Largest dinosaur tracksite in China(Cretaceous,Zhaojue area,Sichuan Province): On the verge of destruction

The Zhaojue(ZJ) tracksites represent multiple steeply-inclined, track-bearing exposures in the clastic Feitianshan Formation of Sichuan Province that have been sequentially, excavated, mapped, expanded and destroyed, by quarrying,erosion or collapse, for almost three decades. The quarried area extends for more almost 1.0 km from north to south and ～0.5 km from east to west. Four important track-bearing surfaces have been identified and identified as ZJ-I, ZJ-II,ZJ-IIN and ZJ-III, some of which are newly exposed surfaces or expanded surfaces that were previously partially described. Others represent surfaces lost since they were first reported in papers published in 2014–2016. The ZJ-II site represents a hugely expanded continuation of a much smaller track-bearing surface described in 2014. It was mapped using drone technology, and now represents the largest tracksite in China, with a minimum count of 933 recognizable tracks, and the longest recorded sauropod and ornithopod trackways from China(～80 m and ～52 m respectively), which also reveal a pronounced change in the direction of trackmaker movement. The ZJ-II surface represents the best Zhaojue paleo-census sample giving a count of 68 individuals from 61 trackways(37 ornithopod, 10 theropod, 14 sauropod) and isolated tracks(representing 7 individuals). Thus, ornithopods(both large and small trackmakers) represent ～54% of the total number of trackways. The smaller ZJ-III surface was mapped using traditional methods, and reveals at least 6 ornithopod-and 4 theropod trackways. Both the ZJ-II and ZJ-III surfaces reveal parallel ornithopod trackways suggestive of social or gregarious behavior. The combined data from all four Zhaojue surfaces reveal a total of 1928 tracks, and include a few previously reported pterosaurs and theropod swim tracks. The Zhaojue quarry complex provide a good example of multiple track-bearing sites(surfaces) that require long term study and monitoring to extract as much trackway data as possible before in situ physical evidence is lost.     

Environmental restoration measures on the Tennessee–Tombigbee Waterway – an update

 The Tennessee–Tombigbee Waterway (Tenn–Tom) was one of the first and largest water resources projects constructed after the enactment of the National Environmental Policy Act of 1969. This highly controversial project was in litigation for 9 of the 13 years it was under construction. Substantial and innovative measures were incorporated into the project design to minimize environmental damage and to promote environmental protection. Additionally, a wide variety of environmental mitigation measures, including the acquisition and management of 35,614 ha of wildlife habitat to compensate for unavoidable impacts. This paper, which updates a paper published by the American Society of Civil Engineers in 1996, presents an update of the environmental and restorative measures incorporated into the design, construction, operation, and management of the Tenn–Tom some 15 years after it was opened for navigation. The paper examines the accuracy of selected predicted impacts, waterway utilization, and the effectiveness of environmental measures. Received: 13 March 2000 · Accepted: 12 June 2000     

A major project in the age of the environment: Out of controversy,complexity, and challenge

The recently completed Tennessee-Tombigbee Waterway (Tenn-Tom) survived many challenges from all three branches of the federal government A brief overview of these challenges over the past 40 years is presented Central among the challenges was the litigation involving allegations under the National Environmental Policy Act (NEPA) The response of the U S Army Corps of Engineers to NEPA and its influence on the Tenn-Tom are presented A summarization of the principal environmental issues related to the Tenn-Tom is provided to describe the wide spectrum of concerns and controversies associated with the development of this major waterway The Tenn-Tom met the test in all forums The measures taken to respond in a meaningful way to NEPA and other environmental statutes are a model that could well be followed in the development of other major projects     

Late Triassic sauropodomorph and Middle Jurassic theropod tracks from the Xichang Basin,Sichuan Province,southwestern China:First report of the ichnogenus Carmelopodus

Upper Triassic and Middle Jurassic strata of the Xichang Basin in Sichuan Province, southwestern China, yielded important dinosaur ichnofossils. From the Xujiahe Formation of the Yiguojiao tracksite, we report a Late Triassic footprint assemblage in China and the first discovery of diagnostic Triassic sauropodomorph tracks in this region. The tracks share a number of features in common with the ichnogenera Eosauropus(Late Triassic) and Liujianpus(Early Jurassic). The neighboring Bingtu tracksite is stratigraphically younger(Shaximiao Formation, Middle Jurassic) and preserves small tridactyl theropod tracks that represent the first occurrence of the ichnotaxon Carmelopodus in China and Asia. While these tracks are morphologically comparable to those from the Middle Jurassic type locality in North America, the specimens from China show the proximal margin of the digit IV impression in a more cranial position, which may indicate a trackmaker with a relatively short metatarsal IV. In addition to the skeletal record, the Carmelopodus footprints document the presence of small theropods in the dinosaur fauna of the Middle Jurassic Shaximiao Formation.     

The WHI Corona from Differential Emission Measure Tomography

A three-dimensional (3D) tomographic reconstruction of the local differential emission measure (LDEM) of the global solar corona during the whole heliosphere interval (WHI, Carrington rotation CR 2068) is presented, based on STEREO/EUVI images. We determine the 3D distribution of the electron density, mean temperature, and temperature spread, in the range of heliocentric heights 1.03 to 1.23 R _??. The reconstruction is complemented with a potential-field source-surface (PFSS) magnetic-field model. The streamer-core, streamer-leg, and subpolar regions are analyzed and compared to a similar analysis previously performed for CR 2077, very near the absolute minimum of Solar Cycle 23. In each region, the typical values of density and temperature are similar in both periods. The WHI corona exhibits a streamer structure of relatively smaller volume and latitudinal extension than during CR 2077, with a global closed-to-open density contrast about 6% lower, and a somewhat more complex morphology. The average basal electron density is found to be about 2.23 and 1.08×10⁸ cm^?3, in the streamer core and subpolar regions, respectively. The electron temperature is quite uniform over the analyzed height range, with average values of about 1.13 and 0.93 MK, in the streamer core and subpolar regions, respectively. Within the streamer closed region, both periods show higher temperatures at mid-latitudes and lower temperatures near the Equator. Both periods show ??>1 in the streamer core and ??<1 in the surrounding open regions, with CR 2077 exhibiting a stronger contrast. Hydrostatic fits to the electron density are performed, and the scale height is compared to the LDEM mean electron temperature. Within the streamer core, the results are consistent with an isothermal hydrostatic plasma regime, with the temperatures of ions and electrons differing by up to about 10%. In the subpolar open regions, the results are consistent with departures from thermal equilibrium with T _ions>T _e (and values of T _ions/T _e up to about 1.5), and/or the presence of wave-pressure mechanisms linear in the density.     

Quantification of TCE Co‐Oxidation in Groundwater Using a 14C–Assay

Bacteria that degrade natural organic matter in groundwater contain oxygenase enzymes that can co‐oxidize trichloroethene (TCE). This degradation pathway is promising for large dilute plumes, but its evaluation is limited because the density of the bacteria with oxygenase enzymes has not been correlated to field scale rates of degradation. A ¹⁴C–TCE assay was developed to determine pseudo first‐order rate constants for the aerobic co‐oxidation of TCE in groundwater. The assay involved incubating ¹⁴C–TCE in samples of groundwater contained in 160 mL serum bottles, and monitoring the accumulation of radiolabel in degradation products. A first‐order rate constant for co‐oxidation was extracted from the rate of accumulation of ¹⁴C in products, accounting for volumetric changes in the serum bottles due to sampling and subsequent changes to the distribution of TCE between the aqueous and gaseous phases. Of the groundwater samples evaluated from 19 wells at five sites, eight samples at three sites had ¹⁴C product accumulation rates that exceeded the accumulation rate in filter‐sterilized groundwater controls. First‐order rate constants ranged from 2.65 to 0.0066 year^?1, which is equivalent to half‐lives of 0.26 to 105 years. Groundwater samples from a few of the wells in which co‐oxidation occurred had volatile organic contaminants in addition to TCE; their presence may have induced the oxygenase enzymes that are needed for TCE co‐oxidation. ¹⁴CO₂ represented ~37% to 97% of the ¹⁴C products that accumulated; the balance of the products was soluble and non‐volatile.     

A 2500 year sediment record from Fayetteville Green Lake, New York: evidence for anthropogenic impacts and historic isotope shift

A series (N = 12) of short (< 1 m) sediment cores were collected from meromictic Green Lake in Fayetteville, New York to investigate potential anthropogenic impacts on the watershed during historic time and environmental change over the past ~ 2,500 years. Stratigraphic data document an abrupt basinwide change during the early 1800's A.D. from brown laminated sediments to grey varved sediments separated by a transition zone rich in aquatic moss. Deforestation of the region by European settlers during the early 1800's A.D. resulted in a flux of nutrients and increased biological productivity followed by a 7fold increase in sediment accumulation rates. Elemental geochemical data document the anthropogenic loading of lead to the to the lake basin via atmospheric fallout. Stable oxygen isotope (¹⁸O calcite) data also provide evidence for an abrupt shift in the isotopic composition of lake water ~ 150–200 years ago. This isotopic shift could have been a local phenomenon related to an increased supply of summer enriched precipitation following removal of forest vegetation, or it might have reflected broader scale climatic changes. We hypothesize that the ¹⁸O calcite shift was the result of the polar front jet stream migrating from a more southerly prehistoric position to a contracted, northerly configuration ~ 150–200 years ago. Such a shift could have been natural, associated with the end of the Little Ice Age or it may have been anthropogenically forced.     

Pito Rift: How a large-offset rift propagates

The Pito Rift area is the site of actively deforming oceanic lithosphere that has been primarily under extension for at least the past million years, based on kinematic reconstructions. The major morphologic features, Pito Deep and Pito Seamount, are aligned toward the Euler pole for relative motion between the Easter and Nazca plates. SeaMARC II side-scan and bathymetry data indicate that there are two general modes of faulting currently active in the Pito Rift area. One is associated with incipient rifting of old (3 Ma) Nazca lithosphere by large NW-SE normal faults, and the other is associated with a broad area of right-lateral transform shear between the Nazca and Easter plates. This transform shear is distributed over a broad region because of the northward growth of the East Rift and parallel tectonic rifting within the Pito Rift area. The majority of the Pito Rift area is composed of preexisting blocks of Nazca plate that are back-tilted away from Pito Deep and strike perpendicular to present and previous relative plate motions. This observation suggests that block-faulting and back-tilting are the primary mechanisms responsible for the distributed lithospheric extension, in agreement with gravity and magnetic analyses (Martinez et al., this issue).The only recent volcanic flows observed in side-scan data are from the Pito Seamount area and to the outside of the outer pseudofault of the East Rift. The significance of the young flows near the outer pseudofault is not understood. We interpret the flows extending northwest from the Pito Seamount as representing a newly formed seafloor spreading axis within the Pito Rift area. Gravity and magnetic analyses (Martinez et al., this issue) together with SeaMARC II bathymetry and side-scan data support this interpretation.Based on the tectonic evolution of the Easter microplate, we propose an evolutionary model for the formation of the Pito Rift area, where new tectonic grabens form immediately west of the previous graben and with slightly more counterclockwise orientation. The duration and history of tectonic activity for each graben are not well constrained.     

Is seagrass an important nursery habitat for the Caribbean spiny lobster,panulirus argus,in Florida?

Caribbean spiny lobster (Panulirus argus) settle preferentially in macroalgal‐covered hard‐bottom habitat, but seagrass is more prevalent in Florida (United States) and the Caribbean, so even low settlement of lobsters within seagrass could contribute substantially to recruitment if post‐settlement survival and growth were high. We tested the role of seagrass and hard‐bottom habitats for P. argus recruitment in three ways. We first explored possible density‐dependent regulation of early benthic juvenile lobster survival within cages deployed in seagrass and hard‐bottom habitats. Second, we compared settlement and survival of P. argus in both habitats, by comparing the recovery of microwire‐tagged early benthic juveniles from patches of seagrass and hard‐bottom. Finally, we assessed the relative abundance of juvenile lobsters in each habitat by deploying artificial structures in seagrass sites and compared these data with data from similar deployments of artificial structures in hard‐bottom habitat in other years. More early benthic juvenile lobsters were recovered from cages placed in hard‐bottom than in seagrass, but mortality of the early benthic life stage was high in both habitats. In regional surveys, the mean number of lobsters recovered from artificial shelters deployed within seagrass was lower than in any year that we sampled hard‐bottom, indicating that fewer lobsters reside naturally in seagrass, particularly large juveniles >40 mm carapace length. The greater abundance (and likely survival) of juvenile P. argus that we observed in hard‐bottom habitat as opposed to seagrass, combined with previous studies demonstrating that postlarval P. argus are attracted to, settle in, and metamorphose more quickly in red macroalgae, confirm that macroalgae‐dominated hard‐bottom habitat appears to be the preferred and more optimal nursery for Caribbean spiny lobster.