Effects of land use on phosphorus loss in the hilly area of the Loess Plateau, China

The hilly area of Loess Plateau has some of the highest soil erosion rates in the world, and serious soil erosion causes great losses of plant nutrients. As the most common land use in Loess Plateau, slope farmland contributed most of the erosion soils. This study was designed to examine the effects of land use and slope angle of farmland on phosphorus (P) loss in the hilly area of loess plateau. Farmland (FR), barrenland (BR), and four forest treantment (seabuckthorn+ poplar (SP), immature seabuckthorn (IS), mature seabuckthorn (MS), immature Chinese pine (ICP)) were the types of land use; 10, 15, 20, 25, 30 degrees were the slope angles of FR that were compared. The results showed a larger proportion of P loss occurred in erosion soil fraction of FR, ICP, ICP, and the five slope treatments of FR; in SP, IS, and MS, P loss was primarily through runoff. FR produced more P loss than SP, IS, ICP, BR, and MS. 20∼30 degrees may be the slope ranges for P loss of FR; FR in this ranges would loss more P with soil erosion. SP, IS, and MS were reasonable land uses for their less runoff, soil loss, and P loss. Farmlands over 15 degrees should be abandoned or reforested for it would produce more runoff, soil loss, and P loss.     

Austal 2000应用于国内“烟塔合一”类项目大气影响评价

简述了德国"烟塔合一"类大气污染扩散模式,以及相关模式Austal 2000的应用方法,修正了气象参数以适合本地化应用。以天津某电厂为实例,将Austal 2000模式"烟塔合一"和烟囱排烟方式的计算结果进行了对比分析。结果表明,在进行本地化修改后,Austal 2000模式适用于国内有关项目大气预测评价,但从环境影响角度考虑,"烟塔合一"相对于高烟囱排放方式没有明显优势,应用时需慎重。     

Dynamics of water soluble phosphorus from surface applied broiler litter

Deionized water is routinely used as an extractant to determine soluble phosphorus (P) in broiler litter, but under N.E. Georgia conditions this technique may underestimate the hazard of P loss in runoff because the alkalinity of the broiler litter-water suspension limits the solubility of P compounds that may be solubilized after being spread on acidic field conditions. In this study under controlled conditions we measured soluble P in thatch and top soil after applying untreated broiler litter, residue of broiler litter after water extraction (WER), or residue of broiler litter after extraction with a 2-(N-morpholino) ethanesulfonic acid (MES) buffer at pH 6 (BER). During the 60 d incubation, the WER released 18 % more Total Dissolved P (TDP) than was determined through a conventional water extraction procedure, whereas the BER released 28 % less TDP than the WER, which reflects the greater amount of TDP removed from the broiler litter by the buffer at pH 6.0. However, the total amount of TDP extracted by the MES buffer, which includes that removed at the initial extraction plus that released during the incubation, was 30 % greater than the total amount of TDP extracted with water from the untreated litter plus the TDP extracted with water from the WER during the incubation. This result suggests the need to fine-tune the solid: liquid ratio and shaking time when the MES buffer is used.     

Hydroxylation of bisphenol A by hyper lignin-degrading fungus Phanerochaete sordida YK-624 under non-ligninolytic condition

Bisphenol A (BPA) is one of the representative compounds of the endocrine disrupting compounds group and the highest volume chemicals produced worldwide. As a result, BPA is often detected in many soil and water environments. In this study, we demonstrated the transformation of BPA from liquid cultures inoculated with hyper lignin-degrading fungus Phanerochaete sordida YK-624. Under non-ligninolytic condition, approximately 80% of BPA was eliminated after 7 d of incubation. High-resolution electrospray ionization mass spectra and nuclear magnetic resonance analyses of a metabolite isolated from the culture supernatant suggested that BPA was metabolized to hydroxy-BPA, 4-(2-(4-hydroxyphenyl)propan-2-yl)benzene-1,2-diol, which has a much lower estrogenic activity than BPA. In addition, we investigated the effect of the cytochrome P450 inhibitor piperonyl butoxide (PB) on the hydroxylation of BPA, markedly lower transformation activity of BPA was observed in cultures containing PB. These results suggest that cytochrome P450 plays an important role in the hydroxylation of BPA by P. sordida YK-624 under non-ligninolytic condition.     

二噁英降解酶的研究进展

二噁英是一类广泛分布于环境中的持久性有机污染物,它们能够在食物链中逐级积累,并可引发多种细胞毒性,严重影响生态系统和人类健康。在众多二噁英降解方法中,生物降解法以环境友好和低成本等优点一直受到国内外学者的青睐,而二噁英降解酶是生物降解法中的关键物质。简要综述了近年来二噁英典型降解酶的降解机制、效果和编码基因等方面研究进展,并对二噁英降解酶未来的研究和应用方向进行了展望。     

Modeling forest floor contribution to phosphorus supply to maritime pine seedlings in two-layered forest soils

The quantitative contribution of the forest floor to P nutrition of maritime pine seedlings was experimentally determined by Jonard et al. (2009) in a greenhouse experiment using the radio-isotopic labeling. To extend the results of the experiment on a known mineral soil, a modeling approach was developed to predict P uptake of maritime pine seedlings growing in a mineral soil covered with a forest floor layer. The classical nutrient uptake model based on the diffusion/mass-flow theory was extended to take into account mineralization of P in dead organic matter, microbial P immobilization and re-mineralization and P leaching. In addition, the buffer power characterizing the P retention properties of the mineral soil was allowed to vary with time and with the P-ion concentration in solution. To account for increasing root competition with time, a moving boundary approach was implemented. According to the model, the forest floor contributed most of the P supply to the seedlings (99.3% after 130 days). Predicted P uptake was consistent with observed P uptake and modeling efficiency was 0.97. The uptake model was then used to evaluate the impact of the P retention properties of the mineral soil on the contribution of the forest floor to P uptake. Simulations showed that the contribution of the forest floor was much lower in the quasi non-reactive soil (45.7%) but rapidly increased with soil P reactivity.     

亚热带丘陵区绿狐尾藻人工湿地处理养猪废水氮磷去向

以亚热带丘陵区为研究区,采取野外定位观测的研究方法,选取耐高氮（N）、磷（P）的绿狐尾藻为湿地植物,建立稻草基质池+6级绿狐尾藻表面流湿地系统,湿地总面积1597 m²,水力负荷0.06~0.14 m·d^-1,水力停留时间31 d,研究此湿地系统对养猪废水（NH₄⁺-N：535.4~591.09 mg·L^-1、TN：682.09~766.96 mg·L^-1、TP：57.73~82.29 mg·L^-1和COD：918.4~1940.43 mg·L^-1）的治理效果,旨在为亚热带高负荷猪废水的生态治理提供参数依据.结果表明,湿地系统对NH₄⁺-N、TN、TP和COD的平均去除率为97.4%、97.1%、91.0%和90.2%,其中以CW1累积贡献率最大（37.3%、38.4%、43.3%和27.4%）.植物N、P吸收量在23.87~79.96 g·m^-2和5.34~18.98 g·m^-2之间,占湿地N、P去除量的19.1%和20.2%;底泥N、P吸附量在19.17~56.62 g·m^-2和10.59~26.62 g·m^-2之间,占去除量的19.8%和61.7%.湿地N、P去除率与影响因子间的关系表明,环境因子解释了湿地N、P去除率的79.9%和70.1%.其中,DO是湿地系统N去除的主要因子,底泥P吸附是P去除的关键.     

UV-LED/P25-based photocatalysis for effective degradation of isothiazolone biocide

• UV-LED with shorter wavelength was beneficial for photocatalytic degradation. • SRNOM dramatically inhibit the degradation. • ·OH acts as the active radical in photocatalytic degradation. • Degradation mainly undergoes oxidation, hydrolysis and chain growth reactions. In this work, LED-based photocatalysis using mixed rutile and anatase phase TiO₂ (P25) as the photocatalyst could effectively remove 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and methylisothiazolone (MIT) simultaneously, with removal efficiencies above 80% within 20 min. The photocatalytic degradation of both CMIT and MIT could be modeled using a pseudo-first-order rate equation. The photocatalytic degradation rates of CMIT and MIT under LED280 illumination were higher than under LED310 or LED360 illumination. At concentrations below 100 mg/L, the degradation rate of CMIT and MIT under LED illumination significantly increased with increasing catalyst dosage. Additionally, the effects of the chloride ion concentration, alkalinity and dissolved organic matter on the photocatalytic degradation reaction were also investigated. The ·OH free radicals were determined to play the primary role in the photocatalytic degradation reaction, with a degradation contribution of >95%. The photocatalytic degradation of CMIT and MIT mainly occurred via oxidation, hydrolysis, and chain growth reactions. Finally, the possible photocatalytic degradation pathways of CMIT and MIT over LED/P25 are proposed.     

REGIONAL NITRATE LEACHING VARIABILITY: WHAT MAKES A DIFFERENCE IN NORTHEASTERN COLORADO

ABSTRACT: The high spatial variability of nitrate concentrations in ground water of many regions is thought to be closely related to spatially-variable leaching rates from agricultural activities. To clarify the relative roles of the different nitrate leaching controlling variables under irrigated agriculture in northeastern Colorado, we conducted an extensive series of leaching simulations with the NLEAP model using best estimates of local agricultural practices. The results of these simulations were then used with GIS to estimate the spatial variability of leachate quality for a 14,000 ha area overlying the alluvial aquifer of the South Platte River. Simulations showed that in the study area, differences in soil type might lead to 5–10 kg/ha of N variation in annual leaching rates while variability due to crop rotations was as much as 65 kg-N/ha for common rotations. Land application of manure from confined animal feeding operations may account for more than 100 kg-N/ha additional leaching. For a selected index rotation, the simulated nitrogen leaching rates across the area varied from 10 to 299 kg/ha and simulated water volumes leached ranged from 13 to 76 cm/yr depending on soil type, irrigation type, and use of manure. Resulting leachate concentrations of 3.5–140 mg/l NO₃ as N were simulated. Land application of manure was found to be the most important factor determining the mass flux of nitrate leached and the combination of sprinkler irrigation and manure application yields the highest leachate concentrations.