ALBERT

Description: Author Posting. © American Chemical Society, 2019. This article is posted here by permission of American Chemical Society for personal use, not for redistribution. The definitive version was published in Kivenson, V., Lemkau, K. L., Pizarro, O., Yoerger, D. R., Kaiser, C., Nelson, R. K., Carmichael, C., Paul, B. G., Reddy, C. M., & Valentine, D. L. (2019). Ocean Dumping of Containerized DDT Waste Was a Sloppy Process. Environmental Science and Technology (2019), doi:10.1021/acs.est.8b05859.

Description: Industrial-scale dumping of organic waste to the deep ocean was once common practice, leaving a legacy of chemical pollution for which a paucity of information exists. Using a nested approach with autonomous and remotely operated underwater vehicles, a dumpsite offshore California was surveyed and sampled. Discarded waste containers littered the site and structured the suboxic benthic environment. Dichlorodiphenyltrichloroethane (DDT) was reportedly dumped in the area, and sediment analysis revealed substantial variability in concentrations of p,p-DDT and its analogs, with a peak concentration of 257 μg g–1, ∼40 times greater than the highest level of surface sediment contamination at the nearby DDT Superfund site. The occurrence of a conspicuous hydrocarbon mixture suggests that multiple petroleum distillates, potentially used in DDT manufacture, contributed to the waste stream. Application of a two end-member mixing model with DDTs and polychlorinated biphenyls enabled source differentiation between shelf discharge versus containerized waste. Ocean dumping was found to be the major source of DDT to more than 3000 km2 of the region’s deep seafloor. These results reveal that ocean dumping of containerized DDT waste was inherently sloppy, with the contents readily breaching containment and leading to regional scale contamination of the deep benthos.

Description: This material is based upon work supported by the National Science Foundation Graduate Research Fellowship for V.K. under Grant No. 1650114. Expeditions AT-18-11 and AT-26-06 were funded by the NSF (OCE-0961725 and OCE-1046144). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. We thank the captain and crew of the RV Atlantis, the pilots and crew of the ROV Jason, the crew of the AUV Sentry, the scientific party of the AT-18-11 and AT-26-06 expeditions, Justin Tran for assistance with the preparation of multibeam data, M. Indira Venkatesan for a helpful discussion of the NOAA datasets, and Nathan Dodder for advice on the procedure for compound identification.

Description: Avian communities of arid ecosystems may be particularly vulnerable to global climate change due to the magnitude of projected change for desert regions and the inherent challenges for species residing in resource limited ecosystems. How arid-zone birds will be affected by rapid increases in air temperature and increased drought frequency and severity is poorly understood because avian responses to climate change have primarily been studied in the relatively mesic northern temperate regions. We studied the effects of increasing air temperature and aridity on a Burrowing Owl ( Athene cunicularia ) population in the southwestern USA from 1998-2013. Over 16 years, the breeding population declined 98.1%, from 52 pairs to 1 pair, and nest success and fledgling output also declined significantly. These trends were strongly associated with the combined effects of decreased precipitation and increased air temperature. Arrival on the breeding grounds, pair formation, nest initiation, and hatch dates all showed significant delays ranging from 9.4 to 25.1 days over 9 years, which have negative effects on reproduction. Adult and juvenile body mass decreased significantly over time, with a loss of 7.9% mass in adult males and 10.9% mass in adult females over 16 years, and a loss of 20.0% mass in nestlings over 8 years. Taken together, these population and reproductive trends have serious implications for local population persistence. The southwestern USA has been identified as a climate change hotspot, with projections of warmer temperatures, less winter precipitation, and an increase in frequency and severity of extreme events including drought and heat waves. An increasingly warm and dry climate may contribute to this species’ decline, and may already be a driving force of their apparent decline in the desert southwest. This article is protected by copyright. All rights reserved.

Description: Inorganic coatings are being developed to protect marble monuments and sculpture from weathering. In this work, the acid resistance of hydroxyapatite (HAP), calcium oxalate, and calcium tartrate coatings on Carrara marble were compared. To quantify the rate of attack on calcite, the pH of the solution was measured. This approach was validated by confirming that the rate of dissolution of untreated calcite inferred from the change in pH agrees with data in the literature. Calcium tartrate coatings were incomplete, and the mineral is so soluble that it offered no significant protection. Calcium oxalate forms coherent coatings, so it serves as a sacrificial coating in spite of having solubility comparable to that of calcite. HAP was deposited from aqueous solutions of 1 M diammonium hydrogen phosphate (DAP), with or without millimolar additions of CaCl 2 (which improved coverage) and (NH 4 ) 2 CO 3 (which resulted in cracking). The best HAP coatings remained porous; nevertheless, they were comparable to oxalate coatings in the short term and superior in the long term, reducing the dissolution rate by about 40%.

Description: Understanding the impacts of natural and human disturbances on forest biota is critical for improving forest management. Many studies have examined the separate impacts on fauna and flora of wildfire, conventional logging and salvage logging, but empirical comparisons across a broad gradient of simultaneous disturbances are lacking. We quantified species richness and frequency of occurrence of vascular plants, and functional group responses, across a gradient of disturbances that occurred concurrently in 2009 in the Mountain Ash forests of southeastern Australia. Our study encompassed replicated sites in undisturbed forest (~70 years post-fire), forest burned at low severity, forest burned at high severity, unburned forest that was clearcut logged, and forest burned at high severity that was clearcut salvage logged post-fire. All sites were sampled two and three years post-fire. Mean species richness decreased across the disturbance gradient from 30.1 spp/site on low severity burned sites and 28.9 spp/site on high severity burned sites, to 25.1 spp/site on clearcut sites and 21.7 spp/site on salvage logged sites. Low severity burned sites were significantly more species-rich than clearcut sites and salvage logged sites; high severity burned sites supported greater species richness than salvage logged sites. Specific traits influenced species’ sensitivity to disturbance. Resprouting species dominated undisturbed Mountain Ash forests, but declined significantly across the gradient. Fern and midstory trees decreased significantly in frequency of occurrence across the gradient. Ferns (excluding Bracken) decreased from 34% of plants in undisturbed forest to 3% on salvage logged sites. High severity burned sites supported a greater frequency of occurrence and species richness of midstory trees compared to clearcut and salvage logged sites. Salvage logging supported fewer midstory trees than any other disturbance category, and were distinctly different from clearcut sites. Plant life form groups, including midstory trees, shrubs and ferns, were dominated by very few species on logged sites. The differences in biotic response across the gradient of natural and human disturbances have significant management implications, particularly the need to reduce mechanical disturbance overall and to leave specific areas with no mechanical disturbance across the cut area during logging operations, to ensure the persistence of resprouting taxa. This article is protected by copyright. All rights reserved.

Description: Global changes are altering many important drivers of ecosystem functioning, with precipitation amount and disturbance frequency being especially important. Carbon (C) and nitrogen (N) pools are key contemporary attributes of ecosystems that can also influence future C uptake via plant growth. Thus, understanding the impacts of altered precipitation amounts (through controls of primary production inputs) and disturbance regimes (through losses of C and N in biomass) is important to project how ecosystem services will respond to future global changes. A major difficulty inherent within this task is that drivers of ecosystem function and processes often interact, resulting in novel ecosystem responses. To examine how changes in precipitation affect grassland ecosystem responses under a frequent disturbance regime (annual fire), we assessed the biogeochemical and ecological consequences of more than two decades of irrigation in an annually burned mesic grassland in the central United States. In this experiment, precipitation amount was increased by 31% relative to ambient and 1 in 3 years were statistically extreme relative to the long-term historical record. Despite evidence that irrigation decreased root:shoot ratios and increased rates of N cycling – each expected to reduce soil C and N with annual burning – we detected no changes in these biogeochemical pools. This surprising biogeochemical resistance highlights the need to explore additional mechanisms within long-term experiments concerning the consequences of global change impacts on ecosystems.

Description: Central to understanding global C cycle dynamics is the functional relationship between precipitation and net primary production (NPP). At large spatial (regional) scales, the responsiveness of aboveground NPP (ANPP) to interannual variation in annual precipitation (AP; ANPP sens ) is inversely related to site-level ANPP, coinciding with turnover of plant communities along precipitation gradients. Within ecosystems experiencing chronic alterations in water availability, plant community change will also occur with unknown consequences for ANPP sens . To examine the role plant community shifts may play in determining alterations in site-level ANPP sens , we experimentally increased precipitation by ~35% for two decades in a native Central U.S. grassland. Consistent with regional models, ANPP sens decreased initially as water availability and ANPP increased. However, ANPP sens shifted back to ambient levels when mesic species increased in abundance in the plant community. Similarly, in grassland sites with distinct mesic and xeric plant communities and corresponding 50% differences in ANPP, ANPP sens did not differ over almost three decades. We conclude that responses in ANPP sens to chronic alterations in water availability within an ecosystem may not conform to regional AP–ANPP patterns, despite expected changes in ANPP and plant communities. The result is unanticipated functional resistance to climate change at the site scale.

Description: Forest policymakers and managers have long sought ways to evaluate the capability of forest landscapes to jointly produce timber, habitat, and other ecosystem services in response to forest management. Currently, carbon is of particular interest as policies for increasing carbon storage on federal lands are being proposed. However, a challenge in joint production analysis of forest management is adequately representing ecological conditions and processes that influence joint production relationships. We used simulation models of vegetation structure, forest sector carbon, and potential wildlife habitat to characterize landscape-level joint production possibilities for carbon storage, timber harvest, and habitat for seven wildlife species across a range of forest management regimes. We sought to: (1) characterize the general relationships of production possibilities for combinations of carbon storage, timber, and habitat; and (2) identify management variables that most influence joint production relationships. Our 160,000-ha study landscape featured environmental conditions typical of forests in the western Cascade Mountains of Oregon (US). Our results indicate that managing forests for carbon storage involves tradeoffs among timber harvest and habitat for focal wildlife species, depending on the disturbance interval and utilization intensity followed. Joint production possibilities for wildlife species varied in shape, ranging from competitive to complementary to compound, reflecting niche breadth and habitat component needs of species examined. Managing Pacific Northwest forests to store forest sector carbon can be roughly complementary with habitat for Northern Spotted Owl, Olive-sided Flycatcher, and Red Tree Vole. However, managing forests to increase carbon storage potentially can be competitive with timber production and habitat for Pacific Marten, Pileated Woodpecker, and Western Bluebird, depending on the disturbance interval and harvest intensity chosen. Our analysis suggest that joint production possibilities under forest management regimes currently typical on industrial forest lands (e.g., 40- to 80-year rotations with some tree retention for wildlife) represent but a small fraction of joint production outcomes possible in the region. Although the theoretical boundaries of the production possibilities sets we developed are probably unachievable in the current management environment, they arguably define the long-term potential of managing forests to produce multiple ecosystem services within and across multiple forest ownerships. This article is protected by copyright. All rights reserved.