Sources and preservation of organic matter in soils of the wetlands in the Liaohe (Liao River) Delta, North China

Abstract

a b s t r a c tTotal organic carbon, total nitrogen, d 13 C org , d 15 N, and aliphatic and polyaromatic hydrocarbons of fiftyfive soil samples collected from the coastal wetlands of the Liaohe Delta were measured, in order to determine the sources and possible preservation of organic matter (OM). The d 15 N and d 13 C org values in the samples ranged from 3.0‰ to 9.4‰ and from À30.4‰ to À20.3‰, respectively, implying that the OM in the soils is predominantly derived from C 3 plant. The long-chain n-alkanes had a strong odd-over-even carbon number predominance, suggesting a significant contribution from waxes of higher plants. The ubiquitous presence of unresolved complex mixture, alkylated polycylic aromatic hydrocarbons and typical biomarkers of petroleum hydrocarbons (pristane, phytane, hopanes and steranes) indicates that there is a contribution of petroleum hydrocarbons to the organic carbon pool in the wetland soils. P. australis-vegetated wetlands have strong potentials for the preservation of organic carbon in the wetlands.

Petroleum hydrocarbons in a water-sediment system from Yellow River estuary and adjacent coastal area, China: Distribution pattern, risk assessment and sources

“…In this study, only AH analysis in sediments was performed. The levels of AH concentration (∑n-C 12-34 ) of the studied sediments was 321.14 ± 122.86 ng/g dry weight, which is relatively lower or moderate compared to those of global locations reported to be chronically contaminated by oil, such as 160-1880 ng/g in the Yangtze River Estuary (Bouloubassi et al, 2001), 500-8120 ng/g in Jiaozhou Bay (Wang et al, 2006), 1440-70,410 ng/g in highly contaminated sediments from Liaohe Delta (Lin et al, 2013), 800-2600 ng/g in coastal Caspian Sea, Iran (Tolosa et al, 2004) and 1388-5896 ng/g in the Andaman Backarc Basin, Indian Ocean (Venkatesan et al, 2003).…”

Seasonal Variations of CDOM Optical Properties in Rivers Across the Liaohe Delta

“…But in May, many uncertain factors, such as snowmelt discharge, soil thawing, increased flow and recovery of phytoplankton growth, negatively influenced the relationship between CDOM and DOC. Urban pollutants or crude oil of the Liaohe oilfield flushed into nearby rivers might have also further complicated this situation (Ji et al 2002;Lin et al 2013).…”

“…Furthermore, due to excessive population growth, expansion of the cities and industrial and agricultural developments, the rivers in the Liaohe River Basin are greatly affected by localized pollution (Li et al 1999;Wen et al 2011;Hu et al 2012). Each year, large amounts of heavy oil-polluted effluents from oil extraction in the Liaohe oilfield, the third largest in China, are discharged into the rivers across the delta (Ji et al 2002;Lin et al 2013) which may affect the CDOM sources and compositions.…”

Polychlorinated biphenyls and organochlorine pesticides in surface sediments from the sand flats of Shuangtaizi Estuary, China: levels, distribution, and possible sources

“…These rivers continuously receive various contaminants such as PCBs and OCPs from a large number of domestic sewage inputs and industrial activities. Meanwhile, the Shuangtaizi Estuary provides excellent conditions for commercial rice planting (Lin et al 2013) as well as crab and clam cultures (Zhang et al 2013). However, the application of excessive pesticides in agriculture and aquaculture would have resulted in increasing residues of OCPs and PCBs in both kind and level during the past decades, which entered into rivers and at last accumulated in the estuarine sediments.…”