Field demonstration of the combined effects of absorption and evapotranspiration on septic system drainfield capacity.

Drainfields for disposal of septic tank effluents are typically designed by considering the loss of water by either upward evapotranspiration into the atmosphere or lateral and downward absorption into the adjacent soil. While this approach is appropriate for evapotranspiration systems, absorption systems allow water loss by both mechanisms. It was proposed that, in areas where high evapotranspiration rates coincide with permeable soils, drainfield sizes could be substantially reduced by accounting for both mechanisms. A two-year field demonstration was conducted to determine appropriate design criteria for areas typical of the Texas High Plains. The study consisted of evaluating the long-term acceptance rates for three different drainfield configurations: evapotranspiration only, absorption only, and combined conditions. A second field demonstration repeated the experiments for additional observation of the combined evapotranspiration and absorption and achieved similar results as the first study. The field tests indicated that the current design loading criteria may be increased by at least a factor of two for the Texas High Plains region and other Texas areas with similar soil composition and evapotranspiration rates, while still retaining a factor of safety of two.     

The establishment of an urban acid deposition monitoring network

Summary Studies into acid rain were first initiated in North-West England and this paper describes the establishment and operation of the Acid Rain Information Centre in Manchester. The urban monitoring surveys conducted by the Centre provide a valuable educational link with local schools. Simple testing and sampling techniques undertaken by pupils support a valuable and comprehensive, local, urban acid deposition study.Dr. James Longhurst is Director of the Acid Rain Information Centre in the Department of Environmental and Geographical Studies at Manchester Polytechnic, where Mr David Lee and Miss Susan Green are Project Officers. Dr. D.R. Gee is Chief Scientist with the Greater Manchester Scientific Services Laboratory, Wilmslow Road, Didsbury, Manchester. The Acid Rain Information Centre (ARIC) is supported by Tameside M.B.C. on behalf of the Association of Greater Manchester Authorities.     

Embryonic and parental preferences for incubation temperature in herring gulls: implications for parent-offspring conflict

According to Trivers (1974), parent-offspring (P-O) conflict arises because offspring are selected to solicit more care than parents are selected to provide. However, should benefits fail to increase with increasing care, the offspring optimum can be reduced to the point where predicted P-O conflict vanishes. We examined offspring demand and parental care in such a benefit-limited system in herring gulls (Larus argentatus). In this species, parents typically neglect their lasthatched (C-) egg during the final hours of hatching (pipped-egg stage), allowing mean temperature to drop by about 4°C, to near 33°C. Other studies indicate that no increased offspring benefit arises from increasing pipped egg incubation temperature above that level, but embryo damage occurs if temperature drops lower. In such a system, P-O conflict over preferred incubation temperature is predicted to be minimal or absent. We assessed phenotypic manifestations of conflict by determining incubation temperature preferences of parent and offspring independently. Temperature provided solely by parental initiative was 33.9°C (artificial eggs, corrected for embryonic heat production). Preferred incubation temperature of pipped embryos was measured by exposing them to moderate chilling (20°C) punctuated by 4-min periods of rewarming when they called. Temperature of vocally thermoregulating embryos stabilized around a mean of 32.9–33.4°C, about 0.5–1.0°C below parental preference. Acting independently, parents and embryos each maintained egg temperature at or near minimum developmentally safe levels. Results provided no evidence for phenotypic conflict, as predicted by a benefit-limited version of Trivers' P-O conflict model. Benefit limitation may also be relevant to P-O conflict in other contexts such as feeding of newly-hatched young.     

Removal of arsenic in tailings by soil flushing and the remediation process monitoring

In order to investigate the optimum conditions for the application of soil flushing of arsenic, a batch test was carried out using EDTA at various concentration and pH levels. Based on the optimum condition derived from the batch test, a column test was conducted to examine the feasibility of the soil-flushing technology under field-equivalent conditions. In this column test, a low flushing solution flow rate showed a significantly higher As removal efficiency (71.6%) than a high flow rate (56.3%). TCLP (toxicity characteristic leaching procedure) and a seed germination test were carried out to monitor the toxicity both during and after the treatment. The finally treated tailings were shown to be significantly remediated, having a reduced toxicity by both the TCLP and seed germination tests.     

气候变化对淡水珍珠蚌种群的威胁

引言 在过去的100年中,淡水珍珠蚌Margaritfera margaritifera(L.)的数量在地球北区范围内已经下降到被IUCN列为濒危品种[1].人们认为主要原因是严重的工业污染和农业(有机)污染,采珠渔民的过度开采,寄主鲑科鱼类的减少,以及由于水力发电和河流管理计划的实施所造成的自然河床栖息环境的退化[2].     

Trace Metals in New England Marine Sediments: Casco Bay, Maine, in relation to Other Sites

The concentrations in surface sediments of the trace metals Cd, Cr, Cu, Ni, Pb and Zn have been determined at 32 stations in the Casco Bay region of the Gulf of Maine. The metals are not distributed homogeneously but exhibit elevated levels around the Portland waterfront and generally low levels at offshore and tidally scoured stations. Comparison of these results to those from both industrialized and non-industrialized sites throughout New England indicates that the sediments in parts of the Casco Bay region are affected by trace metals.     

Absorption and metabolism of the chiral isomers of fonofos in the corn and cotton plant

Root absorption of chiral phenyl-35S-fonofos in cotton and corn plants revealed stereoselective differences between the two enantiomers. (S)p-Fonofos was absorbed at a faster initial rate and to a greater extent than the (R)p enantiomer in both plant species. Approximately 40% and 62% of the applied radioactivity was absorbed into the cotton plant 12 hr after application of (R)p- and (S)p-fonofos, respectively. In the corn plant, approximately 25% and 63% of the applied (R)p- and (S)p-fonofos was absorbed in the first 12 hrs. Little qualitative or quantitative difference in plant translocation between fonofos enantiomers was observed. (R)p-fonofos was found to be metabolized to a greater extent than the (S)p enantiomer in both cotton and corn plants.