The results are presented in Table 2. Individuals with higher NEP scores were more likely to favor the ‘‘don’t build’’ option over the ‘‘build out’’ option, for both open space and agricultural land. Individuals living closer to farms were more likely to favor the ‘‘don’t build’’ option over building single-family homes on agricultural land, and those with ties to the agricultural industry were more likely to oppose development on open land, as well as building single-family homes on agricultural land. We also estimated the probability of selecting each of the three development options for open space and agricultural land . Probabilities were calculated using Clarify , which takes multiple draws from the multivariate normal distribution defined by the coefficients and covariance matrix, calculates a probability for each draw, and then reports summary statistics for these probabilities.To our knowledge, our use of the NEP represents one of the first efforts to explain public opinion on public policies governing agriculture. The NEP has been used to assess the extent of environmental worldviews or to help explain pro-environmental behavior . It has also been used to explain risk perception , and attitudes toward various environmental problems . This is the first study that uses the NEP to help explain variation in attitudes toward agricultural policies. The results supported our first hypothesis. People who scored more highly on the NEP were critical of farmers and ranchers in believing they were not protecting natural areas as strongly as they should. However, they were also more likely to favor buffers around new housing developments to protect farms,round plastic plant pot a strong urban boundary planning tool, and no housing development that encroaches on open space and farmland.

They were more likely to favor the ‘‘don’t build’’ option over the ‘‘build out’’ option, for both open space and agricultural land. Although they were also not more likely to favor giving farmers and ranchers help with their property taxes if they kept their land in agriculture , given that 82% of our respondents favored the Williamson Act and only 5% opposed it, it is fair to say that environmentalists overwhelmingly support this policy. These results suggest that environmentalists support agriculture because they view it as a better option than development, not because they value it per se. What could explain this association between strong environmental attitudes and criticism of agriculture’s environmental effects, and support for conserving farmland in opposition to urban expansion? One possibility is that respondents were differentiating between mainstream industrial agriculture and more environmentally sustainable local, alternative agriculture. There has been a dramatic increase in urbanites’ interest in local food, and it is the smaller farms in and adjacent to expanding cities that tend to supply a disproportionate amount of local food via farmers markets, community-supported agriculture , and local distribution hubs that are most threatened by expanding cities. People tend to assume that this local food is much better for the environment than food produced by large-scale industrial agriculture . Our survey respondents overwhelmingly supported local food, with 89 and 91% in North County and South County respectively seeing buying local produce all, most, or some of the time as important, and 42 and 51% in North County and South County respectively reporting purchasing local food once a week . Yet while there is a strong organic farming element and local food movement in SBC, it is relatively small, with sales of USDA-certified or exempt organically produced commodities accounting for only 2.9% of total sales in SBC in 2012 , and in 2008 less than 5% of produce consumed in SBC was grown in the county, while 99% of the produce grown in SBC was exported out of the county . Large-scale conventional agriculture dominates SBC.

Our results provide only partial support for our second hypothesis. While SBC residents hold a wide range of environmental views, they lean toward the pro-environmental end of the spectrum in both northern and southern SBC, and a majority in both regions support not building on agricultural land. However, there is a clear difference regarding building on open space, with residents in the north less supportive of high-density housing and more supportive of the ‘‘don’t build’’ option, while those in the south are about evenly divided between these two options, with slightly more preferring high-density housing to not building at all.Developments in industry and agriculture have greatly improved people’s living standards, but they often cause negative impacts on environmental health. Water pollution caused by human activities is a progressively growing threat, especially in rapidly developing countries . A wide variety of pollutants are released into natural waters where they pose a serious threat to drinking water safety, human health and aquatic ecosystems . These pollutants may be further transmitted from the water to soils when the polluted water is used for agricultural irrigation, thereby entering plants and threatening food safety . Accordingly, the treatments for remediation of contaminated waste waters are necessary to protect human and ecosystem health. Various techniques have been developed for pollutants removal, including adsorption, biodegradation, coagulation/focculation, oxidation, membrane fltration etc. . Among the various methods applied to water purifcation/remediation in recent decades, sorption techniques display strong efficacy due to their high adsorption capability for selected compounds and their ease of preparation and operation . Commercial sorbents demonstrate high removal rates for selected pollutants from wastewater, however, their high production cost, intricate design and complex operational conditions often limit widespread application. Hence, there is a distinct need for low-cost and effective adsorption materials to remove pollutants from waters .

Nowadays, there is considerable interest in utilization of cheap alternatives based on the sorption potential of agricultural wastes, which provide favorable economic and eco-friendly options . Widespread agricultural and industrial activities generate large amounts of solid wastes. Some of these materials are reused, whereas other materials find no commercial utilization resulting in their ultimate disposal, which often causes environmental damage . Agricultural wastes are ubiquitous and nearly free of cost under most circumstances. Thus, conversion of these waste materials into low-cost adsorbents for water pollutant remediation is a compelling alternative that also solves a solid-waste disposal problem. There are now several examples of the utilization of raw agricultural wastes to successfully remove a myriad of water contaminants . Raw agricultural wastes usually do not have high adsorption capacity for pollutants due to their inherent chemical structure/composition . Te intermingled chemical structures comprising agricultural wastes and the low specific surface area of industrial wastes limit their physical and chemical interactions with many pollutants . Consequently, several studies have investigated modification of agricultural wastes to enhance their adsorption capacity for various contaminants . Modification processes alter several physicochemical properties of agricultural wastes, such as their hydrophilic/hydrophobic characteristics, surface area and porosity, reactive functional groups, resistance to microbiological attack and thermal stability, thereby improving the adsorption performance for pollutant removal . To date, a limited number of reviews exist on the use of agricultural wastes to adsorb pollutants and most of them take a holistic look at a variety of pollutants by focusing on either adsorbate-specific or adsorbent-specific applications . Notably, there are currently no systematic and comprehensive syntheses exploring the use and modification of agricultural wastes for pollutant abatement. Thus, in this review, we compiled and evaluated the various methods used to prepare agricultural waste adsorbents. Further,25 liter round pot we compiled the literature on the extensive use and efficiency of these modified adsorbents for removal of various pollutants. The primary goals of this review were to: present a comprehensive summary on the use of modified agricultural wastes as adsorbents in water pollution treatment; examine the myriad of mechanisms enabling pollutant removal; compile adsorption efficiency metrics for typical agricultural wastes; and provide perspectives on future applications and research needs to facilitate the efficient use of agricultural wastes in water pollution remediation.Agricultural wastes, particularly those containing cellulose, are a by-product of agricultural and forestry production and mainly composed of lignin, cellulose and hemicellulose . These components contain several functional groups in their molecular structures that can adsorb pollutants . The type of functional groups and chemical components comprising different agricultural wastes are similar, but occur in appreciably contrasting amounts. Some functional groups are shielded or sterically hindered inside the bulk structure of the organic matrix rendering them inaccessible to interact with pollutants directly, thereby hindering adsorption performance. Modification alters the nature of surface functional groups, with the specific modification methods selected to optimize products for the intended application and chemical characteristics of the targeted contaminants. Modification methods for agricultural wastes can be classified into physical and chemical modifications. Chemical modification usually creates better physicochemical properties for adsorbents, which enhance the adsorption performance more than that of physical modification techniques . Thus, chemical modification is the most common way to modify agricultural wastes.

Among these methods, alkalization, acidification, esterification, etherification, carbonization and magnetization are common modification procedures for agricultural wastes, along with surfactant modification and grafting . The following discussion provides an overview of the common modification treatments employed to alter the physicochemical properties of agricultural wastes along with a synthesis of supporting studies demonstrating the efficacy of these modified products for pollutant retention/removal.Conventionally, alkaline treatment for modification of agricultural wastes is performed by reaction with NaOH or KOH . The treatment reduces the content of amorphous constituents, such as lignin and hemicellulose, thereby increasing the surface area and exposing additional functional groups within the treated agricultural wastes . After alkaline modification, the mechanical properties and thermal stability of agricultural wastes are also improved, further facilitating enhanced pollutant removal . Asadi et al. demonstrated increased BET surface area of rice hulls following NaOH treatment from 0.7 to 4.3 m2 g−1 , which played an important role in increasing interactions between adsorbent and adsorbates. Some studies demonstrated that modified agricultural waste surfaces have augmented pores compared to the virgin feedstock , which increased pollutant adsorption through improved diffusion into pores. For example, KOH alkalization appears to unblock some pores resulting in the generation of more visible pores than the untreated material, which strongthens the retenion ciprofoxacin and tetracycline on the surface of adsorbent through hydrophobic interactions, H-bonding or van der Waals forces . Moreover, hydroxyl groups are generated in new adsorbents after NaOH treatment via hydrolysis of carbonyl groups and dissolution of lignin and hemicellulose, which enhance chemical reactivity for pollutants . Furthermore, alkaline treatment releases cations from the treated residues that increase the ion exchange capacity contributing to increased retention of cationic pollutants . As a result, NaOH treated rice husk showed strong complexation, ionic exchange and H-bonding interactions with Cu2+ due to increased hydroxyl groups content, cation exchange capacity and porosity. Notably, NaOH treatment may confer differing effects for different types of agricultural wastes. For example, sawdust generated from poplar and fr wood displayed similar adsorption capacities for Zn2+, while the adsorption capacity for Zn2+ increased by approximately 17 and 13 times for poplar and fr sawdust after NaOH treatment . The contrasting sorption capacities induced by NaOH treatment were attributed to differences in the anatomical structure and chemical composition of the contrasting woody materials. Alkaline treatment is an efficient methodology for exposing/generating functional groups on organic materials. The removal rate of Cu2+ by NaOH-thermal treated wheat straw increased to 21.9% , 25.8% , and 28.3% compared with raw wheat straw . An increased intensity of the -C-O- group and Cu2+-complexed functional groups in the FTIR spectrum of the treated wheat straw indicated that an increase of -C-O- functional groups was the main reason for enhanced Cu2+ adsorption. Similarly, NaOH treatment increased the removal rate of UO2 2+ by wheat straw from 32.64% to 84.45% due to an increase of -OH and C=O groups . Moreover, the alkaline treatment exposed more Si=O and P-O on the treated surface, which further promoted UO2 2+ adsorption . Structural changes to alkali modified agricultural wastes promote pollutant retention. Table 1 summarizes the effects of alkalization on the removal of pollutants by modified adsorbents in terms of their maximum adsorption capacities, specific functional groups and adsorption mechanisms. NaOH modified rice straw exhibited excellent adsorption capacity for ciprofoxacin . Adsorption equilibrium with ciprofoxacin was achieved at ~35min for NaOH modified rice straw and the maximum adsorption capacity was 93.5mg g−1 .