Year-round film mulching in winter wheat field facilitates rainwater storage in summer fallow period and reduces water evaporation in growing reason, and then increases water use efficiency in the dryland of the Loess Plateau, China. Optimized fertilization further promotes fertilizer utilization efficiencies. In this study, plastic film mulching was extended from plant growth season to summer fallow, and fertilizers were applied by monitoring soil nutrient availability. Field trials were conducted in the dryland of the Loess Plateau over 4 years by using four types of cultivation to investigate the effects of year-round plastic film mulching with monitored fertilization on utilization efficiencies of rainwater and nitrogen (N), and winter wheat yield. The four types of cultivation were farmer practice (FP), ridge-furrow with plastic film mulching system plus conventional fertilization(RPCF), ridge-furrow with plastic film mulching system plus monitored fertilization (RPFM), and flat soil surface with plastic film mulching system plus monitored fertilization (FPFM). Our results indicate that the average yield of winter wheat in RPFM and FPFM treatments was 4491 kg ha⁻¹. Compared with FP treatment, the combined effects of monitored fertilization and film mulching(RPFM and FPFM treatments) could increase grain yield in the range of 24.7 to 42.1%. The film mulching extended to the fallow season increased the water storage in 2 m depth of soil profile, and the amount of soil water storage in the summer fallow period increased by 27 to 30% in FPFM treatment than FP treatment. After 4-year consecutive planting of wheat, the accumulation of nitrate-N in 2 m soil reached 277 kg·ha⁻¹ in the FP treatment, which is 87.7% higher than of the level at the beginning of the experiment. Seventy-five percent of nitrate-N was distributed in the soil layer of 0–120 cm. In addition, the residual nitrate-N showed downward leaching with rainfall during the experiment. The RPFM and FPFM treatments reduced the apparent loss and residual levels of soil N, whereas increased its apparent mineralization compared with FP treatment. The FPFM treatment exhibited a greater utilization of residual nitrate-N from previous years and showed a higher amount of the mineralized N from soil organic matter, therefore leading to a relatively high apparent utilization rate of N (56.7%). Considering both grain yield production and utilization efficiencies of water and N, FPFM with year-round mulching was the most effective cultivation measure for winter wheat in the Loess Plateau.

Algae are being grown for wastewater purification and biofuels production. Their growth on a substrate facilitates these uses by allowing facile separation of algae from the water. Here, we compare different materials to determine which would best serve this purpose. A mixed culture of Anabaena and Chlorella was grown on various synthetic and natural fiber fabric substrates in a trough system with recirculating simulated wastewater. Filter materials studied as substrates for algal growth were muslin, olefin, pellon (acrylic), two types of polyester, and two types of nylon. Biomass accumulation on the various filter substrates was recorded at 7, 14, and 28 days. Filters were weighed before and after the growth periods and changes in dry biomass were recorded. Biomass accumulation was significantly affected by the fabric type. Olefin fostered the greatest increase in biomass while nylon and polyester also supported competitive increases in biomass. Pellon showed the smallest biomass increase and muslin decreased in mass due to material disintegration. Other concerns such as abrasion resistance and UV susceptibility are discussed.

The affordability of candies and chocolates makes their consumption common especially in children. Heavy metal contamination of these candies is well known. This study has estimated health risks associated with heavy metals (HM; Pb, Cd, Cr, Ni, and Zn) in commonly consumed candies in Nigeria. Fifty candies/sweets and chocolates/chewing gums bought from different stores in Port Harcourt and Uyo in Niger Delta, Nigeria, were processed and digested in perchloric acid. The filtrate was analyzed for these heavy metals using atomic absorption spectroscopy (AAS). Pb/Zn and Cd/Zn ratios were calculated. Daily intake, the target hazard quotient (THQ), the hazard index (HI), and the cancer risk were estimated for children. About 80% of the samples exceeded the 0.1 mg/kg permissible lead level in candies. Milk sweet had the highest Pb:Zn and Cd:Zn ratios of 0.99 and 0.40 respectively. For chocolates, the Emperor had the highest Pb:Zn (0.50) ratios and Trident had the highest Cd:Zn (0.57) ratios. The calculated percentage provisional tolerable weekly intake (%PTWI) of cadmium from consumption of chocolates and candies was higher than the Joint Expert Committee for Food Additives (JECFA) standard, and the cancer risk of lead, cadmium, and chromium ranged between 10⁻⁷ and 10⁻³. Consumption of some candies by children in Nigeria may pose significant health risks.

In situ passivation of heavy metals by biochar mainly focuses on the effect of biochar’s pH, surface oxygen-containing functional groups (OCFGs), and ash content. In this paper, starting with the measurement of biochar’s electrical properties under different pyrolysis atmospheres and temperatures, the changes in the zeta potential of biochar and the consequent effects on cadmium immobilization in soil are studied. The results show that the zeta potential of biochar from the pyrolysis of high temperature (800 °C) is higher than that of biochar at low temperatures, so its electronegativity is weaker than that of biochar at low temperatures, but the protective effect on wheat is stronger than that of biochar obtained at low temperatures. The zeta potential of biochar obtained under a CO₂ atmosphere was higher than that of biochar prepared under a N₂ atmosphere, so its protective effect on wheat was stronger than that of biochar under N₂. The reason is that biochar particles with a high zeta potential and weak electronegativity have higher cohesion and are better at in situ passivation of Cd in soils. Namely, biochar obtained at high pyrolysis temperatures (800 °C) and prepared under a CO₂ atmosphere has better effect on Cd immobilization.

Novel and efficient animal wastewater treatment technologies of bacteria reduction are needed for preventing disease outbreak in animal herds and safeguarding environmental health. Zero-valent iron (ZVI) has been used to treat bacteria contaminated water for the past decades, but its passivation issue has been a major challenge. In this study, batch tests were performed to evaluate the effect of a hybrid zero-valent iron (h-ZVI) or a mixed ZVI/Fe₃O₄ media system on reduction of Escherichia coli (E. coli) levels. The h-ZVI media was created through a wet chemical process that uses nitrate to oxidize ZVI in the presence of externally added Fe²⁺ (aq.). Transforming ZVI into a h-ZVI system could overcome the passivation of ZVI and increase the reactivity of the media. The results demonstrated that E. coli cells in the bulk phase were removed rapidly by h-ZVI media. Majority of E. coli was attached (or adsorbed) to the surface of h-ZVI media within a few minutes, which suggested that adsorption was the dominant mechanism for bacterial removal in the initial phase. This adsorption was confirmed by fluorescence microscopy with CTC-DAPI double staining and transmission electron microscopy (TEM). Increasing contact time steadily inactivated E. coli; all cells were inactivated after 120 min of contact. The TEM results indicated that h-ZVI inactivated E. coli by causing direct damage on bacterial cell membrane. The results of this study strongly suggest that h-ZVI treatment can be used in water treatment industry where bacterial contamination is concerned.

The endogenous release of nutrients from sediments contributes to the eutrophication of landscape water to a certain degree, which depends on the characteristics of sediments. The study explored the characteristics of nitrogen (N) and phosphorus (P) released from two different sediments, which were deposited from reclaimed water (SRW) or surface water (SSW) respectively in Xi’an moat. This paper aimed to compare the effects of nutrient release from SRW and SSW on the water quality. Results showed that the maximum increase rates reached 1.21 mg TN/(L·day) and 0.11 mg TP/(L·day), respectively, in the overlying water of SRW, which were 1.6 and 2.8 times those of SSW. The released amounts of SRW were 0.192 mg TN/g and 0.038 mg TP/g, which were 4.1 and 12.7 times those of SSW. Meanwhile, the densities of benthic algae in SRW and SSW were 5.605 × 10⁹ and 2.846 × 10⁸ cells/L, respectively. Moreover, the species number and individual sizes of benthic algae in SRW were also larger than those in SSW, which played an important role in the nitrogen circulation. Unexpectedly, oxidation reduction potential (ORP) level of SRW was lower than that of SSW, although SRW has a higher dissolved oxygen level. Therefore, the N and P concentrations in the overlying water of SRW were considerably higher than those of SSW, which was mainly attributed to the higher nutrient contents and lower ORP in SRW.

To investigate the effects of antibiotics on nitrogen removal and uptake by wetland plants, four typical macrophyte species, Cyperus alternifolius L., Typha angustifolia L., Lythrum salicaria L., and Acorus calamus L., were grown in hydroponic cultivation systems and fed wastewater polluted with 10 μg L⁻¹ Ofloxacin (OFL) and Tetracycline (TET). Biomass production, nitrogen mass concentration, chlorophyll content, root exudates, and nitrogen removal efficiency of hydroponic cultivation were investigated. The results indicated that in all hydroponic systems, NH₄⁺–N was entirely removed from the hydroponic substrate within 1 day and plant nitrogen accumulation was the main role of the removed NO₃⁻. OFL and TET stimulated the accumulation of biomass and nitrogen of A. calamus but significantly inhibited the NO₃⁻–N removal ability of L. salicaria (98.6 to 76.2%) and T. augustifolia (84.3 to 40.2%). This indicates that A. calamus may be a good choice for nitrogen uptake in wetlands contaminated with antibiotics. OFL and TET improved the concentrations of total organic carbon (TOC), total nitrogen (TN), organic acid, and soluble sugars in root exudates, especially for oxalic acid. Considering the significant correlation between TOC of root exudates and nitrogen removal efficiency, the TOC of root exudates may be an important index for choosing macrophytes to maintain nitrogen removal ability in wetlands contaminated with antibiotics.

Antibiotic residues pose a threat to the health of aquatic organisms. The effects and accumulation of antibiotic ciprofloxacin (CIP) in a floating macrophyte (Eichhornia crassipes) under hydroponic conditions were investigated. It was found that E. crassipes exposure to CIP (< 1000 μg L⁻¹) could maintain a stable photosynthesis efficiency. In response to CIP stress, catalase and peroxidase activities of leaves were 7.24–37.51 nmol min⁻¹ g⁻¹ and 98.46–173.16 U g⁻¹, respectively. The presence of CIP did not inhibit the growth of the plant. After 14 days of exposure, tender leaves became white and withered, ascribed to the decline of chlorophyll content and chlorophyll fluorescence parameters. The CIP concentrations, absorbed by E. crassipes, were highest in the roots, followed by white aerial parts and green aerial parts at CIP concentrations of 100 and 1000 μg L⁻¹. These findings demonstrated that E. crassipes could absorb and tolerate CIP in a limited time-scale and imply an alternative solution for phytoremediation in water bodies contaminated with antibiotics.

This study estimates the carbon emission intensity of China’s provinces during the period from 2000 to 2015. First, the temporal and spatial pattern evolution of China’s carbon emission intensity was analyzed using spatial statistics. Then, from an innovation-driven perspective, combining the data of innovative technologies and scale factors to construct a spatial panel model to explore the main influencing factors of carbon emission intensity and its spatial spillover effect. The results show that: China’s provincial carbon emission intensity has obvious spatial agglomeration characteristics, and regional differences are improving, and the spatial spillover effect of some influencing factors is obvious; innovation indicators such as the number of patent authorizations, technical market turnover, and foreign direct investment, and GDP have a significant negative impact on carbon intensity, and the effects of general scale variables such as urbanization rate, energy consumption, and population density on carbon intensity are significantly positive.

The photochemical removal of acetaldehyde was studied in N₂ or air (O₂ 1–20%) at atmospheric pressure using side-on and head-on types of 172 nm Xe₂ excimer lamps. When CH₃CHO was decomposed in N₂ using the head-on lamp (HL), CH₄, CO, and CO₂ were observed as products in FTIR spectra. The initial removal rate of CH₃CHO in N₂ was ascertained as 0.37 min⁻¹. In air (1–20% O₂), HCHO, HCOOH, CO, and CO₂ were observed as products in FTIR spectra. The removal rate of CH₃CHO in air using the side-on lamp (SL) increased from 3.2 to 18.6 min⁻¹ with decreasing O₂ concentration from 20 to 1%. It also increased from 2.5 to 3.7 min⁻¹ with increasing CH₃CHO concentration from 150 to 1000 ppm at 20% O₂. The best energy efficiency of the CH₃CHO removal using the SL in a flow system was 2.8 g/kWh at 1% O₂. Results show that the contribution of O(₁D) and O₃ is insignificant in the initial decomposition of CH₃CHO. It was inferred that CH₃CHO is initially decomposed by the O(₃P) + CH₃CHO reaction at 5–20% O₂, whereas the contribution of direct vacuum ultraviolet (VUV) photolysis increases concomitantly with decreasing O₂ pressure at < 5% O₂. After initial decomposition of CH₃CHO, it was oxidized further by reactions of O(₃P), OH, and O₃ with various intermediates such as HCHO, HCOOH, and CO, leading to CO₂ as a final product.