The health stakes are considerable. The 2018 Lancet Commission on pollution and health identified air pollution as the largest environmental cause of disease and premature death globally, accounting for roughly 16 percent of all deaths. Particulate matter is a complex mixture of nitrates, sulfates, polycyclic aromatic hydrocarbons, endotoxins, and metals, and exposure to it is linked to cardiovascular and respiratory damage. Urban environments are particular hotspots, yet the exact extent of health effects at the city level remains largely unknown, a gap that is especially alarming in a heavily urbanized country like the United States, where urban sprawl expanded by 11 percent between 2001 and 2011.

Mosses have a long pedigree in pollution science. Researchers have used them for more than five decades to estimate atmospheric heavy metal deposition, and since 1990 an ongoing moss survey has mapped spatial and temporal trends in metal pollution across Europe. Bryophytes are ideal biomonitors for several reasons: they are small, they survive in highly polluted areas, they lack true roots and instead acquire nutrients directly from wet and dry deposition, and they tolerate many substances that are toxic to other organisms. Because they accumulate particles over time, they integrate pollution levels in a way that a single air sample cannot, effectively acting as living recorders of long-term exposure.

The Chicago study, led by researchers working in collaboration with local volunteers and the Field Museum, took advantage of two well-established biomonitoring strategies: passive monitoring with naturally growing moss and active monitoring with transplanted moss. The team chose the active approach, deploying standardized one-gram samples of Sphagnum in small mesh bags hung at strategically chosen sites. Two moss sources were used, a commercially purchased Sphagnum squarrosum and Sphagnum fallax collected in Maine, and the material was carefully cleaned of invertebrates and debris, air-dried, screened, and washed in three sequential treatments of Chicago tap water before deployment.

The site selection read like a map of hypothesized urban pollution sources. Moss bags were placed near a metals recycling facility, at Indian Ridge Marsh adjacent to industrial and transportation infrastructure, at the Des Plaines railroad station, and in a semi-natural reference area in Lake County. In a particularly eye-catching experiment, bags were also taped to the exhaust of a 2006 Ford F-350 diesel truck. Control samples were kept at the Field Museum under both sealed and exposed conditions, and bags were retrieved after one, three, and four weeks of exposure during June and July 2024.

Analysis relied on a Bruker Tracer 5 portable X-ray fluorescence spectrometer. Retrieved moss was frozen with liquid nitrogen, ground into a homogeneous powder, packed into sample cups sealed with a thin Prolene membrane, and measured with identical instrument settings across all samples. The researchers reported results as ratios of exposed sample counts to unexposed control counts, an approach that normalized differences between the two moss sources. Six replicate analyses on two to three bags per location yielded twelve to eighteen measurements per element per site, providing a reasonable statistical footing for an exploratory pilot.

The results showed clear location-specific patterns. The metals recycling facility, as expected for a multi-metal emission source, showed elevated levels of all measured elements. Indian Ridge Marsh, wedged next to industrial and transportation facilities, showed significantly increased iron and nickel. The railroad station exhibited elevated iron, plausibly reflecting particulate generation from steel rail infrastructure, a finding consistent with earlier studies linking rail transport to metal particle emissions. Most strikingly, even the semi-natural Lake County site showed elevated nickel, likely attributable to its proximity of less than one kilometer to a major highway, a demonstration of how far transportation-related emissions can reach.

The vehicle-mounted bags delivered a lesson in temporal dynamics. After just three days on the diesel truck, significant increases were recorded in iron, zinc, copper, titanium, and manganese compared with controls. But after four days, metal levels dropped, coinciding with significant rainfall in the Chicago area, suggesting that rain washed accumulated particulates off the moss. This observation underscores how strongly meteorological factors shape biomonitoring outcomes and points to the need for moss bag designs that mitigate wash-off, as well as standardized exposure durations and the incorporation of weather data into future protocols.

The broader implications extend beyond Chicago. North America lacks the kind of established moss survey network that Europe has maintained for decades, and this study addresses that gap while indicating strong potential for adoption in other US cities. Perhaps most compelling is the prospect of community-based monitoring: because moss bags and portable XRF instruments are inexpensive and accessible, resource-limited communities that are disproportionately affected by pollution could document contamination themselves and advocate for remediation. The authors also suggest that historical herbarium moss specimens could be retrospectively analyzed with pXRF, opening a window onto past pollution profiles and the effectiveness of remediation efforts.

The study is candid about its limitations. Sample sizes and temporal coverage were limited, systematic meteorological evaluation was not conducted, and commercially sourced moss may introduce baseline contamination variability compared with locally gathered material. The washing water and even the newspaper used for drying are potential contamination sources, and pXRF provides semi-quantitative results with detection limits that may be unsuitable for low-level contamination. Still, as a proof of concept, the work makes a persuasive case: standardized Sphagnum moss bags coupled with portable X-ray fluorescence offer a practical, cost-effective, and community-accessible tool for urban air pollution biomonitoring, one that could help cities and their residents see, quite literally in green, the metallic fingerprints of the air they breathe.

Subject of Research: Moss-based biomonitoring of urban metal air pollution using portable X-ray fluorescence in Chicago

Article Title: Green guardians: Mosses as potential low-cost biomonitors of air pollution in urban Chicago

Article References: Campbell, T., Gwilliam III, G. F., Evans, N. M., Peltz, K., Simpson, G., Dussubieux, L., Erazo, E., Guare, K., Krechner, A., Long, E., Maari, S., Oguike, I., Rice, K., Zinke, A., Christian, C., Qazi-Lampert, A., Henkin, J. M., Kreider, D., Maves, C., … von Konrat, M. (2026). Green guardians: Mosses as potential low-cost biomonitors of air pollution in urban Chicago. BioRisk, 24, 55-67. https://doi.org/10.3897/biorisk.24.180507

Image Credits: AI Generated

DOI: 10.3897/biorisk.24.180507

Keywords: air pollution, biomonitoring, moss, Sphagnum, portable X-ray fluorescence, heavy metals, particulate matter, Chicago, urban pollution, environmental justice, pXRF, bryophytes

The team cored four peatland sites along a 470-metre transect in the upper Fimba Valley, also known as Val Fenga: Lower Las Gondas, Upper Las Gondas, Marmot Mire and Lower Coffin Mire. Using a Russian corer, they extracted profiles up to 250 centimetres deep and dated them with radiocarbon measurements processed at the AMS laboratory in Poznań, Poland. Age-depth models were built with the Bayesian software Bacon and the IntCal20 calibration curve. The results reveal a strikingly asynchronous story: peat formation began between 10,450 and 9,000 calibrated years before present at the northern end of the transect, but only around 6,600 years ago at the southern end, tracing the slow retreat of the Fimba Valley glacier after the last ice age.

The methodological heart of the study is geochemical. The researchers measured elements such as titanium, lead, potassium, iron, strontium and rubidium using portable X-ray fluorescence spectrometry, a technique rarely applied quantitatively to peat, and cross-checked the results against 26 samples digested with hydrofluoric acid and measured by inductively coupled plasma mass spectrometry. One profile was also scanned with an XRF core scanner. The inter-calibration worked remarkably well: for peat samples, regression coefficients exceeded 0.95 for titanium and reached 0.99 for lead, meaning that field-portable instruments can deliver near-quantitative data even in these difficult, mineral-rich settings.

Titanium proved to be the key tracer of erosion. Because it arrives on the mires bound in mineral matter washed from the catchment, spikes in titanium mark episodes when glaciers upstream grew and meltwater streams delivered sediment onto the peat, interrupting peat growth. The most dramatic of these interruptions is a massive layer of coarse gravel in the Lower Las Gondas core, dated by the moss beneath it to around 8,200 calibrated years before present. This is strong evidence that the famous 8.2 ka cold event, a abrupt Northern Hemisphere cooling episode best known from Greenland ice cores, left a marked glacial fingerprint in the Silvretta Mountains, where its impact had previously been debated and even doubted.

The authors argue that only a cold and wet climate could have generated enough glacial activity to move coarse gravel into the mire, likely sourced from the Vadret da Fenga glacier field on the flank of the Fluchthorn peak. A similar gravel layer appears at the base of the Marmot Mire sequence at roughly the same age, and a silt layer in the Upper Las Gondas record also falls near 8,200 years ago. The findings align with regional evidence such as a descending treeline and the disappearance of trees near the upper mire after 8,400 years ago. Earlier, a thinner gravel layer at around 9,200 years ago points to another cold pulse, while cooler and wetter intervals follow at roughly 6,300, 5,400, 5,000 and 4,500 years before present.

From the mid-Holocene onwards, the signal becomes harder to read, because a second force begins to disturb the landscape: people. Humans have occupied the Silvretta region repeatedly over the last 11,000 years, and archaeological work has revealed dairy production in the area as early as the Early Iron Age. Mineral accumulation rates in the peat rise around 4,500 and 3,600 years before present, likely reflecting both climatic deterioration and the growing impact of Bronze Age pastoralism. Smaller increases around 3,400 and 3,200 years ago coincide with pollen evidence for agro-pastoral land use, suggesting that livestock management and associated soil disturbance were already reshaping valley slopes at high elevation.

The last 1,500 years tell an increasingly human-dominated story. Mineral accumulation rates in the Lower Las Gondas core climb from about 1 to over 120 grams per square metre per year, illustrating accelerating erosion through the Middle Ages and into modern times. Historical records show why: the village of Ischgl was first mentioned in 1104 CE, management of the Fimba alpine pasture is documented from 1163 CE, Walser settlers intensified deforestation and stocking density after the late fourteenth century, and heavy logging from the sixteenth to the late eighteenth century supplied regional mining. Layered on top of these pressures, the Little Ice Age brought strong glacial activity to the Silvretta, with the Vadret da Fenga reaching its maximum extent by the late nineteenth century.

Remarkably, the mires also preserved traces of atmospheric lead pollution despite their strongly minerotrophic, mineral-fed character, which normally complicates such signals. A distinct lead peak around 2,000 years before present coincides with the well-documented Roman-era metalworking pollution found across Europe, and a second rise after 1,500 years ago matches regional medieval and early modern mining. The authors note that erosion and decomposition in recent layers may have released some of the stored metal, yet the survival of these signals shows that even fen peatlands can archive airborne contamination, validating their age models in the process.

The implications reach beyond the history books. Peatlands store carbon and buffer floodwater, and the study warns that a millennium of grazing, trampling, erosion and drainage has suppressed peat accumulation in the Fimba Valley, undermining exactly these ecosystem services. This matters downstream: the Paznaun Valley, into which the Fimba creeks drain, is a known high-risk zone for severe flooding. The authors argue that land management in the region should explicitly account for the state of these degraded mires.

Perhaps the most encouraging conclusion is methodological. Small, dynamic, glacier-fed stream-bank mires have long been considered too noisy, too heterogeneous and too poorly dated to serve as climate archives. This study turns that weakness into an advantage: the very sediment pulses that disrupt peat growth are themselves records of glacier activity that conventional moraine-based methods often miss, because later glacier advances overprint the evidence. Read carefully, with multiple cores, radiocarbon dating, geochemistry and archaeological context combined, these humble alpine bogs turn out to be among the most complete witnesses to ten thousand years of cold, warmth, shepherds, miners and tourists in the heart of the Alps.

Subject of Research: Holocene climate and human impact recorded in alpine glaciofluvial peatlands of the Silvretta Mountains

Article Title: From the 8.2 ka event to the Little Ice Age: Holocene cold periods and human impact recorded in alpine glaciofluvial peatlands (Silvretta Mountains, Switzerland)

Article References: von Scheffer, C., De Vleeschouwer, F., Le Roux, G., & Unkel, I. (2025). From the 8.2 ka event to the Little Ice Age: Holocene cold periods and human impact recorded in alpine glaciofluvial peatlands (Silvretta Mountains, Switzerland). E&G Quaternary Science Journal, 74(2), 263-279. https://doi.org/10.5194/egqsj-74-263-2025

Image Credits: AI Generated

DOI: 10.5194/egqsj-74-263-2025

Keywords: peatlands, Holocene, 8.2 ka event, Little Ice Age, glaciers, Silvretta Mountains, pXRF, radiocarbon dating, pastoralism, lead pollution, alpine environment, flood mitigation

Panlongcheng, located in present-day Hubei Province near modern Wuhan, flourished during the Erligang period of the Early Shang dynasty, roughly the sixteenth to fourteenth centuries BCE. Archaeologists have recovered more than 500 bronze artifacts from the site, ranging from ritual vessels and weapons to tools and ornaments. Yet before this new investigation, fewer than one-tenth of those objects had ever been subjected to laboratory analysis, and the samples that had been studied came overwhelmingly from the later phases of the occupation. That gap left the earliest chapters of the site’s metallurgical history essentially blank, and it meant that any claims about how Panlongcheng fit into the Shang bronze economy rested on a thin and potentially biased evidentiary base.

The research team, led by Tianyuan Yu of the Henan Museum and the University of Science and Technology of China, together with colleagues including Zhengyao Jin, tackled the problem by analyzing 21 bronze samples that span Phases III through VII of the site’s occupation, extending the analytical record back into periods that had never been sampled before. The researchers deployed a battery of complementary techniques, each of which interrogates a different aspect of the metal. Portable X-ray fluorescence, or pXRF, provided rapid, non-destructive measurements of the elemental composition of the alloys, revealing the proportions of copper, tin, and lead that the ancient founders had combined. Metallographic microscopy, in which polished cross-sections of the metal are examined under high magnification, exposed the crystalline microstructure of the bronze, a kind of metallurgical fingerprint that records how the metal was cast, worked, and reheated.

The third and perhaps most powerful technique was lead isotope analysis. Because lead ores from different geological deposits carry distinctive ratios of the isotopes lead-204, lead-206, lead-207, and lead-208, the isotopic signature of a bronze object can act as a geochemical passport, pointing toward the mines and smelting regions that supplied its raw material. By comparing the isotopic ratios of the Panlongcheng bronzes with published data from other Shang sites, including the royal capital at Zhengzhou, the team could test whether the metal circulating at the frontier came from the same ore sources as the metal used at the center, or whether the outpost drew on separate, more local supply lines.

The results delivered several surprises. First, the metallographic evidence confirmed that bronze tools at the site were remelted and recast, a practice that speaks to the practical realities of life at a remote outpost. Rather than discarding broken implements and waiting for fresh metal to arrive from distant sources, the inhabitants of Panlongcheng recycled their worn tools, feeding old bronze back into the crucible to produce new objects. This kind of secondary casting leaves characteristic traces in the microstructure of the metal, and its confirmation at Panlongcheng provides rare, direct evidence of on-site metallurgical activity at a Shang frontier settlement, complementing earlier discoveries of casting remains in the Xiaozui area of the site.

Second, the compositional analysis showed that high-lead bronzes appear more frequently at Panlongcheng than among the bronzes excavated from the Zhengzhou region, where the Shang royal capital was located. Lead was deliberately added to copper-tin alloys in early Chinese metallurgy to improve the fluidity of the molten metal and to enhance the crispness of cast details, a quality especially prized in the elaborate ritual vessels of the Shang elite. The higher incidence of leaded alloys at the frontier site raises intriguing questions about local casting preferences, the availability of lead metal in the southern regions, or perhaps the kinds of objects being produced there. Whatever the explanation, the pattern marks Panlongcheng as metallurgically distinctive in at least one respect.

Yet the third major finding cuts against any picture of the outpost as an isolated or semi-independent metallurgical center. When the researchers compared alloy types and lead isotope signatures across the two regions, the bronzes from Panlongcheng and Zhengzhou turned out to share more similarities than differences. The same broad range of alloy recipes appears at both sites, and the isotopic data point to common or overlapping sources of metal raw material. In other words, the bronze that flowed through the frontier outpost was drawn from the same metal supply system that fed the royal capital, even if the frontier communities exercised some local variation in how they used it.

The authors interpret this combination of shared resources and local variation through the lens of what they call the resource-political framework of the early Shang polity. On this view, the Shang state did not simply extract raw materials from conquered or colonized territories; it constructed an integrated system in which peripheral regions like the middle Yangtze, rich in copper and other ores, were linked to the political core through administrative and military infrastructure. Panlongcheng, strategically positioned to control access to the metal-bearing regions of the south, functioned as a hub in that system, acquiring metal resources from the surrounding periphery and channeling them into networks that ultimately connected to Zhengzhou. The outpost’s bronzes, on this reading, are the material residue of a political economy that made core and periphery mutually dependent.

The study also carries broader implications for how archaeologists understand the emergence of bronze civilization in China. The Erligang expansion into the Yangtze valley has often been framed as a one-way projection of power from the Central Plains, with the south serving as a passive source of raw wealth. The new data complicate that narrative. If the founders and metalworkers at Panlongcheng were working within the same alloy traditions and drawing on the same ore sources as their counterparts at the capital, while also developing local practices such as more frequent lead alloying and systematic tool recycling, then the frontier was not merely an appendage of the core. It was a place where the technologies and resource systems of the Shang state were actively reproduced, adapted, and sustained, contributing to the broader development of bronze casting technology in the region.

Methodologically, the work demonstrates the value of combining multiple analytical techniques on a single assemblage, and of extending sampling into under-studied phases of a site’s occupation. Each method on its own would have told only part of the story: pXRF alone could not distinguish remelted metal from freshly cast metal, and isotope ratios alone could not reveal how objects were made. Together, the techniques build a layered account of production, circulation, and use that no single measurement could achieve. With more than 90 percent of Panlongcheng’s bronze assemblage still unanalyzed, the 21 samples examined here represent a beginning rather than an end, and future work will test whether the patterns identified in this study hold across the full range of the site’s remarkable corpus. For now, the findings stand as a vivid reminder that the great bronze age of China was knit together not by isolated centers and passive hinterlands, but by a web of connections in which even the most distant outposts participated fully in the metallurgical life of the early Shang state.

Subject of Research: Archaeometric analysis of Early Shang dynasty bronze artifacts from the Panlongcheng site in China

Article Title: Periphery and core: insights from the scientific analysis of bronzes from Panlongcheng

Article References: Yu, T., Fan, A., Zhang, C., Huang, F., & Jin, Z. (2026). Periphery and core: insights from the scientific analysis of bronzes from Panlongcheng. Archaeological and Anthropological Sciences, 18(10), Article 210. https://doi.org/10.1007/s12520-026-02568-5

Image Credits: AI Generated

DOI: 10.1007/s12520-026-02568-5

Keywords: Panlongcheng, Early Shang dynasty, bronze metallurgy, lead isotope analysis, pXRF, metallography, Zhengzhou, Erligang period, archaeometry, Yangtze River, metal provenance, resource-political framework