerals or incorporation of sulfur into organic matter occurs in the near-surface sediments. A comparison of organic-sulfur δ 34 S values in the dominant flora at the U3 site (sawgrass leaves and periphyton) with organic-sulfur δ 34 S values at the top of the U3 core indicates that there was early incorporation of an isotopically light sulfide species into the organic matter.

Speciation and isotopic composition of sulfur in sediments from Jellyfish Lake, Palau

Abstract Jellyfish Lake, Palau, is a meromictic marine lake with high organic productivity, low reactive Fe content, and anoxic bottom waters. Sediment samples from Jellyfish Lake were examined for the distribution of sulfur species and their isotopic signatures in order to gain a better understanding of sedimentary sulfur incorporation in Fe-poor environments. Surface samples were taken along a transect from a near-shore site to the center of the lake, and include a sample below oxic water, a sample below the chemocline layer, and samples below anoxic waters. Three additional samples were taken from a core, 2 m long, collected near the lake center. Sulfur to organic carbon weight ratios in all samples were lower than the expected value of 0.36 for normal marine sediment, probably because the lake water is deficient in reactive Fe to form iron sulfides. Total sulfur contents in the surface sediments indicated no changes with distance from shore; however, the sulfur content of the surface sample at the chemocline layer may be slightly higher. Total sulfur content increased with depth in the core and is inversely related to organic carbon content. Organic sulfur is the major sulfur species in the samples, followed in descending order by sulfate, disulfides and monosulfides. Sulfate sulfur isotope δ 34 S-values are positive (from +20.56 to +12.04‰), reflecting the marine source of sulfate in Jellyfish Lake. Disulfide and monosulfide δ 34 S-values are negative (from −25.07 to −7.60‰), because of fractionation during bacterial reduction of sulfate. Monosulfide δ 34 S-values are somewhat higher than those of disulfides, and they are close to the δ 34 S-values of organic sulfur. These results indicate that most of the organic sulfur is formed by reaction of bacteriogenic monosulfides, or possibly monosulfide-derived polysulfides, with organic matter in the sediment.

Solid-state 13C NMR studies of a large fossil gymnosperm from the Yallourn Open Cut, Latrobe Valley, Australia

Abstract A series of samples taken from the cross section of a 3-m-diameter fossilized gymnospermous log ( Araucariaceae ) in the Yallourn Seam of the Australian brown coals was examined by solid state 13 C nuclear magnetic resonance to delineate chemical changes related to the combined processes of peatification and coalification. The results show that cellulosic materials were degraded and lost on the periphery of the log, however, the degree of such degradation in the central core is substantially less. The lignin is uniformly altered by coalification reactions to a macromolecular substance displaying decreased aryl ether linkages but significantly greater amounts of carbon linkages compared to modern lignin. Changes in the methoxyl carbon contents of lignin in cross section reveal demethylation reactions, but these do not appear to be related to degree of carbon linking. Both the degredation of cellulosic materials and demethylation of lignin appear to be early diagenetic processes occurring during peatification independently of the coalification reactions.

Nutrient Geochemistry of Sediments from Two Tree Islands in Water Conservation Area 3B, the Everglades, Florida

Sediment cores from two tree islands (Nuthouse and Gumbo Limbo) located in Water Conservation Area 3B of the Everglades, Florida were examined for preliminary studies of their nutrient geochemistry and paleoecology. Cores were collected from sites on the head, tail, and surrounding slough/marsh at each of the islands, and sediments from these cores were analyzed for various chemical constituents. Porewater in cores collected from the head and surrounding slough/marsh was also analyzed for its chemical composition for the purpose of evaluating nutrient recycling from tree island heads. Intervals in selected cores from both tree islands were dated using 14C analysis. The major objectives of the study were to: 1) determine the concentrations and accumulation rates of nutrients (carbon, nitrogen, and phosphorus) in sediments of tree islands, 2) examine the role of nutrients (if any) in the development of tree island tails and 3) examine downcore trends in nutrient element concentrations for evidence of ecological changes through time.

Sulfur geochemistry of organic-rich sediments from Mud Lake, Florida, U.S.A.

Abstract Organic-rich sediment cores from Mud Lake, Florida, were analyzed for sulfur species and their isotopic compositions. The cores include the upper 4 m of sediment, which consist of four major horizons based on petrographic analyses of the organic material: from 400- to ∼ 300-cm depth, the sediment consists of a Cladium (sawgrass) peat; from 300- to 200-cm depth, the sediment consists mostly of Nymphaea (water-lily) peat; from 200- to 100-cm depth, the sapropel is more consolidated and contains a high proportion of non-combustible material, mostly from sponge spicules; and the sediment consists of an amorphous sapropel above 100-cm depth. The total-sulfur content of the sediment ranges from ∼1.53% to ∼4.95% (3.35–10.7% on an ash-free and carbonate-free basis) and is dominated by disulfide (pyrite), with maxima for both total sulfur and disulfide-sulfur at 117 and 365 cm. Organic-sulfur contents are slightly lower than those of disulfides but have a similar depth profile. Systematic changes in the isotopic composition of sedimentary disulfide and organic sulfur coincide with variations in the sulfur species and vegetation types. High disulfide contents and low disulfide isotopic ratio values (δ34S) characterize the saw-grass interval, indicating high sulfate availability during deposition or during later diagenesis. The water-lily interval is characterized by a change to higher δ34S-values for both disulfide- and organic sulfur. This change may be the result of higher organic matter accumulation accompanied by a higher rate of sulfate reduction and/or a slower rate of sulfate supply to the sediment. The transition to sapropel is accompanied by a large negative shift in disulfide δ34S-values, consistent with an increase in sulfate availability and a slower rate of sulfate reduction. Reactive iron availability does not appear to play a major role in limiting the amount of sulfide minerals in these sediments. Major shifts in δ34S-values at ∼ 117–350-cm depth coincide with maxima in the amount of non-combustible material (mostly sponge spicules) in the sediment. These maxima may record refractory material which accumulated around the emergent vegetation at the margins of the wetland at the time of deposition. Alternatively, they may be records of dry periods when refractory material was concentrated in the sediment as organic matter became oxidized upon exposure to air.

Studies of a peatified angiosperm log cross section from Indonesia by nuclear magnetic resonance spectroscopy and analytical pyrolysis

Samples from a 10 cm cross-sectional radius of a peatified angiosperm log from Sumatra, Indonesia, were examined by 13C nuclear magnetic resonance and pyrolysis-gas chromatography in order to understand chemical changes due to the peatification process. NMR results show degradation by selective loss of carbohydrates in all parts of the log section compared with fresh wood; however, the degree of degradation is less near the center of the log section. The degree of ring substitution of aromatic lignin monomeric units, as measured by dipolar dephasing NMR methods, appears to be less at the center of the log section than at the periphery. The methoxyl carbon content of lignin in the log is lower than in unaltered angiospermous lignin but does not appear to change as a function of either radial position or the degree of aromatic ring substitution. Pyrolysis-gas chromatography indicates higher yields of catechols in the outer areas relative to the heartwood. Other than the variations in catechol contents and in the yields of carbohydrate-derived pyrolysis products (e.g. levoglucosan, angelicalactones), the pyrolysis results do not show significant changes related to radial position, indicating that the lignin is not significantly altered across the log section.

Health Effects of Toxic Organic Substances from Coal: Toward “Panendemic” Nephropathy

Coal contains myriad organic compounds, some known to be toxic and others that are potentially toxic. Toxic organic compounds found in coal of particular interest include: i) condensed aromatic structures (e.g., polycyclic aromatic hydrocarbons), which can act as mutagens, cancer promoters, and endocrine disrupters; ii) aromatic amines, which have probable nephrotoxic activity; and iii) heterocyclic compounds, which may be carcinogenic and nephrotoxic. Toxic organic compounds can be leached from coal into water supplies, and longterm human exposure to these compounds may lead to disease occurrence, including cancer and renal disease. Despite these potential hazards, little is known about the impact and toxicity of organic substances derived from coal in water supplies. One example of a disease hypothesized to be linked to coal-derived toxic organic compounds in water supplies is Balkan endemic nephropathy (BEN). In this paper, we summarize results from our studies linking BEN to the leaching of toxic organic compounds from low rank (lignite) Pliocene coal deposits into water supplies (well and spring water) of the rural villages where the disease occurs. We also introduce the idea of panendemic nephropathy (PEN) for BEN-like diseases that are linked to coal-derived toxic organic compounds in water supplies, but that occur outside the Balkans. Preliminary results supporting the PEN hypothesis are presented, with results from proposed PEN areas in Wyoming (WY) and Louisiana (LA). Results of toxicological studies of the effects of organic compounds isolated from water supplies in BEN and PEN areas on human cell cultures are also discussed. China, India, Turkey, and Portugal represent other areas where BEN-like diseases may occur, as a result of the presence of extensive low rank coal deposits and rural populations using untreated water in contact with coal in these nations.

Isotopic evidence for the source of sulfur in the Upper Freeport coal bed (west-central Pennsylvania, U.S.A.)

Abstract Sulfur isotopic variations were used to determine the sources of sulfur in a medium-sulfur coal (∼2 wt%S) that lacked marine influence, which is often cited as a major source of sulfur in coal. Variations in the amount and isotopic composition of the organic and pyritic sulfur among the coal-bed facies of the Upper Freeport coal bed (Middle Pennsylvanian) are attributed to differential incorporation of syngenetic and epigenetic sulfur. These variations reflect varying environmental conditions during paleopeat formation, porosity and permeability, and the availability of sulfate and iron. A large increase in the abundance and sulfur isotopic value of pyritic sulfur in the upper facies of the coal bed, in proximity to the overlying lacustrine shale, corresponds to an increase in massive and irregular forms of pyrite. This relationship is attributed to at least two stages of epigenetic pyrite incorporation. An early stage of epigenetic pyrite, moderately enriched in 34S, apparently formed during the fluvial-lacustrine period immediately following peat accumulation. A late stage of epigenetic pyrite, highly enriched in 34S, formed after compaction of the original peat as cleat- and fracture-filling pyrite; this sulfur was probably derived from bacterial reduction of dissolved sulfate in groundwater. Isotopic mass-balance calculations indicate that this late-stage epigenetic pyrite may account for up to ∼50% of the pyritic sulfur in some upper facies of the coal bed. These results suggest that most of the pyritic sulfur in the Upper Freeport coal bed may be epigenetic, incorporated either soon after peat accumulation or later during coalification.