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SUMMARY Using chloroplasts isolated from the senescent primary leaves of barley seedlings, the linolenic acid‐dependent degradation of chlorophyll was studied in incubated thylakoids. This reaction, measured by the decrease of absorbance at 672 nm, was produced by free radicals from linolenic acid oxidation and, thus, was inhibited by n‐propylgallate and α‐tocopherol, general scavengers of free radicals. Although the beginning of the reaction was delayed by heating the thylakoids, this process must be of a non‐enzymatic nature since it is not impeded by thermal treatment and it proved impossible to isolate a crude extract from thylakoids with a degradative enzymatic activity using a mixture of solubilized chlorophylls as substrate. The enzyme chlorophyll oxidase, described by others for thylakoids, was not found. In addition, the reaction of chlorophyll with the peroxidation products of linolenic acid seems to occur with the cooxidation of one or more carotenoids. Due to the high content of esterified linolenic acid in the thylakoid galactolipids, the degradation of chlorophyll studied here may have a physiological significance.

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The increasing shortage of conventional water for crop irrigation in arid and semiarid regions is encouraging the use of non-conventional resources. Nevertheless, concern about the presence and possible negative effects of Contaminants of Emerging Concern (CECs) in reclaimed waters can put in danger the possible use of this water source. To clarify the guarantees that reclaimed water offers, a mesocosm study was carried out. Pots with a lettuce were watered with three different types of water (distilled, reclaimed and spiked with CECs). The results showed a low concentration of these compounds in leachates and in plant tissues when reclaimed water was used. However, their concentrations were high when pots were watered with spiked water, mainly for carbamazepine (CBZ), reaching a maximum of 2982 ng L− 1 in leachates and 45.2 ng g− 1 in plant roots. In lettuces watered with spiked water, CBZ was found in edible part at very low concentrations that did not imply any human risk. Finally, an acute toxicity test was performed with the leachates, which resulted only slightly toxic for spiked water. This work confirms that, with the current technical improvements of active sludge water treatment, reclaimed water can be used for irrigation without risk for CECs contamination.