Co-composting of livestock manure with rice straw: Characterization and establishment of maturity evaluation system

Composting is considered to be a primary treatment method for livestock manure and rice straw, and high degree of maturity is a prerequisite for safe land application of the composting products. In this study pilot-scale experiments were carried out to characterize the co-composting process of livestock manure with rice straw, as well as to establish a maturity evaluation index system for the composts obtained. Two pilot composting piles with different feedstocks were conducted for 3 months: (1) swine manure and rice straw (SM–RS); and (2) dairy manure and rice straw (DM–RS). During the composting process, parameters including temperature, moisture, pH, total organic carbon (TOC), organic matter (OM), different forms of nitrogen (total, ammonia and nitrate), and humification index (humic acid and fulvic acid) were monitored in addition to germination index (GI), plant growth index (PGI) and Solvita maturity index. OM loss followed the first-order kinetic model in both piles, and a slightly faster OM mineralization was achieved in the SM–RS pile. Also, the SM–RS pile exhibited slightly better performance than the DM–RS according to the evolutions of temperature, OM degradation, GI and PGI. The C/N ratio, GI and PGI could be included in the maturity evaluation index system in which GI > 120% and PGI > 1.00 signal mature co-composts.     

基于管理成熟度的大型水利水电工程环境绩效评价研究

借鉴项目管理成熟度模型的研究方法,构建了大型水利水电工程环境管理成熟度模型,对模型的组成、内容和评价方法进行了定义.结合大型水利水电工程施工过程中的生态环境影响因素分析,建立了大型水利水电工程的环境绩效评价体系,并采用数据包络分析(DEA)动态评估模型进行了环境管理成熟模型评价.案例研究表明,大型水利水电工程环境绩效评价结果能较好的反映出工程施工期间的环境管理成熟度水平,并能反映持续改进方面的环境贡献,研究成果对于改善我国大型水利水电工程建设对生态环境的影响及制定相关政策具有重要意义.     

Residual benefits of promiscuous soybean to maize (Zea mays L.) grown on farmers’ fields around Minna in the southern Guinea savanna zone of Nigeria

Biological nitrogen fixation (BNF) by promiscuous cultivars of soybeans (Glycine max (L.) Merr.) in cereal-based cropping systems of Nigeria’s moist savanna zone offers a potential for minimizing the investment made by resource-poor farmers on nitrogen fertilizers. A 3-year trial was conducted on five farmers’ fields in the southern Guinea savanna zone of Nigeria to assess the residual effects of two successive crops of promiscuous soybean cultivars on the yield of a following maize (Zea mays L.) crop. The soybean cultivars, TGX1456-2E (medium maturity) and TGX1660-19F (late maturity), were grown in 1996 and 1997. Treatments, imposed only in the first year of the trial, were: (i) uninoculated, (ii) inoculated with a mixture of two Bradyrhizobium strains, and (iii) fertilized with 60 kg N ha⁻¹. A fourth treatment was a plot left to fallow. In 1998, all the previous soybean and fallow plots were sown to maize without any fertilizer application. Results in 1996 and 1997 showed a soybean response to inoculation in the first year, but differences due to the residual effect of inoculation in the second year were not significant. Both cultivars showed a similar response to inoculation but responses at the five sites were varied. Soybean cultivar 1456-2E fixed 43–52% of its N amounting to 56–70 kg N ha⁻¹ and cultivar 1660-19F derived 39–54% of its N from N₂-fixation which amounted to 51–78 kg N ha⁻¹. Both cultivars had a high N harvest index resulting in a net removal of 52–95 kg N ha⁻¹ when both grain and stover were exported. Even when the stover was returned, there was a depletion of 23–65 kg N ha⁻¹, with 1456-2E removing more N than 1660-19F. Arbuscular-mycorrhizal infection on maize roots was 11–27% and dependent on previous soybean treatments and farmers’ fields. Plant height, shoot biomass, grain yield, and N uptake of maize were significantly greater in plots previously sown to soybean than in the fallow plots. In general, plots sown to the late maturing cultivar 1660-19F exhibited better residual effect, producing larger yield parameters than the plots planted with medium maturing 1456-2E.     

Chlorpyrifos degradation in a biomixture of biobed at different maturity stages

The biomixture is a principal element controlling the degradation efficacy of the biobed. The maturity of the biomixture used in the biobed affects its overall performance of the biobed, but this is not well studied yet. The aim of this research was to evaluate the effect of using a typical composition of Swedish biomixture at different maturity stages on the degradation of chlorpyrifos. Tests were made using biomixture at three maturity stages: 0 d (BC0), 15 d (BC15) and 30 d (BC30); chlorpyrifos was added to the biobeds at final concentration of 200, 320 and 480 mg kg⁻¹. Chlorpyrifos degradation in the biomixture was monitored over time. Formation of TCP (3,5,6-trichloro-2-pyrinidol) was also quantified, and hydrolytic and phenoloxidase activities measured. The biomixture efficiently degraded chlorpyrifos (degradation efficiency >50%) in all the evaluated maturity stages. However, chlorpyrifos degradation decreased with increasing concentrations of the pesticide. TCP formation occurred in all biomixtures, but a major accumulation was observed in BC30. Significant differences were found in both phenoloxidase and hydrolytic activities in the three maturity stages of biomixture evaluated. Also, these two biological activities were affected by the increase in pesticide concentration. In conclusion, our results demonstrated that chlorpyrifos can be degraded efficiently in all the evaluated maturity stages.     

Influence of the composition of the initial mixtures on the chemical composition,physicochemical properties and humic-like substances content of composts

The influence of the proportion of C- and N-rich raw materials (initial C/N ratio) and bulking agent on the chemical functional groups composition, humic-like substances (HS-like) content and physicochemical properties of composts was assessed. To achieve these goals, seven initial mixtures (BA1–6 and C1) of dog food (N-rich raw material) were composted with wheat flour (C-rich raw material). Composts were analyzed in terms of chemical functional groups, physicochemical, maturity and stability parameters.The C-rich raw material favored the formation of oxidized organic matter (OM) during the composting process, as suggested by the variation of the ratios of the peaks intensity of FT-IR spectra, corresponding to a decrease of the polysaccharides and an increase of aromatic and carboxyl-containing compounds. However, although with high proportion of C-rich raw material, mixtures with low initial C/N seems to have favored the accumulation of partially oxidized OM, which may have contributed to high electrical conductivity values in the final composts. Therefore, although favoring the partial transformation of OM into stabilized HS-like, initial mixtures with high proportion of C-rich raw material but with low initial C/N led to unstable composts.On the other hand, as long as a high percentage of bulking agent was used to promote the structure of biomass and consequently improve of the aeration conditions, low initial C/N was not a limiting factor of OM oxidation into extractable stabilized humic-like acids.     

Socially induced delayed primiparity in brown bears Ursus arctos

Reproductive suppression through behavioral or physiological means is common in group-living and cooperative breeding mammals, but to our knowledge it has not been shown in wild large carnivores other than those with a clear form of social organization. Brown bear (Ursus arctos) females form matrilinear assemblages with related females using a common and largely exclusive area. Behavioral reproductive suppression might develop due to a hierarchical system among females within a matrilinear assemblage or due to inbreeding avoidance, because male brown bears can overlap with their daughters. We tested whether natal dispersal influenced the age of primiparity. We predicted that emigrant females, geographically removed from maternal or paternal influence, would reproduce earlier than philopatric females. The average age of primiparity was 4.3 years in females that dispersed outside their mother’s home range (n=8) and 5.2 years in philopatric females (n=10). Only the overlap with the mother’s home range, and not body size, body mass, growth, local population density, or overlap with the father’s home range, had a significant influence on the age of primiparity. The ultimate role of reproductive suppression for brown bears is likely to avoid inbreeding or to minimize resource competition. Due to the low risk of inbreeding and frequent exposure of young females to unrelated males, we conclude that resource competition within female hierarchies causes reproductive suppression in young females.     

Fluorescence excitation-emission spectroscopy with regional integration analysis for assessment of compost maturity

Composting of animal manures is believed as an alternative way for directly recycling them in farms, and therefore assessment of compost maturity is crucial for achieving high quality compost. Fluorescence excitation-emission matrices (EEMs) combined with regional integration analysis is presented to assess compost maturity. The results showed that the EEM contours of water-extract organic matter (WEOM) from immature composts exhibited four peaks at excitation/emission (Ex/Em) of 220/340 nm, 280/340 nm, 220/410 nm, and 330/410 nm, whereas EEM contour of WEOM from mature composts had only two peaks at Ex/Em of 230/420 nm and 330/420 nm. Pearson correlation demonstrated that peaks intensity rather than their ratios had a significantly correlation with the common indices assessing compost maturity, whereas the normalized excitation-emission area volumes (Φ_i,ns) from regional integration analysis had a stronger correlation with the common indices assessing compost maturity than peaks intensity. It is concluded that the Φ_i,ns from regional integration analysis are more suitable to assess the maturity of compost than the intensities of peaks. Therefore, the fluorescence spectroscopy combined with regional integration analysis can be used as a valuable industrial and research tool for assessing compost maturity, given its high sensitivity and selectivity.     

Low-maturity Kulthieth Formation Coal: A Possible Source of Polycyclic Aromatic Hydrocarbons in Benthic Sediment of the Northern Gulf of Alaska

The successful application of forensic geology to contamination studies involving natural systems requires identification of appropriate endmembers and an understanding of the geologic setting and processes affecting the systems. Studies attempting to delineate the background, or natural, source for hydrocarbon contamination in Gulf of Alaska (GOA) benthic sediments have invoked a number of potential sources, including seep oils, source rocks, and coal. Oil seeps have subsequently been questioned as significant sources of hydrocarbons present in benthic sediments of the GOA in part because the pattern of relative polycyclic aromatic hydrocarbon (PAH) abundance characteristic of benthic GOA sediments is inconsistent with patterns typical of weathered seep oils. Likewise, native coal has been dismissed in part because ratios of labile hydrocarbons to total organic carbon (e.g. PAH: TOC) for Bering River coal field (BRCF) sources are too low--i.e. the coals are over mature--to be consistent with GOA sediments. We present evidence here that native coal may have been prematurely dismissed, because BRCF coals do not adequately represent the geochemical signatures of coals elsewhere in the Kulthieth Formation. Contrary to previous thought, Kulthieth Formation coals east of the BRCF have much higher PAH: TOC ratios, and the patterns of labile hydrocarbons in these low thermal maturity coals suggest a possible genetic relationship between Kulthieth Formation coals and nearby oil seeps on the Sullivan anticline. Analyses of low-maturity Kulthieth Formation coal indicate the low maturity coal is a significant source of PAH. Source apportionment models that neglect this source will underestimate the contribution of native coals to the regional background hydrocarbon signature.     

Assessment of nematode community structure as a bioindicator in river monitoring

Nematode communities from river water and sediments were assessed for the abundance, feeding types, maturity indices and nematode channel ratio (NCR). The sampling sites studied included different levels of pollution and contamination from agricultural, industrial and sewage sources. The nematode abundance found in the sediment samples was more than that in the water samples. The lowest nematode abundance in sediment samples and the lowest NCR in water samples were both found at the industrial pollution site. Water samples showed positive correlation between the NCR and river pollution index (RPI). Mean maturity indices in sediment samples were inversely correlated with RPI. The pollutant source determined the relationship between NCR and pollution level, while maturity index always showed negative correlation with pollutant level regardless of the pollutant sources. The nematode abundance and its community structure were both reliable bioindicators for monitoring long-term river pollution in both qualitative and quantitative aspects.     

Different analysis techniques for fluorescence excitation-emission matrix spectroscopy to assess compost maturity

Assessment of compost maturity is essential for achieving high quality compost. In this study, fluorescence excitation-emission matrix spectroscopy combined with different analysis techniques was applied to improve the sensitivity of compost maturity assessment. Results showed that composts in two parallel piles could be believed mature after 37 d when combined with the evolution of temperature, chemical and biological indices in the two piles. Pearson correlation between the common maturity indices and fluorescence analysis parameters demonstrated that fluorescence regional integration (FRI) had a higher correlation coefficient than that of fluorescence intensities and the ratios of peaks, suggesting that FRI technique is more suitable to characterize the maturity of compost than the other two analysis techniques, i.e., peak intensity and peak ratio. Furthermore, the fluorescence spectroscopy combined with FRI analysis could be used as a valuable industrial and research tool for assessing compost maturity.