Environmental Loading Rate Research Articles

Emergy efficiency of land-use systems in the brazilian semi-arid region

Emergy analysis is used to evaluate agricultural management systems in order to diagnose their efficiency in using economic and natural resources. In this study, emergy analysis was used to evaluate an agroforestry production model and compare it to the traditional production model used in the semi-arid region of the northeast of Brazil. The agroforestry model comprises three subsystems: agrosilvopastoral (ASP), silvopastoral (SP) and preserved caatinga (CAT). For the traditional model, three subsystems were evaluated: an area under cultivation (AC); an area lying fallow for six years (F6); and an area fallow for nine years (F9). For each model and its respective subsystems, all input and output energy flows were identified. These flows were later quantified and transformed into emergy using their respective transformity values. The emergy performance of the systems and subsystems was evaluated by the indices: transformity (Tr), emergy investment ratio (EIR), emergy yield ratio (EYR), emergy renewability index (%R), environmental load rate (ELR), and emergy sustainability index (ESI). It was found that the agroforestry model uses a lower quantity (-13%) of natural resources than the traditional model. However, the agroforestry model uses 64% more resources from the economy than used in AC. More than 55% of the emergy required in the ASP and AC subsystems comes from services. The subsystems that required a greater amount of emergy and achieved less efficiency were SP in the agroforestry model and AG in the traditional model. Values for Tr were lower in CAT (2.6E+03) and higher in AC (2.4E+05). The ELR was low in all areas, ranging from 0.00 in F6 and F9 to 0.58 in SP. Values for %R ranged from 60.76 in AC to 99.98 in F6. The agroforestry system displayed better emergy performance due to a lower values for Tr and ELR, and greater renewability.

Evaluation of sustainable development of eco-economic systems in China based on emergy analysis

We comprehensively evaluated the sustainable development level in China from 2006 to 2016 based on emergy theory. According to the differences in the proportion of primary energy input, all the provinces in China were divided into four groups for inter-provincial comparison to further examine the impacts of primary energy input on the sustainable development. The results showed that under the high economic development, the continuous increase in the primary energy input rate enhanced the environmental load rate of Chinese eco-economic system from 2.78 to 3.13. Meanwhile, the increases in imports led to a decline in emergy yield rate and a decline in emergy sustainable index to 5.40. Results of inter-provincial comparison showed that the trend of emergy per area was generally consistent with the change in the primary energy input rate. Currently, economic development in most provinces was dependent on energy consumption. Among them, sustainable development in cities with dual characteristics of highly developed economics and significant environmental pressures was not optimistic, including Beijing and Shanghai. Provinces in southern China with lower energy input and higher emergy yield were stronger in sustainable development, with Jiangsu as the most representative province. Consequently, improving the efficiency of energy utilization in inland provinces, adjusting the mode of economic development and appropriately slowing down the intensity of economic development could fully alleviate the contradiction between economic growth and environmental protection, and thus steadily achieve sustainable development of ecology and economy.

Emergy-based sustainability evaluation of China's marine eco-economic system during 2006–2015

China's sustainable development is inseparable from the sustainable development of marine eco-economic system. This paper applied emergy analysis to evaluate the sustainability of China's marine eco-economic system. The results showed that China's marine eco-economic system mainly depended on renewable resources to operate and renewable resources and economic output were the most important components. The gap between inputs and outputs was expanding in China's marine eco-economic system. The emergy density of China's marine eco-economic system was low. The unit emergy value of the southern areas were higher than that of the northern areas in China. The emergy yield ratio of China's marine eco-economic system increased steadily and the emergy yield ratio showed a pattern of high, medium and low coexistence. The environmental loading rate of China's marine eco-economic system was very low. The emergy sustainability index of China's marine eco-economic system was high, and the sustainability of the marine eco-economic system was good. In order to ensure the long-term sustainable development of China's marine eco-economic system, China should adopt a series of measures.

Study on urban ecological sustainability based on emergy theory-taking Zhenjiang city as an example

With the rapid development of the economy, the deterioration of the ecological environment problem has followed and the city’s ecological assessment has become increasingly important. This article uses a quantitative ecological analysis method-emergy method to assess the ecological status of the city. The research object is Zhenjiang City. Through the calculation of a series of ecological sustainability parameters about Zhenjiang City, the city's ecological system is quantitatively evaluated. The results show that: 1. there is little change in renewable resources from 2012 to 2016 and a rapid increase according to the value of non-renewable resources; 2. the environmental load rate (ELR) has rapidly increased and the urban ecological sustainability has not improved; 3. Through Zhenjiang's GDP and GDP per capita grew rapidly from 2012 to 2016, it did not achieve satisfied results about industrial restructuring. In summary, the development in recent years has not achieved the expected effect and sustainable ecological development of Yangzhou City. The research significance of this article can provide a reference for the Zhenjiang municipal government to formulate better policies. Secondly, it has positive significance for the formulation of other urban policies.

An Evaluation of Input–Output Value for Sustainability in a Chinese Steel Production System Based on Emergy Analysis

: The social investment, natural resource consumption, and pollutant emissions involved in steel production can be evaluated comprehensively using the emergy analysis. We explored the sustainability of the steel production system from four aspects: input index, output index, input–output index, and sustainability index. The results showed that the maximum inputs were the intermediate product/recyclable materials produced within the production line; energy sources were mainly non-renewable and the emergy value of pollutants discharged was rather low. The environmental load rate of the pelletizing and sintering processes were the highest and the proportion of recycled materials for puddling and steel-making were the highest. The emergy investment rate of rolling was the highest; the emergy value of the pollutants discharged in each process was very small, and the emergy yield ratio was highest in the rolling process. Pelletizing, sintering, and steel-making were input consuming processes, but the sustainability index of puddling and rolling processes was sound. The whole process line can be sustainable, considering the useful intermediate and recyclable products.

Study on the construction of ecological network of a heavy chemical industry park based on industrial metabolism analysis: A case study of an energy heavy chemical industry

The industry characteristics of high pollution and high emission of energy heavy chemical industry pose a potential threat to the regional environmental safety. Therefore, it is very important to develop circular economy and carry out ecological transformation to achieve the pollution reduction and control. Based on the industrial metabolic theory and method, taking Energy Heavy Chemical Industry Park in Jinjie of Yulin City as the research object, this paper establishes the development mode of circular economy by constructing ecological chain network and conducted a comparative evaluation in lateral and vertical latitude using the method of energy analysis. The results showed that the energy yield in the cycle development phase (2015 ∼) increases by 51.4% and 26.4% respectively in comparison with the first phase (2008-2015) and the initial development phase (2002-2008). The energy investment rate decreased by 4% and 1.3% respectively; the environmental load rate decreased by 9% and 3.7% respectively and the sustainable energy index increased by 64.6% and 29.2% respectively. It demonstrated that the production efficiency, ecological efficiency, competitiveness and capacity for sustainable development have been significantly improved. In terms of horizontal comparison, the energy investment rate in the cycle of development (2015 ∼) was lower than the average of five provinces in northwestern China by 22%; the environmental load rate was higher than the average of five provinces in northwest China by 0.01%. This indicates that the performance of the system is higher; but the environmental load rate is somewhat high within the acceptable range. It indicates that the environmental pressure in industrial parks is larger and the system ecological efficiency needs to be further improved.

Responses of urban ecosystem health to precipitation extreme: A case study in Beijing and Tianjin

Our research explores the relationship between precipitation extreme and urban ecosystem health by using emergy analysis based on urban ecosystem health assessment and Difference-in-Difference approach. In the case study area of Beijing and Tianjin, their urban ecosystem are getting healthier with the average growth rate of the key index, urban ecosystem health, are 0.23 and 0.12 respectively, simultaneously the overall index of Beijing is a little higher than that of Tianjin. Meanwhile, urban ecosystem seemingly has nothing to do with precipitation extreme, and the health of its urban sub-ecosystem performs significantly to the precipitation extreme except the sub-ecosystems, resilience, public services and human health. Vigor, one of the urban sub-ecosystems, its ecosystem health negatively associated with precipitation extreme. And urban sub-ecosystem health of vigor will reduce 14.42 if a precipitation extreme happens. The precipitation extreme has a positive effect on organization and emergies. And urban sub-ecosystem health of organization and emergies will increase 44.11, 12.02 respectively if a precipitation extreme happens. In addition, it is apparently nonsignificant to the sub-ecosystems, resilience, public services and human health. Moreover, the extreme precipitation consumes more emergies for the city, it seems beneficial for emergy flow for that precipitation extreme negatively affects emergy/dollar ratio, environmental loading rate and positively affects total emergy. But the extreme precipitation also negatively influences emergy yield ratio. Thus, urban ecosystem health associates with precipitation extreme in a complex way, both positively and negatively. Government measures for recovering urban ecosystem health should emphasize the sub-ecosystem vigor of the city, like constructing more public facilities. And policy makers may pay more attention on environmental loading rate, like advocating improving energy use efficiency.

Efficiency estimation of urban metabolism via Emergy, DEA of time-series

Evaluating the efficiency of urban metabolism is an effective tool to quantitatively analyze the relationship between social, environmental and economic input and output in an urban ecosystem. In this paper, there are the combination Emergy synthesis, Principal Component Analysis (PCA) and Date Envelopment Analysis (DEA) of time-series approach to comprehensive assessment urban metabolism for the first time. DEA of time-series has the advantage of fully considering the technology changes every year, it can reflect clearly the overall situation of urban metabolism, including the use of various resources and the development of environmental sustainability cycle.The results show that, with the overall efficiency of metabolism ensured a generally steady rise in Changsha, the trend of urban environmental load rate is increased obviously, there is facing the huge pressure of ecosystem in Changsha. This paper suggests that government and enterprises should take measures to promote the construction of the eco industrial park, gradually realize industrial symbiosis, upgrade through the adjustment of energy structure and industrial structure.

Aerogenerador instalado en edificio multifamiliar: ¿Rentable o no? ¿Sostenible o no?

The purpose of this study was to determine the economic and environmental sustainability of a horizontal wind turbine prototype installed in a multifamily building. Economic sustainability was determined by primary classic economic study and environmental sustainability using the emergy approach. The classic economic analysis indicates that the project is not profitable (NPV = -2971.05 US dollars), and the environmental analysis (percentage of renewability: 0.18, emergy yield rate: 1.23; environmental load rate: 4.48; energy sustainability index: 0.275; energy investment ratio: 4.35 and emergy exchange rate: 0.32) indicates a high dependence of the system regarding imported machineries, an average efficiency regarding the use of local resources for the benefit of society, low environmental impact and an average production cost over other electricity production processes.

Emergy efficiency analysis of sugarcane as a raw material for ethanol production

In recent years, the expansion of sugarcane cultivation in Brazil and its growing importance in the Brazilian economy have been driven by a sharp increase in fuel alcohol production. This increase in fuel alcohol production was accompanied by increasing interest regarding the impacts of fuel crops in Brazil. In this study, regions of sugarcane expansion into deforested areas in the Atlantic Forest were studied by applying the emergy theory and indices. Environmental and economic inputs and the sustainability of the sugarcane production system were evaluated with the emergy method. The transformity (TR) was equal to 1.78E+11 seJ kg-1, the yield rate (EYR) was equal to 1.30, the investment rate was equal to 3.29, the environmental load rate was equal to 4.33, the renewability rate was equal to 18.77, and the exchange rate was equal to 1.09. The emergy indices of corn, cassava, wheat, and sugarcane (as raw materials for ethanol production) were used. In Brazil, sugarcane production for ethanol production was more emergetically sustainable based on the analysed emergy indices.

Elevation and vegetation determine Cryptosporidium oocyst shedding by yellow-bellied marmots (Marmota flaviventris) in the Sierra Nevada Mountains.

Wildlife are increasingly recognized as important biological reservoirs of zoonotic species of Cryptosporidium that might contaminate water and cause human exposure to this protozoal parasite. The habitat range of the yellow-bellied marmot (Marmota flaviventris) overlaps extensively with the watershed boundaries of municipal water supplies for California communities along the foothills of the Sierra Nevada. We conducted a cross-sectional epidemiological study to estimate the fecal shedding of Cryptosporidium oocysts by yellow-bellied marmots and to quantify the environmental loading rate and determine risk factors for Cryptosporidium fecal shedding in this montane wildlife species. The observed proportion of Cryptosporidium positive fecal samples was 14.7% (33/224, positive number relative to total number samples) and the environmental loading rate was estimated to be 10,693 oocysts animal(-1) day(-1). Fecal shedding was associated with the elevation and vegetation status of their habitat. Based on a portion of the 18s rRNA gene sequence of 2 isolates, the Cryptosporidium found in Marmota flaviventris were 99.88%-100% match to multiple isolates of C. parvum in the GenBank.

基于能值分析的无公害设施蔬菜生产系统效率和可持续性评价

PDF HTML阅读 XML下载 导出引用 引用提醒 基于能值分析的无公害设施蔬菜生产系统效率和可持续性评价 DOI: 10.5846/stxb201306041318 作者: 作者单位: 中国农业大学农学与生物技术学院,石家庄信息工程职业学院,中国农业大学农学与生物技术学院,中国农业大学农学与生物技术学院,中国农业大学农学与生物技术学院,中国农业大学农学与生物技术学院,河北省景县津龙公司 作者简介: 通讯作者: 中图分类号: 基金项目: 国家"十二五"科技支撑计划项目(2012BAD14B03) Efficiency and sustainability evaluation of a pollution-free vegetable production system based on emergy analysis Author: Affiliation: College of Agronomy and Biotechnology, China Agricultural University,,,,College of Agronomy and Biotechnology, China Agricultural University,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:发展无公害蔬菜是提高我国蔬菜品质和安全性、增强蔬菜产业竞争力的重要举措。针对蔬菜生产高投入、高产出的特点,采用能值分析方法对无公害设施蔬菜生产系统两种蔬菜栽培模式进行系统效率和可持续性评价,并与一般蔬菜生产模式进行对比。结果表明,无公害蔬菜生产模式能值利用效率、可更新比例、净能值产出率、食品安全性和可持续发展能力分别比一般蔬菜生产系统平均提高24.3%、24.9%、36.0%、98.2%和3.87倍,环境负载率平均下降64.7%,系统投入的能值货币价值平均降低20.0%。在此基础上,通过情景分析表明,如果进一步综合采用收集降雨用于棚内蔬菜灌溉、沼气发电供给蔬菜灌溉利用、通过标准化管理降低人力投入,可以使现有的无公害生产方式的能值利用效率提高3.4%-10.8%,可持续性提高1.2%-31.7%。该研究也表明,将无公害蔬菜生产纳入我国以沼气为纽带的循环农业发展模式中,实现适度的产业结合与规模化经营,能够较好的提高无公害蔬菜生产的生态经济效益和可持续发展能力。 Abstract:Substantial development is needed in the production of pollution-free vegetables to ensure the quality, safety, and competitiveness of vegetables in China. In contrast to customary vegetable production, pollution-free production uses organic fertilizers and biological pesticides instead of chemical fertilizers and chemical pesticides. This mode of production improves the safety of the vegetables and reduces environmental pollution, and the government is encouraging its use throughout China. Nevertheless, there is still considerable scope for research into efficient and sustainable vegetable production. Emergy evaluation is an effective tool in analyzing the efficiency and sustainability of an ecological system, which addresses the weakness of traditional energy analysis and expresses different forms of energy using a common physical basis, namely, solar emergy. It also has the advantage of taking into consideration aspects such as natural resources, labor, and ecosystem services that are generally left uncalculated by other evaluation methods. This paper evaluated the efficiency and sustainability of a pollution-free vegetable production system based on emergy analysis, and results were compared with those of a customary vegetable production system. At the same time, the renewability factor of each input item was introduced in this study to improve analysis of the types of energy input. The emergy input structure and energy-based indices such as emergy efficiency (UEV), renewability (ΦR), net emergy yield ratio (EYR), environmental loading rate (ELR), product safety index based-emergy (PSI), emergy sustainability index (ESI), and emergy-based monetary value (EmRMB) were analyzed to estimate the efficiency and sustainability of the pollution-free vegetable system, and to determine the key points affecting the ecological performance of the system. The results showed that the total energy input of the two modes of the pollution-free vegetables production system were 4.97×1016 sej/year and 4.12×1016 sej/year, respectively. Compared with the customary vegetable production system, the UEV, EYR, ΦR, EPSI, and ESI values of the pollution-free vegetable production system rose on average by 24.3%, 24.9%, 36.0%, 98.2%, and 387.0%, respectively; and on average the ELR value declined by 64.7% and the EmRMB by 20.0%. At the same time, we found that that labor input and irrigation were the core factors that affected the efficiency and sustainability of the system. The scenario analysis revealed that the emergy efficiency and sustainability of the current pollution-free vegetable production system could be improved by 3.4%-10.8% and by 1.2%-31.7%, respectively, by creating an efficient system capable of adjusting to changes such as collection of rainfall to irrigate vegetables in a greenhouse, usage of electricity from a biogas project to irrigate, and reducing the labor input by applying standardized management. From an economic point of view, the reduction in purchased inputs and the higher price of pollution-free vegetables can be beneficial to the farmer. Moreover, the study demonstrates that the introduction of pollution-free vegetable production into recycling agriculture and the usage of biogas slurry as the main fertilizer have positive economic and ecological effects. Consequently, there is a considerable prospect for the development of pollution-free vegetables in China. The results also indicated that emergy evaluation is an effective method to analyze the vegetable ecological system and could provide a useful tool in the development of pollution-free vegetable production in China. 参考文献 相似文献 引证文献

Environmental Efficiency Study for Jiaxing City

The calculation methods of the city emergy yield ratio (EYR), environmental load rate (ELR) and city environmental efficiency index (CEI) are defined based on the emergy analysis of city social- economic- environment complex systems. The change trends of environmental efficiency indexes are studied which is from 2003 to 2009 year of Jiaxing city. The results show that the EYR takes on a slow growth trend, from 1.17 to 1.23. The ELR takes on a growth trend also, from 5.14 to 6.99. But, the EYR average annual growth rate is only 0.66 percent which is much lower than the inflation of ELR, whose rate is 5.13 percent. In general, the CEI has a downward trend, from 0.23 to 0.18. Industrial restructuring in Jiaxing has achieved a considerable success. The study results show that, however, the environment has a high pressure still from the social economic development. The task of industrial restructuring has a long road to walk.

Dairy goat demography and Q fever infection dynamics

Between 2007 and 2009, the largest human Q fever epidemic ever described occurred in the Netherlands. The source was traced back to dairy goat farms, where abortion storms had been observed since 2005. Since one putative cause of these abortion storms is the intensive husbandry systems in which the goats are kept, the objective of this study was to assess whether these could be explained by herd size, reproductive pattern and other demographic aspects of Dutch dairy goat herds alone. We adapted an existing, fully parameterized simulation model for Q fever transmission in French dairy cattle herds to represent the demographics typical for Dutch dairy goat herds. The original model represents the infection dynamics in a herd of 50 dairy cows after introduction of a single infected animal; the adapted model has 770 dairy goats. For a full comparison, herds of 770 cows and 50 goats were also modeled. The effects of herd size and goat versus cattle demographics on the probability of and time to extinction of the infection, environmental bacterial load and abortion rate were studied by simulation. The abortion storms could not be fully explained by demographics alone. Adequate data were lacking at the moment to attribute the difference to characteristics of the pathogen, host, within-herd environment, or a combination thereof. The probability of extinction was higher in goat herds than in cattle herds of the same size. The environmental contamination was highest within cattle herds, which may be taken into account when enlarging cattle farming systems.

Exploration of sustainable development by applying green economy indicators

Following the global trend of sustainable development, development of green economy is the best way of slowing the negative ecological and environmental impact. This research establishes the Taiwan's green economic indicators based on the ecological footprint and energy analysis. The results are as follows: Taiwan's ecological footprint in 2008 intensity index was at 4.364; ecological overshoot index was at 3.364, showing that Taiwan's ecological system is in overload state. Moreover, this study utilizes energy analysis model to study the sustainable development of Taiwan. Findings showed that total energy use in 2008 was 3.14 × 10(23)sej (solar energy joule, sej), energy of renewable resources was 1.30 × 10(22)sej, energy of nonrenewable resources was 2.26 × 10(23)sej, energy of products from renewable resources was 1.30 × 10(22)sej, energy of currency flow was 8.02 × 10(22)sej and energy of wastes flow was 6.55 × 10(22)sej. Taiwan's energy per capita and the utilization rate of energy is lower while the environmental loading rate is significantly higher comparing to some other countries. The foregoing findings indicate that Taiwan currently belongs to an economic development pattern based on high resource consumption. The economic development is mainly established on the exploitation and utilization of nonrenewable resources. Therefore, Taiwan should change the development pattern, regulate the industrial structure, promote the utilization rate of resources, develop green pollution-free products, and enhance the sustainable development of ecological economic system.

Seasonal Shedding of MultipleCryptosporidiumGenotypes in California Ground Squirrels (Spermophilus beecheyi)

Twelve percent of 853 California ground squirrels (Spermophilus beecheyi) from six different geographic locations in Kern County, Calif., were found to be shedding on average 44,482 oocysts g of feces(-1). The mean annual environmental loading rate of Cryptosporidium oocysts was 57,882 oocysts squirrel(-1) day(-1), with seasonal patterns of fecal shedding ranging from <10,000 oocysts squirrel(-1) day(-1) in fall, winter, and spring to levels of 2 x 10(5) oocysts squirrel(-1) day(-1) in summer. Juveniles were about twice as likely as adult squirrels to be infected and shed higher concentrations of oocysts than adults did, with particularly high levels of infection and shedding being found among juvenile male squirrels. Based on DNA sequencing of a portion of the 18S small-subunit rRNA gene, there existed three genotypes of Cryptosporidium species in these populations of squirrels (Sbey03a, Sbey03b, and Sbey03c; accession numbers AY462231 to AY462233, respectively). These unique DNA sequences were most closely related (96 to 97% homology) to porcine C. parvum (AF115377) and C. wrairi (AF115378). Inoculating BALB/c neonatal mice with up to 10,000 Sbey03b or Sbey03c fresh oocysts from different infected hosts did not produce detectable levels of infection, suggesting that this common genotype shed by California ground squirrels is not infectious for mice and may constitute a new species of Cryptosporidium.

Improved quantitative estimates of low environmental loading and sporadic periparturient shedding of Cryptosporidium parvum in adult beef cattle.

Our primary goal was to generate an accurate estimate of the daily environmental loading rate of Cryptosporidium parvum oocysts for adult beef cattle, using immunomagnetic separation coupled with direct immunofluorescence microscopy for a highly sensitive diagnostic assay. An additional goal was to measure the prevalence and intensity of fecal shedding of C. parvum oocysts in pre- and postparturient cows as an indicator of their potential to infect young calves. This diagnostic method could detect with a > or = 90% probability oocyst concentrations as low as 3.2 oocysts g of feces(-1), with a 54% probability of detecting just one oocyst g of feces(-1). Using this diagnostic method, the overall apparent prevalence of adult beef cattle testing positive for C. parvum was 7.1% (17 of 240), with 8.3 and 5.8% of cattle shedding oocysts during the pre- and postcalving periods, respectively. The mean intensity of oocyst shedding for test-positive cattle was 3.38 oocysts g of feces(-1). The estimated environmental loading rate of C. parvum ranged from 3,900 to 9,200 oocysts cow(-1) day(-1), which is substantially less than a previous estimate of 1.7 x 10(5) oocysts cow(-1) day(-1) (range of 7.7 x 10(4) to 2.3 x 10(5) oocysts cow(-1) day(-1)) (B. Hoar, E. R. Atwill, and T. B. Farver, Quant. Microbiol. 2:21-36, 2000). Use of this highly sensitive assay functioned to detect a greater proportion of low-intensity shedders in our population of cattle, which reduced the estimated mean intensity of shedding and thereby reduced the associated environmental loading rate compared to those of previous studies.

Environmental loading rates of the waterborne pathogenic protozoa Cryptosporidium parvum in certain domestic and wildlife species in California

Author(s): Atwill, Edward R.; Phillips, Ralph; Rulofson, Franz | Abstract: Waterborne transmission of the pathogenic protozoa Cryptosporidium parvum has emerged as an important public health concern. To develop focused strategies to minimize the risk of waterborne transmission of this parasite to humans or animals, a standardized methodology is needed for comparing environmental loading rates for different populations of vertebrate hosts for C. parvum. A reasonable approximation for an estimate of the environmental loading rate is to measure the prevalence of infection and the intensity of shedding using cross-sectional surveys of the mammalian population, and then multiplying by an estimate of fecal production. We applied this concept to a variety of livestock and wildlife species found throughout California. In general we found that regardless of age, striped skunks, coyotes, California ground squirrels, and yellow-bellied marmots were substantial sources of C. parvum oocysts. In contrast, only the young stock of beef and dairy cattle were substantial sources of oocysts; adult cattle appear to excrete only limited numbers oocysts relative to either calves or wildlife. Watershed management plans that endeavor to minimize contamination of drinking water with C. parvum need to focus on appropriate management of wildlife reservoirs of C. parvum in addition to the traditional concern of animal agriculture.