An infrared method has been developed for estimating kaolinite in sediments. Hydroxyl stretching bands of kaolinite in sediments can be recorded by using a differential technique which eliminates the overlapping owing to other mineralic constituents present. By adding known amounts of an appropriate standard to the sample and by measuring intensities of the OH bands before and after the addition it is possible to calculate the proportion of kaolinite in the test sample. The choice of the added standard is made from characteristic features of the hydroxyl stretching bands.

Shewanella putrefaciens is a species of metal-reducing bacteria with a versatile respiratory metabolism. This study reports that S. putrefaciens strain MR-1 rapidly reduces Fe(III) within smectite clay minerals. Up to 15% of the structural Fe within ferruginous smectite (sample SWa-1, Source Clays Repository of the Clay Minerals Society) was reduced by MR-1 in 4 h, and a range of 25% to 41% of structural Fe was reduced after 6 to 12 d during culture. Conditions for which smectite reduction was optimal, that is, pH 5 to 6, at 25 to 37 °C, are consistent with an enzymatic process and not with simple chemical reduction. Smectite reduction required viable cells, and was coupled to energy generation and carbon metabolism for MR-1 cultures with smectite added as the sole electron acceptor. Iron(III) reduction catalyzed by MR-1 was inhibited under aerobic conditions, and under anaerobic conditions it was inhibited by the addition of nitrate as an alternate electron acceptor or by the metabolic inhibitors tetrachlorosali-cylanilide (TCS) or quinacrine hydrochloride. Genetic mutants of MR-1 deficient in anaerobic respiration reduced significantly less structural Fe than wild-type cells. In a minimal medium with formate or lactate as the electron donor, more than three times the amount of smectite was reduced over no-carbon controls. These data point to at least one mechanism that may be responsible for the microbial reduction of clay minerals within soils, namely, anaerobic respiration, and indicate that pure cultures of MR-1 provide an effective model system for soil scientists and mineralogists interested in clay reduction. Given the ubiquitous distribution and versatile metabolism of MR-1, these studies may have further implications for bioremediation and water quality in soils and sediments.

A method is described for the separation of the finest particles from soils and sediments without mechanical disturbance. Particles are separated through the induction of osmotic stress. Generally, samples are treated with a concentrated sodium salt solution and then exposed to water by diffusion. Naturally sodic samples are simply exposed to water. Solid samples and the swollen and dispersed material they produce are confined by dialysis tubing. Examples show that the method gives a size gradient of particles in a vertical column of suspension. The compositions of particles can vary with size. The method can be used to show the effects on separated particles of ions other than Na+ and also of other physicochemical treatments of soils and sediments. It is inexpensive and requires little labor.

Radiocarbon (14C) dating of sediment deposition around Antarctica is often challenging due to heterogeneity in sources and ages of organic carbon in the sediment. Chemical and thermochemical techniques have been used to separate organic carbon when microfossils are not present. These techniques generally improve on bulk sediment dates, but they necessitate assumptions about the age spectra of specific molecules or compound classes and about the chemical heterogeneity of thermochemical separations. To address this, the Rafter Radiocarbon Laboratory has established parallel ramped pyrolysis oxidation (RPO) and ramped pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) systems to thermochemically separate distinct carbon fractions, diagnose the chemical composition of each fraction, and target suitable RPO fractions for radiocarbon dating. Three case studies of sediment taken from locations around Antarctica are presented to demonstrate the implementation of combined RPO-AMS and Py-GC-MS to provide more robust age determination in detrital sediment stratigraphy. These three depositional environments are good examples of analytical and interpretive challenges related to oceanographic conditions, carbon sources, and other factors. Using parallel RPO-AMS and Py-GC-MS analyses, we reduce the number of radiocarbon measurements required, minimize run times, provide context for unexpected 14C ages, and better support interpretations of radiocarbon measurements in the context of environmental reconstruction.

Estuaries and deltas are crucial zones to better understand the interactions between continents and oceans, and to characterize the mineralization and burial of different sources of organic matter (OM) and their effect on the carbon cycle. In the present study, we focus on the continental shelf of the northwest Mediterranean Sea near the Rhône river delta. Sediment cores were collected and pore waters were sampled at different depths at one station (Station E) located on this shelf. For each layer, measurements of dissolved inorganic carbon concentration (DIC) and its isotopic composition (δ 13C and Δ14C) were conducted and a mixing model was applied to target the original signature of the mineralized OM. The calculated δ 13C signature of the mineralized organic matter is in accordance with previous results with a δ 13COM of marine origin that is not significantly impacted by the terrestrial particulate inputs from the river. The evolution with depth of Δ14C shows two different trends indicating two different Δ14C signatures for the mineralised OM. In the first 15 cm, the mineralized OM is modern with a Δ14COM = 100 ± 17‰ and corresponds to the OM produced during the nuclear period of the last 50 years. Deeper in the sediment, the result is very different with a depleted value Δ14COM = –172 ± 60‰ which corresponds to the pre-nuclear period. In these two cases, the marine substrate was under the influence of the local marine reservoir effect with more extreme Δ14C results. These differences can be largely explained by the influence of the river plume on the local marine DIC during these two periods.

Petroleum hydrocarbons (PH) toxicity and bioaccumulation in aquatic organisms have been investigated for almost 50 years. Continuous oil spillages necessitate a further understanding of the toxicological effects of PH on brachyuran crabs. Crabs can be exposed to PH through various routes such as the water column, sediment and diet. Numerous investigations have been dedicated to evaluating PH toxicity on different life stages of crab species, but the majority of them have focused on the blue crab Callinectes sapidus as it represents an edible and favourable seafood commodity for human consumption. The objective of the review is to critically assess studies related to PH toxicity on different life stages of 41 crab species representing 13 families across the world. Several physiological, biochemical and genetic endpoints of marine crabs were evaluated in addition to the sublethal effects of PH on crab metabolism, behaviour, moulting, growth and survival. A concise summary of PH deleterious effects on different taxonomic species of marine crabs is discussed and provides evidence that crabs can be used as indicator organisms of biomarker significance for marine pollution. Overall, larval stages appeared to be the most sensitive to the deleterious effects of PH compared with juveniles and adults. However, adult stages have received more research attention than other life stages, followed by larval stages, and juvenile stages are the least investigated stages with respect to PH toxicity. Finally, hepatopancreas and gills were the organs where greatest accumulation of PH was recorded.

The Old Copper Complex (OCC) refers to the production of heavy copper-tool technology by Archaic Native American societies in the Lake Superior region. To better define the timing of the OCC, we evaluated 53 (eight new and 45 published) radiocarbon (14C) dates associated with copper artifacts and mines. We compared these dates to six lake sediment-based chronologies of copper mining and annealing in the Michigan Copper District. 14C dates grouped by archaeological context show that cremation remains, and wood and cordage embedded in copper artifacts have ages that overlap with the timing of high lead (Pb) concentrations in lake sediment. In contrast, dates in stratigraphic association and from mines are younger than those from embedded and cremation materials, suggesting that the former groups reflect the timing of processes that occurred post-abandonment. The comparatively young dates obtained from copper mines therefore likely reflect abandonment and infill of the mines rather than active use. Excluding three anomalously young samples, the ages of embedded organic material associated with 15 OCC copper artifacts range from 8500 to 3580 cal BP, confirming that the OCC is among the oldest known metalworking societies in the world.

Antibiotic residues have entered into the environment owing to the unreasonable use and disposal of antibiotics. The emergence of antibiotic resistance poses a huge threat to ecosystems and human health. In this study, the network analysis method was used to compare publications on antibiotics in water, soil and sediment from the aspects of countries, institutes, journals, subject categories and keywords based on Web of Science Core Collection. The results indicated that the United States of America and China had dominant positions of studies on antibiotics. The Chinese Academy of Sciences published the most articles on antibiotic research. ‘Chemosphere’, ‘Science of the Total Environment’, ‘Environmental Science and Technology’ and ‘Applied and Environmental Microbiology’ all appeared in the top six journals. ‘Environmental Sciences and Ecology’ was the core subject category of antibiotic research. Further analysis results depicted that ‘Antibiotics’, ‘Tetracycline’ and ‘Antibiotic Resistance’ were found as the research hotspots. Tetracycline and oxytetracycline all showed in the top 50 keywords of antibiotics research in water, soil and sediment. However, chlortetracycline, sulfadiazine and tylosin all emerged only in the top 50 keywords of antibiotics study in soil. In future, more attention should be paid to antibiotic resistance genes and antibiotic resistance bacteria in antibiotics research.

Unglaciated coastal areas in East Antarctica provide records of past ice sheet and glacier fluctuations and subsequent environmental conditions. In this paper we review lithological, geochemical, diatom and radiocarbon data from sediment records from inland and epishelf lakes in Bunger Hills, East Antarctica. While some hilltops were unglaciated during the Last Glacial Maximum, till deposits in lake basins indicate infilling by glacier ice prior to the Holocene. Proglacial sedimentation occurred in lakes during the early Holocene. Around 9.6 ka bp, deposition of marine sapropel started under relatively warm climate conditions. Inland lakes were affected by high clastic input from meltwater runoff until c. 7.9 ka bp, when deposition became highly organic and biogenic proxies indicate a period of cooler conditions. Epishelf lakes experienced a decrease in water exchange with the ocean and increased freshwater input around 7.7 ± 0.2 ka bp and after 2.2 ka bp. This probably resulted from grounding line advances of the bounding glaciers, which could be either controlled by relative sea level (RSL) lowering and/or climate-driven glacier dynamics. The absence of marine sediments in the postglacial record of Algae Lake indicates that Holocene RSL probably reached a maximum at or below 10 m above present sea level.

Recent fieldwork and archival sedimentary materials from southern Iraq have revealed new insights into the environment that shaped southern Mesopotamia from the pre-Ubaid (early Holocene) until the early Islamic period. These data have been combined with northern Iraqi speleothem, or stalagmite, data that have revealed relevant palaeoclimate information. The new results are investigated in light of textual sources and satellite remote sensing work. It is evident that areas south of Baghdad, and to the region of Uruk, were already potentially habitable between the eleventh and early eighth millennia B.C., suggesting there were settlements in southern Iraq prior to the Ubaid. Date palms, the earliest recorded for Iraq, are evident before 10,000 B.C., and oak trees are evident south of Baghdad in the early Holocene but disappeared after the mid-sixth millennium B.C. New climate results suggest increased aridity after the end of the fourth millennium B.C. For the third millennium B.C. to first millennium A.D., a negative relationship between grain and date palm cultivation in Nippur is evident, suggesting shifting cultivation emphasising one of these crops at any given time in parts of the city. The Shatt en-Nil was also likely used as a channel for most of Nippur's historical occupation from the third millennium B.C. to the first millennium A.D. In the early to mid-first millennium A.D., around the time of the Sasanian period, a major increase in irrigation is evident in plant remains, likely reflecting large-scale irrigation expansion in the Nippur region. The first millennium B.C. to first millennium A.D. reflects a relatively dry period with periodic increased rainfall. Sedimentary results suggest the Nahrawan, prior to it becoming a well-known canal, formed an ancient branch of the Tigris, while the region just south of Baghdad, around Dalmaj, was near or part of an ancient confluence of the Tigris and Euphrates.

The North Pacific Ocean (NPO) has received abundant aeolian dust transported by westerlies from the Asian inland. The aeolian components preserved in NPO sediments record information on palaeoclimatic and palaeoenvironmental changes in Asian source areas at different timescales. Previous studies have systematically investigated the source–sink effect of aeolian dust using the sedimentology, geochemistry, isotope and magnetic methods. In this study, we focus more on recent developments of aeolian signals in NPO sediments obtained by magnetic approaches. Generally, aeolian components contain a mixture of magnetite, maghemite, hematite and goethite of different origins. Magnetic properties (mineral category, concentration and particle size) of these minerals are modulated primarily by climatic/environmental conditions in source areas and sorting effects during the transportation process. Compared with the other methods, magnetic measurements have the advantages of non-sample destruction, high sensitivity and high efficiency. Finally, future studies are also discussed to address the importance of magnetism for tracing the dynamic transportation processes of the aeolian dust.

The radiocarbon (14C) content of simultaneously deposited substrates in lacustrine archives may differ due to reservoir and detrital effects, complicating the development of age models and interpretation of proxy records. Multi-substrate 14C studies quantifying these effects remain rare, however, particularly for large, terminal lake systems, which are excellent recorders of regional hydroclimate change. We report 14C ages of carbonates, brine shrimp cysts, algal mat biomass, total organic carbon (TOC), terrestrial macrofossils, and n-alkane biomarkers from Holocene sediments of the Great Salt Lake (GSL), Utah. 14C ages for co-deposited aquatic organic substrates are generally consistent, with small offsets that may reflect variable terrestrial organic matter inputs to the system. Carbonates and long-chain n-alkanes derived from vascular plants, however, are ∼1000–4000 14C years older than other substrates, reflecting deposition of pre-aged detrital materials. All lacustrine substrates are 14C-depleted compared to terrestrial macrofossils, suggesting that the reservoir age of the GSL was > 1200 years throughout most of the Holocene, far greater than the modern reservoir age of the lake (∼300 years). These results suggest good potential for multi-substrate paleoenvironmental reconstruction from Holocene GSL sediments but point to limitations including reservoir-induced uncertainty in 14C chronologies and attenuation and time-shifting of some proxy signals due to detrital effects.

In practice, obtaining radiocarbon (14C) composition of organic matter (OM) in sediments requires first removing inorganic carbon (IC) by acid-treatment. Two common treatments are acid rinsing and fumigation. Resulting 14C content obtained by different methods can differ, but underlying causes of these differences remain elusive. To assess the influence of different acid-treatments on 14C content of sedimentary OM, we examine the variability in 14C content for a range of marine and river sediments. By comparing results for unacidified and acidified sediments [HCl rinsing (RinseHCl) and HCl fumigation (FumeHCl)], we demonstrate that the two acid-treatments can affect 14C content differentially. Our findings suggest that, for low-carbonate samples, RinseHCl affects the Fm values due to loss of young labile organic carbon (OC). FumeHCl makes the Fm values for labile OC decrease, leaving the residual OC older. High-carbonate samples can lose relatively old organic components during RinseHCl, causing the Fm values of remaining OC to increase. FumeHCl can remove thermally labile, usually young, OC and reduce the Fm values. We suggest three factors should be taken into account when using acid to remove carbonate from sediments: IC abundance, proportions of labile and refractory OC, and environmental matrix.

A better understanding of the dynamics of different particulate organic matter (OM) pools in the coastal carbon budget is a key issue for quantifying the role of the coastal ocean in the global carbon cycle. To elucidate the benthic component of this carbon cycle at the land-sea interface, we investigated the carbon isotope signatures (δ13C and ∆14C) in the sediment pore waters dissolved inorganic carbon (DIC) in addition to the sediment OM to constrain the origin of the OM mineralized in sediments. The study site is located at the outlet of the Rhône River (Mediterranean Sea), which was chosen because this river is one of the most nuclearized rivers in Europe and nuclear 14C can serve as a tracer to follow the fate of the OM discharged by the river to the coastal sea. The ∆14C results found in the pore waters DIC show a general offset between buried and mineralized OM following a preferential mineralization model of young and fresh particles. For example, we found that the sediment OM has values with a mean ∆14C=–33‰ at sampling stations near the river mouth whereas enriched ∆14C values around +523‰ and +667‰ respectively were found for the pore waters DIC. This indicates complete mineralization of a riverine fraction of OM enriched in 14C in the river conduit during in-stream photosynthesis. In shelf sediments, the ∆14C of pore waters DIC is slightly enriched (+57‰) with sediment OM reaching –570‰. A mixing model shows that particles mineralized near the river mouth are certainly of riverine phytoplanktonic origin whereas OM mineralized on the shelf is of marine origin. This work highlights the fact that pore waters provide additional information compared to sediments alone and it seems essential to work on both pools to study the carbon budget in river prodelta.

The CRP-3 drilling project collected sediments from 3 to 939 mbsf (metres below sea floor) in the Victoria Land Basin in Antarctica. The upper sequence (down to ~790 m bsf) is of Cenozoic age and made up of detrital glaciogenic sediments; the characteristics of clay minerals in this part have been reported elsewhere. Here, the compositional features of clay minerals in the lower sequence such as conglomerates, Devonian sandstones and dolerites are described and genetic processes clarified. Clay minerals in the deepest part of the sequence derive from the alteration of different lithologies that mostly make up the sedimentary basin.

Two clay mineral assemblages were characterized through analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). From 790 to 823 mbsf, samples consist of authigenic smectite of variable chemical composition forming imbricated texture of plates or flakes. The smectites probably result from hydrothermal/diagenetic transformation of earlier minerals. The primary smectite cement underwent reorganization during shearing and cataclasis. The lowest part of the sequence (below 823 mbsf) is characterized by an assemblage of kaolinite, mixed-layer illite-smectite, Fe oxyhydroxide, sporadic smectite and poorly crystallized illite. It reflects a stronger alteration process than that recorded in the upper units of core CRP-3, related to hydrothermalism connected with the intrusion of an igneous body. Both assemblages show clear differences in particle morphology, texture and smectite composition to the clay assemblages found in the Cenozoic glaciomarine sediments in the upper sequence. The different phases of alteration appear related to the processes of rifting, exhumation and faulting that characterized this region since the Mesozoic.

Mineralogical and oxygen isotope analyses have been performed on nine western Indian Ocean core samples in order to distinguish the detrital from authigenic minerals in the sediments. Following the removal of carbonates, organic constituents and Fe and Mn oxides, the residue was separated into five size fractions, the principal minerals present being feldspar, quartz, clinoptilolite, and clay minerals.

Oxygen isotope compositions for two samples reflect an authigenic origin for clinoptilolite by the submarine alteration of volcanic material. Oxygen isotope compositions of two separates (free from feldspar and clays) suggest a detrital origin for the quartz in this area. The same mode of origin is apparent for the other components too, except possibly for some smectite which may have formed authigenically.

The recently uplifted and exposed Pliocene and Pleistocene sedimentary infill of the neotectonic Polis graben provides an excellent opportunity to understand extensional basin development in a marine setting. Fieldwork, facies analysis and dating using nannofossils and strontium isotopes reveal how the sedimentary conditions evolved during infill of the Polis graben during Pliocene and Pleistocene time, and allow a composite succession for the depocentre to be determined for the first time. Six lithofacies are recognized in the northern Polis graben, allowing evolving palaeoenvironments to be inferred. By the end of Miocene time (Messinian) a major c. N–S-trending graben was established; extensional faulting continued during the Pliocene–Pleistocene until recent time. Post-Messinian salinity crisis deposition began with deposition of hemipelagic muds (c. 5.08–2.76 Ma), equivalent to the Nicosia Formation. This was followed by upwards incoming of repeated normal-graded bioclastic carbonates (couplets) (c. 2.76–1.6 Ma), which are interpreted as age-equivalents of the Athalassa Formation elsewhere in Cyprus. The upwards sudden facies change is explained by tectonically controlled shallowing which enabled neritic carbonate production on the basin margins. The appearance of basement-derived material (e.g. ophiolitic extrusive detritus) in the highest stratigraphic levels of the basin fill in the north (c. 1.7–1.6 Ma) reflects onset of rapid surface uplift focused on the Troodos ophiolitic massif. Overall, the syntectonic basin infill appears to document a two-stage, pulsed uplift related to early-stage collision of the African and Eurasian plates in the easternmost Mediterranean region.

A study was conducted to examine the effects of residence time and temperature on atrazine extractability and degradation in a sediment generated from Emporia sandy loam soil submerged under a water column. Sediments amended with 2.8 μg of atrazine were incubated at two temperatures (5 and 24 C), sampled at 0, 14, 28, 112, 168, 252, and 336 d, and then sequentially extracted once with 80 ml 0.01 M CaCl2 aqueous solution, three times with 25 ml of methanol/water mixture (4:1, v/v), and three times with 25 ml of methanol/water/formic acid (20:5:1, v/v pH 3.2) for a total of seven times. Extracts were analyzed for atrazine and metabolites using reverse phase high-performance liquid chromatography. The rate of bound residue formation was greater at 24 than at 5 C. About 30 and 60% of the 14C was bound (nonextractable) to sediments at 5 and 24 C, respectively. Water was less effective in extracting 14C residues from sediments incubated at 24 C than at 5 C. Acidification of the methanol/water mixture with formic acid during the last extraction step improved the removal of hydroxyatrazine from sediment. Atrazine degraded primarily to hydroxyatrazine (HA) and to a lesser extent to deethylatrazine (DEA). Although no DEA was found, HA at 43 μg kg−1 of sediment was detected 112 d after treatment at 5 C, indicating that chemical degradation could occur at a low temperature if sediments are incubated for extended periods of time. At 24 C, HA was found within 28 d and reached the maximum level at day 252. The results suggested that HA is the major metabolite of atrazine in the sediment; a significant fraction of the residue was unavailable for extraction, and this unextractable portion increased with residence time.