Inhibition of polycyclic aromatic hydrocarbon (PAHs) release from sediments in an integrated rice and crab coculture system by rice straw biochar

In order to understand the resource utilization of plant biomass, five types of biomass materials were used to produce biochar to treat wastewater containing phosphorus. The phosphorus adsorption capacity of five materials was preliminarily compared through laboratory experiments, and two materials with strong phosphorus adsorption capacity were screened out. The physicochemical characteristics of the selected biochar were analyzed using scanning electron microscopy and a BET specific surface area analyzer, and the effects of different pH values on phosphorus adsorption of the biochar were investigated. Furthermore, the phosphorus adsorption characteristics of the selected biochar were analyzed via isothermal adsorption and adsorption kinetics models. The results showed that among the five biochar materials, only rice straw and corn straw biochar had the ability to adsorb phosphorus. The Langmuir isothermal adsorption curve showed that the adsorption capacity of rice straw biochar for phosphorus in wastewater was stronger than that of corn straw biochar, and the theoretical maximum adsorption capacity was as follows:rice straw biochar (9.78 mg·g-1)>corn straw biochar (0.39 mg·g-1). The specific surface area (148.30 m2·g-1) and total pore volume (0.11 cm3·g-1) of rice straw biochar were much higher than those of corn straw biochar (8.26 m2·g-1 and 0.03 cm3·g-1, respectively), and the contents of Mg, Ca, Fe, and Al were higher in rice straw biochar. The best pH for phosphorus adsorption of rice straw biochar and corn straw biochar was acidic. In different pH ranges (3.0-11.0), the phosphorus adsorption capacity of rice straw and corn straw biochar decreased with the increase in pH. These results indicated that rice straw biochar has strong phosphorus adsorption capacity and has a better application prospect in wastewater treatment.

Two field experiments were raised at Farm of El-Sirw Agriculture Research Station, Dammitta province, Egypt through 2018 and 2019 seasons. The present study was performed to compromise the influence of rice straw biochar and other two soil amendments of rice straw compost and gypsum on rice growth and yield of three contrasting rice varieties,Giza177 (salt sensitive variety), Giza 178 (salt tolerant variety) and Giza179 new (salt tolerant variety) under saline sodic soil. The field experiments were designed in spilt plot design with four replications. The three rice varieties were scattered in the main plot, whereas the amendment treatments; control, gypsum(G), rice straw compost (RS) and rice straw biochar (RSB) were put in the subplots. The tested rice varieties were significantly different in growth parameters, yield attributes and yields in both seasons. Giza 179 as a new salt tolerant variety provided the maximum values of rice growth characteristics and most of yield contributes and yields without significant difference with Giza178 were considering yields. Applying varying soil amendments greatly improved rice growth and yields in addition to yield attributes comparing to the control treatments. Rice straw biochar surpassed significantly other two amendments, particularly in the first season, meanwhile in the second seasonthe three soil amendments were equally in increasing grain yield. Thereby, rice straw biochar could be applied each two years but rice straw compost has to apply in two successive season to get its efficiency. Two field experiments were raised at Farm of El-Sirw Agriculture Research Station, Dammitta province, Egypt through 2018 and 2019 seasons. The present study was performed to compromise the influence of rice straw biochar and other two soil amendments of rice straw compost and gypsum on rice growth and yield of three contrasting rice varieties,Giza177 (salt sensitive variety), Giza 178 (salt tolerant variety) and Giza179 new (salt tolerant variety) under saline sodic soil. The field experiments were designed in spilt plot design with four replications. The three rice varieties were scattered in the main plot, whereas the amendment treatments; control, gypsum(G), rice straw compost (RS) and rice straw biochar (RSB) were put in the subplots. The tested rice varieties were significantly different in growth parameters, yield attributes and yields in both seasons. Giza 179 as a new salt tolerant variety provided the maximum values of rice growth characteristics and most of yield contributes and yields without significant difference with Giza178 were considering yields. Applying varying soil amendments greatly improved rice growth and yields in addition to yield attributes comparing to the control treatments. Rice straw biochar surpassed significantly other two amendments, particularly in the first season, meanwhile in the second seasonthe three soil amendments were equally in increasing grain yield. Thereby, rice straw biochar could be applied each two years but rice straw compost has to apply in two successive season to get its efficiency.

Concentrations of persistent organic pollutants (POPs), including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined in sediment and biota (fish liver) from around Scotland. The concentrations were investigated using assessment criteria developed by OSPAR and ICES. Organic contaminant concentrations, PAHs, PCBs and PBDEs in sediment, and PCBs and PBDEs in fish liver, were significantly higher in the Clyde compared to all other sea areas. This is mainly due to historic industrial inputs. Highest PCB and PAH concentrations were found in the strata furthest up the Clyde estuary, with concentrations of POPs in these strata being at levels such that there is an unacceptable risk of chronic effects occurring in marine species. Furthermore, for PAHs in Clyde sediment there was a significant negative gradient going from north to south towards the open sea. PAH and PCB concentrations in sediment and biota in all other Scottish sea areas (except for PCBs in sediment from East Scotland) were unlikely to give rise to pollution effects, being below relevant assessment criteria. Although no assessment criteria are available for PBDEs, the concentrations observed in Scottish sediments were low with all congeners below the limit of detection (LoD; 0.03 µg kg(-1) dry weight) in 140 out of a total of 307 samples analysed. Where PBDEs were detected, the dominant congeners were BDE47 and BDE99. PBDEs were detected in fish livers, although concentrations were less than 150 µg kg(-1) lipid weight in all sea areas except the Clyde where concentrations ranged between 8.9 and 2202 µg kg(-1) lipid weight. Few trends were detected in contaminant concentrations in biota or sediment at any Scottish site with more than five years data. Downward trends were detected in PAHs in sediment from the Clyde, Irish Sea and Minches and Malin Sea and PCBs in fish liver from the Moray Firth. Rules were developed for the aggregation of the contaminant data across a sea area. An overall assessment for each sea area was then assigned, looking at the frequency of sites or strata within each sea area that were above or below the relevant assessment criteria. Overall the status of the various sea areas, with respect to the assessed POPs, can be considered to be acceptable in that they were below concentrations likely to result in chronic effects for all sea areas except the Clyde.

This research aims to compare fresh biochar and NPK-enriched biochar and their decomposition levels and nutrient absorption efficiency in acid soil with soybean. Factorial randomized block design was used in this experiment and consisted of two factors. The first factor, biochar source, comprised four levels: B0: biochar without NPK, B1: rice straw biochar + NPK, B2: soybean straw biochar + NPK, and B3: wood biochar + NPK. The second factor, biochar enrichment, comprised four levels: D1: 0.5 tons ha<sup>-1</sup>, D2: 2.5 tons ha<sup>-1</sup>, D3: 5.0 tons ha<sup>-1</sup>, and D4: 10 tons ha<sup>-1</sup>. Each treatment was replicated three times, yielding 48 experiment units. The results showed that biochar enrichment with NPK affected the decomposition level. The percentage of increasing decomposition in enriched wood biochar (0.09%) was lower than rice (0.28%) and soybean (0.53%) straw biochar. An increase in NPK absorbance efficiency and soybean dry weight was evident in NPK-enriched biochar. The highest N absorbance efficiency occurred in wood biochar (21%), followed by soybean and rice straw biochar, respectively, while the highest P and K absorbances were found in rice straw biochar (35% and 26%, respectively), followed by wood and then soybean biochar.

为明确长江中游地区湖泊沉积物中多环芳烃（PAHs）的分布特征、来源及其生态风险，于2018年7月采集了该地区12个湖泊的表层沉积物样品.采用气相色谱-质谱联用仪（GC-MS）测定了沉积物中16种PAHs的含量.结果表明：12个湖泊沉积物中均检测出16种优控PAHs，PAHs的总含量在572.7~1766.2 ng/g （dw）之间（均值为976.5±285.0 ng/g （dw））.武汉市东湖沉积物中PAHs含量最高，达到1634.8±111.4 ng/g （dw）.与国内外其他地区湖泊沉积物相比，长江中游地区湖泊沉积物中PAHs含量高于国内偏远地区的抚仙湖、青海湖及博斯腾湖，低于东部地区的巢湖、太湖及美国经济工业发达地区的湖泊.根据单体PAH的聚类分析结果，12个湖泊可以分成3种类型，类型1主要以低环为主，占比为64.04%±7.02%，类型2低环和中高环分布相对平均，分别为50.76%±5.17%和49.24%±5.17%，类型3低、中、高环分布相对平均，占比分别为35.35%±3.56%、26.17%±0.45%和38.48%±3.84%.综合该区域PAHs的分布特征及异构体比值法与主成分分析法的结果表明，类型1湖泊沉积物中PAHs主要来源为煤炭、木材等生物质的燃烧源；类型2和类型3湖泊沉积物中PAHs主要来源为煤炭、木材等生物质的低温燃烧以及机动车等燃烧汽油、柴油的尾气排放和工业炼焦等化石燃料的高温燃烧源.沉积物中PAHs与总有机碳（TOC）之间显著的相关性表明，沉积物中TOC含量是影响长江中游湖泊沉积物中PAHs归趋分布的主要因素.长江中游流域湖泊沉积物中PAHs的RQ_NCs值均小于800，且RQ_MPCs值大于1的风险商值法生态风险评价结果表明，长江中游流域湖泊表层沉积物中PAHs整体呈中等风险水平.;In order to study the distribution characteristics, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in the sediments of lakes along the middle reaches of the Yangtze River, surface sediments were collected from 12 lakes in the region in July 2018. The contents of 16 PAHs were determined by gas chromatography-mass spectrometry (GC-MS). The results indicated that 16 kinds of priority PAHs were all detected in these lake sediments. The contents of total PAHs were between 572.7-1766.2 ng/g(dw)(with the mean value of 976.5±285.0 ng/g(dw)). The highest content of PAHs in the sediments of Wuhan Lake East was 1634.8±111.4 ng/g (dw). Compared with lake sediments in other domestic and oversea areas, the PAHs content in the middle reaches of the Yangtze River was higher than that of Lake Fuxian, Lake Qinghai and Lake Bosten in remote areas of China, but lower than that of Lake Chaohu and Lake Taihu in the lower reaches of the Yangtze River and the economically and industrially developed areas in the United States. According to the results of single PAH clustering analysis, 12 lakes can be divided into three types. Type 1 was mainly occupied by low ring of 64.04%±7.02%. Type 2 was mainly equivalent occupied by low ring and middle ring, which accounting for 50.76%±5.17% and 49.24%±5.17%, respectively. Type 3 was homogeneous occupied by different rings, which accounting for 35.35%±3.56%, 26.17%±0.45%, and 38.48%±3.84% from low ring to high ring. According to the distribution characteristics of PAHs in this area and the results of isomer ratio method and principal component analysis, the main source of PAHs in type 1 lake sediments is the mixed source of biomass combustion and petroleum, such as coal and wood. The main sources of PAHs in lake sediments of type 2 and type 3 are low-temperature combustion of biomass such as coal and wood, exhaust emissions from motor vehicles burning gasoline and diesel, and high-temperature combustion of fossil fuels such as industrial coking. The significant correlation between PAHs and total organic carbon (TOC) in the sediments indicates that, the content of TOC in the sediments is the key factor affecting the distribution of PAHs in the lake sediments in the middle reaches of the Yangtze River. The risk assessment results of the risk quotient method, that the RQ_NCs of PAHs in lake sediments in the middle reaches of the Yangtze River are all less than 800, and the RQ_MPCs are greater than 1, indicating that the PAHs in the lake sediments along the middle reaches of the Yangtze River presents a moderate risk level.

Polycyclic aromatic hydrocarbons (PAHs) are organic chemicals that consist of carcinogenic and mutagenic properties, which are considered as high-priority persistent organic pollutants (POPs). Their source is due to an incomplete burning of fossil fuels and organic materials. In the present study, the distribution and concentrations of 16 priority PAHs in sediments of the Tampamachoco lagoon and Tuxpan River estuary at the Gulf of Mexico were analyzed. The surface sediment samples were collected during the dry (March–June) and rainy (August–November) seasons. PAHs were analyzed by means of a gas capillary chromatography-FID. In dry season, the average concentration of PAHs in sediments was 860 ± 390 ng/g, and in rainy season, it was 1140 ± 450 ng/g. During both seasons, the total concentration of chrysene was high and a domain of the compounds with 4 benzene rings was observed. The source of PAHs was investigated in 78.6% of the lagoon sites. 45.5% revealed indicators of a mixed origin between pyrolytic and petrogenic sources, and 36.4% was petrogenic, and the remaining 18.2% was pyrolytic PAHs.

This study provides data on the characteristic levels, spatial patterns, sources, and risk of n-alkanes (AHs) [octane, n-C8, totetracontane, n-C40] and polycyclic aromatic hydrocarbons (PAHs) in surficial sediments from the Escravos River Basin (ERB), Nigeria. The n-alkane and PAH concentrations in sediments were quantified by chromatographic methods. The concentrations of AHs and PAHs in the ERB sediments varied from 95 to 3430µgg-1 and from 0.75 to 213µgg-1, respectively. Both the concentrations of AHs and PAHs in ERB sediments exceeded their respective guideline values. The carbon preference index and other AH markers provide evidence that the AHs in the ERB sediments originated from petroleum sources. Ecological risk assessment indicated that the ecological risk relating to an organism's contact with PAHs in the ERB sediments was high. The possible carcinogenic risk arising from human exposure with PAHs in surface sediments through accidental oral ingestion and skin contact exceeded the safe level of 10-6, indicating a considerable probable cancer risk for fishermen and other inhabitants of the ERB. PAH isomer ratios and multivariate statistics suggested that the PAHs in sediments from the ERB originated from gas flaring inputs, discharges from oil drilling platforms, diesel engines, ships, and speed boats, and combustion of wood and other biomass.

Bioturbation by the burrowing crab Helice tiensinensis was investigated to determine its impact on polycyclic aromatic hydrocarbon (PAH)-contaminated estuarine sediments. The concentrations of 16 U.S. Environmental Protection Agency (U.S. EPA) priority PAHs in sediment and pore water from a crab bed (including surface and burrow samples) and a control area, as well as in crabs, were measured. The total concentration of the 16 U.S. EPA priority PAHs in surface sediment of the crab bed (average 2,772 ng/g dry weight) was significantly higher than in the control area (1,173 ng/g dry weight). In the crab bed, the total concentration of PAHs in burrow sediment (1,239 ng/g dry weight) was lower than in surface sediment, and a similar trend was found for most of the individual PAHs, except for indeno[1,2,3-cd]pyrene, and benzo[ghi]perylene. The enhanced PAH desorption in the burrow, which could be attributed to the increase in dissolved organic matter in pore water as well as the mechanical mixing by the crab, is expected to increase PAH flux to the sea. In addition to increased flushing to the sea, incorporation of PAHs in crab biomass and metabolism of PAHs by the crab, stimulated microbial degradation, was proposed as an ignorable factor that lowered the PAH concentration in burrow sediment, because crab bioturbation increases the abundance and activity of microorganisms through several means. Log K(OW) and log K(OC) correlated well for individual PAHs in sediment in the control area, although this correlation was poor for sediments in the crab bed. The log biota-sediment accumulation factor (BSAF) of PAHs exhibited a negative relationship with log K(OW), suggesting that the bioaccumulation of sorbed PAHs was controlled primarily by their bioavailability.

The distribution of Polycyclic Aromatic Hydrocarbons (PAHs) was investigated in surface runoff and sediments of Lagos, Osogbo and Ile-Ife Western areas of Nigeria. Method for the analysis of PAHs was based on Liquid-Liquid extraction of the runoff and a soxhlet extraction of the sediments followed by a clean up adsorption procedure. The PAHs were separated and quantified by Gas Chromatography-Mass spectrometry (GC-MS) technique. A blank experiment was done using triply distilled water and following the same procedure for the samples to establish blank levels. In both street runoff and sediments 13 PAHs were identified and quantified. At Osogbo and Ile-Ife areas, the mean levels of PAHs in surface runoff ranged between 0.10–15.81 mg L-1 while in the Lagos area the levels were between 0.1–73.72 mg L-1. Generally, the PAH levels in surface runoff of Lagos constitute 53.03 mg L-1 average ∑ PAH detected in the study area compared to 31.96 mg L-1 average ∑ PAH contribution made by samples from Osogbo and Ile-Ife. The levels of PAHs in sediments are relatively higher compared to those of the street runoff in the study area. PAHs in sediment of Lagos contribute an average of 228.57 mg kg-1 ∑ PAH to the total sediment PAH burden compared to Osogbo and Ile-Ife areas that contribute only 91.13 mg kg-1 average ∑ PAH to the total PAH burden of the study area. The relatively higher average ∑ PAHs reported for Lagos area compared with those of Osogbo and Ile-Ife, is consistent with higher industrial activities and traffic density of the former (1000–10000 vehicles/hr) than the later (450–1500 vehicles/hr).

The source of polycyclic aromatic hydrocarbons (PAHs) in sediment from the Songhua River, which is located in a cold region, is not fully understood and has not been sufficiently assessed under bad conditions. The 16 priority PAHs in sediment from the Songhua River were analyzed and their potential source was diagnosed in the present study. The total concentrations of the PAHs ranged from 34 to 4456 ng/g dw, and fluoranthene (FlA), pyrene (Pyr), phenanthrene (Phe), and chrysene (Chr) were the dominant PAHs. The coefficient of divergence (CD) was used to compare the similarities of these PAHs in sediments from different sampling sites, and the results showed that their compositions were quite different. Importantly, a positive correlation was found between coal consumption and the total concentrations of PAHs in sediment (R = 0.999, p < 0.001), but no significant correlation was found between the amounts of crude oil/natural gas consumption and the total concentrations of PAHs. Emissions from coal consumption might be the main source of PAHs in sediment from the Songhua River because coal is the main fuel used for heat in this northern, cold region in China.

Historical trends and spatial distributions of polycyclic aromatic hydrocarbons in the upper reach of the Huai River, China: Evidence from the sedimentary record

The spatial distribution, sources, and potential risk of polycyclic aromatic hydrocarbons (PAHs) were systematically investigated in Shanghai port, one of the most important hubs in international trade. The 16 priority PAHs in surface water and sediment were determined. Total concentrations of 16 PAHs (Σ16PAHs) ranged from 140.6 to 647.4ng/L in surface water and from 12.7 to 573.2ng/g (dry weight, dw) in sediment, respectively. The 2-ring and 3-ring PAHs with low molecular weight were main components in water, while the 3-ring and 4-ring PAHs were abundant in sediment. Flu was the main component of the Σ16PAHs in water and sediment. According to the source apportionment, the PAHs in water mostly originated from combustion of fossil fuels and petroleum and petroleum combustion were the main contributors to the PAHs in sediment. The results obtained from potential risk assessment indicate that the PAHs in surface water present a moderate ecological risk, whereas the PAHs in sediment show low ecological risk indicating a less possibility of toxic pollution.

Removal of Pb(II) ions from aqueous solution by manganese oxide coated rice straw biochar A low-cost and highly effective sorbent

Soil organic carbon content affects the stability of biochar in paddy soil

Concentrations, distribution and risk of polycyclic aromatic hydrocarbons in sediments from seven major river basins in China over the past 20 years