Recycling silage leachate and biochar for improving nitrate removal by woodchip bioreactor.

Woodchip bioreactor (WBR) is commonly used to remove nitrate from drainage and runoff. However, the efficiency of nitrate removal in WBR is highly variable due to the properties of filling materials. In this study, we investigated the potential of recycling two waste materials, biochar (B) and silage leachate (SL), to enhance nitrate removal by providing a better living habitat and extra available carbon for denitrification. We constructed twelve lab-scale bioreactors with different filling materials (WBR, WBR + B, WBR + SL, WBR + B + SL), hydraulic retention times (HRT: 0.5-24 h), and nitrate concentrations (5.4-33 mg L-1) to test nitrate removal efficiency (NRE) and nitrate removal rate (NRR). Our results showed that the combination of biochar and silage leachate led to the highest NRE and NRR, with improvements of 23% and 48%, respectively, compared to WBR alone. However, the benefits of adding biochar and silage leachate were less apparent at longer HRTs. According to the results of our structural equation modeling (SEM), we have attributed the improved denitrification to several factors. These factors include the decrease in dissolved oxygen, saturated hydraulic conductivity, and pH value, as well as an increase in dissolved organic carbon after the addition of silage leachate. Therefore, our study provides evidence that recycling biochar and silage leachate as an additive to WBR could be a beneficial strategy for enhancing nitrate removal. Overall, this study highlights the potential of a win-win solution to improve the efficiency of nitrate removal in water treatment processes.

Soil elemental changes during human decomposition.

Mammalian decomposition provides pulses of organic matter to the local ecosystem creating ephemeral hotspots of nutrient cycling. While changes to soil biogeochemistry in these hotspots have been described for C and N, patterns associated with deposition and cycling of other elements have not received the same attention. The goal of our study was to evaluate temporal changes to a broad suite of dissolved elements in soils impacted by human decomposition on the soil surface including: 1) abundant mineral elements in the human body (K, Na, S, P, Ca, and Mg), 2) trace elements in the human body (Fe, Mn, Se, Zn, Cu, Co, and B), and 3) Al which is transient in the human body but common in soils. We performed a four-month human decomposition trial at the University of Tennessee Anthropology Research Facility and quantified elemental concentrations dissolved in the soil solution, targeting the mobile and bioavailable fraction. We identified three groups of elements based on their temporal patterns. Group 1 elements appeared to be cadaver-derived (Na, K, P, S) and their persistence in soil varied based upon soluble organic forms (P), the dynamics of the soil exchange complex (Na, K), and gradual releases attributable to microbial degradation (S). Group 2 elements (Ca, Mg, Mn, Se, B) included three elements that have greater concentrations in soil than would be expected based on cadaver inputs alone, suggesting that these elements partially originate from the soil exchange (Ca, Mg), or are solubilized as a result of soil acidification (Mn). Group 3 elements (Fe, Cu, Zn, Co, Al) increased late in the decomposition process, suggesting a gradual solubilization from soil minerals under acidic pH conditions. This work presents a detailed longitudinal characterization of changes in dissolved soil elements during human decomposition furthering our understanding of elemental deposition and cycling in these environments.

Amorphous calcium phosphate-coated surfaces as a model for bone microenvironment in prostate cancer.

Bone metastasis remains one of the biggest challenges in the treatment of prostate cancer, and other solid tumors such as breast, lung, and colon. Modeling a complex microenvironment in-vitro, such as the bone niche, requires interrogation of cell-cell interactions, specific extracellular matrix proteins and a high calcium environment. Here, we present a fast and cost-effective system in which commercially available, non-adhesive, cell culture vessels are coated with amorphous calcium phosphate (ACP) as a surrogate for bone matrix. We further present modified protocols for subculturing cells, as well as nucleic acid and protein collection in high calcium samples. We find that prostate epithelial cell lines show increased adhesion and proliferation when cultured in these surfaces, as well as independence from androgen starvation. We observe gene expression changes on ACP surfaces in early adenocarcinoma cell lines which may reflect alterations relevant to prostate cancer progression. Summary statement: To model the role of calcium in the microenvironment of the metastatic bone niche, we developed a cost-effective way to coat cell culture vessels in bioavailable calcium, and show that it has an effect on prostate cancer cell survival.

The global significance of abiotic factors affecting nitrate removal in woodchip bioreactors.

Woodchip bioreactor (WBR) is one of the green infrastructures in the agriculture system to reduce nitrate from agricultural drainage and stormwater. A lot of abiotic factors have been reported that affect nitrate removal lacking a comprehensive understanding. In this study, we studied eight important abiotic factors, including media age, hydraulic retention time (HRT), influent nitrate concentration (Cin), temperature, dissolved organic carbon (DOC), dissolved oxygen (DO), pH, and effective porosity (ρe) of WBR-filling materials. Based on a database that included 10,179 sets of data from 63 peer-reviewed articles, the nitrate removal rate (NRR) and nitrate removal efficiency (NRE) corresponding to the eight abiotic factors by different categories were comprehensively reported. According to this database, this study found the optimal range of abiotic factors for NRR and NRE in WBR were different. Regarding NRR, the optimal range of media age, HRT, Cin, temperature, effluent DOC, DO, pH, and ρe were in the first year, 0-5 h, 10-20 mg L-1, 20-25 °C, 0-5 mg L-1, 0-0.5 mg L-1, 7-8, and 0.6-0.7, respectively. For NRE, the optimal range of media age, HRT, Cin, temperature, effluent DOC, DO, pH, and ρe were in the first year, 500-3000 h, 0-10 mg L-1, 10-15 °C, >50 mg L-1, 0-0.5 mg L-1, 4-5, and 0.4-0.5, respectively. Moreover, the principal component analysis (PCA) indicated the field studies' principal components were different from laboratory studies. Furthermore, the structural equation modeling (SEM) also revealed the causal relationship of the eight abiotic factors on NRR and NRE is totally different. Lessons from this study can be incorporated into DNBR designs, especially improving nitrate removal rates by optimizing different abiotic factors. It also provides insights regarding the contributions of different abiotic factors for NRR and NRE independently and comprehensively.

The cation exchange behavior of tylosin in loess-derived soil.

Tylosin (Tyl) is a veterinary antibiotic commonly used in swine and poultry production. Due to metabolic inefficiencies, it enters the environment through manure applications. Ion exchange is an important retention mechanism for Tyl, particularly for smectite clay. The objectives of this study are to characterize the exchange interactions of Tyl with common soil cations in subsoil horizons that contain smectite and to investigate the interactions using in situ Fourier transform infrared (FTIR) spectroscopy. Adsorbed Tyl in pH neutral, smectitic subsoil horizons is divided into exchangeable and nonexchangeable forms. The percentage of adsorbed Tyl that is exchangeable varies from 36% to 43% when Na+ is the competing cation, and from 57% to 66% when Ca2+ competes. In NaX-TylX binary exchange systems, neither Na+ nor Tyl+ is preferred by the clay exchange phase, and the Vanselow selectivity coefficients (KV) for the NaX→TylX exchange reaction range between 0.79 and 1.41. In the CaX2-TylX systems, Tyl+ is preferred by the clay exchange phase when the equivalent fraction of TylX (ETylX) is less than 0.4. The KV values for the CaX2→TylX exchange reaction are at a maximum at the lowest ETylX values, with 17.6

Ammonia Volatilization Loss and Corn Nitrogen Nutrition and Productivity with Efficiency Enhanced UAN and Urea under No-tillage.

New urease and nitrification inhibitors and polymer coatings were introduced in recent years, but their effects on N loss and plant N nutrition were scarcely examined in agronomic no-tillage production systems. A field experiment of urea treated with efficiency enhancers was conducted on no-tillage corn (Zea mays L.) in Tennessee, the USA during 2013-2015. A field experiment on urea and ammonium nitrate (UAN) treated with efficiency enhancers was carried out on no-tillage corn in Tennessee in 2014 and 2015. Urea treated with N-(n-butyl) thiophosphoric triamide (NBPT) at concentrations of 20% (NBPT1), 26.7% (NBPT2), or 30% (NBPT3) and polymer coated urea (PCU) were effective but maleic-itaconic copolymer treated urea was ineffective in reducing ammonia volatilization loss and improving N nutrition, grain yield, and N agronomic use efficiency of corn compared with untreated urea. Specifically, NBPT1, NBPT2, or NBPT3 treated urea and PCU reduced the total ammonia volatilization loss by 29.1-78.8%, 35.4-81.9%, 77.3-87.4%, and 59.1-83.3% during the 20 days after N applications, but increased grain yield by 15.6-31.4%, 12.9-34.8%, 18.7-19.9%, and 14.6-41.1%, respectively. The inhibitory effect of NBPT on ammonia volatilization did not improve with NBPT concentration increased from 20% to 30%. UAN treated with NBPT3 or a combination of urease and nitrification inhibitors resulted in 16.5-16.6% higher corn yield than untreated UAN only when they were surface applied. In conclusion, when urea-containing fertilizers are surface applied without any incorporation into the soil under no-tillage, their use efficiencies and performances on corn can be enhanced with an effective urease inhibitor in areas and years with noticeable urea N losses.

Effect of pH on surface characteristics of switchgrass-derived biochars produced by fast pyrolysis.

Surface properties of switchgrass-derived biochars produced at fast pyrolysis temperatures of 450, 600 and 800 °C were characterized at different solution pHs in order to determine the structural and chemical changes of artificially-weathered biochars when incorporated into soil. As biochars were acidified from pH 7 to 3, crystalline minerals dissolved slowly releasing nutrients; however, residual minerals were still detected in biochars produced at higher pyrolysis temperatures after pH treatment. Moreover, the amount of exchangeable bases and other inorganic compounds released from the biochars increased when pH decreased. As minerals dissolved from the biochars, total surface area and pore volume were found to increase. Surface functional groups and water vapor adsorption capacity at 0.8 P/Po also increased, whereas the potential CEC of biochars decreased due to the replacement of exchangeable sites by hydrogen ion. Therefore, during the aging process, it is predicted that soil-incorporated biochars will slowly release nutrients with changes in surface functionality and porosity, which are expected to enhance water holding capacity of soil and provide a beneficial habitat for microbial colonization.

Metallohistins: a new class of plant metal-binding proteins.

Two small multimeric histidine-rich proteins, AgNt84 and Ag164, encoded by two nodule-specific cDNAs isolated from nodule cDNA libraries of the actinorhizal host plant Alnus glutinosa, represent a new class of plant metal binding proteins. This paper reports the characterization of the purified in vitro-expressed proteins by size exclusion chromatography, circular dichroism, equilibrium dialysis, metal affinity chromatography coupled with mass spectrometry, and nuclear magnetic resonance spectroscopy. These analyses reveal that each polypeptide is capable of binding multiple atoms of Zn2+, Ni2-, Co2+, Cu2+, Cd2+ and Hg2+. A reversible shift in histidine Cepsilon1 and Cdelta2 protons in NMR analysis occurred during titration of this protein with ZnCl2 strongly suggesting that histidine residues are responsible for metal binding. AgNt84 and Ag164 are not related to metal binding metallothioneins and phytochelatins and represent a new class of plant metal binding proteins that we propose to call metallohistins. Possible biological roles in symbioses for AgNt84 and Ag164, and their potential for use in bioremediation are discussed.