Terrestrial Contamination Research Articles

Rapid colonization of a space‐returned Ryugu sample by terrestrial microorganisms

AbstractThe presence of microorganisms within meteorites has been used as evidence for extraterrestrial life, however, the potential for terrestrial contamination makes their interpretation highly controversial. Here, we report the discovery of rods and filaments of organic matter, which are interpreted as filamentous microorganisms, on a space‐returned sample from 162173 Ryugu recovered by the Hayabusa 2 mission. The observed carbonaceous filaments have sizes and morphologies consistent with microorganisms and are spatially associated with indigenous organic matter. The abundance of filaments changed with time and suggests the growth and decline of a prokaryote population with a generation time of 5.2 days. The population statistics indicate an extant microbial community originating through terrestrial contamination. The discovery emphasizes that terrestrial biota can rapidly colonize extraterrestrial specimens even given contamination control precautions. The colonization of a space‐returned sample emphasizes that extraterrestrial organic matter can provide a suitable source of metabolic energy for heterotrophic organisms on Earth and other planets.

P21-23 First data on polybrominated diphenyl ethers occurrence and a follow-up on polychlorinated biphenyl levels in European brown bear as a bioindicator of terrestrial environment contamination

P21-23 First data on polybrominated diphenyl ethers occurrence and a follow-up on polychlorinated biphenyl levels in European brown bear as a bioindicator of terrestrial environment contamination

Revisiting the formation of lunar anorthosites via the Rb[sbnd]Sr isotope systematics

The incorporation of KREEP (potassium, rare-earth element, and phosphorus), mantle-derived mafic melts and trapped liquid into the lunar ferroan anorthosite (FAN) suite plays a pivotal role in generating their geochemical and isotopic variations. Nonetheless, the specific involvement and distinct roles of these different components remain controversial. This study presents in-situ Sr isotopic data for 28 anorthositic clasts found within lunar feldspathic meteorites to trace their sources and post-modification processes. We find that these plagioclases exhibit substantial variations in their measured 87Sr/86Sr values (0.69978–0.70357), in contrast to the relatively narrow range observed in Apollo 16 FANs, thereby likely reflecting a diverse chemical composition of lunar crustal rocks. In contrast, the analyzed plagioclases have consistently low 87Rb/86Sr ratios (0.00185–0.03962), similar to those of Apollo samples, reflecting impact-induced loss of Rb. Detailed investigations indicate that certain elevated 87Sr/86Sr ratios are probably not caused by terrestrial contamination or instrumental analysis, but most likely result from the decay of 87Rb from sources with initial 87Rb/86Sr higher than 0.0119–0.1380. However, such elevated 87Rb/86Sr values cannot solely result from crystallization of the lunar magma ocean (LMO) and likely involve KREEP components. Combined with trace element data, we estimate the maximum proportion of KREEP melt in the formation of lunar anorthosites. Future analyses of lunar anorthosites collected by China's Chang'e-5 and Chang'e-6 missions will be crucial for validating the observed Sr isotopic heterogeneity.

Characterization and source apportionment of pharmaceuticals in surface water of the Yangtze Estuary and adjacent sea.

Pharmaceuticals, which are closely linked to human activities, have attracted global attention. This study investigated the occurrence characteristics of 20 pharmaceuticals in surface water of the Yangtze Estuary and adjacent sea. A total of 14 targeted pharmaceuticals were detected in both spring and summer sampling campaigns. The mean concentrations of sulfonamides and non-sulfonamides were 36.60 ± 19.43ng·L-1 and 50.02 ± 41.07ng·L-1, respectively. As for non-antibiotics, their concentrations were in the range of 24.34 ± 916.8ng·L-1 with caffeine accounting for 6.17 ~ 86.70% (average percentage of 42.22%). Meanwhile, spatial distribution patterns showed similarities between antibiotics and non-antibiotics, with high levels occurring near the upper estuary, aquaculture areas, wastewater treatment plants, and the maximum turbidity zone. This phenomenon could be related to the sources of pharmaceuticals and the physicochemical properties of water bodies. Obviously, the first three areas are highly impacted by human activities or serve as important sources of terrestrial contaminants entering the East China Sea. The last area retains high amounts of suspended particles which may exert strong trapping effects on hydrophobic chemicals. Principal component analysis revealed the presence of three potential sources for pharmaceuticals in the Yangtze Estuary, with a relatively high percentage originating from incompletely treated municipal sewage. As for the temporal trend, pharmaceutical contamination was found to be higher in spring compared to summer, potentially due to variations in pharmaceutical consumption patterns, local rainfalls, and water temperatures. These findings provide fundamental data support for implementing appropriate local management strategies for pharmaceutical usages.

Terrestrial solute fingering flow behind subsurface physical barriers during seawater intrusion

Blocking seawater intrusion in coastal aquifers through impervious subsurface physical barriers is a commonly used method, which creates a relatively closed hydrodynamic environment behind the barrier for the transport of land-sourced contaminants. This study investigated the phenomenon of terrestrial solute fingering flow behind subsurface physical barriers for the first time under field-scale hydrological and hydrogeological conditions. A prediction model for the onset of flow instability and the size of subsequent solute fingers was proposed based on the identified effects of these conditions. Once a modified Rayleigh number exceeded 4000, solute fingering flow behind subsurface physical barriers would occur, and the size of individual fingers followed a sigmoidal function growth with increasing Rayleigh number. Solute fingering flow resulted in a series of morphological changes in individual fingers from finger-like to foot-like with decreased salinity. The movement of solute fingers altered the trajectory and residence time of tracer particles, which led to an early particle arrival for those initially located behind. Compared to a no-finger situation, solute fingering flow accelerated the movement of tracer particles out of the suspended barriers with a reduced residence time by 45%. Shortened residence times and changed transport patterns as a result of solute fingering flow may have significant implications for the fate of terrestrial contaminants. Thus, caution should be exercised in the interpretation of field measurements on groundwater contamination in coastal aquifers if solute fingering flow behind subsurface physical barriers is expected, e.g., from the present prediction model.

Extracting very small amounts of potassium from iron meteorites for the analysis of potassium isotope ratios

The isotope abundance of cosmogenic K, especially the ratios of cosmogenic 40K/41K, can be used to determine reliable cosmic-ray exposure (CRE) ages for iron meteorites. Despite this potential, there are only very few studies and essentially no new data since the pioneering work by H. Voshage more than 40 years ago. This shortfall is likely due to the immense analytical difficulties encountered when extracting cosmogenic K from iron meteorites with typical concentrations in the range of a few ppb or below. Chemical extraction procedures are very challenging, resulting in large blank contributions that must be subtracted, and do have low yields preventing an efficient separation of K from the Fe matrix. The K extracted from iron meteorites is dominated by native K (non-cosmogenic K from the sample), includes K from terrestrial contamination, and only a tiny amount is of cosmogenic origin. In order to separate K from iron meteorites a physical extraction technique was developed that involves extraction of K from molten iron meteorites. In this set-up, terrestrial and native K can be partly separated from cosmogenic K by sophisticated pre-heating and extraction techniques. Sample K is ion-optically collected on a rhenium filament. The filaments are then used as evaporation filaments in a double filament set-up of a Triton Plus Thermal-Ionization Mass Spectrometer (TIMS). Though, cosmogenic K is detectable in all samples, the measured isotope ratios are always close to terrestrial, indicating that the majority of the measured 39K and 41K is from K with almost terrestrial isotope composition. The measured 40K signal is dominantly of cosmogenic origin. The K background is either native K from the sample or terrestrial contamination. The measurements are compromised by unstable signals, i.e., by large fluctuations of the ion currents and/or large variations in the isotope ratios during the course of a single run, sometimes even with fractionation reversals. Such difficulties are likely due to the fact that the K ions are implanted into the filament rather than deposited onto the surface. In addition, parts of the filaments are covered with condensed iron, also affecting the signal stability. Despite these analytical challenges, clear cosmogenic signals were detected in almost all studied iron meteorites and cosmogenic 40K/41K ratios could be determined. However, the data quality is not yet sufficient for precise K isotope studies and for calculating reliable 40K/41K CRE ages for iron meteorites.

YOLO-ET: A Machine Learning model for detecting, localising and classifying anthropogenic contaminants and extraterrestrial microparticles optimised for mobile processing systems

Imminent robotic and human activities on the Moon and other planetary bodies would benefit from advanced in situ Computer Vision and Machine Learning capabilities to identify and quantify microparticle terrestrial contaminants, lunar regolith disturbances, the flux of interplanetary dust particles, possible interstellar dust, β-meteoroids, and secondary impact ejecta. The YOLO-ET (ExtraTerrestrial) algorithm, an innovation in this field, fine-tunes Tiny-YOLO to specifically address these challenges. Designed for coreML model transference to mobile devices, the algorithm facilitates edge computing in space environment conditions. YOLO-ET is deployable as an app on an iPhone with LabCam® optical enhancement, ready for space application ruggedisation. Training on images from the Tanpopo aerogel panels returned from Japan’s Kibo module of the International Space Station, YOLO-ET demonstrates a 90% detection rate for surface contaminant microparticles on the aerogels, and shows promising early results for detection of both microparticle contaminants on the Moon and for evaluating asteroid return samples. YOLO-ET’s application to identifying spacecraft-derived microparticles in lunar regolith simulant samples and SEM images of asteroid Ryugu samples returned by Hayabusa2 and curated by JAXA’s Institute of Space and Astronautical Sciences indicate strong model performance and transfer learning capabilities for future extraterrestrial applications.

A Cretaceous siliceous sinter in NE China: Sedimentological and geochemical constraints on its genesis

Phanerozoic sinter deposits have been reported globally, with their identification mainly based on sedimentological, petrological, and mineralogical studies. In this study, a detailed geochemical investigation, combined with sedimentological characterization, was conducted on the Wugonglilu siliceous deposit, a Cretaceous (106 Ma) sinter in NE China, to examine its genesis. The deposit is inferred as a siliceous hot spring deposit (sinter) owing to its geological setting in an epithermal gold-mining district, its morphologically variable microbial textures typical of subaerial sinters, and nearly pure silica composition. Three lithofacies were recognized in this study, including laminated to thinly bedded sinter, silica-cemented breccia, and epithermal vein, which represent deposits from three contrasting hydrothermal environments. The 87Sr/86Sr ratios of the sinter are similar to the bedrock through which the geothermal fluids passed, namely the Upper Triassic Dajiahe Formation (T3dj), a marine siliceous rock unit, and the Lower Cretaceous Datashanlinchang Formation (K1d), a rhyolite unit. Results indicate that both underlying units are possible Sr sources of the silica in the Wugonglilu sinter. The REE + Y (rare-earth elements and yttrium) patterns of the sinter exhibit significant variability, primarily due to terrestrial detrital contamination. Differential REE + Y contamination by terrestrial detritus was striking in the white and dark laminae/beds of the laminated to thinly bedded sinter. The white laminae/beds, generally less contaminated, were probably formed during the dry season, whereas the dark laminae/beds exhibiting greater detrital contamination were likely formed during the wet season. When excluding the samples strongly contaminated by detritus, the sinter exhibits Y anomalies comparable to Post-Archean Australian Shale (PAAS), and to the adjacent underlying K1d rhyolite and T3dj siliceous rock samples, indicating that these anomalies were not inherited from rocks dominating the reservoirs. Furthermore, the sinter shows a (Ce/Ce*)N range close to that of the underlying marine siliceous rock and rhyolite samples, reflecting that the (Ce/Ce*)N of the sinter is largely inherited from the reservoir rock(s). The overall REE + Y patterns of the sinter range from nearly flat to LREE-depleted, similar to some samples of the K1d rhyolite and T3dj siliceous rock units. However, most samples of the K1d rhyolite and T3dj siliceous rock display (Pr/Tb)N and (Pr/Yb)N higher than many studied sinter samples. This is likely because of the formation of strong HREE–carbonate complexes during groundwater migration. Based on these results, a generalized formation model of the studied sinter system was constructed. This study suggests that integrated sedimentological and geochemical investigations can aid in interpreting the genesis of sinter deposits, in particular the link between sinter deposits and corresponding reservoir rocks.

Trace Element Distribution and Arsenic Speciation in Toenails as Affected by External Contamination and Evaluation of a Cleaning Protocol.

Trace element concentrations in toenail clippings have increasingly been used to measure trace element exposure in epidemeological research. Conventional methods such as inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography ICP-MS (HPLC-ICP-MS) are commonly used to measure trace elements and their speciation in toenails. However, the impact of the removal of external contamination on trace element quantification has not been thoroughly studied. In this work, the microdistribution of trace elements (As, Ca, Co, Cu, Fe, K, Mn, Ni, Rb, S, Sr, Ti, and Zn) in dirty and washed toenails and the speciation of As in situ in toenails were investigated using synchrotron X-ray fluorescence microscopy (XFM) and laterally resolved X-ray absorption near edge spectroscopy (XANES). XFM showed different distribution patterns for each trace element, consistent with their binding properties and nail structure. External (terrestrial) contamination was identified and distinguished from the endogenous accumulation of trace elements in toenails─contaminated areas were characterized by the co-occurrence of Co, Fe, and Mn with elements such as Ti and Rb (i.e., indicators of terrestrial contamination). The XANES spectra showed the presence of one As species in washed toenails, corresponding to As bound to sulfhydryl groups. In dirty specimens, a mixed speciation was found in localized areas, containing AsIII-S species and AsV species. ArsenicV is thought to be associated with surface contamination and exogenous As. These findings provide new insights into the speciation of arsenic in toenails, the microdistribution of trace elements, and the effectiveness of a cleaning protocol in removing external contamination.

Molecular distribution and 13C isotope composition of volatile organic compounds in the Murchison and Sutter's Mill carbonaceous chondrites

AbstractVolatile organic compounds (VOCs) are carbon‐containing chemicals that may evaporate rapidly at room temperature and standard pressure. Such organic compounds can be preserved inside carbonaceous chondrite matrices. However, unlike meteoritic soluble organic matter (SOM) and insoluble organic matter (IOM), VOCs are typically lost (at least in part) during sample processing (meteorite crushing) and exposure to terrestrial atmosphere and/or solvents. Like SOM and IOM, VOCs can provide valuable insights into the chemical inventory of the meteorite parent body and even the presolar cloud from which our solar system formed, as well as the composition and processes that occurred during the early formation of our solar system and the asteroidal stage. Thus, in this work, we designed and built an instrument that allowed us to access the VOCs present in samples of the carbonaceous chondrites Murchison and Sutter's Mill after mineral disaggregation by means of freeze–thaw cycling. We simultaneously evaluated the abundances and compound‐specific 13C‐distributions of the volatiles evolving after meteorite powdering at ~20, 60, and 100°C. Carbon monoxide (CO) and methane (CH4) were released from these meteorites as the most abundant VOCs. They were combusted together for analysis and showed positive δ13C values, indicative of their extraterrestrial origins. Carbon dioxide (CO2) was also an abundant VOC in both meteorites, and its isotopic values suggest that it was mainly formed from dissolved carbonates in the samples. We also detected aldehydes, ketones, and aromatic compounds in low amounts. Contrary to Murchison, which mostly yielded VOCs with positive δ13C values, Sutter's Mill yielded VOCs with negative δ13C values. The less enriched 13C isotope composition of the VOCs detected in Sutter's Mill suggest that they are either terrestrial contaminants, such as VOCs in compressed gas dusters and common laboratory solvents, or compounds disconnected from interstellar sources and/or formed through parent body processing. Understanding the relative abundances and determining the molecular distributions and isotopic compositions of free meteoritic VOCs are key in assessing their extraterrestrial origins and those of chondritic SOM and IOM. Our newly developed technique will be valuable in the study of the samples brought to the Earth from carbonaceous asteroid Bennu by NASA's OSIRIS‐REx mission.

Co-exposure to tire wear particles and nickel inhibits mung bean yield by reducing nutrient uptake.

Soil and terrestrial contamination with microplastics and nanoplastics has been discussed extensively, while tire wear particles (TWPs) have been largely overlooked. We investigated the root-surface interactions and growth response of mung bean (Vigna radiata L.) plants exposed to tire wear particles (TWPs) (0.05, 0.1, and 0.25% w/w) and nickel sulfate (50 and 100 mg kg-1 NiSO4) alone and in co-exposure scenarios for the full life cycle (105 days) under soil conditions. The results show that TWPs adhered to the root surface and reduced the water and nutrient uptake by the plant, particularly at higher concentrations of TWPs (0.25% w/w), without any observed organic contaminant accumulation in the root tissue. TWPs alone at 0.01, 0.1, and 0.25% (w/w) decreased mung bean yield by 11, 28, and 52%, respectively. Co-exposure to TWPs at 0.01, 0.1 and 0.25% w/w with 100 mg kg-1 NiSO4 decreased yield by 73, 79 and 88%, respectively. However, co-exposure to TWPs at 0.01 and 0.1% w/w with 50 mg kg-1 NiSO4 enhanced the yield by 32% and 7%, respectively. These changes in yield and nutritional aspects appear to be linked to Ni's regulatory influence on mineral homeostasis. Moreover, exposure to NiSO4 at 100 mg kg-1 increased Ni uptake in the root, shoot, and grain by 9, 26, and 20-fold, respectively as compared to the unamended control; this corresponded to increased antioxidant enzyme activity (10-127%) as compared to the control. TWPs caused blockages, significantly reducing plant yield and altering nutrient dynamics, highlighting emerging risks to plant health.

Hidden risk of terrestrial food chain contamination from organochlorine insecticides in a vegetable cultivation area of Northwest Bangladesh

Organochlorine insecticide (OCI) exposures in terrestrial food chains from historical or current applications were studied in a vegetable production area in northwest Bangladesh. A total of 57 subsoil, 57 topsoil, and 57 vegetable samples, as well as 30 cow's milk samples, were collected from 57 farms. Multiple OCI residues were detected using GC–MS/MS with modified QuEChERS in 20 % of subsoils, 21 % of topsoils, 23 % of vegetables, and 7 % of cow's milk samples. Diversified OCI residues were detected in subsoils (17 residues with a concentration of 179.15 ± 148.61 μg kg−1) rather than in topsoils (3 DDT residues with a concentration of 25.76 ± 20.19 μg kg−1). Isomeric ratios indicate intensive historical applications of OCIs. According to Dutch and Chinese standards, the lower concentrations of individual OCI residues in the soil indicate negligible to slight soil pollution, assuming local farmers follow local pesticide use regulations. However, a maximum of 78.24 μg kg−1 ΣAldrines and 35.57 μg kg−1 ΣHCHs were detected (1–4 residues) in 60 % of brinjal, 28 % of cucumber, 29 % of sponge gourd, and 20 % of lady's finger samples, which could be a result of either historical or current OCI applications, or both. A strong positive correlation between aldrines in subsoils and cucurbit vegetables indicates greater bioaccumulation. Cow milk samples contained up to 6.96 μg kg−1 ΣDDTs, which resulted either from rationing contaminated vegetables or grazing on contaminated land. Individual OCI in both vegetables and cow's milk was below the respective maximum residue limits of US and FAO/WHO CODEX and poses little or no risk to human health. However, combined exposure to multiple pesticides could increase human health risks. A cumulative health risk assessment of multiple pesticide residues is suggested to assess the suitability of those soils for cultivation and grazing, as well as the safety of vegetables and cow's milk for human consumption.

The water content of CM carbonaceous chondrite falls and finds, and their susceptibility to terrestrial contamination

AbstractCM carbonaceous chondrites can be used to constrain the abundance and H isotopic composition of water and OH in C‐complex asteroids. Previous measurements of the water/OH content of the CMs are at the higher end of the compositional range of asteroids as determined by remote sensing. One possible explanation is that the indigenous water/OH content of meteorites has been overestimated due to contamination during their time on Earth. Here we have sought to better understand the magnitude and rate of terrestrial contamination through quantifying the concentration and H isotopic composition of telluric and indigenous water in CM falls by stepwise pyrolysis. These measurements have been integrated with published pyrolysis data from CM falls and finds. Once exposed to Earth's atmosphere CM falls are contaminated rapidly, with some acquiring weight percent concentrations of water within days. The amount of water added does not progressively increase with time because CM falls have a similar range of adsorbed water contents to finds. Instead, the petrologic types of CMs strongly influence the amount of terrestrial water that they can acquire. This relationship is probably controlled by mineralogical and/or petrophysical properties of the meteorites that affect their hygroscopicity. Irrespective of the quantity of water that a sample adsorbs or its terrestrial age, there is minimal exchange of H in indigenous phyllosilicates with the terrestrial environment. The falls and finds discussed here contain 1.9–10.5 wt% indigenous water (average 7.0 wt%) that is consistent with recent measurements of C‐complex asteroids including Bennu.

Variability in methylmercury exposure across migratory terrestrial bird species: Influencing factors, biomagnification and potential risks

Despite China's considerable mercury (Hg) emissions, monitoring of methylmercury (MeHg) levels in its terrestrial environments remains limited. This study examined the occurrence and accumulation of MeHg in body feathers of 12 migratory terrestrial bird species originating from Siberia and northeastern China. Considerable variations in foraging habits and MeHg levels were observed among these species. Accipiters, including Eurasian and Japanese sparrowhawks (A. gularis and A. nisus) and northern goshawk (A. gentilis), along with insectivorous songbirds including grey-backed thrush (T. hortulorum) and orange-flanked bluetail (T. cyanurus), showed notable levels of MeHg (0.62–1.20 mg/kg). Up to 25 % of the individuals within these species were classified as low-risk based on feather Hg toxicity thresholds, while the remaining species fell into the no-risk category. Despite showing enriched δ15N, MeHg concentrations in short-eared and long-eared owls (A. flammeus and A. otus) were lower than in sparrowhawks. The herbivorous oriental turtle dove (S. orientalis) exhibited significantly lower MeHg levels compared to all other species. There was a significant positive correlation between MeHg concentrations and δ15N across species, highlighting the substantial biomagnification potential of MeHg within the terrestrial food web. Additionally, we found significantly higher MeHg levels in adults than juveniles in both sparrowhawk species. Our results demonstrate the effectiveness of utilizing migratory bird feathers for monitoring terrestrial Hg contamination, and underscore the importance of further assessment.

The H content of aubrites: An evaluation of bulk versus in situ methods for quantifying water in meteorites

Aubrites and enstatite chondrites (ECs) are isotopically similar to the Earth and therefore may resemble the primary materials that accreted to form our planet. Recent bulk H elemental and isotopic analyses of ECs and the Norton County aubrite suggest that enstatite-rich materials are H-rich and may represent a significant source of terrestrial water, with measured values of 3000±2000 μg/g H2O and 5300±900 μg/g H2O in the bulk and enstatite fractions of Norton County (Piani et al., Science, 2020). Here, we present a detailed investigation of in situ H2O concentrations in enstatite, diopside, forsterite, and plagioclase from a suite of main group aubrites, including Norton County, and Shallowater. We find that enstatite (4±2 μg/g H2O), diopside (4.8±0.5 μg/g H2O), and forsterite (5±3 μg/g H2O) have similar H2O concentrations, and all are significantly lower than plagioclase (24±3 μg/g H2O). We combine our in situ analyses of H2O contents with equilibrium partition coefficients and bulk mineralogies to estimate the bulk H2O content of our samples. We compare these first order estimates with bulk volatile analyses conducted using sample pyrolysis and find that the previous bulk H2O analyses of aubrites predominantly reflect terrestrial contamination and alteration. If our conclusion that the reported bulk H2O analyses of Norton County primarily reflect terrestrial contamination and alteration extends to bulk analyses of ECs, then EC-like material may not be a significant source of terrestrial water. Our results support the hypothesis that thermal metamorphism, melting, and differentiation leads to efficient desiccation of planetesimals relative to chondrites, and that differentiated planetesimals contributed, at most, trace amounts to Earth's water budget.

Dehydrated thin film media to rapidly estimate bioburden for planetary protection flight implementation

AbstractPlanetary Protection (PP) is the practice of safeguarding solar system bodies from terrestrial biological contamination and screening the Earth against potentially harmful extraterrestrial biological contamination. On Earth, cleanrooms and spacecraft surfaces are assayed using swabs and wipes that are then heat shocked for 15 min at 80°C to select for spores. The samples are further processed using the pour-plate method and Petri plates (TSA plates), with trypticase soy agar (TSA) serving as the growth medium. This sampling and processing procedure, called the NASA Standard Assay (NSA), is used by PP engineers around the world. Recent years have seen an increase in the incorporation of state-of-the-art technology, such as membrane filtration, into the NSA, with a push for implementing environmentally friendly technology into day-to-day activities. Dehydrated thin film media, such as Petrifilm Rapid Aerobic Count (RAC) plates, suit these goals as an alternative method to TSA plates. RAC plates show bacterial growth (and distinguish colonies from foreign particles such as bubbles) faster than TSA plates due to the incorporation of chromogenic colour indicators in the media. RAC plates also possess a much smaller environmental footprint than TSA plates, and are designed to evaluate even some of the challenging-to-detect environmental organisms, including spreaders that fill over 25% of the plate area in only a few hours. With these benefits in mind the PP Group at the NASA Jet Propulsion Laboratory took on the task of comparing RAC plates directly to TSA plates within the context of the NSA. Not only were the RAC plates able to detect surface environmental samples and in vitro spiked samples equivalent to NSA-processed TSA plates, but spreader organisms were countable on RAC plates at culture densities 10- to 100-fold greater than on TSA plates. In addition, RAC plates showed a robust, linear detection capability when challenged with membrane filter incorporation and organisms were easily acquired from RAC plates for archiving or post-processing experiments including MALDI-TOF bacterial identification. With their ease of use, small footprint, and both rapid and accurate bioburden measurements, RAC plates have the potential to overcome limitations posed by current PP culturing protocols.

Assessment of Marine Coastal Water Pollution from Karachi Harbour Pakistan

In Pakistan, marine pollution is a major problem that is caused by the waste from industrial, municipal, agronomy, and oil leak sources. The pollutant loads along with the coastline areas near Karachi is received from terrestrial contaminants including discharges from Karachi Harbour located on the estuary of the Lyari river. Karachi generates 472 Million Gallon per Day (MGD) of wastewater out of which only 55 MGD is treated and the rest is discharged in the sea. The prevailing sewage treatment plants are functioning at reduced capacity due to the insufficient transmission capacity of interceptors. Water sampling was carried out from the Lyari River and five different selected coastal point around Karachi harbour for physicochemical parameters and selected heavy metals. Results show that the Karachi Harbour area is noticeably polluted, whereas; the coastal environment in the vicinity of Karachi is also under the stress of pollution. High COD and BOD5 values were noticed at the Lyari river samples and the sampling locations close to the Lyari river outfall area. The Pb, Cd, Ni, and Hg heavy metals that pollute marine water are found. This situation is due to the discharge of mixed effluents of industrial and domestic wastes as well as dredging, cargo handling, dumping of ship waste and other coastal activities. The highest value of pollution observed at Karachi Harbour which is near Lyari river mouth, where the domestic and industrial effluents with organic and inorganic wastes have a greater influence on the water quality and the marine environment. At present, there is no effective controlling mechanism for industries to treat their waste, nor has any investigation to assess increasing marine pollution been carried out. As a result, there is an adverse impact on fish habitat and mangroves, corrosion of cargo ships, naval vessels and the residents living in the coastal area. Therefore, the government agencies and industrial sectors should work together to avert marine pollution and attain total environmental sustainability.

The high-temperature origin of hydrogen in enstatite chondrite chondrules and implications for the origin of terrestrial water

Due to their numerous isotopic similarities to terrestrial rocks, enstatite chondrites (ECs) are commonly proposed as Earth's main building blocks. Although ECs contain sufficient H concentrations to account for the mass of Earth's oceans, the physicochemical process(es) behind their H incorporation remain under constrained. Here, we combined secondary ion mass spectrometry analyses of volatile contents (H, C, F, Cl, S) and H isotopic compositions with Raman spectroscopy analyses of H speciation in the glassy mesostases of EC chondrules. EC chondrule mesostases (68–830 wt. ppm H) contain much more H than chondrule silicates (5–25 wt. ppm) and are characterized by H isotopic compositions of δD = −109 ± 27‰. Hydrogen and sulfur contents are positively correlated in EC chondrule mesostases, and we commonly observed well-resolved Raman peaks at 2580 cm−1, corresponding to HS− or H2S bonding. These results illustrate that the high H abundances in EC chondrule mesostases do not result from terrestrial contamination or secondary asteroidal processes, nor were their high volatile contents inherited from chondrule precursors. Instead, they were established at high temperature during chondrule formation via interactions between Fe-poor melts and S-rich gas under extremely reducing conditions. Our data confirm that ECs contain sufficient primordial hydrogen to explain the terrestrial water budget, and likely contributed important amounts of other volatile elements such as carbon, which was fundamental to the formation of life.

Impact of microplastic pollution in terrestrial ecosystem on index and engineering properties of sandy soil: An experimental investigation

Sandy soils cover a major portion of various natural and managed ecosystems. Soil health plays a key role in achieving sustainable development goals 2, 3,11, 12, 13 and 15. The engineering properties of soil are crucial in determining the stability and safety of structures. The increasing microplastic contamination in the soil ecosystem creates a need to study the effect of terrestrial microplastic contamination on the strength and stability of soil and therefore on the index properties and engineering properties of the soil. The present paper investigates, the effects of varying concentrations (2 %,4 %,6 % (w/w)) of Low-density polyethylene (LDPE), Polyvinyl chloride (PVC), and High-density polyethylene (HDPE) microplastics on the index properties and engineering properties of sandy soil for varying observation days. The moisture content, specific gravity, shear strength, compaction characteristics and permeability are found to be significantly altered by changing the concentrations of microplastics but, insignificant changes are observed with respect to observation days. The shear strength value of non-contaminated sandy soil is 1.74 kg/cm2 which reduces after 5th observation days as 0.85 kg/cm2, 0.90 kg/cm2, and 0.91 kg/cm2 for 2 %, 4 %, and 6 % LDPE microplastic contamination respectively. Similar trends are observed for PVC and HDPE microplastic contamination. It is also observed that although the shear strength value decreases, the cohesion value increases for the microplastics-contaminated sandy soil. The coefficient of permeability for non-contaminated sample is 0.0004 m/s which reduces for 2 % LDPE microplastic contamination to 0.000319 m/s, for 4 % to 0.000217 m/s, and 6 % to 0.000208 m/s respectively. Similar trends of are observed for the PVC and HDPE microplastic contamination. The soil strength and structural stability are affected due to alterations in soil index and engineering properties. The paper provides detailed experimental evidence of the impact of microplastic pollution on index properties and engineering properties of sandy soil.

Upper limits of water contents in olivine and orthopyroxene of equilibrated chondrites and several achondrites

AbstractHydroxyl defects in nominally anhydrous minerals (NAMs) were potential carriers of water in the early Solar System and might have contributed to the accretion of terrestrial water. To better understand this, we have conducted a nanoscale secondary ion mass spectrometry survey of water contents in olivine and orthopyroxene from a set of equilibrated ordinary chondrites of the L and LL groups (Baszkówka, Bensour, Kheneg Ljouâd, and Tuxtuac) and several ultramafic achondrites (Zakłodzie, Dhofar 125, Northwest Africa [NWA] 4969, NWA 6693, and NWA 7317). For calibration, we used terrestrial olivine and orthopyroxene with H2O contents determined by Fourier transform infrared. Our 99.7% (~3SD) detection limits are 3.6–5.4 ppmw H2O for olivine and 7.7–10.9 ppmw H2O for orthopyroxene. None of the meteoritic samples studied consistently shows water contents above the detection limits. A few exceptions slightly above the detection limits are suspected of terrestrial contamination by ferric oxyhydroxides. If the meteorite samples investigated accreted in the presence of small amounts of water ice, the upper limits of water contents provided by our survey suggest that the retention of hydrogen during thermal metamorphism and differentiation was ineffective. We suggest that loss occurred through combinations of low internal pressures, high permeability along grain boundaries, and speciation of hydrogen into reduced compounds such as H2 and methane, which are less soluble in NAMs than in water.