Modelling Korean extreme rainfall using a Kappa distribution and maximum likelihood estimate

Summary Attempts to use the 4-parameter Kappa distribution (K4D) with the maximum likelihood estimates (MLE) on the summer extreme daily rainfall data at 61 gauging stations over South Korea have been made to obtain reliable quantile estimates for several return periods. A numerical algorithm for searching MLE of K4D by minimizing the negative log-likelihood function with penalty method has been described. The isopluvial maps of estimated design values corresponding to selected return periods have been presented. The highest return values are centered at sites in the south-western part of the Korean peninsula. The distribution of return values for annual maxima of 2-day precipitation (AMP2) is more similar to the climatological features of annual total precipitation of Korea than that of annual maxima of daily precipitation (AMP1). Our results of return values delineate well the horizontal patterns of the heavy precipitation over the Korean peninsula. Received January 15, 2001 Revised October 8, 2001     

Ecological characteristics of Walleye pollock eggs and larvae in the southeastern Bering Sea during the late 1970s

Walleye pollock (Theragra chalcogramma) is an ecologically and economically important groundfish in the eastern Bering Sea. Its population size fluctuates widely, driving and being driven by changes in other components of the ecosystem. It is becoming apparent that dramatic shifts in climate occur on a decadal scale, and these “regime shifts” strongly affect the biota. This paper examines quantitative collections of planktonic eggs and larvae of pollock from the southeastern Bering Sea during 1976–1979. Mortality, advection, and growth rates were estimated, and compared among the years encompassing the 1970s’ regime shift. These data indicate that pollock spawning starts in late February over the basin north of Bogoslof Island. Over the shelf, most spawning occurs north of Unimak Island near the 100 m isobath in early or mid April. Pollock eggs are advected to the northwest from the main spawning area at 5–10 cm/sec. Larvae are found over the basin north of Bogoslof Island in April, and over the shelf between Unimak Island and the Priblof Islands in May. Compared to 1977, the spawning period appeared to be later in 1976 (a cold year) and earlier in 1978 (a warm year) in the study area. At the lower temperatures in 1976, egg duration would be longer and thus egg mortality would operate over a longer period than in the other years. Mean larval growth appeared to be lower in 1976 than in 1977 and 1979. Estimated egg mortality rate in 1977 was 0.6 in April and 0.3 in early May.     

A new record of pasiphaeid shrimp of the genus <Emphasis Type="Italic">Pasiphaea</Emphasis> (Crustacea: Decapoda: Caridea) in Korean waters

A single specimen of the pelagic shrimps, Pasiphaea japonica Omori, 1976 (Pasiphaeidae) collected in the southeastern waters of Korea is described and illustrated. Although this species occurs widely in the Indo-West Pacific including the Japanese coast of the East/Japan Sea and the middle and southern parts of the East China Sea, this is the first record of the species and the genus in Korean waters. The species is distinguished from other congeners by the following combination of characteristics: non-carinate dorsal sixth abdominal somite with a terminal tooth, rudimentary pleurobranch on the eighth thoracic somite, merus of the first pereopod with more than eight spines, and almost entirely transparent white color.     

Impact of wildfire on source water contributions in Devil Creek,CA: evidence from end‐member mixing analysis

A geochemical and end‐member mixing analysis (EMMA) is undertaken in Devil Canyon catchment, located in southern California, to further understanding of watershed behaviour and source water contributions after an acute and extensive wildfire. Physical and chemical transformations in post‐fire watersheds are known to increase overland flow and decrease infiltration, mainly due to formation of a hydrophobic layer at, or near, the soil surface. However, less is known about subsurface flow response in burned watersheds. The current study incorporates EMMA to evaluate and quantify source water contributions before, and after, a catchment affected by wildfires in southern California during the fall of 2003. Pre‐ and post‐fire stream water data were available at several sampling sites within the catchment, allowing the identification of contributing water sources at varying spatial scales. Proposed end‐member observations (groundwater, overland flow, shallow subsurface flow) were also collected to constrain and develop the catchment mixing model. Post‐fire source water changes are more evident in the smaller and faster responding sub‐basin (interior sampling point). Early post‐fire storm events are dominated by overland flow with no significant soil water or groundwater flow contribution. Inter‐storm streamwater in this smaller basin shows an increase in groundwater and a decrease in soil water. In the larger, baseflow‐dominated system, source water components appear less affected by fire. A slight increase in lateral flow is observed with only a slight decrease in baseflow. Changes in the post‐fire flow regimes affect nutrient loading and chemical response of the basin. Relatively rapid recovery of the chaparral ecosystem is evidenced, with active re‐growth and evapotranspiration evidenced by the fourth post‐fire rainy season. Copyright © 2008 John Wiley & Sons, Ltd.     

Titanium- and water-rich metamorphic olivine in high-pressure serpentinites from the Voltri Massif (Ligurian Alps,Italy): evidence for deep subduction of high-field strength and fluid-mobile elements

Titanium- and water-rich metamorphic olivine (Fo 86–88) is reported from partially dehydrated serpentinites from the Voltri complex, Ligurian Alps. The rocks are composed of mostly antigorite and olivine in addition to magnetite, chlorite, clinopyroxene and Ti-clinohumite. In situ secondary ion mass spectrometry (SIMS) data show that metamorphic olivine has very high and strongly correlated H₂O (up to 0.7 wt%) and TiO₂ contents (up to 0.85 wt%). Ti-rich olivine shows colourless to yellow pleochroism. Olivine associated with Ti-clinohumite contains low Ti, suggesting that Ti-rich olivine is not the breakdown product of Ti-clinohumite. Fourier transform infrared spectroscopy (FTIR) absorption spectra show peaks of serpentine, Ti-clinohumite and OH-related Si vacancies. Combining FTIR and SIMS data, we suggest the presence of clustered planar defects or nanoscale exsolutions of Ti-clinohumite in olivine. These defects or exsolutions contain more H₂O (x ~ 0.1 in the formula 4Mg₂SiO₄·(1?x)Mg(OH,F)₂·xTiO₂) than Ti-clinohumite in the sample matrix (x = 0.34–0.46). In addition to TiO₂ and H₂O, secondary olivine contains significant Li (2–60 ppm), B (10–20 ppm), F (10–130 ppm) and Zr (0.9–2.1 ppm). It is enriched in ¹¹B (δ¹¹B = +17 to +23 ‰). Our data indicate that secondary olivine may play a significant role in transporting water, high-field strength and fluid-mobile elements into the deeper mantle as well as introduce significant B isotope anomalies. Release of hydrogen from H₂O-rich olivine subducted into the deep mantle may result in strongly reduced mantle domains.     

Effects of natural and calcined poultry waste on Cd, Pb and As mobility in contaminated soil

The reuse of waste materials as soil additives could be a welcome development in soil remediation. The mobility of Cd, Pb and As in a contaminated soil was investigated using natural and calcined poultry wastes (eggshell and chicken bone), CaCO₃ and CaO at different application rates (0, 1, 3 and 5 %). The chemical composition accompanied with mineralogical composition indicated that CaCO₃ and CaO were the major components in natural and calcined eggshells, respectively, while hydroxyapatite (HAP) dominated the natural and calcined chicken bones. The results showed that soil pH tended to increase in response to increasing application rates of all soil additives. The effectiveness of the additives in reducing Cd, Pb and As mobility was assessed by means of chemical extractions with 0.1 N HCl for Cd and Pb or 1 N HCl for As, according to Korean Standard Test (KST) method. Both calcined eggshell and chicken bone were equally effective with CaO or CaCO₃ in reducing the concentration of 0.1 N HCl-extractable Cd from 6.17 mg kg^?1 to below warning level of 1.5 mg kg^?1, especially at the highest application rate. The application of calcined eggshell, CaO and CaCO₃ also decreased the concentration of 0.1 N HCl-extractable Pb from 1,012 mg kg^?1 to below warning level of 100 mg kg^?1. The Pb concentration decreased significantly with an increasing application rate of chicken bone, but remained above warning level even at the highest application rate. On the contrary, natural and calcined chicken bones led to a significant increase in the mobility of As when compared with the control soil. These findings illustrate that calcined eggshell in particular is equally effective as pure chemical additives in stabilizing Cd and Pb in a contaminated agricultural soil. The presence of As in metal-contaminated soils should be taken into consideration when applying phosphate-containing materials as soil additives, because phosphate can compete with arsenate on adsorption sites and result in As mobilization.     

Lower crustal melting and the role of open-system processes in the genesis of syn-orogenic quartz diorite–granite–leucogranite associations: constraints from Sr–Nd–O isotopes from the Bandombaai Complex, Namibia

The Bandombaai Complex (southern Kaoko Belt, Namibia) consists of three main intrusive rock types including metaluminous hornblende- and sphene-bearing quartz diorites, allanite-bearing granodiorites and granites, and peraluminous garnet- and muscovite-bearing leucogranites. Intrusion of the quartz diorites is constrained by a U–Pb zircon age of 540±3 Ma.

Quartz diorites, granodiorites and granites display heterogeneous initial Nd- and O isotope compositions (_{Nd (540 Ma)}=−6.3 to −19.8; δ¹⁸O=9.0–11.6‰) but rather low and uniform initial Sr isotope compositions (⁸⁷Sr/⁸⁶Sr_initial=0.70794–0.70982). Two leucogranites and one aplite have higher initial ⁸⁷Sr/⁸⁶Sr ratios (0.70828–0.71559), but similar initial _Nd (−11.9 to −15.8) and oxygen isotope values (10.5–12.9‰). The geochemical and isotopic characteristics of the Bandombaai Complex are distinct from other granitoids of the Kaoko Belt and the Central Zone of the Damara orogen. Our study suggests that the quartz diorites of the Bandombaai Complex are generated by melting of heterogeneous mafic lower crust. Based on a comparison with results from amphibolite-dehydration melting experiments, a lower crustal garnet- and amphibole-bearing metabasalt, probably enriched in K₂O, is a likely source rock for the quartz diorites. The granodiorites/granites show low Rb/Sr (<0.6) ratios and are probably generated by partial melting of meta-igneous (intermediate) lower crustal sources by amphibole-dehydration melting. Most of the leucogranites display higher Rb/Sr ratios (>1) and are most likely generated by biotite-dehydration melting of heterogeneous felsic lower crust. All segments of the lower crust underwent partial melting during the Pan-African orogeny at a time (540 Ma) when the middle crust of the central Damara orogen also underwent high T, medium P regional metamorphism and melting. Geochemical and isotope data from the Bandombaai Complex suggest that the Pan-African orogeny in this part of the orogen was not a major crust-forming episode. Instead, even the most primitive rock types of the region, the quartz diorites, represent recycled lower crustal material.     

The legacy of crystal-plastic deformation in olivine: high-diffusivity pathways during serpentinization

Crystal-plastic olivine deformation to produce subgrain boundaries composed of edge dislocations is an inevitable consequence of asthenospheric mantle flow. Although crystal-plastic deformation and serpentinization are spatio-temporally decoupled, we identified compositional readjustments expressed on the micrometric level as a striped Fe-enriched ( [`(X)]<sub>\textFe</sub> \bar{X}_{\text{Fe}}  = 0.24 ± 0.02 (zones); 0.12 ± 0.02 (bulk)) or Fe-depleted ( [`(X)]_\textFe \bar{X}_{\text{Fe}}  = 0.10 ± 0.01 (zones); 0.13 ± 0.01 (bulk)) zoning in partly serpentinized olivine grains from two upper mantle sections in Norway. Focused ion beam sample preparation combined with transmission electron microscopy (TEM) and aberration-corrected scanning TEM, enabling atomic-level resolved electron energy-loss spectroscopic line profiling, reveals that every zone is immediately associated with a subgrain boundary. We infer that the zonings are a result of the environmental Fe²⁺Mg₋₁ exchange potential during antigorite serpentinization of olivine and the drive toward element exchange equilibrium. This is facilitated by enhanced solid-state diffusion along subgrain boundaries in a system, which otherwise re-equilibrates via dissolution-reprecipitation. Fe enrichment or depletion is controlled by the silica activity imposed on the system by the local olivine/orthopyroxene mass ratio, temperature and the effect of magnetite stability. The Fe-Mg exchange coefficients K_\textD^{\textAtg/\textOl} K_{\text{D}}^{{{\text{Atg}}/{\text{Ol}}}} between both types of zoning and antigorite display coalescence toward exchange equilibrium. With both types of zoning, Mn is enriched and Ni depleted compared with the unaffected bulk composition. Nanometer-sized, heterogeneously distributed antigorite precipitates along olivine subgrain boundaries suggest that water was able to ingress along them. Crystallographic orientation relationships gained via electron backscatter diffraction between olivine grain domains and different serpentine vein generations support the hypothesis that serpentinization was initiated along olivine subgrain boundaries.