Silver concentrations in Welsh soils and their dispersal from derelict mine sites

In west and north Wales silver was mined extensively between 1750 and 1900, where it was frequently present as its sulphide form, argentite, whilst also occurring as a guest element in galena and sphalerite. Determination of the silver content of a range of soil types from areas devoid of mines by flameless atomic absorption spectrometry established normal background levels. Soils derived from black shales, or rich in organic matter were inherently richer in silver than the sandstone or limestone derived soils examined. Soils once exposed to contamination from the mining activities of the 19th Century can still be identified as they show elevated levels of silver. Fluvially derived contamination is confined to valley floodplains, but aerial transportation of mine spoil wastes enhance metal levels around derelict mine sites. Spoil analysed from areas of different geology contained a range of silver values reflecting variations in ore type, grain size and technique of ore extraction.     

Chemical contaminants in feedlot wastes: concentrations, effects and attenuation

Commercial feedlots for beef cattle finishing are potential sources of a range of trace chemicals which have human health or environmental significance. To ensure adequate protection of human and environmental health from exposure to these chemicals, the application of effective manure and effluent management practices is warranted. The Australian meat and livestock industry has adopted a proactive approach to the identification of best management practices. Accordingly, this review was undertaken to identify key chemical species that may require consideration in the development of guidelines for feedlot manure and effluent management practices in Australia. Important classes of trace chemicals identified include steroidal hormones, antibiotics, ectoparasiticides, mycotoxins, heavy metals and dioxins. These are described in terms of their likely sources, expected concentrations and public health or environmental significance based on international data and research. Androgenic hormones such as testosterone and trenbolone are significantly active in feedlot wastes, but they are poorly understood in terms of fate and environmental implications. The careful management of residues of antibiotics including virginiamycin, tylosin and oxytetracycline appears prudent in terms of minimising the risk of potential public health impacts from resistant strains of bacteria. Good management of ectoparasiticides including synthetic pyrethroids, macrocyclic lactones, fluazuron, and amitraz is important for the prevention of potential ecological implications, particularly towards dung beetles. Very few of these individual chemical contaminants have been thoroughly investigated in terms of concentrations, effects and attenuation in Australian feedlot wastes.     

Restoration of Mountain Big Sagebrush Steppe Following Prescribed Burning to Control Western Juniper

Western juniper (Juniperus occidentalis ssp. occidentalis Hook) encroachment into mountain big sagebrush (Artemisia tridentata spp. vaseyana (Rydb.) Beetle) steppe has reduced livestock forage production, increased erosion risk, and degraded sagebrush-associated wildlife habitat. Western juniper has been successfully controlled with partial cutting followed by prescribed burning the next fall, but the herbaceous understory and sagebrush may be slow to recover. We evaluated the effectiveness of seeding perennial herbaceous vegetation and sagebrush at five sites where juniper was controlled by partially cutting and prescribed burning. Treatments tested at each site included an unseeded control, herbaceous seed mix (aerially seeded), and the herbaceous seed mix plus sagebrush seed. In the third year post-treatment, perennial grass cover and density were twice as high in plots receiving the herbaceous seed mix compared to the control plots. Sagebrush cover and density in the sagebrush seeded plots were between 74- and 290-fold and 62- and 155-fold greater than the other treatments. By the third year after treatment, sagebrush cover was as high as 12 % in the sagebrush seeded plots and between 0 % and 0.4 % where it was not seeded. These results indicate that aerial seeding perennial herbaceous vegetation can accelerate the recovery of perennial grasses which likely stabilize the site. Our results also suggest that seeding mountain big sagebrush after prescribed burning encroaching juniper can rapidly recover sagebrush cover and density. In areas where sagebrush habitat is limited, seeding sagebrush after juniper control may increase sagebrush habitat and decrease the risks to sagebrush-associated species.     

Thermodynamics of metal cation binding by a solid soil-derived humic acid: binding of Fe(III), Pb(II), and Cu(II)

Metal binding and release by solid humic acids (HAs) in soils and sediments can affect metal mobility and bioavailability. Isotherms for tight binding of Fe(III), Pb(II) and Cu(II) by a solid humic acid at pH2.0 fit the Langmuir binding model. Low pH was chosen to protonate the HA carboxylate groups and avoid metal cation hydrolysis. Binding of Fe(III), Pb(II) and Cu(II) occurs in one detectable step labeled A. Site capacities nu(A) are temperature-independent from 10.0 to 40.0 degrees C and point to binding by charge-neutralization to form solid complexes M(OOC-R)(n)(s), where n appears to be 2 for Pb(II) and 3 for Fe(III). Thermodynamic data pairs (DeltaH(A), DeltaS(A)) for metal binding are linearly correlated with previous data for Ca(II), Co(II) and Mg(II) binding by solid HAs.     

Identifying opportunities for expert-mediated triangulation in monitoring wildlife trade on social media

Wildlife trade has rapidly expanded on social media platforms in recent years, offering an easy means for traders to access international markets. Investigating this trade activity poses a complex challenge to researchers seeking to understand online trade and moderators seeking to disrupt illicit and harmful activity. Current survey methods frequently rely on text-based searches and focus on posts in which the advertisement is explicit. However, such approaches risk overlooking a growing volume of relevant content, particularly outside social media groups. We used posts from pages promoting West African birds for trade as a case study to explore the availability of information for making inferences about trade activity on social media, specifically information indicating that trade activity was occurring or that could be used to infer trade routes. We recorded 400 posts from 12 pages that we inferred either promoted or facilitated wildlife trade, of which 19.7% were explicit advertisements and 23.8% contained taxa-related terms. In the remaining 341 posts, profile information was the most common indicator of trade activity, but a variety of indicators (e.g., images of birds in trade and trade enquiries) were identified across imagery, text, and comments. We identified multiple types of geographical information that could help infer trade routes and thus the likely legality of trade, although most were relatively rare and sometimes contradictory. Our findings suggest that triangulating multiple types of information from within, across, and beyond posts is vital for effectively identifying and interpreting wildlife trade content on social media. Therefore, were commend that expert-mediated triangulation should be integrated in and used alongside automated detection systems and moderating practices of social media companies.