Naïve Simplicity: The Overlooked Piece of the Complexity‐Simplicity Paradigm

Concepts of simplicity and complexity in modeling have been explored in papers, editorials, and talks. The concept is not well understood because there are at least two flavors of simplicity. Modelers envision simplicity (i.e., elegant simplicity) as the sought‐after goal in modeling, but naïve simplicity, which is the focus of this paper, is commonly unrecognized and dangerous. The problem is that naïve or simple ideas are often mistaken for settled science and come with the prospect of being more wrong than right. The concept of the so‐called simplicity cycle, in relation to classical problems of carbon‐14 age and salinity in closed‐basin lakes, is used to illustrate these points. The emerging problems of water‐mosquitoes‐diseases show the value of mapping new problems to the simplicity cycle. Researchers can “know what they do not know” and avoid the dangers of naïve simplicity.     

Temporal and spatial patterns of trace elements in the Patuxent River: A whole watershed approach

Trace element distributions, partitioning, and speciation were examined at 15 sites in the Patuxent River watershed from May 1995 through October 1997 to determine possible sources of trace elements to the river and estuary, to examine the relationship of the trace element discharges to freshwater discharges as well as to land use and geographic region, to validate previous estimates of loadings to the river, and to provide baseline data for trace elements in the Patuxent River watershed and estuary. Six freshwater sites were examined, representing different basins and geographic provinces, and nine sites along the estuarine salinity gradient. Subregions within the watershed varied considerably in concentrations and areal yields for some elements. Concentrations of As, Cd, Ni, Pb, and Zn were elevated in the Coastal Plain sites compared to the Piedmont sites, while Cu and Hg were more evenly distributed. Cadmium, Cu, Hg, Ni, Pb, and Zn showed overall positive correlations with river flow while As and methylHg (meHg) showed negative correlations with river flow. Concentrations of trace elements in the estuarine portion of the river were generally low, and consistent with mixing between Patuxent River water with elevated concentrations and the lower concentrations of the Chesapeake Bay. Interesting features included a local Cd maximum in the low salinity region of the estuary, probably caused by desorption from suspended sediments, and a significant input of water containing high As concentrations from the Chesapeake Bay and from As being released from bottom sediments in summer. Comparisons between the estimated annual flux of trace elements and the estimates of suspected source terms (atmospheric deposition, urban runoff, and known point sources) suggest that, except for Hg, direct atmospheric deposition is small compared to fluvial loads. Current estimates of trace element inputs from point sources or from urban runoff are inadequate for comparison with other sources, because of inappropriate techniques and/or unacceptably high detection limits. A complete examination of trace element dynamics in the Patuxent River (and in other coastal systems) will require better data for these potential sources.     

左手地图，右手生活

很喜欢英国作家R．L．斯蒂文森。他的小说《金银岛》开创了以发掘宝藏为题材的探险小说之先河,而另一部充满想象力的《化身博士》则以神秘诡异的故事探讨人性善恶,既引人入胜又寓有深意。但不久前,我于无意中发现,斯蒂文森竟然还说过这样一句话：“据说,一些人认为地图可有可无,而我对此难以置信。”甫见此言,颇有些惊讶,转而一想,他在《金银岛》中把那幅海盗绘制的藏宝图描绘得生动细致,看来是很有些情感依据的。不过,地图当真如斯蒂文森所说,是不可或缺的吗？我开始留心自己的日常生活,并做下相应的记录。     

Diurnal-period internal waves near point conception,California

Diurnal-period internal waves were observed near Point Conception California, using an array of moorings extending 120 km along the inner shelf. The waves have an along-shelf coherence scale of at least 50 km, and appear to propagate nearly straight onshore. Wave amplitudes vary over time, depending on thermal stratification and the amplitude of the diurnal sea breeze oscillation. Barotropic tides and vorticity over the mid-shelf are not correlated with internal wave amplitude. Large amplitude internal waves, with supercritical Froude numbers, are observed in mid-summer. Although such waves may drive vertical mixing and cross-shelf transport of passive particles, there is no significant correlation between wave amplitude and invertebrate settlement in the Santa Barbara Channel.     

The application of in situ permeable reactive (zero-valent iron) barrier technology for the remediation of chromate-contaminated groundwater: a field test

A small-scale field test was initiated in September 1994 to evaluate the in situ remediation of groundwater contaminated with chromate using a permeable reactive barrier composed of a mixture of zero-valent Fe, sand and aquifer sediment. The site used was an old chrome-plating facility located on a U.S. Coast Guard air base near Elizabeth City, North Carolina. Dissolved chromate concentrations were reduced to less than 0.01 mg/L via reduction from Cr(VI) to Cr(III) as a result of the corrosion of the Fe. As the Fe corrodes, pH increases, oxidation-reduction potential declines, dissolved oxygen is consumed, and Fe(II) is generated. Mineral phases formed as a result of the Fe corrosion include ferrous sulfides and various Fe oxides, hydroxides, and oxyhydroxides.     

Variations of phytoplankton community structure related to water quality trends in a tropical karstic coastal zone

Phytoplankton community structure in coastal areas is a result of various environmental factors such as nutrients, light, grazing, temperature, and salinity. The Yucatan Peninsula is a karstic tropical region that is strongly influenced by submerged groundwater discharge (SGD) into the coastal zone. Phytoplankton community structure and its relationship with regional and local water quality variables were studied in four ports of the northwestern Yucatan Peninsula. Water quality was strongly related to SGD, and variations in phytoplankton community structure were related to local nutrient loading and hydrographic conditions, turbulence, and human impacts. Our study provides an ecological baseline for the Yucatan Peninsula and serves as a basis for establishing monitoring programs to predict changes at sites with high hydrological variation and in developing an early alert system for harmful toxic algal blooms.     

Ranching and the new global range: Amazônia in the 21st century

This paper seeks to understand how the Brazilian Amazon, which many thought unsuitable for agricultural development, has yielded to a dynamic cattle economy in only a few decades. It does so by embedding the Thunian model of location rents within the regime of capital accumulation that has driven the Brazilian economy since the mid-20th century. The paper addresses policies that have created location rents in Amazônia, the effect of these rents on land managers, and the spatial implications of their behavior on forests. Thus, the paper connects macro-processes and structures to agents on the ground, in providing a political ecological explanation relevant to land change science. The policy discussion focuses on reductions in transportation costs, improvements in animal health, and monetary and trade reforms. To illustrate the impact of policy, the paper presents data on the geography of Amazonian herd expansion, on the growth of Amazonian exports, and on the profitability of the region’s cattle economy. It follows the empirical presentation with more abstract consideration of the spatial relations between cattle ranching and soy farming, and implications for deforestation. The paper concludes on a speculative note by considering the likelihood of forest transition in the region, given the transformation of Amazônia into a global resource frontier.     

Infrared contamination in Galactic X-ray novae

The most widely used means of measuring the mass of black holes in Galactic binaries – specifically the X-ray novae – involves both radial velocity measurements of the secondary star, and photometric measurements of its ellipsoidal variability. The latter is important in constraining the inclination and mass ratio, and requires as direct a measure of the flux of the secondary as possible. Up to now, such measurements have been preferentially carried out in the near-infrared (NIR:  1–2.5 μm  ), where the flux from the cooler secondary is expected to dominate over that from the accretion disc. However, here we present evidence of a significant non-stellar contribution to the NIR flux in many of those quiescent X-ray novae that are thought to contain a black hole primary. We discuss origins of this excess and the effect of such contamination on Galactic black hole mass measurements.     

Using social media data to understand and assess disasters

This paper contributes to the understanding of disasters from the perspective of social media activities. We develop a measure based on Twitter activities that can be used to quantify the evolution of disasters and thus demonstrate temporal–spatial patterns of Twitter activities particularly near the coastline and in large urban areas during Hurricane Sandy. We also show a close relationship between hurricane damages and Twitter activities. Our findings suggest the potential of using social media activities for rapid damage assessment.