Individual tree and stand-level carbon and nutrient contents across one rotation of loblolly pine plantations on a reclaimed surface mine

New Forests - While reclaimed loblolly pine (Pinus taeda L.) plantations in east Texas, USA have demonstrated similar aboveground productivity levels relative to unmined forests, there is interest...     

Release of plant-available silicon from various silicon-rich amendments into soil solutions and leachates

Journal of Soils and Sediments - This study assessed the efficacy of selected silicon-rich soil amendments in terms of their ability to provide dissolved silicon (Si) to soil solutions during a...     

Suspended matter and associated contaminants in Danish streams: a national analysis

Purpose

Suspended matter (SM) in streams is usually considered of minor importance in Danish environmental management. However, SM has some ecological effects as it may (1) clog fish spawning grounds and (2) act as an important agent for transport and exposure of biota to chemical substances, such as phosphorus and toxic inorganic (e.g. heavy metals) and organic (e.g. pesticides) substances.

Materials and methods

A large national data set of >?100,000 water samples analysed for SM and loss on ignition was investigated for spatial concentration patterns, sediment yields and temporal trends. Moreover, the importance of SM as a transport agent for phosphorus and heavy metals in streams was investigated through a correlation analysis.

Results and discussion

The mean suspended matter concentration (SMC) (including organic matter) amounted to 12 mg l^?1, with an organic content of 4.9 mg l^?1 (41%). A clear difference in SMC temporal trends over the sampling period was found between geographical regions. Sediment yields were calculated for all major catchments revealing low sediment yields (1–15 t km^?2 year^?1) compared to neighbouring countries and showed clear geographical patterns. Statistically significant relationships were established between SMCs, suspended sediment concentrations (SSCs) (excluding organic matter) and organic matter concentrations (OMCs) and particulate phosphorus (PP) concentrations, and again spatial patterns appeared. However, it was clearly shown that SMC/SSC/OMC could not be used as a robust, nationwide, indicator for PP concentrations. Analyses of the relationship between SMC and particle-bound heavy metal concentrations generally revealed weak correlations except for Pb and Ni (median R²?>?0.3).

Conclusions

Relatively low SM concentrations and sediment yields were found. SM is, in some geographical regions, an important transport agent for PP. Clear geographical patterns occurred in the relationships between SMC/SSC/OMC and both river water discharge and PP, as well as for sediment yields and for temporal trends in SMC.

     

The impact of soil structure on the establishment of winter wheat (Triticum aestivum)

Soil physical properties affect the establishment of crops; these properties are influenced by cultivation employed during seedbed preparation and vary greatly depending upon the intensity of cultivations. However, there is little quantified data concerning the influence of cultivation on the precise soil structural arrangement of the seedbed and the effects of this on crop establishment. The dynamics of soil structure at the meso-scale (10–1000 μm), on a range of seedbeds and how they relate to crop establishment are considered in this paper. Significant interactions between cultivation techniques including soil structural properties and the interaction with crop establishment were identified. The relationship between soil structure and crop establishment was highly significant, with increased pore space reducing final establishment numbers. An improvement to a previous model (soil quality of establishment (SQE)) was developed following the addition of soil structural properties, accounting for an improved predictability of 14% of the variation across soil texture (sandy loam and clay loam) from ca. 56% to ca. 70%.     

The Economics of Intensifying Catfish Production: A Production Function Analysis1

Yields of channel catfish in the United States have increased as a result of higher levels of stocking, feeding and aeration. A Cobb-Douglas production function was estimated using survey data from 66 catfish ponds in West-Central Alabama to determine if further intensification of catfish production in West-Central Alabama would be profitable. Feed, capital, stocking rate, and length of production period explained most of the variation in yield. Values of the marginal products for feed, stocking rate and capital were consistently higher than input costs during the study period. Profit-maximizing levels of input use were higher than the levels of inputs used in West-Central Alabama during the study period. Results indicated that more intensive use of production inputs would increase yield and profits. However, careful interpretation of these results requires consideration of non-profit factors such ns cash Row and risk as well as the specific nature of the data used to develop the production relationship. The method utilized in this study can generally be applied to any aquaculture production system, but the recommendation for more intensive input use is specific to the pond data collected for this study.     

Larval Lobster (Homarus americanus Milne Edwards) Development with Great Salt Lake, Utah and Reference I Strains of Artemia Nauplii

Lobster larvae were reared on a diet of unfed Artemia nauplii from either Great Salt Lake, Utah, USA (harvested in late 1981), or from the Artemia Reference Center, Ghent, Belgium. The two strains produced equivalent survival, development, and growth rates in the experimental animals. Success at metamorphosis for lobsters fed each strain was high despite observations in the literature that other larvae which experience a pronounced metamorphosis could show high mortalities when fed Utah Artemia . The results indicate that either temporal variability in nutritional value of Utah Artemia can alter growth patterns of predaceous lanae or that larval lobsters have appropriate metabolic mechanisms to overcome dietary deficiencies previously associated with Utah Artemia .     

Chlorpyrifos-methyl plus bioresmethrin; Methacrifos; Pirimiphos-methyl plus bioresmethrin; and synergised bioresmethrin as grain protectants for wheat

Field trials with various pesticide combinations were carried out on bulk wheat in commercial silos in Queensland, South Australia and Western Australia. Laboratory bioassays on samples of treated grain at intervals over 8 months using malathion-susceptible and malathion-resistant strains established the following orders of efficacy: against Sitophilus oryzae (L.), chlorpyrifos-methyl 10 mg kg^?1 + bioresmethrin 1 mg kg^?1 = methacrifos 15 mg kg^?1 in aerated storage > pirimiphos-methyl 4 or 6 mg kg^?1 + bioresmethrin 1 mg kg^?1 = bioresmethrin 4 mg kg^?1 + piperonyl butoxide 16 mg kg^?1; against Rhyzopertha dominica (F.), bioresmethrin 4 mg kg^?1 + piperonyl butoxide 16 mg kg^?1 > methacrifos 15 mg kg^?1 > chlorpyrifos-methyl 10 mg kg^?1 + bioresmethrin 1 mg kg^?1 = pirimiphos-methyl 4 or 6 mg kg^?1 + bioresmethrin 1 mg kg^?1. All treatments completely prevented production of progeny in Sitophilus granarius (L.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.). The biological efficacy of methacrifos was greater and the rate of degradation lower in aerated than in non-aerated storage. Residue levels of all compounds were determined chemically and were below proposed international residue levels to be considered by the Codex Alimentarius Commission.     

A retrospective study of 44 canine apocrine sweat gland adenocarcinomas

Apocrine sweat gland adenocarcinomas (AACs) are relatively uncommon skin tumors in dogs. Little prognostic or behavioral information has been published for these tumors. In this retrospective study, 44 AACs from diagnostic archives were reexamined and clinical postexcisional follow-ups for 25 of the 44 cases were obtained by a survey. There were 28 out of 44 (65.9%) AACs that invaded the capsule, stroma, or both, 5 of 44 (11.4%) invaded blood vessels and stroma, and 1 out of 25 (4%) had distant metastases. The presence or absence of stromal and vascular invasion was predicted by clinical examination with more than 80% accuracy. Postexcisional median survival of dogs with AACs was 30 mo at the time of survey. Determination of a correlation between histological features and malignant behavior of AACs was compromised by the low number of cases with clinical AAC-related problems; however, it appears that intravascular invasion is an important indicator of potential systemic metastases.     

Use of a test for proteins induced by vitamin K absence or antagonism in diagnosis of anticoagulant poisoning in dogs: 325 cases (1987-1997)

OBJECTIVE: To determine usefulness of the test for proteins induced by vitamin K absence or antagonism (PIVKA) to identify anticoagulant-poisoned dogs, compared with one-stage prothrombin time (OSPT) and activated partial thromboplastin time (APTT) tests. DESIGN: Retrospective study. ANIMALS: 325 dogs. PROCEDURE: Comparisons of results of PIVKA, OSPT, and APTT measurements in dogs with anticoagulant poisoning, hepatic disease, disseminated intravascular coagulation, other blood-related disorders, immune-mediated diseases, or other chronic and acute diseases were performed. Median, quartile, and range values were determined. RESULTS: PIVKA tests with a 150-second critical value had > 98% specificity and > 90% sensitivity for diagnosis of anticoagulant poisoning versus > 99% specificity and > 79% sensitivity with a 300-second critical value. Comparison of PIVKA values among diagnostic groups revealed significant differences between dogs with anticoagulant poisoning and all other groups. CONCLUSIONS AND CLINICAL RELEVANCE: The PIVKA test with a 150-second critical value is diagnostically useful for distinguishing anticoagulant poisoning from other coagulopathies. Severe liver disease can cause false-positive results. Administration of vitamin K1 or early evaluation (within a few hours of ingesting anticoagulant) may cause false-negative results. Dogs with PIVKA test values > 150 seconds and clinical signs of anticoagulant poisoning can confidently be considered to have anticoagulant poisoning because of the high test sensitivity and specificity.