Dissolved organic carbon in runoff and tile-drain water under corn and forage fertilized with hog manure

Dissolved organic carbon (DOC) export from soils can play a significant role in soil C cycling and in nutrient and pollutant transport. However, information about DOC losses from agricultural soils as influenced by management practices is scarce. We compared the effects of mineral fertilizer (MF) and liquid hog manure (LHM) applications on the concentration and molecular size of DOC released in runoff and tile-drain water under corn (Zea mays L.) and forage cropping systems. Runoff and tile-drain water samples were collected during a 2-mo period (October to December 1998) and DOC concentration was measured. Characterization of DOC was performed by tangential ultrafiltration with nominal cut-offs at 3 and 100 kDa. Mean concentration of DOC in runoff water (12.7 mg DOC L(-1)) was higher than in tile-drain water (6.5 mg DOC L(-1)). Incorporation of corn residues increased the DOC concentration by 6- to 17-fold in surface runoff, but this effect was short-lived. In runoff water, the relative size of the DOC molecules increased when corn residues and LHM were applied probably due to partial microbial breakdown of these organic materials and to a faster decomposition or preferential adsorption of the small molecules. The DOC concentration in tile-drain water was slightly higher under forage (7.5 mg DOC L(-1)) than under corn (5.4 mg DOC L(-1)) even though the application rates of LHM were higher in corn plots. We suggest that preferential flow facilitated the migration of DOC to tile drains in forage plots. In conclusion, incorporation of corn residues and LHM increased the concentration of DOC and the relative size of the molecules in surface runoff water, whereas DOC in tile-drain water was mostly influenced by the cropping system with relatively more DOC and larger molecules under forage than corn.     

Management and Limnology Interact to Drive Water Temperature Patterns in a Middle Rockies River‐Reservoir System

This study seeks to improve understanding of temperature patterns in reservoir outflows. We examined water temperatures in an irrigation storage reservoir, Island Park Reservoir, and its outflow, Henry’s Fork of the Snake River in eastern Idaho. Our objectives were to (1) quantify the extent to which daily temperature ranges in the reservoir outflow deviated from other reaches of the Henry’s Fork, and (2) test whether the reservoir’s net volume change during the summer — expressed as the volume of water remaining in the reservoir on September 1 — predicted mean summer temperature in the outflow. Two years of temperature data showed dampened diel temperature cycles in the reservoir outflow. Model selection with 17 years of climatic, hydrologic, and reservoir management variables found mean summer temperature in the outflow was best predicted by September 1 reservoir volume and average summer air temperature. Two years of weekly reservoir thermal profiles indicated large changes in reservoir volume eliminated cool hypolimnetic water and encouraged mixing, allowing warm epilimnetic water to be discharged into the outflow. Increases in future drought frequency and severity and increases in summer air temperatures could increase the frequency of occurrence of high mean summertime water temperatures in the outflow. Our study provides important information for local managers by quantifying influences on outflow temperatures and the downstream river ecosystem.     

Prenatal exclusion of X-linked hydrocephalus-stenosis of the aqueduct of sylvius sequence using closely linked DNA markers

X-linked hydrocephalus-stenosis of the aqueduct of Sylvius sequence (H-SAS, MIM number 307 000) is a rare genetic disorder characterized by hydrocephalus, macrocephaly, adducted thumbs, spasticity, mental retardation, and cerebral malformations. This regularly lethal condition is usually diagnosed at birth or prenatally by ultrasound, but hydrocephalus may be moderate or even undetectable on fetal ultrasound examination. Moreover, since heterozygous women are asymptomatic, carrier detection is at present impossible before the birth of an affected son. Therefore, mapping the H-SAS locus to distal Xq (Xq28) was of primary importance for genetic counselling and prenatal diagnosis. Here, we report prenatal exclusion of H-SAS with a probability of 97.6 per cent in two male fetuses with a 50 per cent a priori risk of being affected using closely linked Xq28 DNA markers.     

Conjunctive Water Use in Confined Basalt Aquifers: An Evaluation Using Geochemistry,a Numerical Model,and Historical Water Level

As withdrawals from deep compartmentalized aquifers increasingly exceed recharge throughout the western United States, conjunctive water use management alternatives have become an applied research priority. This study highlights both details and limitations of the role of irrigation canal seepage as groundwater recharge, revealing the regional limitations of canal seepage as a dependable source of recharge in overdrawn aquifers. A suite of geochemical indicators were used together with a numerical model to evaluate current and future management scenarios focused on recharge derived from seepage from a region‐wide irrigation canal system. Twenty‐five years of static groundwater level data were used to relate spatial trends determined using geochemistry and groundwater modeling with “on‐the‐ground” management practices, which vary based on acreage, crop, and irrigation scheduling. Increasing groundwater age determined using isotope analysis, and declines in potentiometric heads, each correlate with increasing distance from the canal reaches. Predictive modeling indicates that if pumping is gradually reduced, as has been suggested by management agencies, that recharge from canal seepage will be negligible by 2035 due to regional groundwater through‐flow and the pattern of potentiometric head recovery. Unfortunately, historic hydrographs suggest that under current groundwater development conditions most wells are not sustainable, irrespective of proximity to the canal.     

可持续发展与零售部门的社会重要性

去年秋天世界可持续发展峰会(WSSD)倡议,要全面认识可持续发展的社会支柱作用,包括消除贫困、争取权利和公平,以及有收入的就业等问题.自从1992年地球峰会以来,这些已经成为国际自由工会联合会(ICFTU)、经济合作与发展组织的工会咨询委员会(TUAC)和全球工会联合会(GUF)优先解决的问题.     

Prenatal diagnosis of carnitine palmitoyltransferase 2 deficiency in chorionic villi: a novel approach

Carnitine palmitoyltransferase 2 (CPT2) deficiency, the most common autosomal recessive inherited disease of the mitochondrial long-chain fatty acid (LCFA) β-oxidation, may result in three distinct clinical phenotypes, namely, a mild adult muscular form, a severe infantile hepatocardiomuscular disease, and a neonatal form, which includes dysmorphic features in addition to hepatocardiomuscular symptoms. Both the latter forms are life-threatening diseases, and prenatal diagnosis (PND) can be offered to couples at a one-fourth risk of having an affected child. PND of CPT2 deficiency hitherto relied mostly on mutation detection from fresh chorionic villi (10 weeks' gestation), since CPT2 activity could be assayed on cultured amniocytes only (16–17 weeks' gestation). We devised a CPT2 activity assay from 10 mg of chorionic villi sampling (CVS). Combining this enzymatic assay to haplotype study using polymorphic markers linked to the CPT2 gene, we were able to carry out within 2 days, CPT2 deficiency PND, in two unrelated families, using a CVS performed at the 11th week of gestation. Copyright © 2003 John Wiley & Sons, Ltd.     

Oxygen isotope fractionation between bird bone phosphate and drinking water

Oxygen isotope compositions of bone phosphate (δ¹⁸O_p) were measured in broiler chickens reared in 21 farms worldwide characterized by contrasted latitudes and local climates. These sedentary birds were raised during an approximately 3 to 4-month period, and local precipitation was the ultimate source of their drinking water. This sampling strategy allowed the relationship to be determined between the bone phosphate δ¹⁸O_p values (from 9.8 to 22.5‰ V-SMOW) and the local rainfall δ¹⁸O_w values estimated from nearby IAEA/WMO stations (from ?16.0 to ?1.0‰ V-SMOW). Linear least square fitting of data provided the following isotopic fractionation equation: δ¹⁸O_w = 1.119 (±0.040) δ¹⁸O_p ? 24.222 (±0.644); R ² = 0.98. The δ¹⁸O_p–δ¹⁸O_w couples of five extant mallard ducks, a common buzzard, a European herring gull, a common ostrich, and a greater rhea fall within the predicted range of the equation, indicating that the relationship established for extant chickens can also be applied to birds of various ecologies and body masses. Applied to published oxygen isotope compositions of Miocene and Pliocene penguins from Peru, this new equation computes estimates of local seawater similar to those previously calculated. Applied to the basal bird Confuciusornis from the Early Cretaceous of Northeastern China, our equation gives a slightly higher δ¹⁸O_w value compared to the previously estimated one, possibly as a result of lower body temperature. These data indicate that caution should be exercised when the relationship estimated for modern birds is applied to their basal counterparts that likely had a metabolism intermediate between that of their theropod dinosaur ancestors and that of advanced ornithurines.     

Deposition and biological availability of diesel particles and their associated mutagenic chemicals

To estimate the human health risk of inhaled diesel particles, it is necessary to know their deposition and retention in the respiratory tract and the rate of dissociation of mutagenic compounds associated with the particles. The deposition of a chain aggregate aerosol of ⁶⁷Ga₂O₃ with size and shape characteristics similar to diesel exhaust particles has been evaluated using Beagle dogs. Approximately one-third of the inhaled activity is deposited in the respiratory tract with most of the particles deposited in the lung. The mutagenic activity present in dichloromethane, dog serum, dog lung lavage fluid, saline, dipalmitoyl lecithin (DPL) and albumin following incubation of these fluids with diesel exhaust particles was determined in the Ames Salmonella system. As observed by other investigators, large quantities of mutagenic activity were removed by dichloromethane. A very small amount of mutagenic activity was removed by the serum and lavage fluid over a 3-day incubation period. No activity was detected following elution with the other solvents. The finding that minimal mutagenic activity could be demonstrated in the biological media following incubation with diesel exhaust particles may be due to a lack of removal of mutagens from the particles or an inactivation of removed mutagens by protein binding or other processes.     

Testing sexual segregation and aggregation: old ways are best

The study of sexual segregation has received increasing attention over the last two decades. Several hypotheses have been proposed to explain the existence of sexual segregation, such as the "predation risk hypothesis," the "forage selection hypothesis," and the "activity budget hypothesis." Testing which hypothesis drives sexual segregation is hampered, however, by the lack of consensus regarding a formal measurement of sexual segregation. By using a derivation of the well-known chi-square (here called the sexual segregation and aggregation statistic [SSAS]) instead of existent segregation coefficients, we offer a reliable way to test for temporal variation in the occurrence of sexual segregation and aggregation, even in cases where a large proportion of animals are observed alone. A randomization procedure provides a test for the null hypothesis of independence of the distributions of males and females among the groups. The usefulness of SSAS in the study of sexual segregation is demonstrated with three case studies on ungulate populations belonging to species with contrasting life histories and annual grouping patterns (isard, red deer, and roe deer). The existent segregation coefficients were unreliable since, for a given value, sexual segregation could or could not occur. Similarly, the existent segregation coefficients performed badly when males and females aggregated. The new SSAS was not prone to such limitations and allowed clear conclusions regarding whether males and females segregate, aggregate, or simply mix at random applicable to all species.     

Relationships among nutrients, chlorophyll-a, and dissolved oxygen in agricultural streams in Illinois

A better understanding of the controls on algae and dissolved O2 in agricultural streams of Illinois is needed to aid in development of nutrient standards. We investigated the relationships between dissolved nutrients, algal abundance, and dissolved O2 in five streams in east-central Illinois from March through November 2004. The streams drained watersheds from 25 to 777 km2 that were dominated by row crop agriculture. Three sites had open canopies and two were bordered by a narrow forest of deciduous trees. Algal abundance was measured as chlorophyll-a (chl-a) concentration in the water column (sestonic) and on the streambed (periphytic). Mean NO3-N concentrations ranged from 5.5 to 8.8 mg N L(-1) and did not relate to algal abundance. Sestonic chl-a values ranged from nearly zero to >15 mg m(-3) with no differences between open and shaded streams and only a weak correlation with dissolved reactive P (mean concentrations were 44-479 microg L(-1)). The results suggest that sestonic chl-a is a poor criterion for assessing nutrient-related problems in these streams. Greatest periphytic chl-a occurred during low flow from August through October, but periphyton occurred consistently in only two of the five streams. The abundance of filamentous algae explained 64% of the variation in diel O2 saturation, but was not correlated with nutrients. Currently it appears that hydrology and light, rather than nutrients, control algal abundance in these streams, and in the agricultural landscape of east-central Illinois, it may not be possible to reduce nutrient concentrations sufficiently to limit filamentous algal blooms.