Limited Occurrence of Denitrification in Four Shallow Aquifers in Agricultural Areas of the United States

The ability of natural attenuation to mitigate agricultural nitrate contamination in recharging aquifers was investigated in four important agricultural settings in the United States. The study used laboratory analyses, field measurements, and flow and transport modeling for monitoring well transects (0.5 to 2.5 km in length) in the San Joaquin watershed, California, the Elkhorn watershed, Nebraska, the Yakima watershed, Washington, and the Chester watershed, Maryland. Ground water analyses included major ion chemistry, dissolved gases, nitrogen and oxygen stable isotopes, and estimates of recharge date. Sediment analyses included potential electron donors and stable nitrogen and carbon isotopes. Within each site and among aquifer-based medians, dissolved oxygen decreases with ground water age, and excess N2 from denitrification increases with age. Stable isotopes and excess N2 imply minimal denitrifying activity at the Maryland and Washington sites, partial denitrification at the California site, and total denitrification across portions of the Nebraska site. At all sites, recharging electron donor concentrations are not sufficient to account for the losses of dissolved oxygen and nitrate, implying that relict, solid phase electron donors drive redox reactions. Zero-order rates of denitrification range from 0 to 0.14 μmol N L−1d−1, comparable to observations of other studies using the same methods. Many values reported in the literature are, however, orders of magnitude higher, which is attributed to a combination of method limitations and bias for selection of sites with rapid denitrification. In the shallow aquifers below these agricultural fields, denitrification is limited in extent and will require residence times of decades or longer to mitigate modern nitrate contamination

Child welfare reform in the United States: findings from a local agency survey.

Efforts to improve the public welfare and child welfare system sparked an unprecedented amount of federal legislation in the 1990s, including the Adoption and Safe Families Act of 1997 (ASFA), the Multiethnic Placement Act of 1994 and Interethnic Adoption Provisions of 1996 (MEPA-IEP), and welfare reform. Such reforms allow an unprecedented degree of flexibility, but little is known about their implementation. Researchers administered the Local Agency Survey to the first national probability sample of public child welfare agencies from 1999 to 2000. Findings indicate that ASFA has had the most effect on child welfare service delivery. Welfare reform has had less effect, and MEPA-IEP seems to have had little effect at all

Possibilities and limitations of validating modelled nitrate inputs into groundwater at the macroscale using the N2/Ar-method

Valide Modelle zur flächenhaften Abschätzung von Nitratausträgen aus der Landwirtschaft ins Grundwasser sind ein unerlässliches Prognosewerkzeug. Eine wesentliche Herausforderung für die Validierung solcher Modelle ist die räumliche und zeitliche Inkongruenz zwischen Daten aus Grundwassermessstellen und modellierten Nitrateinträgen ins Grundwasser und der Umstand, dass viele der bestehenden Grundwassermessstellen bisher nicht zur Validierung genutzt werden können.Mithilfe der N2/Ar-Methode können erstmals auch Grundwassermessstellen, die reduziertes Grundwasser fördern, zur Modellvalidierung verwendet werden. Dazu wurden niedersachsenweit über 484 Grundwassermessstellen beprobt und jeweils mit dem DENUZ-Modell modellierte potenzielle Nitratkonzentrationen im neugebildeten Grundwasser mit Nitrateintragskonzentrationen, die mit der N2/Ar-Methode berechnet wurden, verglichen.Die Ergebnisse der Modellvalidierung zeigen eine gute Übereinstimmung beider Methoden im Bereich der niedersächsischen Geest. In grundwassernahen Niederungsregionen, in denen Nitratabbauprozesse im Boden und Grundwasser ineinander übergehen, modelliert das DENUZ-Modell ca. 27 % höhere Nitratemissionen ins Grundwasser als die N2/Ar-Methode. Die hohe räumliche und zeitliche Variabilität der Nitrateinträge ins Grundwasser bedingt die Einbeziehung einer großen Anzahl von Grundwassermessstellen bei der Modellvalidierung

A novel X–linked gene, DDP, shows mutations in families with deafness (DFN–1), dystonia, mental deficiency and blindness

In 1960, progressive sensorineural deafness (McKu-sick 304700, DFN-1) was shown to be X-linked based on a description of a large Norwegian pedigree1 . More recently, it was shown that this original DFN-1 family represented a new type of recessive neurodegenerative syndrome characterized by postlingual progressive sensorineural deafness as the first presenting symptom in early childhood, followed by progressive dystonia, spasticity, dysphagia, mental deterioration, paranoia and cortical blindness. This new disorder, termed Mohr-Tranebjasrg syndrome (referred to here as DFN-1/MTS) was mapped to the Xq21.3–Xq22 region2. Using positional information from a patient with a 21-kb deletion in chromosome Xq22 and sensorineural deafness along with dystonia, we characterized a novel transcript lying within the deletion as a candidate for this complex syndrome. We now report small deletions in this candidate gene in the original DFN-1/MTS family, and in a family with deafness, dystonia and mental deficiency but not blindness. This gene, named DDP (deaf-ness/dystonia peptide), shows high levels of expression in fetal and adult brain. The DDP protein demonstrates striking similarity to a predicted Schizosaccharomyces pombe protein of no known function. Thus, is it likely that the DDP gene encodes an evolutionarily conserved novel polypeptide necessary for normal human neurological development