Sterile Sediment Research Articles

Integration of radiocarbon dating and paleomagnetic secular variation to date Las Brusquillas (LB4) archaeological site, Pampas region, Argentina

This article presents the first age model built with a combination of paleomagnetic data and radiocarbon dating for the Las Brusquillas 4 archaeological site (Pampas region, Argentina). The sedimentary sequence represents fluvio-lacustrine deposits where faunal remains and lithic artefacts were found in two archaeological layers separated by culturally sterile sediments. Our age model is fundamental to date the human occupation in the area during the Holocene and determine when paleoenvironmental changes occurred at a local scale. Paleomagnetic secular variations (PSV) recorded in 129 cm of this sedimentary sequence were compared to four global geomagnetic field models. Rock magnetic results suggest that the magnetic signal is carried by low-coercivity magnetic minerals like magnetite with an important contribution of antiferromagnetic minerals (hematite-type). The PSV of Las Brusquillas 4 compare well with other natural archives from different regions of Argentina but some differences were found in the declination data, showing the importance of further records from this region to better constrain the secular variation of the geomagnetic field.

Inoculating rhizome-propagated Sporobolus pumilus with a native mycorrhizal fungus increases salt marsh plant growth and survival

Salt marshes are ecosystems of significant ecological importance for coastal stability and fundamental roles in marine ecosystems. Salt marshes are declining due to anthropogenic and natural causes including sea level rise. Coastal restoration efforts have increased worldwide, but many fail in long-term coastal stability. We used a naturally occurring arbuscular mycorrhizal fungus (AMF) to test whether survival and early growth of the salt marsh grass Sporobolus pumilus (formerly Spartina patens) improved under simulated salt marsh conditions. Using a tidal mesocosm bench, we grew inoculated plants with varying AMF treatments under simulated tidal regimes to determine if AMF could aid in establishment of healthy Sporobolus communities. Rhizome-derived S. pumilus had greater survival and grew faster than seed-derived plants. Plants inoculated with propagated AMF consistently outperformed both sterile and native sediment controls in terms of plant survival and growth. Use of rhizome-derived Sporobolus inoculated with propagated Funneliformis geosporum showed the most promise in producing successful plant populations for salt marsh restoration. This may be due to plant life stage and improved plant nutrient status, allowing rhizome-derived plants to grow more quickly than seed-derived plants. Using these plants in future large-scale restoration may increase re-establishment of salt marsh ecosystems.

Pluridisciplinary evidence for burial for the La Ferrassie 8 Neandertal child

The origin of funerary practices has important implications for the emergence of so-called modern cognitive capacities and behaviour. We provide new multidisciplinary information on the archaeological context of the La Ferrassie 8 Neandertal skeleton (grand abri of La Ferrassie, Dordogne, France), including geochronological data -14C and OSL-, ZooMS and ancient DNA data, geological and stratigraphic information from the surrounding context, complete taphonomic study of the skeleton and associated remains, spatial information from the 1968–1973 excavations, and new (2014) fieldwork data. Our results show that a pit was dug in a sterile sediment layer and the corpse of a two-year-old child was laid there. A hominin bone from this context, identified through Zooarchaeology by Mass Spectrometry (ZooMS) and associated with Neandertal based on its mitochondrial DNA, yielded a direct 14C age of 41.7–40.8 ka cal BP (95%), younger than the 14C dates of the overlying archaeopaleontological layers and the OSL age of the surrounding sediment. This age makes the bone one of the most recent directly dated Neandertals. It is consistent with the age range for the Châtelperronian in the site and in this region and represents the third association of Neandertal taxa to Initial Upper Palaeolithic lithic technocomplex in Western Europe. A detailed multidisciplinary approach, as presented here, is essential to advance understanding of Neandertal behavior, including funerary practices.

Neandertal camps and hyena dens. Living floor 150A at Grotta dei Santi (Monte Argentario, Tuscany, Italy)

Grotta dei Santi represents a very suitable investigation field for carrying out an inquiry into the Neandertal behaviour at a high-resolution time scale, in order to obtain data useful for the “functional” reading of the economic and settling strategies. This cave opens into the Monte Argentario Promontory (southern coast of Tuscany, central Italy), almost at sea-level, at the base of a limestone falaise about 50 m high. During MIS 3, when Neandertals occupied the site, there was a wide plain in front of the cave. Excavations carried out by the University of Siena over the last 13 years brought to light several Mousterian occupation phases represented, most of the times, by thin living floors separated from one another by sterile sediments. However, another “occupant”, the spotted hyena (Crocuta crocuta), left clear traces in the cave in layers other than those occupied by humans. Although there usually is a clear-cut stratigraphic separation, a partial overlapping between the human and hyena occupations is sometimes documented, owing to their closeness in time. This is the case for the uppermost “living floor” of layer 150, which is the object of our study. A multidisciplinary integrated analytic methodology was applied, including lithic technology, taxonomic analysis of faunal remains, taphonomy, use-wear analysis and spatial analysis by means of a GIS platform. This approach allowed us to detect a set of parameters useful for identifying activities due to each of these two predators individually, which provided substantial information about their behaviours.

45,610–52,160 years of site and landscape occupation at Nawarla Gabarnmang, Arnhem Land plateau (northern Australia)

We present Bayesian modelling on a long sequence of radiocarbon ages from the archaeological site of Nawarla Gabarnmang, central Arnhem Land plateau, northern Australia. A horizon of wind-borne sediments containing flaked stone artefacts and charcoal commencing >45,610 cal BP (the young end of the modelled boundary age range, which extends beyond the limit of the calibration curve), with a median modelled age of 48,500 cal BP, signals the onset of aeolian mobilisation of fine sands and silts across the landscape, and re-deposition within the site at a time synchronous with the first evidence of people. This earliest cultural horizon (Stratigraphic Unit 4) contains 509 stone artefacts, and is marked by a contemporaneous sedimentary break, from underlying culturally sterile sediments consisting of disintegrating roof-fall and in situ sandstone and quartzite to overlying culturally-rich wind-blown sand. The new radiocarbon ages and wind-blown sediments together provide evidence for the commencement of noticeable landscape burning on the Arnhem Land plateau c. 48,500 cal BP, suggesting an intensification of landscape management practices at the summit of the Arnhem Land plateau some 10,000–15,000 years after the lowest dense band of artefacts (Phase 2) at Madjedbebe on the floodplains 90 km to the north. These results have ramifications for the structure and timing of the spread of people across Australia, and the extinction of megafauna in Sahul.

Non-random processes determine the colonization of groundwater sediments by microbial communities in a pristine porous aquifer.

Sediments accommodate the dominating share of groundwater microbiomes, however the processes that govern the assembly and succession of sediment-attached microbial communities in groundwater aquifers are not well understood. To elucidate these processes, we followed the microbial colonization of sterile sediments in in situ microcosms that were exposed to groundwater for almost 1 year at two distant but hydrologically connected sites of a pristine, shallow, porous aquifer. Our results revealed intriguing similarities between the community succession on the newly-colonized sediments and succession patterns previously observed for biofilms in other more dynamic aquatic environments, indicating that the assembly of microbial communities on surfaces may be governed by similar underlying mechanisms across a wide range of different habitats. Null model simulations on spatiotemporally resolved 16S rRNA amplicon sequencing data further indicated selection of specific OTUs rather than random colonization as the main driver of community assembly. A small fraction of persistent OTUs that had established on the sediments during the first 115 days dominated the final communities (68%-85%), suggesting a key role of these early-colonizing organisms, in particular specific genera within the Comamonadaceae and Oxalobacteraceae, for community assembly and succession during the colonization of the sediments. Overall, our study suggests that differences between planktonic and sediment-attached communities often reported for groundwater environments are not the result of purely stochastic events, but that sediment surfaces select for specific groups of microorganisms that assemble over time in a reproducible, non-random way.

Positron emission tomography to visualise in-situ microbial metabolism in natural sediments

Positron Emission Tomography simultaneously monitored flow dynamics and in-situ microbial activity in opaque sediment columns. An 18F labelled electron donor, 2-deoxy-2-[18F]-fluoro-D-glucose (18FDG), was added to flowing columns containing sterile sediment, microbially active sediment and quartz sand. 18FDG accumulated in microbially active, glucose primed, sediment (105–106 cells g-1) at 10–16 mol g-1 (~40% of the 100 MBq spike) giving the first example of 18FDG uptake by indigenous microorganisms in a complex sediment system at flow rates representative of the shallow subsurface.

Optimisation of decontamination method and influence of culture media on the recovery of Mycobacterium avium subspecies paratuberculosis from spiked water sediments

The recovery of Mycobacterium avium subspecies paratuberculosis (Map) from the environment can be a laborious process – owing to Map being fastidious, its low number, and also high numbers of other microbial populations in such settings. Protocols i.e. filtration, decontamination and modified elution were devised to recover Map from spiked water sediments. Three culture media: Herrold's Egg Yolk Media (HEYM), Middlebrook 7H10 (M-7H10) and Bactec 12B were then employed to grow the organism following its elution. In the sterile sediment samples the recovery of Map was significant between the time of exposure for each of HEYM and M-7H10, and insignificant between both media (P < 0.05). However, in the non-sterile sediment samples, the HEYM grew other background microflora including moulds at all the times of exposure whilst 4 h followed by M-7H10 culture yielded Map colonies without any background microflora. Using sterile samples only for the Bactec 12B, the recovery of Map decreased as time of exposure increased. Based on these findings, M-7H10 should be considered for the recovery of Map from the natural environment including water sediments where the recovery of diverse microbial species remains a challenge. Significance of the studyMap is a robust pathogen that abides in the environment. In water treatment operations, Map associates with floccules and other particulate matter including sediments. It is also a fastidious organism, and its detection and recovery from the water environment is a laborious process and can be misleading within the abundance of other mycobacterial species owing to their close resemblance in phylogenetic traits. In the absence of a reliable recovery method, Map continues to pose public health risks through biofilm in household water tanks, hence the need for the development of a reliable recovery protocol to monitor the presence of Map in water systems in order to curtail its public health risks.

Open-air preservation of miniaturised lithics: experimental research in the Cederberg Mountains, southern Africa

Open-air archaeology plays a limited role in southern African Late Pleistocene research, with most studies focused on rock shelter assemblages. Recently, archaeologists have noted discrepancies in the composition of Late Pleistocene lithic assemblages between some of the region’s open-air and rock shelter sites. For example, although relatively abundant in rock shelters, Late Pleistocene Later Stone Age (LSA, c. 44–12 kcal. BP) bipolar cores are rare in open-air contexts. In this paper, we assess this discrepancy by testing for differential preservation of specific artefact classes and sizes in semi-arid open-air conditions. We placed a replicated assemblage of miniaturised cores and flakes on an archaeologically sterile sediment surface in the Doring River Valley (South Africa) and recorded their movements over 22 months. Our results indicate that bipolar and freehand cores moved comparable distances within the study interval and that surface slope is the strongest predictor of miniaturised tool movement. We also show that (1) relatively flat lithics move disproportionately more and (2) random artefact orientations do not preclude local (i.e. metre) scale artefact transport. In terms of the archaeology of our study area, the observed clustering of surface artefacts on sediment bodies likely results from their recent exposure. Our data suggest that the paucity of open-air bipolar artefacts in Late Pleistocene LSA assemblages may have more to do with human behavioural variability at landscape scales than differential preservation. Southern Africa’s rich rock shelter record is, therefore, unlikely to represent the full suite of prehistoric hunter-gatherer behaviours.

Towards an Accurate and Precise Chronology for the Colonization of Australia: The Example of Riwi, Kimberley, Western Australia.

An extensive series of 44 radiocarbon (14C) and 37 optically stimulated luminescence (OSL) ages have been obtained from the site of Riwi, south central Kimberley (NW Australia). As one of the earliest known Pleistocene sites in Australia, with archaeologically sterile sediment beneath deposits containing occupation, the chronology of the site is important in renewed debates surrounding the colonization of Sahul. Charcoal is preserved throughout the sequence and within multiple discrete hearth features. Prior to 14C dating, charcoal has been pretreated with both acid-base-acid (ABA) and acid base oxidation-stepped combustion (ABOx-SC) methods at multiple laboratories. Ages are consistent between laboratories and also between the two pretreatment methods, suggesting that contamination is easily removed from charcoal at Riwi and the Pleistocene ages are likely to be accurate. Whilst some charcoal samples recovered from outside hearth features are identified as outliers within a Bayesian model, all ages on charcoal within hearth features are consistent with stratigraphy. OSL dating has been undertaken using single quartz grains from the sandy matrix. The majority of samples show De distributions that are well-bleached but that also include evidence for mixing as a result of post-depositional bioturbation of the sediment. The results of the two techniques are compared and evaluated within a Bayesian model. Consistency between the two methods is good, and we demonstrate human occupation at this site from 46.4–44.6 cal kBP (95.4% probability range). Importantly, the lowest archaeological horizon at Riwi is underlain by sterile sediments which have been dated by OSL making it possible to demonstrate the absence of human occupation for between 0.9–5.2 ka (68.2% probability range) prior to occupation.

Examining the Colonization and Survival of E. coli from Varying Host Sources in Drainage Basin Sediments and Stormwater.

It is widely understood that stormwater drainage has a significant impact on the health of tidal creek systems via regular inputs of runoff from the surrounding watershed. Due to this hydrologic connection, contamination of the upstream drainage basin will have a direct effect on estuaries and tidal creeks that often act as receiving waters. This study focuses on the importance of drainage basin sediments as they enhance the persistence and transport of the fecal indicator bacteria E. coli within a watershed. Experiments presented use microcosm environments with drainage basin sediments and stormwater to investigate E. coli colonization of stagnant waters and to examine the importance of host sources to bacterial survival. A novel method for establishing microcosms using environmental sediments with in situ bacterial populations and sterile overlying waters is used to examine E. coli colonization of the water column in the absence of flow. Colonization of sterile sediment environments also is examined using two common host sources (human and avian). Each experiment uses sediments of varying grain size and organic content to examine the influence of physical characteristics on bacterial prevalence. Results suggest host source of bacteria may be more important to initial bacterial colonization while physical characteristics of drainage basin sediments better explains extended E. coli persistence. Findings also suggest an indirect control of water column bacterial concentration by sediment type and erodibility.

Site formation and chronology of the new Paleolithic site Sima de Las Palomas de Teba, southern Spain

The newly identified Paleolithic site Sima de Las Palomas de Teba hosts an almost seven-m-thick sediment profile investigated here to elucidate the rock shelter's chronostratigraphy and formation processes. At its base, the sediment sequence contains rich archeological deposits recording intensive occupation by Neanderthals. Luminescence provides a terminus ante quem of 39.4±2.6ka or 44.9±4.1ka (OSL) and 51.4±8.4ka (TL). This occupation ended with a rockfall event followed by accumulation of archeologically sterile sediments. These were covered by sediments containing few Middle Paleolithic artifacts, which either indicate ephemeral occupation by Neanderthals or reworking as suggested by micromorphological features. Above this unit, scattered lithic artifacts of undiagnostic character may represent undefined Paleolithic occupations. Sediment burial ages between about 23.0±1.5ka (OSL) and 40.5±3.4ka (pIRIR) provide an Upper Paleolithic chronology for sediments deposited above the rockfall. Finally, a dung-bearing Holocene layer in the uppermost part of the sequence contains a fragment of a human mandible dated to 4032±3914CyrBP. Overall, the sequence represents an important new site for studying the end of Neanderthal occupation in southern Spain.

Characterization and Evaluation of the Potential of a Diesel-Degrading Bacterial Consortium Isolated from Fresh Mangrove Sediment

Hydrocarbons are ubiquitous and persistent organic pollutants in the environment. In wetlands and marine environments, particularly in mangrove ecosystems, their increase and significant accumulation result from human activities such as oil and gas exploration and exploitation operations. Remediation of these ecosystems requires the development of adequate and effective strategies. Natural attenuation, biostimulation, and bioaugmentation are all biological soil treatment techniques that can be adapted to mangroves. Our experiments were performed on samples of fresh mangrove sediments from the Cameroon estuary and mainly from the Wouri River in Cameroon. This study aims to assess the degradation potential of a bacterial consortium isolated from mangrove sediment. The principle of our bioremediation experiments is based on a series of tests designed to evaluate the potential of an active indigenous microflora and three exogenous pure strains, to degrade diesel with/without adding nutrients. The experiments were conducted in laboratory flasks and a greenhouse in microcosms. In one case, as in the other, the endogenous microflora showed that it was able to degrade diesel. Under stress of the pollutant, the endogenous microflora fits well enough in the middle to enable metabolism of the pollutant. However, the Rhodococcus strain was more effective over time. The degradation rate was 77 and 90 % in the vials containing the sterile sediments and non-sterile sediments, respectively. The results are comparable with those obtained in the microcosms in a greenhouse where only the endogenous microflora were used. The results of this study show that mangrove sediment contains an active microflora that can metabolize diesel. Indigenous and active microflora show an interesting potential for diesel degradation.

Sedimentation rapidly induces an immune response and depletes energy stores in a hard coral

High sedimentation rates have been linked to reduced coral health within multiple systems; however, whether this is a direct result of compromised coral immunity has not been previously investigated. The potential effects of sedimentation on immunity of the hard coral Montipora patula were examined by comparing physiological responses of coral fragments inoculated with sterilized marine sediments and those under control conditions. Sediments were collected from terrestrial runoff-affected reefs in SW Madagascar and applied cyclically for a total of 24 h at a rate observed during precipitation-induced sedimentation events. Coral health was determined 24 h after the onset of the sedimentation stress through measuring metabolic proxies of O2 budget and lipid ratios. Immune response of the melanin synthesis pathway was measured by quantifying phenoloxidase activity and melanin deposits. Sedimentation induced both immune and metabolic responses in M. patula. Both phenoloxidase activity and melanin deposition were significantly higher in the sediment treatment compared to controls, indicating an induced immune response. Sediment-treated corals also showed a tendency towards increased respiration (during the night) and decreased photosynthesis (during the day) and a significant depletion of energy reserves as compared to controls. These data highlight that short-term (24 h) sedimentation, free of live microorganisms, compromises the health of M. patula. The energetically costly immune response, potentially elicited by residual endotoxins and other inflammatory particles associated with the sterile sediments, likely contributes to the energy depletion. Overall, exposure to sedimentation adversely affects coral health and continued exposure may lead to resource depletion and an increased susceptibility to disease.

Fiddler crabs (Uca thayeri, Brachyura: Ocypodidae) affect bacterial assemblages in mangrove forest sediments

To clarify the relationship between the detritivore fiddler crab, Uca thayeri, and sediment bacteria, we quantified morphotype richness, abundance and evenness of these microorganisms inside the crabs’ guts and in mangrove-associated sediments in Sisal, Mexico (21° 9′ N, 90° 1′ W) from July to September 2008. Increased bacterial richness and abundance were observed in mesocosm experiments when nutrients were added to the sediment or in the absence of fiddler crabs. Thus, crab disturbance seems to play a role in shaping the bacterial assemblage by reducing richness and abundance just as nutrient limitation does. Crabs can also play a second role by harboring a subset of bacterial morphotypes inside their gut. We exposed sterile sediment to fiddler crabs and found that viable cells were expelled from the crab’s gut and proliferated in previously sterile substratum. The bacterial community is thus structured by the foraging behavior of fiddler crabs since it benefits some bacteria and restricts others. By agar plating we have obtained conservative results, yet the data suggest that the crab influences the bacterial assemblage in two ways by allowing inoculation of the sand from the gut and reducing bacteria diversity through disturbance when foraging on sediments.

Single-species bacteria in sediments induce larval settlement of the infaunal polychaetes Polydora cornuta and Streblospio benedicti

Larval settlement of the infaunal spionid polychaetes Polydora cornuta and Streblospio benedicti is mediated by sediment-associated microorganisms. To investigate if larval preference for certain sediment is guided by individual sediment-associated bacteria, 13 bacterial isolates (5 phyla) obtained from the natural habitat of adult polychaetes (Wadden Sea, Germany) in 2008 were screened in still-water, no-choice settlement assays. Two isolates (α-Proteobacterium-Strain DF11 and Flavobacterium-Strain 54) significantly triggered larval settlement in comparison with sterile sediment. In still-water, multiple-choice settlement assays comprising natural and sterile sediment and sediment re-inoculated with isolates DF11 and 54, significant preferences for natural sediment and sediment containing bacterial isolates at 108 cells g−1 were observed. Larval settlement was influenced by bacterial abundance in sediment but the correlation was not strictly positive; thus, maximum larval settlement in response to single bacterial species may occur at certain optimum densities. Non-viable or suspended bacteria and water-soluble bacterial products did not induce larval settlement, suggesting that sediment-associated bacterial settlement cues for P. cornuta and S. benedicti were either produced in situ and/or consisted of heat-labile bacterial products.

Spatio-temporal patterns of microbial communities in a hydrologically dynamic pristine aquifer

Seasonal patterns of groundwater and sediment microbial communities were explored in a hydrologically dynamic alpine oligotrophic porous aquifer, characterized by pronounced groundwater table fluctuations. Rising of the groundwater level in consequence of snow melting water recharge was accompanied by a dramatic drop of bacterial Shannon diversity in groundwater from H' = 3.22 ± 0.28 in autumn and winter to H' = 1.31 ± 0.35 in spring and summer, evaluated based on T-RFLP community fingerprinting. Elevated numbers of bacteria in groundwater in autumn followed nutrient inputs via recharge from summer rains and correlated well with highest concentrations of assimilable organic carbon. Sterile sediments incubated to groundwater in monitoring wells were readily colonized reaching maximum cell densities within 2 months, followed by a consecutive but delayed increase and leveling-off of bacterial diversity. After 1 year of incubation, the initially sterile sediments exhibited a similar number of bacteria and Shannon diversity when compared to vital sediment from a nearby river incubated in parallel. The river bed sediment microbial communities hardly changed in composition, diversity, and cell numbers during 1 year of exposure to groundwater. Summing up, the seasonal hydrological dynamics were found to induce considerable dynamics of microbial communities suspended in groundwater, while sediment communities seem unaffected and stable in terms of biomass and diversity.

Bias in bacteriophage morphological classification by transmission electron microscopy due to breakage or loss of tail structures

Virtually every study that has used transmission electron microscopy (TEM) to estimate viral diversity has acknowledged that loss of phage tails during sample preparation may have biased the results. However, the magnitude of this potential bias has yet to be constrained. To characterize biases in virus morphological diversity due to tail loss, six phage strains representing the order Caudovirales were inoculated into sterile sediments and soils. Phage particles were then extracted using standard methods. Morphologies of extracted phage particles were compared to those of unmanipulated control samples to determine the extent of tail breakage incurred by extraction procedures. Podoviruses exhibited the smallest frequency of tail loss during extraction (1.2-14%), myoviruses were moderately susceptible to tail breakage (15-40%), and siphoviruses were highly susceptible (32-76%). Thus, TEM assessments of viral diversity in soils or sediments by distribution of tail morphologies may be biased toward podoviruses and virions lacking tails, while simultaneously underestimating the abundance of siphoviruses. However, since the majority of viral capsids observed under TEM were intact, estimates of viral diversity based on the distribution of capsid diameters may provide a more reliable basis for morphological comparisons within and across ecosystems.

Isolation and characterization of RDX-degrading Rhodococcus species from a contaminated aquifer

Groundwater contamination by the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a global problem. Israel's coastal aquifer was contaminated with RDX. This aquifer is mostly aerobic and we therefore sought aerobic bacteria that might be involved in natural attenuation of the compound in the aquifer. RDX-degrading bacteria were captured by passively sampling the indigenous bacteria onto sterile sediments placed within sampling boreholes. Aerobic RDX biodegradation potential was detected in the sediments sampled from different locations along the plume. RDX degradation with the native sampled consortium was accompanied by 4-nitro-2,4-diazabutanal formation. Two bacterial strains of the genus Rhodococcus were isolated from the sediments and identified as aerobic RDX degraders. The xplA gene encoding the cytochrome P450 enzyme was partially (~500bp) sequenced from both isolates. The obtained DNA sequences had 99% identity with corresponding gene fragments of previously isolated RDX-degrading Rhodococcus strains. RDX degradation by both strains was prevented by 200μM of the cytochrome P450 inhibitor metyrapone, suggesting that cytochrome P450 indeed mediates the initial step in RDX degradation. RDX biodegradation activity by the T7 isolate was inhibited in the presence of nitrate or ammonium concentrations above 1.6 and 5.5mM, respectively (100mgl(-1)) while the T9N isolate's activity was retarded only by ammonium concentrations above 5.5mM. This study shows that bacteria from the genus Rhodococcus, potentially degrade RDX in the saturated zone as well, following the same aerobic degradation pathway defined for other Rhodococcus species. RDX-degrading activity by the Rhodococcus species isolate T9N may have important implications for the bioremediation of nitrate-rich RDX-contaminated aquifers.

Detection of Oospore of Pythium porphyrae from Sterile Sediments by Using PCR

Detection of Oospore of Pythium porphyrae from Sterile Sediments by Using PCR