A LAND-USE POLICY BASED ON WATER SUPPLY1

ABSTRACT: Santa Fe Country, New Mexico, has adopted a land-use policy in which zoning densities provide a balance between the water use on a parcel of land and the water supply available bencath that land. In two of four mapped hydrologic zones, ground water in storage will be allowed to be mined to exhaustion in 100 years (40 years in urban areas). Elsewhere, the policy is for a steady state with use balanced by recharge. Equations to determine storage or recharge can be solved using site specific data or regional estimates of hydrologic conditions. Substantial reductions in the lot size requirements are allowed if water conservation convenants are adopted. Public acceptance indicates that the policy successfully integrates technical and political concerns. It is simple to administer, yet reflects widely expressed public goals and values.     

DEVELOPMENT AND EVALUATION OF A DIMENSIONLESS UNIT HYDROGRAPH1

ABSTRACT: A generalized unit hydrograph method is developed and evaluated for ungaged watersheds. A key component in this method is the value of a dimensionless storage coefficient. Procedures to estimate this coefficient are given using calibrated values from 142 rainfall-runoff events gaged in watershed located mainly in the Eastern US. Only limited success was obtained in predicting this storage coefficient. Thirty-seven, independent rainfall-runoff events were used to test the proposed technique. The generalized unit hydrograph predicted the observed runoff hydrographs fairly well with considerable improvement in accuracy over the SCS dimensionless unit hydrograph. Approximately one-half of test storms had percent errors in predicted peak flow rates that were less than 34 percent compared to percent error of 88 percent with the SCS method.     

The influence of mycorrhizal symbiosis and fertilizer amendments on establishment of vegetation in heavy metal mine spoil

Biomass production of Andropogon gerardii and Festuca arundinacea was assessed in mine tailings (chat), a material containing high levels of zinc. The effects of organic and inorganic fertilizer amendments, the addition of an expanded clay material, and mycorrhizal fungi on the revegetation of chat were assessed. Plant growth in chat was best with mycorrhizal inoculation combined with nitrogen (either organic or inorganic) and phosphorus fertilization. Plant growth was also achieved if the chat material was amended with expanded clay and N and P fertilizer. However, the biomass produced in contaminated soil did not equal that of similarly fertilized uncontaminated soil. Regression analysis and canonical discriminate analysis revealed significant differences in the responses of the two plant species to the various chat amendments. Although F. arundinacea generally produced greater biomass than A. gerardii, it tended to accumulate more zinc in the shoots than A. gerardii. Therefore, if plant cover is to be used as forage or if wind-blown plant dry matter is of concern, A. gerardii may be more appropriate than F. arundinacea for revegetation of these toxic sites. Alternatively, if maximum plant cover is of primary importance to reduce wind or water erosion from contaminated soils, F. arundinacea may be the species of choice.     

SO2-induced growth reductions and sulphur accumulation in wheat

Ten open-top chambers were used to obtain SO(2) concentration-response relationships for growth in wheat cv. Banks, and to study the associated sulphur accumulation. Two-week-old seedlings were exposed to 0.004, 0.042, 0.121, 0.256 or 0.517 microl litre(-1) SO(2) for 79 days, 4 h per day. Response variables measured included height, shoot weight, development stage, tiller number, ear weight per plant, average ear weight, total ear number and shoot sulphur concentration. All growth parameters were significantly negatively affected by SO(2) concentrations above and including 0.042 microl litre(-1). A highly significant positive correlation existed between shoot sulphur concentration and ambient SO(2) concentration.     

PCBs and other organochlorines in human tissue samples from the Welsh population: I--Adipose

The general exposure of humans to polychlorinated biphenyls (PCBs) and SigmaDDT (i.e., p,p'-DDT + p,p'DDE = p,p'-DDD) in Wales (UK) was determined through the analysis of adipose tissue samples collected from 75 individuals during post-mortem examinations in 1990-1991. Fifty PCB congeners were screened, of which 29 were identified in most of the samples. Congener IUPAC numbers 138, 153 and 180 were the most abundant compounds, accounting for an average of 55% of the SigmaPCB congeners analysed. SigmaPCB concentrations varied between 0.2 and 1.8 microg g(-1) of adipose tissue and were positively correlated with the donors age and negatively associated with the percentage of lipid in the adipose tissue. A progressive change in the congener pattern was noted with increasing subject age. Tissue from older individuals generally contained a relatively high proportion of the more persistent and higher chlorinated congeners. SigmaDDT concentrations ranged from 0.11 to 5.6 microg g(-1) adipose tissue, with p,p'-DDE contributing 96% towards the SigmaDDT concentration. SigmaDDT levels were also positively correlated with age. No significant differences in the SigmaPCB and SigmaDDT concentrations were noted between males and females, between people living in rural and urban locations or with the subjects' body weight at the time of their death.     

Quadrupole ion storage tandem mass spectrometry and high-resolution mass spectrometry: complementary application in the measurement of 2,3,7,8-chlorine substituted dibenzo-p-dioxins and dibenzofurans in US foods

The US Food and Drug Administration has simultaneously utilized both high-resolution mass spectrometry (HRMS) and quadrupole ion storage tandem mass spectrometry (QISTMS) in the measurement of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in 147 food samples collected in 1998 and 1999 in the US. In 1998, 20 egg samples, six scallop, 10 blue crab, eight American lobster, 10 pollack, 15 striped bass, five rockfish, 10 crawfish, seven aqua-cultured and 13 wild-caught salmon, along with 19 cream and 18 mozzarella cheese samples were measured for PCDD/Fs. QISTMS provided limits of detection (LODs) close to those produced using HRMS for many congeners in 56 samples analyzed by both techniques in 1998 and three salmon and three striped bass collected in 1999. The I-TEQs of the mean levels for measured congeners in 40 samples of fish and shellfish and 16 cheese and eggs from 1998 analyzed by HRMS and QISTMS were 0.99 and 1.1 ng/kg wet weight, respectively. The I-TEQ for mean congener levels in the 40 fish and shellfish measured by HRMS was 1.4 ng/kg wet weight. A higher sample throughput with greater data quality at a lower cost is achievable by using both QISTMS and HRMS.     

Semi-volatile species in PM2.5: comparison of integrated and continuous samplers for PM2.5 research or monitoring

Fine particles in urban atmospheres contain substantial quantities of semi-volatile material [e.g., NH4NO3 and semi-volatile organic compounds (SVOCs)] that are lost from particles during collection on a filter. Several diffusion denuder samplers have been developed for the determination of both NO3- and organic semi-volatile fine particulate components. The combination of technology used in the BOSS diffusion denuder sampler and the Harvard particle concentrator has resulted in the Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) for the 24-hr (or less) integrated collection of PM2.5, including NH4NO3 and semi-volatile organic material. Modification of the BOSS sampler allows for the weekly determination of these same species. Combination of BOSS denuder and tapered element oscillating microbalance (TEOM) monitor technology has resulted in the real-time ambient mass sampler (RAMS) for the continuous measurement of PM2.5, including the semi-volatile components. Comparison of the results obtained with the BOSS and with each of the newly developed modifications of the BOSS indicates that the modified versions can be used for the continuous, daily, or weekly monitoring of PM2.5, including semi-volatile species, as appropriate to the design of each sampler.     

Particle retention and selection by larvae and spat of Ostrea edulis in algal suspensions

Grazing rates and electivity indices of larvae and spat of Ostrea edulis L. were, measured and examined in relation to certain physical parameters using a flow-through system. Retention and size-selection were determined for the major particle sizes present in cultures of Isochrysis galbana Parke, an alga used frequently as food for bivalves. Cultures of the algae Dunaliella tertiolecta Butcher and Phaeodactylum tricornutum Bohlin were used as sources of particle suspensions of various sizes and shapes, respectively. While increases in flow rate caused increased grazing, the mode of selection of I. galbana particles remained constant. Filtration rate, F _f was related to body size, W, by the general allometric equation R _f =aW ^b,while particle-size preference in suspensions of I. galbana by both larvae and spat of O. edulis was independent of W. Grazing rates increased with temperature to an optimum temperature, which was related to the acclimation temperature. Increases above this optimum caused a reduction in feeding activity. No significant change in particle size-preference in the I. galbana suspension with temperature was observed. Grazing rates and selection were dependent, however, on particle number and volume. Both larvae and spat displayed maximum retention at optimum particle concentrations which tended to decrease with increasing particle size. Variations in cell shape of P. tricornutum had no measurable effect on selectivity by O. edulis.     

Mussels flexing their muscles: a new method for quantifying bivalve behaviour

We employed a novel technique to quantify how blue mussels Mytilus edulis react to predation risk in their environment by quantifying mussel gape using a Hall sensor attached to one shell valve reacting to a magnet attached to the other. Change in gape angle per second (CHIGA) versus gape angle plots resulted in a distribution with a boundary, which defined the maximum CHIGA of a mussel at all gape angles. CHIGA boundary plots for all individual mussels were similar in form. However, the CHIGA boundary increased in extent with mussel length (maximum CHIGA for mussel valve closures for mussels 2.98 and 79.6 mm long were −1.5 and −11°s⁻¹, respectively), showing that larger mussels opened and closed most rapidly. Mussel extract added to the seawater, a factor believed to signal predation, caused mussels to close significantly faster than otherwise (P < 0.001). This approach for assessing how mussels react to their environment indicates that mussel response to predation is graded and complex and may well indicate animal-based assessments of the trade-off between effective feeding and the likelihood of predation.